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Spencer Tracy

Spencer Bonaventure Tracy (April 5, 1900 – June 10, 1967) was an American actor. He was known for his natural performing style and versatility. One of the major stars of Hollywood's Golden Age, Tracy was the first actor to win two consecutive Academy Awards for Best Actor, from nine nominations. During his career, he appeared in 75 films and developed a reputation among his peers as one of the screen's greatest actors. In 1999, the American Film Institute ranked Tracy as the 9th greatest male star of Classic Hollywood Cinema.

Tracy first discovered his talent for acting while attending Ripon College, and he later received a scholarship for the American Academy of Dramatic Arts. He spent seven years in the theatre, working in a succession of stock companies and intermittently on Broadway. His breakthrough came in 1930, when his lead performance in The Last Mile caught the attention of Hollywood. After a successful film debut in John Ford's Up the River (in which he starred with Humphrey Bogart), he was signed to a contract with Fox Film Corporation. Tracy's five years with Fox featured one acting tour de force after another that were usually ignored at the box office, and he remained largely unknown to movie audiences after 25 films, nearly all of them starring him as the leading man. None of them were hits, although his performance in The Power and the Glory (1933) was highly praised at the time.

In 1935, he joined Metro-Goldwyn-Mayer (MGM), at the time Hollywood's most prestigious studio. His career flourished from his fifth MGM film Fury (1936) onwards, and in 1937 and 1938 he won consecutive Oscars for Captains Courageous and Boys Town. He teamed with Clark Gable, the studio's most prominent leading man for three major box office successes, so that by the early 1940s Tracy was one of MGM's top stars. In 1942, he appeared with Katharine Hepburn in Woman of the Year, beginning a professional and personal partnership, which led to nine films over 25 years. In 1955, Tracy won the Cannes Film Festival Award for Best Actor for his performance in the film Bad Day at Black Rock.

Tracy left MGM in 1955, and continued to work regularly as a freelance star, despite several health issues and an increasing weariness and irritability as he aged. His personal life was troubled, with a lifelong struggle against severe alcoholism and guilt over his son's deafness. Tracy and his wife Louise became estranged in the 1930s, but the couple never divorced; his 25-year long relationship with Katharine Hepburn was an open secret. Towards the end of his life, Tracy worked almost exclusively for director Stanley Kramer. It was for Kramer that he made his last film, Guess Who's Coming to Dinner (1967), completed just 17 days before he died.

Early life

Spencer Bonaventure Tracy was born in Milwaukee on April 5, 1900, the second son of Caroline (Brown; 1874–1942) and truck salesman John Edward Tracy (1873–1928). His mother was from a wealthy Presbyterian Midwestern family, while his father was of Irish Catholic descent. He had a brother Carroll, who was four years older.

Tracy was a difficult and hyperactive child  with poor school attendance. Raised Catholic, he was placed in the care of Dominican Order nuns at the age of nine in an attempt to transform his behavior. Later in life, he remarked that he "never would have gone back to school if there had been any other way of learning to read the subtitles in the movies". He became fascinated with movies, watching the same ones repeatedly and later re-enacting scenes to his friends and neighbors. He attended several Jesuit academies in his teenage years, which he claimed took the "badness" out of him and helped him improve his grades.

At Marquette Academy, he began attending plays with lifelong friend and fellow actor Pat O'Brien, awakening his interest in the theatre. With little care for their studies and "itching for a chance to go and see some excitement", Tracy and O'Brien enlisted in the Navy together when Tracy turned 18. They were sent to the Naval Training Station in northern Illinois, where they were still students when World War I came to an end. Tracy achieved the rank of seaman second class, but never went to sea and was discharged in February 1919. His father's desire to see one of his sons gain a college degree drove Tracy back to high school to finish his diploma. Studies at two more institutions, plus the additional allowance of "war credits", won Tracy a place at Ripon College. He entered in February 1921, declaring his intention to major in medicine.

Tracy was a popular student at Ripon, where he served as president of his hall and was involved in a number of college activities. He made his stage debut in June 1921, playing the male lead in The Truth. He was very well received in the role and quickly developed a passion for the stage; he was reportedly "obsessive about acting to the degree that he talked about little else". He and some friends formed an acting company called the Campus Players, which they took on tour. As a member of the college debate team, Tracy excelled in arguing and public speaking. It was during a tour with the debate team that he auditioned for the American Academy of Dramatic Arts (AADA) in New York City. He was offered a scholarship to attend the school after performing a scene from one of his earlier roles.

Tracy left Ripon and began classes at AADA in April 1922. O'Brien was also enrolled there and the two shared a small studio apartment. Money was scarce, and the two often lived on meals of rice and pretzels and shared one decent suit between them. Tracy was deemed fit to progress to the senior class, allowing him to join the academy's stock company. He made his New York debut in a play called The Wedding Guests, which opened in October 1922. He made his debut Broadway appearance three months later, playing a wordless robot in R.U.R. He graduated from AADA in March 1923.

Stock theatre and Broadway (1923–1930)
Immediately following graduation, Tracy joined a new stock company based in White Plains, New York, where he was given peripheral roles. Unhappy there, he moved to a company in Cincinnati, but failed to make an impact. In November 1923, he landed a small part on Broadway in the comedy A Royal Fandango, starring Ethel Barrymore. Reviews for the show were poor and it closed after 25 performances; Tracy later said of the failure, "My ego took an awful beating." When he took a position with a struggling company in New Jersey, Tracy was living on an allowance of 35 cents a day. In January 1924, he played his first leading role with a company in Winnipeg, but the organization soon closed.

Tracy finally achieved some success by joining forces with the notable stock manager William H. Wright in the spring of 1924. A stage partnership was formed with the young actress Selena Royle, who had already made her name on Broadway. It proved a popular draw and their productions were favorably received. One of these performances brought Tracy to the attention of a Broadway producer, who offered him the lead in a new play. The Sheepman previewed in October 1925, but it received poor reviews and closed after its trial run in Connecticut. Dejected, Tracy was forced back to Wright and the stock circuit.

In the fall of 1926, Tracy was offered his third shot at Broadway: a role in a new George M. Cohan play called Yellow. Tracy swore that if the play failed to be a hit he would leave stock and work in a "regular" business instead. Tracy was nervous about working with Cohan, one of the most important figures in American theatre, but during rehearsals Cohan announced, "Tracy, you're the best goddamned actor I've ever seen!" Yellow opened on September 21; reviews were mixed but it ran for 135 performances. It was the beginning of an important collaboration for Tracy: "I'd have quit the stage completely," he later commented, "if it hadn't been for George M. Cohan." Cohan wrote a part specifically for Tracy in his next play, The Baby Cyclone. It opened on Broadway in September 1927 and was a hit.

Tracy followed this success with another Cohan play, Whispering Friends, and in 1929 took over from Clark Gable in Conflict, a Broadway drama. Other roles followed, but it was the lead in Dread, written by Pulitzer Prize-winning dramatist Owen Davis that gave Tracy high hopes for success. The story of a man's descent into madness, Dread previewed in Brooklyn to an excellent reception, but on the next day—October 29—the New York stock market crashed. Unable to obtain funding, Dread did not open on Broadway. Following this disappointment, Tracy again considered leaving the theatre and returning to Milwaukee for a more stable life.

In January 1930, Tracy was approached about a new play called The Last Mile. Looking to cast the lead role of a murderer on death row, producer Herman Shumlin met with Tracy, and later recounted: "beneath the surface, here was a man of passion, violence, sensitivity and desperation: no ordinary man, and just the man for the part." The Last Mile opened on Broadway in February, where Tracy's performance was met by a standing ovation that lasted 14 curtain calls. The Commonweal described him as "one of our best and most versatile young actors". The play was a hit with critics, and ran for 289 performances.

Fox (1930–1935)

In 1930, Broadway was being scouted to find actors to work in the new medium of sound films. Tracy was cast in two Vitaphone shorts (Taxi Talks and The Hard Guy), but he had not considered becoming a film actor: "I had no ambition in that direction and I was perfectly happy on the stage", he later explained in an interview. One person who saw Tracy in The Last Mile was director John Ford.

Ford wanted Tracy for the lead role in his next picture, a prison movie. Production company Fox Film Corporation was unsure about Tracy, saying that he did not photograph well, but Ford convinced them that he was right for the role. Up the River (1930) marked the film debut of both Tracy and Humphrey Bogart. After seeing the rushes, Fox immediately offered Tracy a long-term contract. Knowing that he needed the money for his family, with his young son deaf and recovering from polio, Tracy signed with Fox and moved to California. He appeared on the stage only once more in his life.

Winfield Sheehan, the head of Fox, committed to making Tracy a bankable commodity. The studio promoted the actor, releasing ads for his second film Quick Millions (1931) with the headline "A New Star Shines". Three films were made in quick succession, all of which were unsuccessful at the box office. Tracy found himself typecast in comedies, usually playing a crook or a con man. The mold was broken with his seventh picture, Disorderly Conduct (1932), and it was the first of his films since Up the River to return a profit.

In mid-1932, after nine pictures, Tracy remained virtually unknown to the public. He considered leaving Fox once his contract was up for renewal, but a raise in his weekly salary to $1,500 convinced him to stay. He continued to appear in unpopular films, with Me and My Gal (1932) setting an all-time low attendance record for the Roxy Theatre in New York City. He was loaned to Warner Bros. for 20,000 Years in Sing Sing (1932), a prison drama co-starring Bette Davis. Tracy was hopeful that it would be his break-out role, but despite good reviews, this failed to materialize.

Critics began to notice Tracy with The Power and the Glory (1933). The story of a man's rise to prosperity had a screenplay by Preston Sturges and Tracy's performance as railroad tycoon Tom Garner received uniformly strong reviews. William Wilkerson of The Hollywood Reporter wrote: "This sterling performer has finally been given an opportunity to show an ability that has been boxed in by gangster roles ... [the film] has introduced Mr. Tracy as one of the screen's best performers". Mordaunt Hall of The New York Times stated: "No more convincing performance has been given on the screen than Spencer Tracy's impersonation of Tom Garner." Shanghai Madness (1933), meanwhile, revealed Tracy to have a previously unseen sex appeal and served to advance his standing. Despite this attention, Tracy's next two movies went largely unnoticed. Man's Castle (1933) with Loretta Young was anticipated to be a hit, but made only a small profit. The Show-Off (1934), for which he was lent to Metro-Goldwyn-Mayer, proved popular, but his subsequent outings continued to be unsuccessful.

Tracy drank heavily during his years with Fox and gained a reputation as an alcoholic. He failed to report for filming on Marie Galante in June 1934, and was found in his hotel room, virtually unconscious after a two-week binge. Tracy was removed from the Fox payroll while he recovered in a hospital, and then sued for $125,000 for delaying the production. He completed only two more pictures with the studio.

The details on how Tracy's relationship with Fox ended are unclear: later in life Tracy maintained that he was fired for his drunken behavior, but the Fox records do not support such an account. He was still under contract with the studio when MGM expressed their interest in the actor. They were in need of a new male star, and contacted Tracy on April 2, 1935, offering him a seven-year deal. That afternoon, the contract between Tracy and Fox was terminated "by mutual consent". Tracy made a total of 25 pictures in the five years he was with Fox Film Corporation, most of which lost money at the box office.

Growing reputation

In the 1930s, Metro-Goldwyn-Mayer was the most respected movie production studio in Hollywood. When Tracy arrived there, he was all but unknown. Biographer James Curtis writes: "Tracy was scarcely a blip on the box office barometer in 1935, a critics' darling and little more". He was, however, well known for being a troublemaker. Producer Irving Thalberg was nevertheless enthusiastic about working with the actor, telling journalist Louella Parsons: "Spencer Tracy will become one of MGM's most valuable stars."

Curtis notes that the studio managed Tracy with care, a welcome change from the ineptitude and apathy he had known while at Fox, which was like "a shot of adrenaline" for the actor. His first film under the new contract was the quickly produced The Murder Man (1935), which included the feature film debut of James Stewart. Thalberg then began a strategy of pairing Tracy with the studio's top actresses: Whipsaw (1935) co-starred Myrna Loy and was a commercial success. Riffraff (1936) put Tracy opposite Jean Harlow. Both films were, however, designed and promoted to showcase their leading ladies, thus continuing Tracy's reputation as a secondary star.

Fury (1936) was the first film to prove that Tracy could make a success on his own merit. Directed by Fritz Lang, Tracy played an innocent man who swears revenge after narrowly escaping death by a lynch mob. The film and performance received excellent reviews. It made a profit of $1.3 million worldwide. Curtis writes: "audiences who, just a year earlier, had no clear handle on him, were suddenly turning out to see him. It was a transition that was nothing short of miraculous ... [and showed] a willingness on the part of the public to embrace a leading man who was not textbook handsome nor bigger than life."

Fury was followed one month later with the release of the big-budget disaster movie San Francisco (1936). Tracy played a supporting role alongside Clark Gable in the film, allowing audiences to see him with the top male star in Hollywood. Taking on the role of a priest, Tracy reportedly felt a heavy responsibility in representing the church. Despite having only 17 minutes of screen time, Tracy was highly praised for his performance and received an Oscar nomination for Best Actor. San Francisco became the highest-grossing picture of 1936. Donald Deschner, in his book on Tracy, credits Fury and San Francisco as the "two films that changed his career and gave him the status of a major star".

By this point, Tracy entered a period of self-imposed sobriety and MGM expressed pleasure with Tracy's professionalism. His public reputation continued to grow with Libeled Lady (also 1936), a screwball comedy that cast him with William Powell, Loy and Harlow. According to Curtis, "Powell, Harlow and Loy were among the biggest draws in the industry, and equal billing in such a powerhouse company could only serve to advance Tracy's standing". Libeled Lady was his third hit picture in the space of six months.

Oscar wins
Tracy appeared in four films released in 1937. They Gave Him a Gun, a crime-drama, went largely unnoticed, but Captains Courageous was one of the major film events of the year. Tracy played a Portuguese fisherman in the adventure movie, based on the novel by Rudyard Kipling. He was uncomfortable feigning a foreign accent, and resented having his hair curled, but the role was a hit with audiences and Tracy won the Academy Award for Best Actor. Captains Courageous was followed by Big City with Luise Rainer and Mannequin with Joan Crawford, the latter of which performed well at the box office. With two years of hit movies and industry recognition, Tracy became a star in the United States. A 1937 poll of 20 million people to find the "King and Queen of Hollywood" ranked Tracy sixth among males.

Tracy was reunited with Clark Gable and Myrna Loy for Test Pilot (1938). The film was another enormous commercial and critical success, permanently cementing the notion of Gable and Tracy as a team in the public imagination.

Based on the positive response he had received in San Francisco, MGM again cast Tracy as a priest in Boys Town (also 1938). Portraying Edward J. Flanagan, a Catholic priest and founder of Boys Town in Nebraska, was a role Tracy took seriously: "I'm so anxious to do a good job as Father Flanagan that it worries me, keeps me awake at night." Tracy received strong reviews for his performance, and the movie grossed $4 million worldwide. For the second year running, Tracy received an Academy Award for Best Actor. He was humble about the recognition, saying in his acceptance speech: "I honestly do not feel that I can accept this award ... I can accept it only as it was meant to be for a great man—Father Flanagan". Although he did keep his Oscar, a second statuette was struck and immediately sent to Flanagan. Tracy was listed as the fifth biggest box office star of 1938.

Tracy was absent from screens for almost a year before returning to Fox on loan and appearing as Henry M. Stanley in Stanley and Livingstone (1939) with Nancy Kelly. Curtis maintains that Tracy's non-visibility did little to affect his standing with the public or exhibitors. In October 1939, a Fortune magazine survey of the nation's favorite movie actors listed Tracy in first place.

Established star
MGM capitalized on Tracy's popularity, casting him in four movies for 1940. I Take This Woman with Hedy Lamarr was a critical and commercial failure, but the historical drama Northwest Passage—Tracy's first film in Technicolor—proved popular. He then portrayed Thomas Edison in Edison, the Man. Howard Barnes of the New York Herald Tribune was not charmed by the story, but wrote that Tracy, "by sheer persuasion of his acting", made the film worthy. Boom Town was the third and final Gable-Tracy picture, also starring Claudette Colbert and Hedy Lamarr, making it one of the most anticipated films of the year. The film opened to the biggest crowd since Gone With the Wind.

Tracy signed a new contract with MGM in April 1941, which paid $5,000 a week and limited him to three pictures a year (Tracy had previously expressed a need to reduce his workload). The contract also stated for the first time that his billing was to be "that of a star". Contrary to popular belief, the contract did not include a clause that he receive top billing, but from this point onward, every film Tracy appeared in featured his name first.

Tracy returned to the role of Father Flanagan for the sequel Men of Boys Town (1941). It was followed by Tracy's only venture into the horror genre, an adaptation of Dr. Jekyll and Mr. Hyde (also 1941), co-starring Ingrid Bergman and Lana Turner. Tracy was unhappy with the film, disliking the heavy make-up he needed to portray Hyde. Critical response to the film was mixed and brought Tracy the only negative reviews of his career. Theodore Strauss of The New York Times wrote that "Mr. Tracy's portrait of Hyde is not so much evil incarnate as it is the ham rampant." The film was financially successful, however, taking in more than $2 million at the box office. Tracy was set to star in a film version of The Yearling for 1942, but several on-set difficulties and bad weather on location forced MGM to shelve the production. With the end of that project, he became available for the new Katharine Hepburn film, Woman of the Year (1942). Hepburn greatly admired Tracy, calling him "the best movie actor there was". She had wanted him for her comeback vehicle, The Philadelphia Story (1940). Hepburn was delighted that Tracy was available for Woman of the Year, saying "I was just damned grateful he was willing to work with me." The romantic comedy performed well at the box office and received strong reviews. William Boehnel wrote in the New York World-Telegram, "To begin with, it has Katharine Hepburn and Spencer Tracy in the leading roles. This in itself would be enough to make any film memorable. But when you get Tracy and Hepburn turning in brilliant performances to boot, you've got something to cheer about."

Woman of the Year was followed by an adaptation of John Steinbeck's Tortilla Flat (also 1942) which met with a tepid response. MGM did not hesitate to repeat the teaming of Tracy and Hepburn and cast them in the dark mystery Keeper of the Flame (1943). Despite a weak critical reception the film out-grossed Woman of the Year confirming the strength of their partnership.

Tracy's next three appearances were all war-based. A Guy Named Joe (1943) with Irene Dunne surpassed San Francisco to become his highest-grossing film to date. The Seventh Cross (1944), a suspense film about an escape from a Nazi concentration camp, met with critical acclaim. It was followed by the aviation film Thirty Seconds Over Tokyo (1944). On the strength of these three releases, the annual Quigley poll revealed Tracy was MGM's biggest money-making star of 1944, His only film the following year was his third with Hepburn, Without Love (1945), a light romantic comedy that performed well at the box office despite muted enthusiasm from critics.

Stage and screen

In 1945, Tracy returned to the stage for the first time in 15 years. He had been through a dark patch personally—culminating with a hospital stay—and Hepburn felt that a play would help restore his focus. Tracy told a journalist in April, "I'm coming back to Broadway to see if I can still act." The play was The Rugged Path by Robert E. Sherwood. It first previewed in Providence on September 28, to a sold-out crowd and tepid response. It was a difficult production; director Garson Kanin later wrote: "In the ten days prior to the New York opening all the important relationships had deteriorated. Spencer was tense and unbending, could not, or would not, take direction". Tracy considered leaving the show before it even opened on Broadway, and lasted there just six weeks before announcing his intention to close the show. It closed on January 19, 1946, after 81 performances. Tracy later explained to a friend: "I couldn't say those goddamn lines over and over and over again every night ... At least every day is a new day for me in films ... But this thing—every day, every day, over and over again."

Tracy was absent from screens in 1946, the first year since his motion picture debut that there was no Spencer Tracy release. His next film was The Sea of Grass (1947), a melodrama set in the American Old West with Hepburn. Similar to Keeper of the Flame and Without Love, a lukewarm response from critics did not stop it from being a financial success both at home and abroad. He followed it later that year with Cass Timberlane, in which he played a judge. It was a commercial success, but Curtis notes that co-star Lana Turner overshadowed Tracy in most of the reviews.

A fifth film with Hepburn, Frank Capra's political drama State of the Union, was released in 1948. Tracy played a presidential candidate in the movie, which was warmly received. He then appeared in Edward, My Son (1949) with Deborah Kerr. Tracy disliked the role, and told director George Cukor, "It's rather disconcerting to me to find how easily I play a heel." Upon its release, The New Yorker wrote of the "hopeless miscasting of Mr. Tracy". The film became Tracy's biggest money-loser at MGM.

Tracy finished off the 1940s with Malaya (1949), an adventure film with James Stewart, and Adam's Rib (also 1949), a comedy with Tracy and Hepburn playing married lawyers who oppose each other in court. Tracy and Hepburn's friends, Garson Kanin and Ruth Gordon, wrote the parts specifically for the two leads. The film received strong reviews and became the highest-grossing Tracy-Hepburn picture to date. Film critic Bosley Crowther wrote, "Mr. Tracy and Miss Hepburn are the stellar performers in this show and their perfect compatibility in comic capers is delightful to see."

Final MGM years

Tracy received his first Academy Award nomination in 12 years for playing the role of Stanley Banks in Father of the Bride (1950). In the comedy film, Banks attempts to handle preparations for the upcoming wedding of his daughter (Elizabeth Taylor). "It's the second strong comedy in a row for Spencer Tracy, doing the title role, and he socks it", Variety commented. The film was the biggest commercial success of Tracy's career to date, earning $6 million worldwide. MGM wanted a sequel, and while Tracy was unsure, he accepted. Father's Little Dividend (1951) was released ten months later and performed well at the box office. On the strength of the two movies, Tracy polled as one of the nation's top stars once more.

Tracy portrayed a lawyer in The People Against O'Hara (1951) and re-teamed with Hepburn for the sports comedy Pat and Mike (1952), the second feature written expressly for them by Kanin and Gordon. Pat and Mike became one of the duo's most popular and critically acclaimed films. Tracy followed it with Plymouth Adventure (also 1952), an historical drama set aboard the Mayflower, co-starring Gene Tierney. It met with poor critical and box office response and posted a loss of $1.8 million for MGM. Tracy returned to the role of a concerned father in The Actress (1953). Producer Lawrence Weingarten recalled: "That film ... got more [acclaim] from the critics than any film I ever made in all the years, and we didn't make enough to pay for the ushers in the theatre." For his performance in The Actress, Tracy won a Golden Globe Award and received a nomination for the British Academy Film Award.

MGM lent Tracy to Fox for the well-received Western film Broken Lance, his only film released in 1954. In 1955, Tracy turned down William Wyler's The Desperate Hours because he refused to take second-billing to Humphrey Bogart. Instead, Tracy appeared as a one-armed protagonist who faces the hostility of a small desert town in Bad Day at Black Rock (1955), a film directed by John Sturges. For his work, Tracy received a fifth Oscar nomination and was awarded the Best Actor prize at the Cannes Film Festival.

Tracy had personally been unhappy with the picture and threatened to leave during production. This behavior became a regular occurrence for Tracy, who was increasingly lethargic and cynical. He began production on Tribute to a Bad Man in the summer of 1955, but pulled out when he claimed that the shooting location in the Colorado mountains gave him altitude sickness. The problems caused by the picture fractured Tracy's relationship with MGM. In June 1955, he was one of the two remaining stars of the studio's peak years (the other being Robert Taylor), but with his contract up for renewal, Tracy opted to freelance for the first time in his movie career.

Independent player (1956–1967)
Tracy's first post-MGM appearance was in The Mountain (1956) with Robert Wagner, who played his much younger brother (Wagner had earlier played his son in Broken Lance). The location filming in the French Alps proved a difficult experience, and he threatened to leave the project. His performance earned a BAFTA nomination for Best Foreign Actor. Tracy and Hepburn then paired together for the eighth time in the office-based comedy Desk Set (1957). He again had to be convinced to stay with the film, one which met with a weak response.

Tracy appeared in The Old Man and the Sea (1958), a project that had been in development for five years. An adaptation of Ernest Hemingway's novella of the same title, Hemingway's agent, Leland Hayward, had previously written to the author: "Of all Hollywood people, the one that comes the closest to me in quality, in personality and voice, in personal dignity and ability, is Spencer Tracy." Tracy was delighted to be offered the role. He was told to lose some of his 210 pounds before filming began but failed to do so. Hemingway thus reported that Tracy was a "terrible liability to the picture", and had to be reassured that the star was being carefully photographed to disguise his weight problem. Appearing alone on screen for most of the film, Tracy considered The Old Man and the Sea the toughest part he ever played. In reviewing the performance, Jack Moffitt of The Hollywood Reporter said it was "so intimate and revealing of universal human experience that, to me, it almost transcended acting and became reality". Tracy received Oscar and BAFTA Award nominations for the work.

After abandoning two projects, including a proposed remake of The Blue Angel with Marilyn Monroe, Tracy's next feature was The Last Hurrah (1958). It reunited him with his debut director, John Ford, after 28 years and his childhood friend Pat O'Brien. Tracy took a year to commit to the project, in which he played an Irish-American mayor seeking re-election. The movie was favorably reviewed, but not commercially successful. At the end of 1958, the National Board of Review named Tracy the year's Best Actor. He nevertheless began to ponder retirement, with Curtis writing that he was "chronically tired, unhappy, ill, and uninterested in work".

Stanley Kramer partnership

Tracy did not appear on the screen again until the release of Inherit the Wind (1960), a film based on the 1925 Scopes "Monkey Trial" which debated the right to teach evolution in schools. Director Stanley Kramer sought Tracy for the role of lawyer Henry Drummond (based on Clarence Darrow), from the outset. Starring opposite Tracy was Fredric March, a pairing Variety described as "a stroke of casting genius ... Both men are spellbinders in the most laudatory sense of the word." The film garnered Tracy some of the strongest reviews of his career—he was nominated for an Academy Award, BAFTA Award and Golden Globe Award for the performance—but it was not a commercial hit.

In the volcano disaster movie The Devil at 4 O'Clock (1961), Tracy played a priest for the fourth time in his career. His co-star, Frank Sinatra, ceded top-billing to guarantee Tracy for the picture. Continuing his pattern of indecisiveness, Tracy briefly pulled out of the production before recommitting. Critics were unenthusiastic about the film, which was nevertheless Tracy's most successful box-office outing since Father of the Bride.

Inherit the Wind began an enduring collaboration between Stanley Kramer and Tracy—Kramer directed Tracy's three final films. Judgment at Nuremberg, released at the end of 1961, was their second feature together. The film depicts the "Judges' Trial", the trial of Nazi judges for their role in the Holocaust. Abby Mann wrote the role of Judge Haywood with Tracy in mind; Tracy called it the best script he had ever read. At the end of the film, Tracy delivered a 13-minute speech. He recorded it in one take and received a round of applause from the cast and crew. Upon seeing the film, Mann wrote to Tracy: "Every writer ought to have the experience of having Spencer Tracy do his lines. There is nothing in the world quite like it." The film met with positive reviews and a large audience; Tracy received an eighth Oscar nomination for his performance.

Tracy turned down roles in Long Day's Journey into Night (1962) and The Leopard (1963), and had to pull out of MGM's all-star How the West Was Won (1962) when it clashed with Judgment at Nuremberg. He was, however, able to record the film's narration track. Tracy was in very poor health by this time, and working became a challenge. In 1962, he took the role of Captain T. G. Culpeper in Kramer's comedy It's a Mad, Mad, Mad, Mad World (1963), a small but key part that he was able to complete in nine non-consecutive days. The film was released in November 1963. Tracy's name topped the list of performers, and the comedy became one of the highest-grossing American films of the year. As his health worsened, he had to cancel commitments to Cheyenne Autumn (1964) and The Cincinnati Kid (1965). Film offers continued to come, but Tracy did not work again until 1967 when he took the starring role in Kramer's Guess Who's Coming to Dinner (1967), Tracy's ninth and final film with Hepburn.

Guess Who's Coming to Dinner explored the topic of interracial marriage, with Tracy playing a liberal-minded newspaper publisher whose values are challenged when his daughter wishes to marry a black man, played by Sidney Poitier. Tracy appeared happy to be working again, but he told journalists visiting the set that the movie would be his last for he would permanently retire after filming due to his health problems. To commence filming, Tracy had to be insured for the high premium of $71,000 if he died during filming; Hepburn and Kramer both put their salaries in escrow until Tracy completed his scenes. In poor health, Tracy could work for only two or three hours each day. He completed his last scene on May 24, 1967. Tracy died 17 days later from a heart attack on June 10.

The film was released in December 1967, and although reviews were mixed, Curtis notes that "Tracy's performance was singled out for praise in nearly every instance." Brendan Gill of The New Yorker wrote that Tracy gave "a faultless and, under the circumstances, heartbreaking performance". The movie became Tracy's highest grossing picture. He received a posthumous nomination for Best Actor—his ninth—at the 40th Academy Awards, along with a Golden Globe Award nomination and a BAFTA win for Best Actor.

Marriage and family
Tracy met actress Louise Treadwell while they were both members of the Wood Players in White Plains, New York—the first stock company Tracy joined after graduating. The couple was engaged in May 1923, and married on September 10 of that year between the matinee and evening performances of his show.

Their son, John Ten Broeck Tracy, was born in June 1924. When John was 10 months old, Louise discovered that the boy was deaf. She resisted telling Tracy for three months. Tracy was devastated by the news and felt lifelong guilt over his son's deafness. He was convinced that John's hearing impairment was a punishment for his own sins. As a result, Tracy had trouble connecting with his son and distanced himself from his family. Joseph L. Mankiewicz, a friend of Tracy's, later theorized: "[Tracy] didn't leave Louise. He left the scene of his guilt." A second child, Louise "Susie" Treadwell Tracy, was born in July 1932. The children were raised in their mother's Episcopal faith.

Tracy left the family home in 1933, and he and Louise openly discussed the separation with the media, maintaining that they were still friends and had not taken divorce action. From September 1933 to June 1934, Tracy had a public affair with Loretta Young, his co-star in Man's Castle. He reconciled with Louise in 1935. There was never again an official separation between Tracy and his wife, but the marriage continued to be troubled. Tracy increasingly lived in hotels and by the 1940s, the two were effectively living separate lives. Tracy frequently engaged in extramarital affairs, including with co-stars Joan Crawford in 1937 and Ingrid Bergman in 1941. He had an affair with Myrna Loy in 1935 and 1936. In 1990, during a phone interview with educator Alan Greenberg, Loy revealed she was in love with Tracy. "I loved Spence, he was adorable...I loved him and I really did love him. I loved him. I mean I was in love with him and she [Katharine Hepburn] got in the way." Later, during the 1940s, Loy regularly visited Tracy at Beverly Hills in his hotel room.

Katharine Hepburn

While making Woman of the Year in September 1941, Tracy began what was to become a lifelong relationship with Katharine Hepburn. The actress became devoted to him, and their relationship lasted until his death 26 years later. Tracy never returned to live in the family home, although he visited regularly.

The MGM moguls were careful to protect their stars from controversy, and Tracy wished to conceal his relationship with Hepburn from his wife, so it was hidden from the public. The couple did not live together until the final years of Tracy's life, when they shared a cottage on George Cukor's estate in Beverly Hills. In Hollywood, however, the intimate nature of the Tracy-Hepburn partnership was an open secret. Angela Lansbury, who worked with the pair on State of the Union, later said: "We all knew, but nobody ever said anything. In those days it wasn't discussed." Tracy was not someone to express his emotions, but Tracy's friend, actress Betsy Drake believed that he "was utterly dependent upon Hepburn". Tracy's infidelity apparently continued, however, and he reportedly had an affair with Gene Tierney during the making of Plymouth Adventure in 1952.

Neither Tracy nor his wife ever pursued a divorce, despite their estrangement. He told Joan Fontaine, "I can get a divorce whenever I want to, but my wife and Kate like things just as they are." Louise, meanwhile, reportedly commented, "I will be Mrs. Spencer Tracy until the day I die." Hepburn did not interfere and never fought for marriage.

Character
Tracy was an avowed Catholic, but his cousin, Jane Feely, said that he did not devoutly follow the religion: "He was often not a practical Catholic either. I would call him a spiritual Catholic." Garson Kanin, a friend of Tracy's for 25 years, described him as "a true believer" who respected his religion. At periods in his life, Tracy attended Mass regularly. Tracy did not believe actors should publicize their political views, but in 1940 lent his name to the "Hollywood for Roosevelt" committee and personally identified as a Democrat.

Tracy struggled with alcoholism throughout his adult life, an ailment that ran in his father's side of the family. Rather than being a steady drinker, as commonly thought, he was prone to periods of binging on alcohol. Loretta Young remarked that Tracy was "awful" when he was drunk, and he was twice arrested for his behavior while intoxicated. Because of this bad reaction to alcohol, Tracy regularly embarked on prolonged periods of sobriety and developed an all-or-nothing routine. Myrna Loy said: "Days of drinking had left him belligerent." Hepburn commented that he would stop drinking for "months, even years at a time" before falling off the wagon without warning.

Tracy was prone to bouts of depression and anxiety: he was described by Mrs. Tracy as having "the most volatile disposition I've ever seen—up in the clouds one minute and down in the depths the next. And when he's low, he's very, very low." He was plagued by insomnia throughout his life. As a result, Tracy became dependent on barbiturates to sleep, followed by dexedrine to function. Hepburn, who adopted a nursing role towards Tracy, was unable to understand her partner's unhappiness. She wrote in her autobiography: "What was it? ... Never at peace ... Tortured by some sort of guilt. Some terrible misery."

Illness and death
Tracy's adult life of alcoholism, smoking cigarettes, taking pills and being overweight left him in poor health by the time he reached his 60s. On July 21, 1963, Tracy was hospitalized after a severe attack of breathlessness. Doctors found that he was suffering from pulmonary edema, where fluid accumulates in the lungs due to an inability of the heart to pump properly. They also declared his blood pressure dangerously high. From this point on Tracy remained very weak, and Hepburn moved into his home to provide constant care. In January 1965, he was diagnosed with hypertensive heart disease and also began treatment for a previously ignored diagnosis of Type II diabetes. Tracy almost died in September 1965: a stay in the hospital following a prostatectomy resulted in his kidneys failing, and he spent the night in a coma. His recovery the next day was described by his attending doctor as "a kind of miracle".

Tracy spent most of the next two years at home with Hepburn, living what she described as a quiet life: reading, painting, and listening to music. On June 10, 1967, 17 days after completing what was his last film role in Guess Who's Coming to Dinner, Tracy awakened at 3:00 am to make himself a cup of tea in his apartment in Beverly Hills, California. Hepburn described in her autobiography how she followed him to the kitchen: "Just as I was about to give [the door] a push, there was a sound of a cup smashing to the floor—then clump—a loud clump." She entered the room to find Tracy lying dead from a heart attack. He was 67. Hepburn recalled, "He looked so happy to be done with living, which for all his accomplishments had been a frightful burden for him." MGM publicist Howard Strickling told the media that Tracy had been alone when he died and was found by his housekeeper.

A Requiem Mass was held for Tracy on June 12 at the Immaculate Heart of Mary Catholic Church in East Hollywood. Active pallbearers included George Cukor, Stanley Kramer, Frank Sinatra, James Stewart, and John Ford. Out of consideration for Tracy's family, Hepburn did not attend the funeral. Tracy is interred at Glendale's Forest Lawn Memorial Park, near his wife Louise, son John and daughter Susie.

Reputation and acting style
Tracy had a solid reputation among his peers and received considerable praise from the film industry. After his death, MGM head Dore Schary said that there "can be no question that [Tracy] was the best and most protean actor of our screen". He was referred to as the greatest actor of his generation by Clark Gable, James Cagney, Humphrey Bogart, John Ford, Garson Kanin, and Katharine Hepburn. Actor Richard Widmark, who idolized Tracy, called him "the greatest movie actor there ever was" and said that he had "learned more about acting from watching Tracy than in any other way".

Tracy was particularly respected for his naturalism onscreen. Hume Cronyn, who worked with Tracy on The Seventh Cross, admired his screen presence: "His method appeared to be as simple as it is difficult to achieve. He appeared to do nothing. He listened, he felt, he said the words without forcing anything." Joan Crawford likewise expressed her admiration for Tracy's seemingly effortless performances, stating that it was "inspiring" to co-star with him and that "his is such simplicity of performance, such naturalness and humor [...] he walks through a scene [and] makes it seem so easy". His four-time co-star Joan Bennett said that she "never had the feeling he was 'acting' in a scene, but the truth of the situation was actually happening, spontaneously, at the moment he spoke his lines". Cagney noted that Tracy was rarely the target of impressionists because "you can't mimic reserve and control very well [...] there's nothing to imitate except his genius and that can't be mimicked".

Tracy was praised for his listening and reacting skills; Barry Nelson said that he "brought the art of reacting to a new height", while Stanley Kramer declared that he "thought and listened better than anyone in the history of motion pictures". Millard Kaufman noted that Tracy "listened with every fiber of his entire body". In his memoir, Burt Reynolds noted Tracy's emphasis on naturalism when, as a rookie actor, he observed Tracy on the set of Inherit the Wind. Reynolds later introduced himself to Tracy as an actor and Tracy replied, "An actor, huh? Just remember not to ever let anyone catch you at it."

Despite the perception that he was able to turn up to a shoot and perform effortlessly, Tracy's acquaintances said that he would carefully prepare for each role in private. Joseph L. Mankiewicz lived with him during the production of Test Pilot, and recounted that Tracy would lock himself in his bedroom "working extremely hard" each night. Many co-workers commented on his strong work ethic and professionalism. However, he did not like to rehearse and would quickly lose his "effectiveness" after shooting two or three takes of the same scene. Kanin described him as "an instinctive player, who trusted the moment of creation". Tracy's close friend Chester Erskine pinpointed his acting style as one of "selection", stating that he strove to give as little as was needed to be effective and reached "a minimum to make the maximum".

Tracy disliked being asked about his technique or what advice he would give to others. He often belittled the profession of acting, once saying to Kanin, "Why do actors think they're so goddamn important? They're not. Acting is not an important job in the scheme of things. Plumbing is." He was also humble about his abilities, telling a journalist, "It's just that I try no tricks. No profile. No 'great lover' act ... I just project myself as I am—plain, trying to be honest." He was known to have enjoyed the quip once made by Alfred Lunt, "The art of acting is: learn your lines and don't bump into the furniture!" Hepburn, in an interview six years after Tracy's death, suggested that Tracy wished he had held a different profession.

Assessment and legacy

In the 21st century, Tracy is best known to general audiences for his association with Katharine Hepburn. He continues to receive praise from film scholars: critic Leonard Maltin calls Tracy "one of the 20th century's finest actors", while film historian Jeanine Basinger describes his career as a "golden record of movie achievement". Charles Matthews, writing for The Washington Post, argues that "Tracy deserves to be remembered for himself, as a master of acting technique".

An award for excellence in film acting is bestowed in Tracy's name at the University of California, Los Angeles. Past recipients of the UCLA Spencer Tracy Award include Kirk Douglas, Michael Douglas, Morgan Freeman, Tom Hanks, Anthony Hopkins, James Stewart, and Denzel Washington.

A 1986 PBS documentary titled The Spencer Tracy Legacy was hosted by Hepburn. It includes clips from Tracy's films, and behind-the-scenes archival footage and home movies of Tracy's private life and career, as well as newly filmed interviews with many of his former co-stars, and with his daughter Susie Tracy. In 2009, Tracy provided inspiration for the character Carl in Pixar's Oscar-winning film Up. Director Pete Docter explained that there is "something sweet about these grumpy old guys". In 2014, a film about Tracy's relationship with Katharine Hepburn was announced to be in development.

Several of Tracy's films, particularly his comedies, are regarded as classics of American cinema. He starred in four of the titles on the American Film Institute's list of "100 Years ... 100 Laughs": Adam's Rib, It's a Mad, Mad, Mad, Mad World, Father of the Bride and Woman of the Year. Guess Who's Coming to Dinner was included on AFI's list of the 100 greatest American movies, while Captains Courageous was featured on their list of America's most inspiring movies.

Awards and nominations
Tracy was nominated for nine Academy Awards for Best Actor, a category record he holds with Laurence Olivier. He was the first of nine actors to win the award twice, and is one of two actors to receive it consecutively, the other being Tom Hanks. Tracy was also nominated for five British Academy Film Awards, of which he won two, and four Golden Globe Awards, winning once. In addition, he received the Cannes Film Festival award for Best Actor and was once named Best Actor by the National Board of Review.

Tracy was recognized by the Academy of Motion Picture Arts and Sciences for the following performances:
 * 1937: Nomination for San Francisco
 * 1938: Win for Captains Courageous
 * 1939: Win for Boys Town
 * 1951: Nomination for Father of the Bride
 * 1956: Nomination for Bad Day at Black Rock
 * 1959: Nomination for The Old Man and the Sea
 * 1961: Nomination for Inherit the Wind
 * 1962: Nomination for Judgment at Nuremberg
 * 1968: Nomination for Guess Who's Coming to Dinner (posthumous nomination)

Filmography
Selected filmography:

 * Up the River (1930) with Humphrey Bogart
 * Quick Millions (1931)
 * 20,000 Years in Sing Sing (1932) with Bette Davis
 * The Power and the Glory (1933) with Colleen Moore
 * Man's Castle (1933) with Loretta Young
 * Whipsaw (1935) with Myrna Loy
 * Fury (1936) with Sylvia Sidney
 * San Francisco (1936) with Clark Gable
 * Libeled Lady (1936) with Jean Harlow
 * Captains Courageous (1937) with Freddie Bartholomew and Lionel Barrymore
 * They Gave Him a Gun (1937)
 * Mannequin (1937) with Joan Crawford and Alan Curtis
 * Test Pilot (1938) with Clark Gable and Myrna Loy
 * Boys Town (1938) with Mickey Rooney
 * Boom Town (1940) with Clark Gable
 * Edison, the Man  (1940) with Gene Lockhart
 * Northwest Passage (1940) with Robert Young and Walter Brennan
 * Dr. Jekyll and Mr. Hyde (1941) with Ingrid Bergman
 * Woman of the Year (1942) with Katharine Hepburn
 * Ring of Steel (1942) as narrator
 * Keeper of the Flame (1943) with Katharine Hepburn
 * A Guy Named Joe (1943) with Irene Dunne
 * The Seventh Cross (1944) with Hume Cronyn
 * Thirty Seconds Over Tokyo (1944) with Van Johnson
 * Without Love (1945) with Katharine Hepburn
 * Sea of Grass (1947) with Katharine Hepburn
 * State of the Union (1948) with Katharine Hepburn
 * Adam's Rib (1949) with Katharine Hepburn
 * Malaya (1949) with James Stewart
 * Father of the Bride (1950) with Elizabeth Taylor
 * Father's Little Dividend (1951) with Joan Bennett
 * Plymouth Adventure (1952) with Gene Tierney
 * Pat and Mike (1952) with Katharine Hepburn
 * The Actress (1953) with Jean Simmons
 * Broken Lance (1954) with Richard Widmark
 * Bad Day at Black Rock (1955) with Robert Ryan
 * The Mountain (1956) with Robert Wagner
 * Desk Set (1957) with Katharine Hepburn
 * The Old Man and the Sea (1958)
 * The Last Hurrah (1958) with Jeffrey Hunter
 * Inherit the Wind (1960) with Fredric March
 * The Devil at 4 O'Clock (1961) with Frank Sinatra, Kerwin Mathews
 * Judgment at Nuremberg (1961) with Burt Lancaster
 * It's a Mad, Mad, Mad, Mad World (1963) with Jonathan Winters, Milton Berle, Mickey Rooney, Sid Caesar, Ethel Merman
 * Guess Who's Coming to Dinner (1967) with Katharine Hepburn

title: Spencer Tracy


text:
Genotype–phenotype distinction

The genotype–phenotype distinction is drawn in genetics. The "genotype" is an organism's full hereditary information. The "phenotype" is an organism's actual observed properties, such as morphology, development, or behavior. This distinction is fundamental in the study of inheritance of traits and their evolution.

Overview
The terms "genotype" and "phenotype" were created by Wilhelm Johannsen in 1911, although the meaning of the terms and the significance of the distinction have evolved since they were introduced.

It is the organism's physical properties that directly determine its chances of survival and reproductive output, but the inheritance of physical properties is dependent on the inheritance of genes. Therefore, understanding the theory of evolution via natural selection requires understanding the genotype–phenotype distinction. The genes contribute to a trait, and the phenotype is the observable manifestation of the genes (and therefore the genotype that affects the trait). If a white mouse had recessive genes that caused the genes responsible for color to be inactive, its genotype would be responsible for its phenotype (the white color).

The mapping of a set of genotypes to a set of phenotypes is sometimes referred to as the genotype–phenotype map.

An organism's genotype is a major (the largest by far for morphology) influencing factor in the development of its phenotype, but it is not the only one. Even two organisms with identical genotypes may differ in their phenotypes, due to phenotypic plasticity. To what extent a particular genotype influences a phenotype depends on the relative dominance, penetrance, and expresivity of the alleles in question.

One experiences this in everyday life with monozygous (i.e. identical) twins. Identical twins share the same genotype, since their genomes are identical; but they never have the same phenotype, although their phenotypes may be very similar. This is apparent in the fact that close relations can always tell them apart, even though others might not be able to see the subtle differences. Further, identical twins can be distinguished by their fingerprints, which are never completely identical.

Phenotypic plasticity
The concept of phenotypic plasticity defines the degree to which an organism's phenotype is determined by its genotype. A high level of plasticity means that environmental factors have a strong influence on the particular phenotype that develops. If there is little plasticity, the phenotype of an organism can be reliably predicted from knowledge of the genotype, regardless of environmental peculiarities during development. An example of high plasticity can be observed in larval newts1: when these larvae sense the presence of predators such as dragonflies, they develop larger heads and tails relative to their body size and display darker pigmentation. Larvae with these traits have a higher chance of survival when exposed to the predators, but grow more slowly than other phenotypes.

Genetic canalization
In contrast to phenotypic plasticity, the concept of genetic canalization addresses the extent to which an organism's phenotype allows conclusions about its genotype. A phenotype is said to be canalized if mutations (changes in the genome) do not noticeably affect the physical properties of the organism. This means that a canalized phenotype may form from a large variety of different genotypes, in which case it is not possible to exactly predict the genotype from knowledge of the phenotype (i.e. the genotype–phenotype map is not invertible). If canalization is not present, small changes in the genome have an immediate effect on the phenotype that develops.

Importance to evolutionary biology
According to Lewontin, the theoretical task for population genetics is a process in two spaces: a "genotypic space" and a "phenotypic space". The challenge of a complete theory of population genetics is to provide a set of laws that predictably map a population of genotypes (G1) to a phenotype space (P1), where selection takes place, and another set of laws that map the resulting population (P2) back to genotype space (G2) where Mendelian genetics can predict the next generation of genotypes, thus completing the cycle. Even if non-Mendelian aspects of molecular genetics are ignored, this is a gargantuan task. Visualizing the transformation schematically:

 * $$G_1 \; \stackrel{T_1}{\rightarrow} \; P_1 \; \stackrel{T_2}{\rightarrow} \; P_2 \; \stackrel{T_3}{\rightarrow} \; G_2 \;

\stackrel{T_4}{\rightarrow} \; G_1' \; \rightarrow \cdots$$

(adapted from Lewontin 1974, p. 12). T1 represents the genetic and epigenetic laws, the aspects of functional biology, or development, that transform a genotype into phenotype. This is the "genotype–phenotype map". T2 is the transformation due to natural selection, T3 are epigenetic relations that predict genotypes based on the selected phenotypes and finally T4 the rules of Mendelian genetics.

In practice, there are two bodies of evolutionary theory that exist in parallel, traditional population genetics operating in the genotype space and the biometric theory used in plant and animal breeding, operating in phenotype space. The missing part is the mapping between the genotype and phenotype space. This leads to a "sleight of hand" (as Lewontin terms it) whereby variables in the equations of one domain, are considered parameters or constants, where, in a full-treatment, they would be transformed themselves by the evolutionary process and are functions of the state variables in the other domain. The "sleight of hand" is assuming that the mapping is known. Proceeding as if it is understood is enough to analyze many cases of interest. For example, if the phenotype is almost one-to-one with genotype (sickle-cell disease) or the time-scale is sufficiently short, the "constants" can be treated as such; however, there are also many situations where that assumption does not hold.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Genotype–phenotype distinction


text:
Biomimetics

Biomimetics or biomimicry is the emulation of the models, systems, and elements of nature for the purpose of solving complex human problems. The terms "biomimetics" and "biomimicry" are derived from βίος (bios), life, and μίμησις (mīmēsis), imitation, from μιμεῖσθαι (mīmeisthai), to imitate, from μῖμος (mimos), actor. A closely related field is bionics.

Nature has gone through evolution over the 3.8 billion years since life is estimated to have appeared on the Earth. It has evolved species with high performance using commonly found materials. Surfaces of solids interact with other surfaces and the environment and derive the properties of materials. Biological materials are highly organized from the molecular to the nano-, micro-, and macroscales, often in a hierarchical manner with intricate nanoarchitecture that ultimately makes up a myriad of different functional elements. Properties of materials and surfaces result from a complex interplay between surface structure and morphology and physical and chemical properties. Many materials, surfaces, and objects in general provide multifunctionality.

Various materials, structures, and devices have been fabricated for commercial interest by engineers, material scientists, chemists, and biologists, and for beauty, structure, and design by artists and architects. Nature has solved engineering problems such as self-healing abilities, environmental exposure tolerance and resistance, hydrophobicity, self-assembly, and harnessing solar energy. Economic impact of bioinspired materials and surfaces is significant, on the order of several hundred billion dollars per year worldwide.

History
One of the early examples of biomimicry was the study of birds to enable human flight. Although never successful in creating a "flying machine", Leonardo da Vinci (1452–1519) was a keen observer of the anatomy and flight of birds, and made numerous notes and sketches on his observations as well as sketches of "flying machines". The Wright Brothers, who succeeded in flying the first heavier-than-air aircraft in 1903, allegedly derived inspiration from observations of pigeons in flight.

During the 1950s the American biophysicist and polymath Otto Schmitt developed the concept of "biomimetics". During his doctoral research he developed the Schmitt trigger by studying the nerves in squid, attempting to engineer a device that replicated the biological system of nerve propagation. He continued to focus on devices that mimic natural systems and by 1957 he had perceived a converse to the standard view of biophysics at that time, a view he would come to call biomimetics.

"Biophysics is not so much a subject matter as it is a point of view. It is an approach to problems of biological science utilizing the theory and technology of the physical sciences. Conversely, biophysics is also a biologist's approach to problems of physical science and engineering, although this aspect has largely been neglected."

In 1960 Jack E. Steele coined a similar term, bionics, at Wright-Patterson Air Force Base in Dayton, Ohio, where Otto Schmitt also worked. Steele defined bionics as "the science of systems which have some function copied from nature, or which represent characteristics of natural systems or their analogues". During a later meeting in 1963 Schmitt stated,

"Let us consider what bionics has come to mean operationally and what it or some word like it (I prefer biomimetics) ought to mean in order to make good use of the technical skills of scientists specializing, or rather, I should say, despecializing into this area of research."

In 1969, Schmitt used the term "biomimetic" in the title one of his papers, and by 1974 it had found its way into Webster's Dictionary. Bionics entered the same dictionary earlier in 1960 as "a science concerned with the application of data about the functioning of biological systems to the solution of engineering problems". Bionic took on a different connotation when Martin Caidin referenced Jack Steele and his work in the novel Cyborg which later resulted in the 1974 television series The Six Million Dollar Man and its spin-offs. The term bionic then became associated with "the use of electronically operated artificial body parts" and "having ordinary human powers increased by or as if by the aid of such devices". Because the term bionic took on the implication of supernatural strength, the scientific community in English speaking countries largely abandoned it.

The term biomimicry appeared as early as 1982. Biomimicry was popularized by scientist and author Janine Benyus in her 1997 book Biomimicry: Innovation Inspired by Nature. Biomimicry is defined in the book as a "new science that studies nature's models and then imitates or takes inspiration from these designs and processes to solve human problems". Benyus suggests looking to Nature as a "Model, Measure, and Mentor" and emphasizes sustainability as an objective of biomimicry.

One of the latest examples of biomimicry has been created by Johannes-Paul Fladerer and Ernst Kurzmann by the description of "managemANT". This term (a combination of the words "management" and "ant"), describes the usage of behavioural strategies of ants in economic and management strategies. The potential long-term impacts of biomimicry were quantified in a 2013 Fermanian Business & Economic Institute Report commissioned by the San Diego Zoo. The findings demonstrated the potential economic and environmental benefits of biomimicry, which can be further seen in Johannes-Paul Fladerer and Ernst Kurzmann's "managemANT" approach. This approach utilizes the behavioral strategies of ants in economic and management strategies.

Bio-inspired technologies
Biomimetics could in principle be applied in many fields. Because of the diversity and complexity of biological systems, the number of features that might be imitated is large. Biomimetic applications are at various stages of development from technologies that might become commercially usable to prototypes. Murray's law, which in conventional form determined the optimum diameter of blood vessels, has been re-derived to provide simple equations for the pipe or tube diameter which gives a minimum mass engineering system.

Locomotion
Aircraft wing design and flight techniques are being inspired by birds and bats. The aerodynamics of streamlined design of improved Japanese high speed train Shinkansen 500 Series were modelled after the beak of Kingfisher bird.

Biorobots based on the physiology and methods of locomotion of animals include BionicKangaroo which moves like a kangaroo, saving energy from one jump and transferring it to its next jump; Kamigami Robots, a children's toy, mimic cockroach locomotion to run quickly and efficiently over indoor and outdoor surfaces, and Pleobot, a shrimp-inspired robot to study metachronal swimming and the ecological impacts of this propulsive gait on the environment.

Biomimetic flying robots (BFRs)
BFRs take inspiration from flying mammals, birds, or insects. BFRs can have flapping wings, which generate the lift and thrust, or they can be propeller actuated. BFRs with flapping wings have increased stroke efficiencies, increased maneuverability, and reduced energy consumption in comparison to propeller actuated BFRs. Mammal and bird inspired BFRs share similar flight characteristics and design considerations. For instance, both mammal and bird inspired BFRs minimize edge fluttering and pressure-induced wingtip curl by increasing the rigidity of the wing edge and wingtips. Mammal and insect inspired BFRs can be impact resistant, making them useful in cluttered environments.

Mammal inspired BFRs typically take inspiration from bats, but the flying squirrel has also inspired a prototype. Examples of bat inspired BFRs include Bat Bot and the DALER. Mammal inspired BFRs can be designed to be multi-modal; therefore, they're capable of both flight and terrestrial movement. To reduce the impact of landing, shock absorbers can be implemented along the wings. Alternatively, the BFR can pitch up and increase the amount of drag it experiences. By increasing the drag force, the BFR will decelerate and minimize the impact upon grounding. Different land gait patterns can also be implemented. Bird inspired BFRs can take inspiration from raptors, gulls, and everything in-between. Bird inspired BFRs can be feathered to increase the angle of attack range over which the prototype can operate before stalling. The wings of bird inspired BFRs allow for in-plane deformation, and the in-plane wing deformation can be adjusted to maximize flight efficiency depending on the flight gait. An example of a raptor inspired BFR is the prototype by Savastano et al. The prototype has fully deformable flapping wings and is capable of carrying a payload of up to 0.8 kg while performing a parabolic climb, steep descent, and rapid recovery. The gull inspired prototype by Grant et al. accurately mimics the elbow and wrist rotation of gulls, and they find that lift generation is maximized when the elbow and wrist deformations are opposite but equal.

Insect inspired BFRs typically take inspiration from beetles or dragonflies. An example of a beetle inspired BFR is the prototype by Phan and Park, and a dragonfly inspired BFR is the prototype by Hu et al. The flapping frequency of insect inspired BFRs are much higher than those of other BFRs; this is because of the aerodynamics of insect flight. Insect inspired BFRs are much smaller than those inspired by mammals or birds, so they are more suitable for dense environments. The prototype by Phan and Park took inspiration from the rhinoceros beetle, so it can successfully continue flight even after a collision by deforming its hindwings.

Biomimetic architecture
Living beings have adapted to a constantly changing environment during evolution through mutation, recombination, and selection. The core idea of the biomimetic philosophy is that nature's inhabitants including animals, plants, and microbes have the most experience in solving problems and have already found the most appropriate ways to last on planet Earth. Similarly, biomimetic architecture seeks solutions for building sustainability present in nature. While nature serves as a model, there are few examples of biomimetic architecture that aim to be nature positive.

The 21st century has seen a ubiquitous waste of energy due to inefficient building designs, in addition to the over-utilization of energy during the operational phase of its life cycle. In parallel, recent advancements in fabrication techniques, computational imaging, and simulation tools have opened up new possibilities to mimic nature across different architectural scales. As a result, there has been a rapid growth in devising innovative design approaches and solutions to counter energy problems. Biomimetic architecture is one of these multi-disciplinary approaches to sustainable design that follows a set of principles rather than stylistic codes, going beyond using nature as inspiration for the aesthetic components of built form but instead seeking to use nature to solve problems of the building's functioning and saving energy.

Characteristics
The term biomimetic architecture refers to the study and application of construction principles which are found in natural environments and species, and are translated into the design of sustainable solutions for architecture. Biomimetic architecture uses nature as a model, measure and mentor for providing architectural solutions across scales, which are inspired by natural organisms that have solved similar problems in nature. Using nature as a measure refers to using an ecological standard of measuring sustainability, and efficiency of man-made innovations, while the term mentor refers to learning from natural principles and using biology as an inspirational source.

Biomorphic architecture, also referred to as bio-decoration, on the other hand, refers to the use of formal and geometric elements found in nature, as a source of inspiration for aesthetic properties in designed architecture, and may not necessarily have non-physical, or economic functions. A historic example of biomorphic architecture dates back to Egyptian, Greek and Roman cultures, using tree and plant forms in the ornamentation of structural columns.

Procedures
Within biomimetic architecture, two basic procedures can be identified, namely, the bottom-up approach (biology push) and top-down approach (technology pull). The boundary between the two approaches is blurry with the possibility of transition between the two, depending on each individual case. Biomimetic architecture is typically carried out in interdisciplinary teams in which biologists and other natural scientists work in collaboration with engineers, material scientists, architects, designers, mathematicians and computer scientists.

In the bottom-up approach, the starting point is a new result from basic biological research promising for biomimetic implementation. For example, developing a biomimetic material system after the quantitative analysis of the mechanical, physical, and chemical properties of a biological system.

In the top-down approach, biomimetic innovations are sought for already existing developments that have been successfully established on the market. The cooperation focuses on the improvement or further development of an existing product.

Examples
Researchers studied the termite's ability to maintain virtually constant temperature and humidity in their termite mounds in Africa despite outside temperatures that vary from 1.5 to 40 C. Researchers initially scanned a termite mound and created 3-D images of the mound structure, which revealed construction that could influence human building design. The Eastgate Centre, a mid-rise office complex in Harare, Zimbabwe, stays cool via a passive cooling architecture that uses only 10% of the energy of a conventional building of the same size.

Researchers in the Sapienza University of Rome were inspired by the natural ventilation in termite mounds and designed a double façade that significantly cuts down over lit areas in a building. Scientists have imitated the porous nature of mound walls by designing a facade with double panels that was able to reduce heat gained by radiation and increase heat loss by convection in cavity between the two panels. The overall cooling load on the building's energy consumption was reduced by 15%.

A similar inspiration was drawn from the porous walls of termite mounds to design a naturally ventilated façade with a small ventilation gap. This design of façade is able to induce air flow due to the Venturi effect and continuously circulates rising air in the ventilation slot. Significant transfer of heat between the building's external wall surface and the air flowing over it was observed. The design is coupled with greening of the façade. Green wall facilitates additional natural cooling via evaporation, respiration and transpiration in plants. The damp plant substrate further support the cooling effect. Scientists in Shanghai University were able to replicate the complex microstructure of clay-made conduit network in the mound to mimic the excellent humidity control in mounds. They proposed a porous humidity control material (HCM) using sepiolite and calcium chloride with water vapor adsorption-desorption content at 550 grams per meter squared. Calcium chloride is a desiccant and improves the water vapor adsorption-desorption property of the Bio-HCM. The proposed bio-HCM has a regime of interfiber mesopores which acts as a mini reservoir. The flexural strength of the proposed material was estimated to be 10.3 MPa using computational simulations.

In structural engineering, the Swiss Federal Institute of Technology (EPFL) has incorporated biomimetic characteristics in an adaptive deployable "tensegrity" bridge. The bridge can carry out self-diagnosis and self-repair. The arrangement of leaves on a plant has been adapted for better solar power collection.

Analysis of the elastic deformation happening when a pollinator lands on the sheath-like perch part of the flower Strelitzia reginae (known as bird-of-paradise flower) has inspired architects and scientists from the University of Freiburg and University of Stuttgart to create hingeless shading systems that can react to their environment. These bio-inspired products are sold under the name Flectofin.

Other hingeless bioinspired systems include Flectofold. Flectofold has been inspired from the trapping system developed by the carnivorous plant Aldrovanda vesiculosa.

Structural materials
There is a great need for new structural materials that are light weight but offer exceptional combinations of stiffness, strength, and toughness.

Such materials would need to be manufactured into bulk materials with complex shapes at high volume and low cost and would serve a variety of fields such as construction, transportation, energy storage and conversion. In a classic design problem, strength and toughness are more likely to be mutually exclusive, i.e., strong materials are brittle and tough materials are weak. However, natural materials with complex and hierarchical material gradients that span from nano- to macro-scales are both strong and tough. Generally, most natural materials utilize limited chemical components but complex material architectures that give rise to exceptional mechanical properties. Understanding the highly diverse and multi functional biological materials and discovering approaches to replicate such structures will lead to advanced and more efficient technologies. Bone, nacre (abalone shell), teeth, the dactyl clubs of stomatopod shrimps and bamboo are great examples of damage tolerant materials. The exceptional resistance to fracture of bone is due to complex deformation and toughening mechanisms that operate at spanning different size scales — nanoscale structure of protein molecules to macroscopic physiological scale. Nacre exhibits similar mechanical properties however with rather simpler structure. Nacre shows a brick and mortar like structure with thick mineral layer (0.2–0.9 μm) of closely packed aragonite structures and thin organic matrix (~20 nm). While thin films and micrometer sized samples that mimic these structures are already produced, successful production of bulk biomimetic structural materials is yet to be realized. However, numerous processing techniques have been proposed for producing nacre like materials. Pavement cells, epidermal cells on the surface of plant leaves and petals, often form wavy interlocking patterns resembling jigsaw puzzle pieces and are shown to enhance the fracture toughness of leaves, key to plant survival. Their pattern, replicated in laser-engraved Poly(methyl methacrylate) samples, was also demonstrated to lead to increased fracture toughness. It is suggested that the arrangement and patterning of cells play a role in managing crack propagation in tissues.

Biomorphic mineralization is a technique that produces materials with morphologies and structures resembling those of natural living organisms by using bio-structures as templates for mineralization. Compared to other methods of material production, biomorphic mineralization is facile, environmentally benign and economic.

Freeze casting (ice templating), an inexpensive method to mimic natural layered structures, was employed by researchers at Lawrence Berkeley National Laboratory to create alumina-Al-Si and IT HAP-epoxy layered composites that match the mechanical properties of bone with an equivalent mineral/organic content. Various further studies   also employed similar methods to produce high strength and high toughness composites involving a variety of constituent phases.

Recent studies demonstrated production of cohesive and self supporting macroscopic tissue constructs that mimic living tissues by printing tens of thousands of heterologous picoliter droplets in software-defined, 3D millimeter-scale geometries. Efforts are also taken up to mimic the design of nacre in artificial composite materials using fused deposition modelling and the helicoidal structures of stomatopod clubs in the fabrication of high performance carbon fiber-epoxy composites.

Various established and novel additive manufacturing technologies like PolyJet printing, direct ink writing, 3D magnetic printing, multi-material magnetically assisted 3D printing and magnetically assisted slip casting have also been utilized to mimic the complex micro-scale architectures of natural materials and provide huge scope for future research.

Spider silk is tougher than Kevlar used in bulletproof vests. Engineers could in principle use such a material, if it could be reengineered to have a long enough life, for parachute lines, suspension bridge cables, artificial ligaments for medicine, and other purposes. The self-sharpening teeth of many animals have been copied to make better cutting tools.

New ceramics that exhibit giant electret hysteresis have also been realized.

Neuronal computers
Neuromorphic computers and sensors are electrical devices that copy the structure and function of biological neurons in order to compute. One example of this is the event camera in which only the pixels that receive a new signal update to a new state. All other pixels do not update until a signal is received.

Self healing-materials
In some biological systems, self-healing occurs via chemical releases at the site of fracture, which initiate a systemic response to transport repairing agents to the fracture site. This promotes autonomic healing. To demonstrate the use of micro-vascular networks for autonomic healing, researchers developed a microvascular coating–substrate architecture that mimics human skin. Bio-inspired self-healing structural color hydrogels that maintain the stability of an inverse opal structure and its resultant structural colors were developed. A self-repairing membrane inspired by rapid self-sealing processes in plants was developed for inflatable lightweight structures such as rubber boats or Tensairity constructions. The researchers applied a thin soft cellular polyurethane foam coating on the inside of a fabric substrate, which closes the crack if the membrane is punctured with a spike. Self-healing materials, polymers and composite materials capable of mending cracks have been produced based on biological materials.

The self-healing properties may also be achieved by the breaking and reforming of hydrogen bonds upon cyclical stress of the material.

Surfaces
Surfaces that recreate properties of shark skin are intended to enable more efficient movement through water. Efforts have been made to produce fabric that emulates shark skin.

Surface tension biomimetics are being researched for technologies such as hydrophobic or hydrophilic coatings and microactuators.

Wet adhesion
Some amphibians, such as tree and torrent frogs and arboreal salamanders, are able to attach to and move over wet or even flooded environments without falling. This kind of organisms have toe pads which are permanently wetted by mucus secreted from glands that open into the channels between epidermal cells. They attach to mating surfaces by wet adhesion and they are capable of climbing on wet rocks even when water is flowing over the surface. Tire treads have also been inspired by the toe pads of tree frogs. 3D printed hierarchical surface models, inspired from tree and torrent frogs toe pad design, have been observed to produce better wet traction than conventional tire design.

Marine mussels can stick easily and efficiently to surfaces underwater under the harsh conditions of the ocean. Mussels use strong filaments to adhere to rocks in the inter-tidal zones of wave-swept beaches, preventing them from being swept away in strong sea currents. Mussel foot proteins attach the filaments to rocks, boats and practically any surface in nature including other mussels. These proteins contain a mix of amino acid residues which has been adapted specifically for adhesive purposes. Researchers from the University of California Santa Barbara borrowed and simplified chemistries that the mussel foot uses to overcome this engineering challenge of wet adhesion to create copolyampholytes, and one-component adhesive systems with potential for employment in nanofabrication protocols. Other research has proposed adhesive glue from mussels.

Dry adhesion
Leg attachment pads of several animals, including many insects (e.g., beetles and flies), spiders and lizards (e.g., geckos), are capable of attaching to a variety of surfaces and are used for locomotion, even on vertical walls or across ceilings. Attachment systems in these organisms have similar structures at their terminal elements of contact, known as setae. Such biological examples have offered inspiration in order to produce climbing robots, boots and tape. Synthetic setae have also been developed for the production of dry adhesives.

Liquid repellency
Superliquiphobicity refers to a remarkable surface property where a solid surface exhibits an extreme aversion to liquids, causing droplets to bead up and roll off almost instantaneously upon contact. This behavior arises from intricate surface textures and interactions at the nanoscale, effectively preventing liquids from wetting or adhering to the surface. The term "superliquiphobic" is derived from "superhydrophobic," which describes surfaces highly resistant to water. Superliquiphobic surfaces go beyond water repellency and display repellent characteristics towards a wide range of liquids, including those with very low surface tension or containing surfactants.

Superliquiphobicity, a remarkable phenomenon, emerges when a solid surface possesses minute roughness, forming interfaces with droplets through wetting while altering contact angles. This behavior hinges on the roughness factor (Rf), defining the ratio of solid-liquid area to its projection, influencing contact angles. On rough surfaces, non-wetting liquids give rise to composite solid-liquid-air interfaces, their contact angles determined by the distribution of wet and air-pocket areas. The achievement of superliquiphobicity involves increasing the fractional flat geometrical area (fLA) and Rf, leading to surfaces that actively repel liquids.

The inspiration for crafting such surfaces draws from nature's ingenuity, prominently illustrated by the renowned "lotus effect". Leaves of water-repellent plants, like the lotus, exhibit inherent hierarchical structures featuring nanoscale wax-coated formations. These structures lead to superhydrophobicity, where water droplets perch on trapped air bubbles, resulting in high contact angles and minimal contact angle hysteresis. This natural example guides the development of superliquiphobic surfaces, capitalizing on re-entrant geometries that can repel low surface tension liquids and achieve near-zero contact angles.

Creating superliquiphobic surfaces involves pairing re-entrant geometries with low surface energy materials, such as fluorinated substances. These geometries include overhangs that widen beneath the surface, enabling repellency even for minimal contact angles. Researchers have successfully fabricated various re-entrant geometries, offering a pathway for practical applications in diverse fields. These surfaces find utility in self-cleaning, anti-icing, anti-fogging, antifouling, and more, presenting innovative solutions to challenges in biomedicine, desalination, and energy conversion.

In essence, superliquiphobicity, inspired by natural models like the lotus leaf, capitalizes on re-entrant geometries and surface properties to create interfaces that actively repel liquids. These surfaces hold immense promise across a range of applications, promising enhanced functionality and performance in various technological and industrial contexts.

Optics
Biomimetic materials are gaining increasing attention in the field of optics and photonics. There are still little known bioinspired or biomimetic products involving the photonic properties of plants or animals. However, understanding how nature designed such optical materials from biological resources is a current field of research.

Inspiration from fruits and plants
One source of biomimetic inspiration is from plants. Plants have proven to be concept generations for the following functions; re(action)-coupling, self (adaptability), self-repair, and energy-autonomy. As plants do not have a centralized decision making unit (i.e. a brain), most plants have a decentralized autonomous system in various organs and tissues of the plant. Therefore, they react to multiple stimulus such as light, heat, and humidity.

One example is the carnivorous plant species Dionaea muscipula (Venus flytrap). For the last 25 years, there has been research focus on the motion principles of the plant to develop AVFT (artificial Venus flytrap robots). Through the movement during prey capture, the plant inspired soft robotic motion systems. The fast snap buckling (within 100–300 ms) of the trap closure movement is initiated when prey triggers the hairs of the plant within a certain time (twice within 20 s). AVFT systems exist, in which the trap closure movements are actuated via magnetism, electricity, pressurized air, and temperature changes.

Another example of mimicking plants, is the Pollia condensata, also known as the marble berry. The chiral self-assembly of cellulose inspired by the Pollia condensata berry has been exploited to make optically active films. Such films are made from cellulose which is a biodegradable and biobased resource obtained from wood or cotton. The structural colours can potentially be everlasting and have more vibrant colour than the ones obtained from chemical absorption of light. Pollia condensata is not the only fruit showing a structural coloured skin; iridescence is also found in berries of other species such as Margaritaria nobilis. These fruits show iridescent colors in the blue-green region of the visible spectrum which gives the fruit a strong metallic and shiny visual appearance. The structural colours come from the organisation of cellulose chains in the fruit's epicarp, a part of the fruit skin. Each cell of the epicarp is made of a multilayered envelope that behaves like a Bragg reflector. However, the light which is reflected from the skin of these fruits is not polarised unlike the one arising from man-made replicates obtained from the self-assembly of cellulose nanocrystals into helicoids, which only reflect left-handed circularly polarised light.

The fruit of Elaeocarpus angustifolius also show structural colour that come arises from the presence of specialised cells called iridosomes which have layered structures. Similar iridosomes have also been found in Delarbrea michieana fruits.

In plants, multi layer structures can be found either at the surface of the leaves (on top of the epidermis), such as in Selaginella willdenowii or within specialized intra-cellular organelles, the so-called iridoplasts, which are located inside the cells of the upper epidermis. For instance, the rain forest plants Begonia pavonina have iridoplasts located inside the epidermal cells.

Structural colours have also been found in several algae, such as in the red alga Chondrus crispus (Irish Moss).

Inspiration from animals

Structural coloration produces the rainbow colours of soap bubbles, butterfly wings and many beetle scales. Phase-separation has been used to fabricate ultra-white scattering membranes from polymethylmethacrylate, mimicking the beetle Cyphochilus. LED lights can be designed to mimic the patterns of scales on fireflies' abdomens, improving their efficiency.

Morpho butterfly wings are structurally coloured to produce a vibrant blue that does not vary with angle. This effect can be mimicked by a variety of technologies. Lotus Cars claim to have developed a paint that mimics the Morpho butterfly's structural blue colour. In 2007, Qualcomm commercialised an interferometric modulator display technology, "Mirasol", using Morpho-like optical interference. In 2010, the dressmaker Donna Sgro made a dress from Teijin Fibers' Morphotex, an undyed fabric woven from structurally coloured fibres, mimicking the microstructure of Morpho butterfly wing scales.

Canon Inc.'s SubWavelength structure Coating uses wedge-shaped structures the size of the wavelength of visible light. The wedge-shaped structures cause a continuously changing refractive index as light travels through the coating, significantly reducing lens flare. This imitates the structure of a moth's eye. Notable figures such as the Wright Brothers and Leonardo da Vinci attempted to replicate the flight observed in birds. In an effort to reduce aircraft noise researchers have looked to the leading edge of owl feathers, which have an array of small finlets or rachis adapted to disperse aerodynamic pressure and provide nearly silent flight to the bird.

Agricultural systems
Holistic planned grazing, using fencing and/or herders, seeks to restore grasslands by carefully planning movements of large herds of livestock to mimic the vast herds found in nature. The natural system being mimicked and used as a template is grazing animals concentrated by pack predators that must move on after eating, trampling, and manuring an area, and returning only after it has fully recovered. Its founder Allan Savory and some others have claimed potential in building soil, increasing biodiversity, and reversing desertification. However, many researchers have disputed Savory's claim. Studies have often found that the method increases desertification instead of reducing it.

Other uses
Some air conditioning systems use biomimicry in their fans to increase airflow while reducing power consumption.

Technologists like Jas Johl have speculated that the functionality of vacuole cells could be used to design highly adaptable security systems. "The functionality of a vacuole, a biological structure that guards and promotes growth, illuminates the value of adaptability as a guiding principle for security." The functions and significance of vacuoles are fractal in nature, the organelle has no basic shape or size; its structure varies according to the requirements of the cell. Vacuoles not only isolate threats, contain what's necessary, export waste, maintain pressure—they also help the cell scale and grow. Johl argues these functions are necessary for any security system design. The 500 Series Shinkansen used biomimicry to reduce energy consumption and noise levels while increasing passenger comfort. With reference to space travel, NASA and other firms have sought to develop swarm-type space drones inspired by bee behavioural patterns, and oxtapod terrestrial drones designed with reference to desert spiders.

Other technologies
Protein folding has been used to control material formation for self-assembled functional nanostructures. Polar bear fur has inspired the design of thermal collectors and clothing. The light refractive properties of the moth's eye has been studied to reduce the reflectivity of solar panels.

The Bombardier beetle's powerful repellent spray inspired a Swedish company to develop a "micro mist" spray technology, which is claimed to have a low carbon impact (compared to aerosol sprays). The beetle mixes chemicals and releases its spray via a steerable nozzle at the end of its abdomen, stinging and confusing the victim.

Most viruses have an outer capsule 20 to 300 nm in diameter. Virus capsules are remarkably robust and capable of withstanding temperatures as high as 60 °C; they are stable across the pH range 2–10. Viral capsules can be used to create nano device components such as nanowires, nanotubes, and quantum dots. Tubular virus particles such as the tobacco mosaic virus (TMV) can be used as templates to create nanofibers and nanotubes, since both the inner and outer layers of the virus are charged surfaces which can induce nucleation of crystal growth. This was demonstrated through the production of platinum and gold nanotubes using TMV as a template. Mineralized virus particles have been shown to withstand various pH values by mineralizing the viruses with different materials such as silicon, PbS, and CdS and could therefore serve as a useful carriers of material. A spherical plant virus called cowpea chlorotic mottle virus (CCMV) has interesting expanding properties when exposed to environments of pH higher than 6.5. Above this pH, 60 independent pores with diameters about 2 nm begin to exchange substance with the environment. The structural transition of the viral capsid can be utilized in Biomorphic mineralization for selective uptake and deposition of minerals by controlling the solution pH. Possible applications include using the viral cage to produce uniformly shaped and sized quantum dot semiconductor nanoparticles through a series of pH washes. This is an alternative to the apoferritin cage technique currently used to synthesize uniform CdSe nanoparticles. Such materials could also be used for targeted drug delivery since particles release contents upon exposure to specific pH levels.

title: Biomimetics