Christian Brassac

Pierre Fixmer

Lorenza Mondada

Dominique Vinck

Interweaving Objects, Gestures

Keywords:

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

This paper focuses on the articulation between collective activities, objects, and multimodal resources. Discussing recent theories on action, activity, interaction, and social practices, it points out the fact that although the ecology of action is becoming a key topic in various disciplines, studies that explicitly take artifacts and gestures into account -both theoretically and empirically -as they are actually mobilized by participants in interaction have remained underdeveloped. This raises some questions about the praxeological definition of these objects and multimodal resources, and the way in which an empirical analysis can deal with them.

In this paper, we will propose an interdisciplinary attempt to articulate objects, gestures, and talk within collective activities in context. We will do this by presenting a general discussion of contemporary paradigms dealing with activity (Section 1: An Interdisciplinary Framework for Rethinking Activity) and recognizing the importance of artifacts (Section 3: Objects in Action ), and we will do so not only by reviewing existing proposals, but also by tackling an empirical case, the introduction of computarized medical records at a hospital (Section 2: An Empirical Case: Implementing Computarized Records in a Hospital). Our analysis of a meeting about the project (Section 4: "Prescription" versus "Ordonnance") will provide an empirical opportunity to discuss the interrelationship between the definitions of various kinds of artifacts, and multimodal collective practices.

The Distributed Cognition approach was developed by Edwin Hutchins and his colleagues in the mid-to late 1980's as a new paradigm for rethinking cognitive phenomena in all domains. The theoretical and methodological bases of the approach derive from the cognitive sciences, cognitive anthropology, and the social sciences. Distributed Cognition argues that human cognition can best be understood by considering it as a social-culturaltechnical phenomenon. The components of cognitive activity cannot be limited to mental representations, but must include social structures, culture, individuals, and tools. Human activity is not characterized solely by brain activity; on the contrary, the cognitive process is distributed across the members of a social group, across individuals and material or environmental structures, and across time (products of earlier events can transform the nature of later events). Distributed Cognition is able to highlight complex interdependencies between individuals, and between individuals and artifacts, in their collaborative activities. This perspective grants importance to an ethnographic approach, and its unit of analysis includes all elements of the setting without putting actors before artifacts. Unlike Activity Theory, Distributed Cognition accords an equal weight to human beings and material objects (artifacts) in understanding cognitive processes, although both paradigms see objects as the key to understanding social and cognitive activity.

A major focus of ethnomethodologically-inspired Conversation Analysis, launched in the 1960's by Harvey Sacks and Emanuel Schegloff, has always seen social activities as locally-situated practical accomplishments. In order to describe the central role of these practices and the procedures (or methods, according to [START_REF] Garfinkel | Studies in ethnomethodology[END_REF]) that organize them, Conversation Analysis is based on empirical data constituted by naturally occurring interactional events that have been audio-or videotaped. Recordings of this sort are aimed at preserving the fundamental temporal and praxeological features of the activity, which are indispensable for its analysis [START_REF] Mondada | Video recording as the preservation of fundamental features for analysis[END_REF]. The recorded data undergo a fine-grained transcription. Both the recordings and the transcriptions provide the details participants attend to in order to locally accomplish the organization of their actions and the production of their accountability. Thus, these details are not just used by researchers to empirically support their analysis; rather, they are considered first and foremost as they are treated in an endogenous way by the participants as they give order, intelligibility, and coherence to their social actions. Analyses focusing on these locally relevant details have been elaborated within the frameworks of ethnomethodology and Conversation Analysis, although these two fields are much more distinct today. Both have inspired a number of different approaches to conducting detailed analyses of work activities, such as the study of talk in interaction in institutional settings [START_REF] Drew | Talk at work[END_REF] which focuses on the organization of talk, workplace studies [START_REF] Luff | Workplace studies: Recovering work practice and informing system design[END_REF] which look more specifically at the organization of professional activities within complex spaces, technologically mediated environments, and multimodal practices, and ethnomethodological studies of work [START_REF] Garfinkel | Ethnomethodological studies of work[END_REF], which are more ethnographically oriented. In this framework, the work by [START_REF] Suchman | Plans and situated actions: The problem of human/machine communication[END_REF], deeply inspired by Garfinkel's reading of Wittgenstein, has crossed over into a number of these fields (for instance, via its participation in workplace studies) and has been labelled situated action, now influential for researchers in ergonomics and in situated and distributed cognition. Suchman's study (1987) was one of the first to introduce into this intellectual framework the importance not only of talk but also of objects and situated elements within courses of action such as problem solving, which in this study takes place around a photocopy machine. In studying how users interact with the photocopy machine, Suchman points out the importance of the indexicality of action and critically re-specifies the role of plans, not as determining action but as a resource for action.

Actor-Network Theory has its origins in sociology and in the anthropology of the sciences, initiated in the 1980's by Bruno Latour and Michel Callon. It focuses on setting up relations and networks without any a priori distinctions between the involved entities, whatever their qualities and their human or non-human nature. Relations are the result of a translation process in which each entity moves. They mutually redefine and engage each other. From relation to relation, a heterogeneous sociotechnical network emerges, which can be limited or extended, and which can be interconnected in a hard-and-fast or slack way. When the network is highly interconnected, it evolves as a new entity or a new actor (actornetwork). Any entity can be considered as a network in itself. For instance, a scientific statement is the summary of a sociotechnical network. In the same way, a machine, a human being, or an organization can be seen as a network. The Actor-Network Theory approach focuses on practices for sociotechnical network building. It requires the observer to avoid any a priori asymmetries (for instance, between the human and the non-human) and to follow associations without any a priori limitations. Two major methodological principles are: follow actors and artifacts from one point or place to another (do not confine oneself to a specific situation), and think symmetrically (give equal consideration to winners and losers, truths and beliefs, humans and others, innovators and users, etc.). These paradigms vary not only in their epistemological premises or analytical mentalities, but also in how they approach empirical data and actually define the very data on which they work. In the next section, we will emphasize the way in which these various methodological insights have inspired our interdisciplinary approach to an empirical case.

An Empirical Case: Implementing Computarized Records in a Hospital

The implementation of a new computer device in a professional and institutional milieu is an exemplary and perspicuous [START_REF] Garfinkel | Two incommensurable, asymmetrically alternate technologies of social analysis[END_REF] setting to observe when interested in the intertwining of technologies, practices, objects, and participants. Among other professional and institutional settings, hospitals are an ideal place for doing fieldwork because of their complex organization, fragmented activities, and heterogeneous participants [START_REF] Keating | Biomedical platforms[END_REF][START_REF] Strauss | The social organization of medical work[END_REF]. In the medical context, formalizing procedures in order to introduce electronic records or computerbased decision tools may involve many obstacles and often generates considerable resistance [START_REF] Berg | Rationalizing medical work: Decision-support techniques and medical practices[END_REF] among a large number of heterogeneous yet autonomous actors who are difficult to enroll [START_REF] Callon | On interests and their transformation: Enrolment and counterenrolment[END_REF]. Even defining the tasks or entities to be formalized and computerized, which necessitates negotiation to obtain widespread agreement, can take a very long time.

In what follows, we will focus on a specific case, the computerization of medical files in a large French hospital. The aim of this technological innovation was to secure the traceability of blood products by developing an electronic medical record for each newly hospitalized patient. The creation of a unique electronic record for each patient that would store all transfusions and blood products he or she would receive was designed as a solution to the huge problems caused by poor traceability of blood products (only 96%), ending in the disappearance of thousands of products. This case was approached through a variety of field methods. Attempts to introduce computarized patient records have been going on for six years, but the process is still not finished since such records have not yet been implemented. For one year, fieldwork was carried out: field notes were taken; participant emails, written documents, minutes of meetings, slide shows, and copies of screens circulating among the actors were collected; and interviews were conducted with various actors with different responsibilities and perspectives within the project. In the entire history of the project, the representatives of the involved entities met only once, and this meeting was videotaped.

The corpus that attempts to document this project, although rich, is therefore partial, fragmented, and heterogeneous. If the observers had only partial and limited access to the unfolding of the project, this was even more so for the participants themselves, whose picture of the situation was much more incomplete and often relied on fragments of information provided by the observers as they tried to understand what was going on. On the other hand, the participants had some information and knowledge the observers did not get. Many documents produced by the actors were included in our corpus, but the actors also used some of the documents we produced, such as interview summaries or narratives of the project's history. The corpus thus played a part in the development of the events, reflexively contributing to shaping the local understanding of the project and the generation of meaning.

In this paper, we will focus on the videotaped meeting in which the medical staff, the computer engineers, and the administrative personnel of the hospital are discussing the state of the project and negotiating the tasks to be accomplished and the objectives to be met.

Since 1993, French law requires hospitals to draw up and save a single blood transfusion record for every patient. At the time that our fieldwork was carried out at Vinatier Hospital, records were being produced by every hospital department where the patient entered, and were kept in the patient's paper file specific to individual wards. Thus, records were not shared among departments, and the history of antecedents was lost. However, a discussion was held regarding the possibility of computerizing patient files, which was seen as an opportunity to develop blood transfusion database shared by all hospital wards. The implantation of such a database was complicated by various problems (i.e., traceability of blood products, traceability of the patient's medical history, data protection and access, data exchange between blood-product suppliers and hospitals). In March 1996, while waiting for further developments regarding electronic records, the hospital hemovigilance commission set up a procedure using paper files only, at the same time as a work group started discussions among hospital system departments and blood suppliers. Even though the latter were considered a national leader in the field, they faced problems of data incompatibility and the negotiations were stopped.

Regarding the electronic blood-transfusion records, the physician at the head of the hemovigilance service defined the specifications, and acted as a mediator between the director of data processing and the hemovigilance commission. The latter presented and discussed a first model in December 2001. A few weeks later, the hospital was audited for quality certification. Because the auditors were very critical regarding the blood-transfusion records, the hospital director wrote a mission letter in January 2002 and set up a project group to solve the problem. The group was run by the president of the hemovigilance commission (Dr Lamblet), the director of data processing (Mr. Steiner), and the head of the hemovigilance department. Many e-mails were circulating at this period among the medical staff, but no formal meetings were held. Through these informal interactions, medical doctors and system engineers re-defined the problem and agreed on a solution. A new model for electronic records began to circulate, and the data processing department started development. In April, a computer engineer gave a power point presentation of the model in front of the hemovigilance commission, and then during the summer, a prototype was tested in a resuscitation unit in which Dr Régnier works. From the doctors' and the nurses' points of view, the experiment failed. There were no meetings between computer engineers and practitioners until several months later when, thanks to the mediation of the head of the hemovigilance department, the actors (from the resuscitation unit, data processing staff, and the hemovigilance department) agreed to meet in the presence of a sociologist who videotaped the event.

The intertwining of intermediary objects (many e-mails, drafts of procedures, minutes of meetings, powerpoint presentations, "sheets in use" or prototype sheets of the patient file, computer screens, etc.), talk and actors evolved throughout the project. What appears in the excerpts quoted below is only a part of these entities, including objects entering into the scene for the first time.

The meeting is thus the unique occasion where representatives of the various groups involved in the project are co-present and can assess areas of agreement and disagreement, by way of a discussion organized not only by verbal resources, but also by body movements and gestures, and by showing, exhibiting, and putting on the table various artifacts that create complex links with the electronic medical record being discussed. The electronic record and the computerized device are complex entities, materialized in software, in printed records, in extra-technological objects, in ways of using the computer, and in ways of organizing ordinary work around the file; the virtual electronic record is an entity that travels around to various places, going from the computer of the engineers designing the system to the computer of the doctors and nurses who use (or do not use) it, and to the addressees of the blood product orders, etc. The electronic medical record links very different contexts, people, objects, and problems, and the aim of the meeting is to determine to what extent these links are working, could work, or will never work. In this sense, the meeting brings into play a number of relationships between the entities that are abstractly or materially related within the project.

Let us now introduce a first excerpt of this meeting. Its analysis will provide a basis for tackling the question of objects and artifacts, as well as questions related to the unavoidable choices that have to be made when presenting such a corpus and the reasons for focusing our analysis on this particular moment. (Our transcription conventions are explained at the end of the paper.) Excerpt 1 (tape 1/9'20) [xxx LAM le le noyau/ (.) du du système/ il a l'air de fonctionner/ the the core/ (.) of the the system/ it seems to work/ le problème c'est son intégration en amont et en aval the problem is including it upstream and downstream

* EFS: French Blood Organization

This excerpt shows how Lamblet succeeds in (momentarily) obtaining from Dr Régnier an agreement about the "simplicity" of the device. However, coming to this agreement takes time -thus showing that it is to some extent problematic -and implies a series of reformulations of the problem that gradually transform it until it becomes acceptable. Lamblet's long speeches are characterized by a fragmented syntax with frequent insertions. For example, on line 1 he begins with a question, but then changes it into a declarative statement in reported speech; he reformulates the question on line 5, but again on line 8 and 10 inserts other considerations, delaying the question until line 11 and transforming it into a yes/no question. Interestingly, these insertions concern two fundamental features of the electronic record: (a) the difference between working on paper (2) and working on the screen (6), and (b) problems arising before and after the moment when the file is printed (8 and 10).

After echoing the part of the question (12) that states the conditions under which he can answer positively (i.e., disregarding file-access problems), Régnier repeats the positive content of his agreement. This kind of answer contrasts with a simple "yes," which would implicitly ratify and accept all of the question's premises.

After a side sequence (omitted in the transcription), Lamblet again summarizes Régnier's position, where he reformulates his "the prescription is easy" (14) as "ordering is relatively simple" (31) and reformulates it again (35-36) after having inserted a justification (32). This time he doesn't wait for Régnier to agree but targets the agreement of the nurse, who answers with a collaborative sentence (39: she adds a prepositional phrase to his statement about the simplicity of the device). On this turn, Lamblet is using the terms "simple," "simply," "simplicity" in an overgeneralized way, concerning not only the device but also his ongoing evaluation of it.

Having obtained the local agreement of the doctor and the nurse, Lamblet can conclude that the "core seems to work" (45). This final assessment takes two minutes to be produced and secured. It requires questioning the doctor in quite an elaborate way, and before it can be obtained, some fundamental limitations about the clearly delineated domain the medical staff agrees to consider "simple to use" have to be formulated.

In this excerpt, the participants focus on both a difference between two material realms, the paper and the electronic record on the screen, and on an object, the "prescription," which moves back and forth between them but is nevertheless considered stable among them. Thus, although recognizing an important change between ways of working with paper and ways of working on the computer, the participants deal with the objects manipulated in these activities as if they were indifferent to their materializations. Moreover, in the discussion, an agreement is reached about the "simplicity" of the device. This agreement is based on a simplification of the objects, procedures, and context involved; it is based on an exercise consisting in abstracting the practical and detailed features that characterize the objects and actions as they are ordinarily managed. Thus, the agreement is reached about a fiction actively fabricated through discursive devices that disembody the objects and the everyday work.

In a way, what the participants have done here is what is routinely done within the social sciences, namely, ignoring the situated, embodied nature of work objects and gestures; in order to reach a momentaneous and fragile agreement, the participants are, for all practical purposes, producing disincarnated objects, i.e., objects simple enough to travel across contexts without changing, objects accomplished as "immobile mobiles" [START_REF] Latour | Les « vues » de l'esprit[END_REF]. In fact, the very next moment of the meeting will show that this disembodiment does not hold for long, that it is fragile and contingent, and will be radically problemized in the very next exchange. In an analogous way, we will argue that objects have to be treated in the social sciences with all their richness, complexity, and embodied depth in order to retain their efficiency within activities.

Objects in Action

The four fields of study briefly described above have been influential in the conceptualization of objects and artifacts within social practices. The viewpoint of each one will be presented while paying particular attention to the question of objects as "intermediaries," a notion borrowed from actor-network theory.

Distributed cognition has placed emphasis on the fact that cognition is not a purely mental kind of processing, but rather, takes place within a relationship to the surrounding world that is made up of concrete, material entities and is supported by the corporeal mobilization of the cognitive entity. This non-internalist view thus quite naturally leads one to consider the crucial role of the object in this externalization movement. When [START_REF] Hutchins | Cognition in the wild[END_REF] studied the operator in action, he showed how the readout on a control panel fulfills a constitutive function of the operator's activity. As underlined by [START_REF] Nardi | Some reflections on the application of activity theory[END_REF], who insists that we not reject the computational stance of cognition, the process is distributed over the human entity (body and central nervous system) and the technical device (see also the special issue of Intellectica introduced by [START_REF] Brassac | Computers and knowledge: A dialogical approach[END_REF]). The latter is thus considered to shape the cognitive process. In this field of study, then, the object is at the core of reflection on cognitive processes. [START_REF] Kaptelinin | The object of activity: Making sense of the sense maker[END_REF] stresses the complexity and the multiple uses of the term "object" in various versions of activity theory: he distinguishes the intended goal toward which activity is always oriented, in other words, Leont'ev's "predmet' or the artifact used to act, from Leont'ev's "object" (Leontiev, 1975(Leontiev, /1984)). It can nevertheless be stated that, according to activity theorists, activity mediates interactions between subjects (actors) and objects (as "physical things"). Mediation is achieved through the use of a set of cultural means. Their means consist not only of technical tools, which are artifactual structures, but also of signs, which are semiotic and psychological processes [START_REF] Béguin | Designing for instrument-mediated ctivity[END_REF].

Even though conversation analysis started to develop with a strong emphasis on the organization of talk-in-interaction, as described on the basis of telephone calls and face-toface conversations (among other data), this research approach is also an analytical domain where systematic video analyses were developed very early on (see, for instance, the work by C. Goodwin in the US and C. Heath in the UK, already initiated by the late 1970's) [START_REF] Goodwin | Conversational organization: Interaction between speakers and hearers[END_REF][START_REF] Heath | Body movement and speech in medical interaction[END_REF]. Video analysis makes it possible to consider not only the verbal resources that contribute to the interactional order, but also, and more broadly, multimodal resources including gestures, body behavior, gazes, and kinesic practices. As far as multimodality is concerned, the analysis focuses on technologies, artifacts, documents, and other objects, seen as material resources that are locally and contingently mobilized within the action and provide for its organization in both a systematic and indexical way. The analysis of embodied action [START_REF] Goodwin | Action and embodiment within situated human interaction[END_REF], of actions with objects, and of technologies in action has been massively developed in workplace studies [START_REF] Button | Technology in working order: Studies of work, interaction and technology[END_REF][START_REF] Suchman | Constituting Shared Workspaces[END_REF][START_REF] Luff | Workplace studies: Recovering work practice and informing system design[END_REF]Heath & Luff, 2000) aimed at examining occupational and expert practices, which often occur in complex spaces -called "coordination centres" by [START_REF] Suchman | Constituting Shared Workspaces[END_REF] -involving sophisticated information and communication technologies. One of the goals is to show how action uses the possibilities and limitations of technology as situated resources, which in turn contribute to shaping them (Mondada, in press).

Inspired by Actor-Network Theory, and the study of collective scientific and technical activities such as scientific cooperation networks [START_REF] Vinck | Les objets intermédiaires dans les réseaux de coopération scientifique. Contribution à la prise en compte des objets dans les dynamiques sociales [Intermediary objects in scientific cooperation networks. A contribution to taking objects into account in social dynamics[END_REF][START_REF] Vinck | A network approach to studying research programmes: Mobilising and coordinating public responses to HIV/AIDS[END_REF]) and product-design processes in the manufacturing industry [START_REF] Jeantet | Les objets intermédiaires dans les processus de conception des produits [Intermediary objects in the product design process[END_REF][START_REF] Vinck | Everyday engineering: An ethnography of design and innovation[END_REF][START_REF] Vinck | Mediating and commissioning objects in the sociotechnical process of product design: A conceptual approach[END_REF]), the notion of "intermediary object" refers to a physical entity that connects human actors. [START_REF] Latour | Science in action: How to follow scientists and engineers through society[END_REF] showed that the monitoring of recorded data (drawings based on analysis instruments, tables of figures, diagrams, and texts) provides a different perspective on the analysis of scientific practices and gets past epistemological questions. Investigations into scientific and technical practices have shown that actors rely heavily on such intermediary objects, setting them up, making sure they are passed on to others, and generally making use of them. In design activities, intermediary objects supply a channel for many important interactions. They are used to back up action, convey information, make intentions or compromises come true, impose constraints on actors, mediate between diverging logic-based actions, and so on. They represent a virtual object that has yet to be manufactured. By way of these representations, actors assume they will be able to communicate their idea of the problems they have to solve, the possible solutions, and the constraints to be taken into account. Intermediary objects mediate the way each specialist expresses him/herself and the setting-up of a compromise. When the object is robust enough to support interactions between various social worlds, they can be called boundary objects [START_REF] Star | Institutional ecology, 'translations' and boundary objects: Amateurs and professionals on Berkeley's Museum of Vertrebate Zoology, 1907-1939[END_REF].

The circulation of objects constitutes an area of collective action. Looking at intermediary objects thus provides a means of understanding a large part of professional activities; it reveals the organization of these practices, the distribution of tasks, their sequencing, and the areas where regulation between actors takes place. Following objects provides a means for analyzing how the actors' different interpretations and perspectives on the object are uncovered. The present investigation records the multitude of adjustments that take place throughout these ongoing dynamics. They are useful indexes for studying actionbased logic, conventions, and power struggles. They also mark the transition from one stage to the next.

As ending points, objects reflect agreement among the actors, and materialize that agreement in the form of an artifact. They become representatives of the actors who contributed to build them, and they are used by other actors who have to interpret them and change them into something else. They offer anchor points, new points of departure, and future perspectives all the while limiting the possibilities for action. Their agentivity (Latour, 1996) relates to the fact they sometimes carry more things than intended by the actors. They have unforeseen effects. If actors work so hard to "discipline" them, it is precisely because they are always in danger of slipping out of their control and introducing some new element into the action.

"Prescription" versus "Ordonnance"

In order to develop our conception of how objects are dealt with within an activity, we will concentrate on a second excerpt that immediately followed the first. We will see that the agreement reached with some effort in the first excerpt is immediately destroyed by the fact that the conditions under which it could work did not hold up for long -as if the objects and the complexity of their situated use resisted all attempted oversimplifications. We will use these two excerpts, chosen from among a set of very rich field materials, to propose a detailed analysis that shows how the processes involved in the use and design of objects can be observed as they actually appear during, and while constraining, the interaction. The exact conditions, positions, environments, and modalities in which the relevance of objects emerges within interactions fundamentally interest us. Descriptions based on a single transcript allow us to identify processes in their making and the dimensions that constitute them. In this sense, the procedural mechanisms by which objects are used, are made relevant, and constrain the course of action are not just those at play in this particular excerpt; they have a more general scope. Failing to look at the details of how they are manipulated and transformed, would mean side stepping-and thus making unavailable for analytical scrutiny -their embodied and situated properties, i.e., it would mean pursuing a simplification of their use and power.

In the second excerpt, we will take into consideration not only how the participants refer to and categorize various objects during talk-in-interaction, but also how those objects are materially designated and called up during the meeting. To do so, we will propose the transcribed excerpt in its entirety. We will refine it later, with references to gestures and object manipulations. In this excerpt, the consensus established by Lamblet (LAM) is not held for very long in the confrontation between the system's user, Régnier (REG), and the system's designer, Steiner (STE). We will try to understand the praxeology of this disagreement, which has to do with divergent conceptual as well as material and practical views on two related, indissociable, but yet different objects: "prescription" and "ordonnance." Since the status of these objects undergoes continuous changes within the action, we will not try to translate or clarify their meaning once and for all, but will use the same original categories as the participants, trying to reconstruct the meanings they successively attribute to them.

The re-emergence of disagreement The beginning of the second excerpt immediately follows the ending of the first. Lamblet makes a proposal (1-3) aimed at reaching an agreement, even if only a minimal one, about the positive evaluation of the system (of his "core") [1]). This statement is aimed especially at Régnier (3): Lamblet asks Régnier to ratify it, and in doing so, presents the importance of sharing his statement, which is to be achieved by obtaining the acceptance of the other actors. Instead of subscribing to Lamblet's projection of a minimal agreement, Régnier produces an overlapping reply (4) that raises a new issue. In this manner, Régnier gradually introduces a point of disagreement, which is built up from an opposition (8-10) between "you might have a tendency to click and send/" (8) and "you have to convert this prescription into an order" (9-10), the two assertions connected with the particle "no" (9). Régnier thus pinpoints two procedures which he differentiates and which will trigger a lengthy discussion about the contrasted terms, "prescription" and "ordonnance."

Right away, Régnier's objection is received in different ways: first, by incomplete turns at talk by Lamblet (11) and Steiner (12) marked by a typical dispreferred format ("yes but"), and second, by Lamblet's attempt to play down the status of the system (he is no longer talking about the "core" but about the "pro-", which is probably the first syllable of "provisional" or "prototype," and about the "test"; this recategorization of the system insinuates that the objection is about a fixable detail, and this opens up a negotiation to that effect). By contrast, Steiner reacts in a very different way (beginning with "no no" [15]) and re-asserts, on the contrary, that the problem is central (and not marginal) ("we're k-in the heart of the software" [16]). While Lamblet points out the possibility of a conversion, Steiner defends the device as it is, relying on the previous act of "commanding" (17-24) and restating the fact that the device conforms to that command. In other words, he brings another actor into the picture, and in doing so shows that the legitimate frame of reference for evaluating the device is not the user but the orderer. By invoking the command, Steiner reformulates the task Régnier had mentioned in his objection: "that's how you've got to do it\ once you've done the prescription you do the order and the order / you fax it\" (18-21). This reformulation is interesting in several respects: firstly, it is stated in a prescriptive fashion ("you've got to do it"), and secondly, it defines the sequence of a series of actions imputed to "you" (in the second person, here, addressing Régnier) and spread out over time (the prescription -> the order -> the fax). This sequencing of actions is in sharp contrast with the "tendency" invoked by Régnier, who outlines another series of actions (click -> send [9]). This reply, which, by way of the command, rejects Régnier's position, receives no reaction at all from either Régnier himself or Lamblet ( 22), despite Steiner's new attempt to prompt a response (23-24), which is answered by a silence (25).

The discussion only resumes through the introduction of a new aspect, "the regulations" (26-27), ascribed to Régnier, who allows Steiner to reinforce the importance of the "paper order" and thus of the middle phase of the three successive actions he just sketched out. Here again, Régnier's reaction is an explicit disagreement ("no it's not in the regulations" [28]), to which Steiner replies, speaking at the same time ("oh yes it is" [29]).

The disagreement between them is quite clear.

Régnier proceeds (34) to make a move that breaks away from the chain of negations in the preceding turn, by shifting from the argument that just took place to pointing at a document. There is thus a change in the mode of discussion and a shift from an exchange that brought up referents verbally (the referents are discourse objects) to an exchange that brings up referents via the gestural modality (the referents are material objects that are present and pointed to on the table). This second interaction mode will be initiated twice, the first time by Régnier (34) and the second time by Steiner (74). We will take a close look at these two moments, which grant a fundamental role to artifacts.

Régnier's overt use of the yellow sheet [34-54]

On line 34, Régnier initiates a new sequence, with a description, using a deictic term "ça" ("that") and showing a yellow sheet he has just taken out of a pile of documents in front of him. "Ça" is categorized first as an "ordonnance" by himself in an interrogative mode and by the nurse (as Régnier holds the sheet up in front of him), and then as a "fiche de prescription" in a subsequent repair (as he shows the sheet to the co-participants) (36) (see image 1). Steiner immediately equates this object with the one printed by the software ("well that's what you print out/" [37]), again using the deictic term "ça" (and not the name). Régnier, who is still holding the yellow sheet, produces a second descriptive turn (38), using the term "fiche de prescription" once again, with which Steiner agrees on his next turn (39). This local agreement is destroyed by Régnier's subsequent turn (40-41): whereas Steiner equates the exhibited object with the formalized one produced by the computer, Régnier differentiates them, introducing a difference between "fiche de prescription" and "ordonnance," and claiming that when using the software the doctor sends the latter, not the former.

Lamblet tries to dismiss this distinction as being just a "terminological" problem ( 43), but Régnier insists (44), pointing out that the conversion of the former into the latter necessitates an extra operation using the software. So, Régnier shows the yellow sheet in order to speak about another set of objects and practices which is supposed to replace the sheet but is not equal to it, contrary to what Steiner suggests. This is done using the gesture that "animates" the yellow sheet (for transcript conventions concerning gestures, see the end of the paper):

(from excerpt 2, lines 44-46) REG oui mais/ pour passer de de *la fiche de prescription/* (.) *UNDERSCORES THE TITLE "F. DE P. " * ON THE TOP OF THE YELLOW SHEET--* y a une manoeuvre informatique/ *pour (.) transformer**ça/ en ordonnance* *WIDESEMICIRCULAR GESTURE* *HOLDS IT* FROM RIGHT TO LEFT----------* Régnier's gestures use the yellow sheet to materialize the starting point of a conversion process iconically represented by a semicircular hand movement that ends at a point on his left (the "ordonnance"). The conversion is thus spatialized by Régnier's gestures. In subsequent referential gestures, Regnier will use this same gestural space again (for uses and conservations of diagrams drawn gesturally in the air, see [START_REF] Enfield | Demonstratives in space and interaction: Data from Lao speakers and implications for semantic analysis[END_REF][START_REF] Liddell | Real, surrogate, and token space: Grammatical consequences in ASL[END_REF]. He again emphasizes the same point on the sheet when he speaks of the formalized "fiche de prescription" (which he does clearly on line 48, and faster on line 53), and he once again points to the same location on the table to his left when mentioning the "ordonnance" (54). Thus, the conceptual distinction Régnier is making -in order to demonstrate and criticize the added complexity of the software -is materialized in gestures and locations using an artifact that precisely escapes his critique.

Steiner's use of his powerpoint documents [54-85]

While Régnier is explaining further complexities of the software (54-59), Steiner looks through his own stock of documents. He continues to do so as a question being raised by Dillet (a computer engineer) -which interestingly brings out his difficulty understanding Régnier's distinctions and proposes a clarification of the status of the yellow sheet as an "older document" (60-73). During the sequence initiated by Dillet, Steiner reads and arranges his documents. This activity is both very distinct from Régnier's concealment of the nolonger-useful yellow sheet, and similar to another participant's (Rioux) picking up and reading through his own documents. Régnier has created the opportunity for a mode of discussion based on the showing of various objects. Steiner brings to bear other documents exhibiting his preparatory activity during the sequence opened by Dillet. All this creates a "contextual configuration" [START_REF] Goodwin | Action and embodiment within situated human interaction[END_REF] where documents are moved, reordered, and significantly positioned on the table for the sake of the ongoing argumentation -not only on the part of the speakers, but also of all participants around the table who begin to search through their own documents (see also [START_REF] Streeck | How to Do Things with Things[END_REF]. This contextual configuration, which makes the document uses relevant, is acknowledged by Régnier who gets out his glasses even before Dillet's sequence is closed (70), as if he were adjusting very early to the possible next move.

Indeed, the next sequence is initiated by Steiner (74) with a gesture very similar to Régnier's initiation of the previous one ( 34 ) into a new materialization, a representation of the electronic prescription and its printed version. In this way, Steiner goes along with Régnier's differentiation, adopting it for his own documents. He also goes along with Régnier's previous statement ("you might have a tendency to click and send/" 8-9), thereby concentrating the manipulations of the same object. He does this in a proposal (82), firmly formulated first and then rephrased in a modalized way ("uh:: may be/ (.)" [82]) by pointing twice with his pen to the same document (83). To some extent, Steiner is using his first document in a way similar to Régnier's use of his yellow sheet.

Régnier, supported by Lamblet (85), rejects the suggestion, repeating his critique of the system: if the user checks off a series of products on the "fiche de prescription" and then prints it, he obtains a long list of all eligible products and not (as in the "ordonnance") a short list containing only the selected ones. This difference is relevant and visible on the (new) image 2 image 3 electronic sheet (where the user has to check off items on a list) and not in the (old) yellow sheet (where the user has to write in the items he needs). In the new system, then, two distinct files have to be handled, whereas in the old system a single object contained two final, detachable documents, thanks to the old carbon copy system.

The limits of the negotiation This debate confronts and partially superimposes various referential realms, anchored in various contexts of practice. Régnier speaks of "prescription" and "ordonnance" as two distinct entities, but he himself and also the nurse (34-35) erase the distinction, which is questioned by Dillet, dismissed by Lamblet, and self-repaired by . Each actor points to different objects in order to refer to these two entities: these objects constitute their representations, not their materializations. And each person tries to bring to bear practices where these entities are either unified or separate. But each one does so within his or her own sphere, mobilizing objects related to his or her professional expertise, and thereby displaying their distance from each other through their bodies and the spaces they occupy.

Régnier's criticism of the software is repeatedly categorized by Lamblet as marginal and by Steiner as central. On Steiner's side, this produces a refusal to consider any change and repeated references to the original "commande": note that every time Steiner points out that the criticism of the system is central, he does not address it directly but instead refers to the initial command (16)(17)109). Interestingly, when referring to the initial command, Steiner repeats and maintains a strict distinction between "prescription" (to be filled in) and "ordonnance" (to be sent) (19)(20)(90)(91). This reference displaces the problem by no longer focusing on the user and his difficulties but on the administrative hierarchy. Régnier's criticism and request unify both the acts and the objects (i.e., the possibility of filling in and printing the same file), and refer to a different view of actual medical practices.

The systematic production of disagreement

In this paper, we analyzed a fragment of a meeting where attempts to come to an agreement accompanied by misaligned moves are repeatedly accomplished by the participants. These attempts and the responses they obtain shed light on the mechanisms underlying the production of a shared view of problem solutions. The common definition of the situation is not the condition for a successful discussion; on the contrary, a common definition has to be achieved through and by means of discussion -and this will be crucial for the potential continuation of a common project that can be further developed in a collaborative way. The moment we analyzed here gives us a glimpse of how, in this case, the medical staff and the computer staff were unable to achieve a common view of their mutual involvement in the project. Our method of analysis emphasizes the importance of the sequential organization of the turns at talk. For instance, the turns in which Lamblet is summarizing the situation so as to achieve a minimal agreement (at the end of Excerpt 1, beginning of Excerpt 2) are the end and the result of the extended sequences that precede it, sometimes suspended or deviated by other inserted sequences. In this sense, these turns appear to be summarizing the positions set forth, and have a closing effect on the current phase of the activity: they are located at a specific point in the sequential unfolding process, in a place where the joint arrival of all participants at this momentary closing point has been organized [START_REF] Schegloff | Opening up closings[END_REF]. This attempt to stabilize a mutual agreement is also the beginning and the condition for initiating the next activity phase, where the agreement reached can be the basis for further developments. In this sense, the summarizing turns claiming that there is an agreement project more to come: either turns displaying agreement (for the difference between claiming and displaying agreement see [START_REF] Lynch | Art and artifact in laboratory: A study of shop work and shop talk in a research laboratory[END_REF] -for example, turns initiating the collective development of a topic -or turns contesting the recapitulation -for example, turns introducing a new difficulty. This is precisely what happens at the beginning of Excerpt 2, where Régnier adds a new problematic element instead of falling in line with what Lamblet says in his turn.

In this sense, what is considered and dealt with by the participants as a "problem," a "difficulty," an "obstacle," is locally defined by the very way in which they produce their next turns; it is also the result of local (and potentially divergent; see Lamblet line 13 versus Steiner line 16) categorizations of a new topical entity as one that is "central" or "peripheral" to the topic being discussed, and as such, as one that constitutes a "marginal" or "fundamental" criticism. In our analysis, we have tried to follow the methodical organization of these various attempts to limit or expand divergent accounts of what is going on and what has been done.

Flexible transformations of artifacts-in-action

Our analysis focuses on the sequential organization of a fragment of a discussion, but also reveals the multimodal dimension of its organization. The sequential unfolding of the discussion is not only based on linguistic resources but also mobilizes multimodal resources such as bodily postures, gestures, and artifacts.

The way in which artifacts are brought to bear in this discussion sheds a light on the malleability of these objects within the course of action, and has a number of analytical and methodological consequences. The role of objects is now acknowledged in the literature, but it has not yet given rise to a systematic account of how these objects are configured, categorized, and used locally within actions, i.e., in the reflexive definitions of actions and objects, each one mutually shaping the other. In the fragment we studied, various objects were used; our analysis focused on Régnier's yellow sheet and on Steiner's printed powerpoint slides. These objects cannot be qualified and categorized once and for all by the analyst, since they change with the sequential positions in which they are invoked within the activity that uses them, and within the gestures and movements that mobilize them. For instance, Régnier mobilizes his yellow sheet in different ways: by just sketching out the move of removing it from the pile of documents where it was inserted and hidden, by holding it up in front of the audience, by showing it to Steiner, by pointing to a particular line while speaking. In each case, the document has a different kind of visibility, a different status as an object publicly displayed. The detailed make-up of the object can be rendered irrelevant (as in the vague and interrupted removal of the invisible document from the pile) or, on the contrary, can be pointed to and made relevant (when Régnier emphasizes "fiche de prescription" while referring to it with this name). Documents can be shown from afar, from within his personal space, as was Régnier's yellow sheet, or can be shown in an adresseeoriented way, as were Steiner's PowerPoint prints put in front of his interlocutor and displayed in view of being read. Each categorization of the object is accomplished by a specific gesturality, and reflexively reshapes the contextual configuration of the table as a differentiated public space.

Mobilizing documents plays an active part in the sequential organization of the talk: documents can be referred to without being shown, and the sheer act of holding up a document or putting it in the middle of the table accomplishes an accountable move within the discussion. Displaying objects -even if they are not the objects the talking is about -is a powerful way of producing evidence. In the case analyzed here, we have seen that although objects are used in this way, they do not always produce the expected consequences. For instance, Steiner displays two documents but then points twice to the first one, thereby recognizing that one document may be enough -which is precisely the point Régnier is trying to make. Objects create evidence that is not always the same as the evidence the participant's actions were aimed at creating. In this sense, they shape the action and are shaped by it.

Concluding on Objects and Multimodality

This paper focuses on the articulation of objects, gestures, and talk during collective activities in situ. Our interdisciplinary attempt is inspired by contemporary paradigms that address human activity and recognize the importance of artifacts. Tackling an empirical case, our analysis provides an opportunity to discuss the interrelationships between artifacts and multimodal collective practices.

We have brought to the fore the ecology of action and interaction by explicitly taking artifacts and gestures into account. The analysis reveals the sequential unfolding of the discussion based on the interweaving of linguistic practices and postures, gestures, and artifacts. It focused on the achieving a (dis)agreement, and on the multimodal practices that produce misalignment. The paper showed that some objects are defined praxeologically and contextually both as categories ("ordonnance" and "prescription") and as artifacts (their plasticity mobilized in interaction). These artifacts were, in this case, intermediary objects that mediated the way each specialist expressed him/herself and tried to configure the interaction dynamics so as to reach a conclusion. The artifacts were not effective instruments for fulfilling a function specified once and for all. They were mobilized and redefined as the discussion unfolded and as physical moves took place, thereby establishing their plasticity within the course of the action. They were locally configured, categorized, and used in action at the same time as they contributed to configuring the dynamics, postures, talk, and accomplishments taking place therein. These objects could not be qualified once and for all, neither by the actors nor by the analyst, but changed with the sequential positions in which they were engaged. Their qualities varied according to the categorizations they underwent via talk and gesture. They participated in the configuration of the physical and collective space, which was divided up and rearranged. This paper showed that artifacts are defined not only through their design and circulation, but also through a subtle interweaving that includes gesture and talk; they are malleable, not only when there are broken down and rebuilt, and when their meaning changes, but also through their involvement in a local configuration of people and artifacts, and in a sequence of postures, gestures, and talk. It also showed that artifacts are neither mere instruments in the service of an ongoing practice nor vectors of a social history, which would make things and persons asymmetrical. In some circumstances, the configuration -made up of talk, postures, and artifacts -escapes from the subject's orientation toward objects. Objects create evidence that is not always the same as what the participants want to create. In this sense, they configure and are configured by action. They can even acquire some autonomy from the actors who made them.

By bringing to bear the intersecting views of the linguist, the sociologist, and the psychologist, this interdisciplinary study shows that the interweaving of the discursive, gestural, and artifactual registers is at the core of the group's activity during the session analyzed here. A sequence of utterances connected to each other can only provide a scaffolding for the construction of meaning [START_REF] Bruner | Acts of meaning[END_REF] because they are deeply anchored in an embodied relationship incorporated in artifacts and distributed among persons and objects. Objects and properties in the material environment are reflexively constituted in, and by, verbal interaction. Conversely, discursive elements acquire their interactive statuses solely in, and by, their relationships to the ambient "artifactuality." A social interaction, the locus of knowledge generation, is a dynamic that comes to be via the shaping of formsforms of language, forms of bodies, and forms of artifacts. Humans and non-humans [START_REF] Latour | Politiques de la nature: Comment faire entrer les sciences en démocratie[END_REF] were at the heart of this collective practice here, which engendered the history of this particular work group. described phenomena < > delimitation of described phenomena xxxx string of talk for which no hearing could be achieved Descriptions of gestures and actions are transcribed according to the following conventions: * * a gesture is delimited between two symbols and synchronized with corresponding stretches of talk ste the participant making the movement is identified in the margin if (s)he is not the same person as the actual speaker im the temporal location of the screen shot is indicated within the turn POINTS gestures and movements are described in small capitals -----the gesture is held until the next closing boundary symbol ----> the gesture is held until the next symbol, situated on the following line ---->> the gesture is held until after the end of the excerpt .... gesture preparation ,,,, gesture retraction An indicative translation is provided line per line (in italics), in order to help reading the original.

  ): (from exerpt 2, lines 74-85) 74 STE mais quand vous diφtes fiche de prescription c'est φ ça φTAKES DOC 1, MAKE A WIDE SEMI-CIRCULARφ HOLDS DOC---> φGESTURE FOR PUTTING IT IN FRONT OF REGφ 75 REG *(2)* # *PUTS HIS GLASSES ON HIS NOSE AND LEANS OVER STE'S DOC* im # oui c'est ça * φ *MOVES BACK* ste ----->φ 79 STE ce que φvous imprimez c'est ça\# φTAKES THE SECOND DOC AND PUTS IT NEARBY THE FIRSToui c'est ça\* *HOLDS-------* 82 STE *alors rien ne vous empêche* aujourd'hui/ euh:: φ*peut-être/ (.) φ φMOVES HAND ON DOC1φ reg *MOVES BACK------------------* *LEANS OVER

  LAM de ce qu'y a après/ et des problèmes de l'EFS*\ une fois que what's after/ and problems with the EFS\ once you t'es d'ssus/ est-ce QUE: la prescription/ est simple ou compliquée\ you're on it/ is IT: the prescription/ simple or complicated\ REG euh une fois qu'on est euh sur l'é[-l'écrAN/ ((asks a question and gets an answer, 12 lines omitted)) LAM alors\ le le le parce que si j'ai bien compris le tu dis software en lui-même/ -fin le le le comment est-ce qu'on dirait itself/ -mean the the the what do you call it le le kernel du [sy-le le the the kernel of the [sy-the the RIC?

		uh once	you're	uh on the s[-the screen/
	LAM			[oui/
				[yes/
	REG c'est:: l-la prescription est facile/ il faut cocher le
		it's:: th-the prescription is easy/ you have to check off the
		nombre de de de produits sanguins/ eh de concentrés
		number of of of blood products/ eh of concentrates
		euh [c'est
		uh [it's
	LAM	[alors j'te pose une question tout d'suite/
		[so I'll ask you a question right away/
	1 LAM le système en lui-même\ est-ce que tu d-tu tu disais que
		the system itself\	were you say-	were you you saying that
	2	par rapport à la prescription papier c'était c'était la
		compared	to prescriptions on paper	it was it was the
	3	prescription papier était simple/ on collait les étiquettes/
		prescriptions on paper were simple/ you stuck the labels on/
	4 REG hum
	5 LAM on remplissait/ (.) .h est-ce que: par rapport une fois quand
		you filled in/	(.) .h is it:	concerning once
	6	tu es sur l'ecran/ euh de: de commande\
		you're on the screen/ uh for: for ordering\
	7 REG °oui°
		˚yes˚
	8 LAM abstraction de ce qu'y a avant pour y accéder/=
		disregard	what's	before to get to it/=
	9 REG =oui:
		=yes:

so\ the the the because if I understand right you're saying que la commande est relativement simple\ that ordering is relatively simple\ j'essaie pas de de: (.) de défen[dre qui que ce soit I'm not trying to to:(.) to defen[d anything at all REG [non non non [no no no LAM j'essaie simplement de faire un bilan des choses\ .h tu I'm just trying to get the big picture\ .h you dis que le système est relativement simple à utiliser pour say the system is relatively easy to use for faire la commande/ euh:: donc madame Richter dit que (.) POUR ordering/ ehm:: so Mrs Richter says that (.) FOR les infirmières y a (quand même)/ simplement sur la saisie nurses it's (anyway) only when entering du code à barre une simplicité de fonctio[nnement the bar code it's easy to [operate RIC [avec la douchette [with the douchette LAM avec la douchette qui apporte quelque cho:se/ donc on with the douchette which adds some:thing/ so we est/ (.) si on regarde simplement le nou-le le: le logiciel are/ (.) if you simply look at the co-the the: the

TABLE - -

 - >> 83 φd'imprimer ça/φ (.) φet d'envoyer ça/φ φPOINTS TO DOC1φ φPOINTS TO DOC 1φ 84 REG oui mais vous allez [voir tout c'qui va so[rtir 85 LAM [ça [ça fait trois mètres Steiner puts two documents on the table, in an overt way and with an emphatic gesture (like shuffling cards on the table), and then turns to Régnier (74, 79). The documents are powerpoint slides, containing the forms produced by the computer program. Twice, Régnier leans overtly over the table to recognize each document and moves back to his original position. Both movements accompany a request for confirmation, by which Steiner translates Régnier's categories ("fiche de prescription" and "what you print"


Dr Chris Tyler-Smith
email: chris@bioch.ox.ac.uk

Report

The Genetic Legacy of the Mongols Tatiana Zerjal, 1 Yali Xue, 1,2 Giorgio Bertorelle, 3 R. Spencer Wells, 4 Weidong Bao, 1,5 Suling Zhu, 1,5 Raheel Qamar, 1,6 Qasim Ayub, 1,6 Aisha Mohyuddin, 1,6 Songbin Fu, 2 Pu Li, 2 Nadira Yuldasheva, 4,7 Ruslan Ruzibakiev, 7 Jiujin Xu, 5 Qunfang Shu, 5 Ruofu Du, 5 Huanming Yang, 5 Matthew E. Hurles, 8 Elizabeth Robinson, 1,* Tudevdagva Gerelsaikhan, 1, † Bumbein Dashnyam, 9 S. Qasim Mehdi, 5 and Chris Tyler-Smith We have identified a Y-chromosomal lineage with several unusual features. It was found in 16 populations throughout a large region of Asia, stretching from the Pacific to the Caspian Sea, and was present at high frequency: ∼8% of the men in this region carry it, and it thus makes up ∼0.5% of the world total. The pattern of variation within the lineage suggested that it originated in Mongolia ∼1,000 years ago. Such a rapid spread cannot have occurred by chance; it must have been a result of selection. The lineage is carried by likely male-line descendants of Genghis Khan, and we therefore propose that it has spread by a novel form of social selection resulting from their behavior.

The patterns of variation found in human DNA are usually considered to result from a balance between neutral processes and natural selection. Among the former, mutation, recombination, and migration increase variation, whereas genetic drift decreases it. Natural selection can act to remove deleterious variants (purifying selection), maintain polymorphism (balancing selection), or produce a trend (directional selection). Clear examples of the latter are rare in humans, but probable cases, such as those associated with resistance to malaria [START_REF] Hamblin | Detection of the signature of natural selection in humans: evidence from the Duffy blood group locus[END_REF] or unidentified pathogens [START_REF] Stephens | Dating the origin of the CCR5-D32 AIDS-resistance allele by the coalescence of haplotypes[END_REF], can be recognized by the "signature" they leave in the genome. The rapid increase in frequency of the selected allele and its linked sequences results in a haplotype that is found at higher frequency than would be expected from its degree of variation. We have now identified such a haplotype on the Y chromosome, but we suggest that its spread results not from a biological advantage, but from human activities recorded in history.

In surveys of DNA variation in Asia, we typed 2,123 men with у32 markers to produce a Y haplotype for each man; these included 1,126 individuals described elsewhere [START_REF] Qamar | Y-chromosomal DNA variation in Pakistan[END_REF][START_REF] Zerjal | A genetic landscape reshaped by recent events: Y-chromosomal insights into Central Asia[END_REF]. Over 90% of the haplotypes showed the usual pattern [START_REF] Mohyuddin | Y-chromosomal STR haplotypes in Pakistani populations[END_REF]: most males had a unique code; and the few haplotypes present in more than one individual were generally found within the same population. However, we also saw one pattern that was novel in two respects. First, there was a high frequency of a cluster of closely related lineages, collectively called the "star cluster" (fig. 1, shaded area). Second, star-cluster chromosomes were found in 16 populations throughout a large geographical area extending from Central Asia to the Pacific (fig. 2); thus, they do not result from an event specific to any single population. We can deduce the most likely time to the most recent common ancestor (TMRCA) and place of origin of this unusual lineage from the observed genetic variation. To do this, it is first necessary to distinguish star-cluster chromosomes from the remainder. For this, we used the criterion that haplotypes linked to the central one in the shaded area of the network without gaps would be included (fig. 1).

Figure 1

Median-joining network [START_REF] Bandelt | Median-joining networks for inferring intraspecific phylogenies[END_REF]) representing Y-chromosomal variation within haplogroup C*(xC3c). Chromosomes were typed with a minimum of 16 binary markers [START_REF] Qamar | Y-chromosomal DNA variation in Pakistan[END_REF][START_REF] Zerjal | A genetic landscape reshaped by recent events: Y-chromosomal insights into Central Asia[END_REF]our We then used two approaches to calculate a TMRCA for the star-cluster chromosomes. The program BAT-WING [START_REF] Wilson | Genealogical inference from microsatellite data[END_REF] uses models of both mutation and population processes, which were specified as described elsewhere [START_REF] Qamar | Y-chromosomal DNA variation in Pakistan[END_REF]. With this program, we estimated ∼1,000 years for the TMRCA (95% confidence interval limits ∼700-1,300 years). The use of alternative demographic models with constant or exponentially increasing population size changed the estimate by !10%. A method that does not consider population structure [START_REF] Morral | The origin of the major cystic fibrosis mutation (DF508) in European populations[END_REF]), r, suggested ∼860 (∼590-1,300) years. In both calculations, we assumed a generation time of 30 years. The origin was most likely in Mongolia, where the largest number of different starcluster haplotypes is found (fig. 1). Thus, a single male line, probably originating in Mongolia, has spread in the last ∼1,000 years to represent ∼8% of the males in a region stretching from northeast China to Uzbekistan. If this spread were due to a general population expansion, we would expect to find multiple lineages with the same characteristics of high frequency and presence in multiple populations, but we do not [START_REF] Zerjal | A genetic landscape reshaped by recent events: Y-chromosomal insights into Central Asia[END_REF]. The star-cluster pattern is unique.

This rise in frequency, if spread evenly over ∼34 generations, would require an average increase by a factor of ∼1.36 per generation and is thus comparable to the most extreme selective events observed in natural populations, such as the spread of melanic moths in 19thcentury England in response to industrial pollution [START_REF] Edleston | Amphydasis betularia[END_REF]. We evaluated whether it could have occurred by chance. If the population growth rate is known, it is possible to test whether the observed frequency of a lineage is consistent with its level of variation, assuming neutrality [START_REF] Slatkin | The use of intraallelic variability for testing neutrality and estimating population growth rate[END_REF]. Using this method, we estimated the chance of finding the low degree of variation observed in the star cluster, with a current frequency of ∼8%, under neutral conditions. Even with the demographic model most likely to lead to rapid increase of the lineage, double exponential growth, the probability was !10 Ϫ237 ; if the mutation rate were 10 times lower, the probability would still be !10 Ϫ10 . Thus, chance can be excluded: selection must have acted on this haplotype.

Could biological selection be responsible? Although this possibility cannot be entirely ruled out, the small number of genes on the Y chromosome and their specialized functions provide few opportunities for selection [START_REF] Jobling | New uses for new haplotypes: the human Y chromosome, disease and selection[END_REF]. It is therefore necessary to look for alternative explanations. Increased reproductive fitness, transmitted socially from generation to generation, of males carrying the same Y chromosome would lead to the increase in frequency of their Y lineage, and this effect would be enhanced by the elimination of unrelated males. Within the last 1,000 years in this part of the world, these conditions are met by Genghis (Chingis) Khan (c. 1162-1227) and his male relatives. He established the largest land empire in history and often slaughtered the conquered populations, and he and his close male relatives had many children. Although the Mongol empire soon disintegrated as a political unit, his male-line descendants ruled large areas of Asia for many generations. These included China, where the Yu ¨an Dynasty emperors remained in power until 1368, after which the Mongols continued to dominate the country north of the Great Wall for several more centuries, and the region west to the Aral Sea, where the Chaghatai Khans ruled. Although their power diminished over time, they remained at Kashghar near the Kyrgyzstan/ China border until the middle of the 17th century [START_REF] Morgan | The Mongols[END_REF].

It is striking that the boundary of the Mongol empire when Genghis Khan died (fig. 2), which also corresponds to the boundaries of the regions controlled by later Khans, matches the distribution of star-cluster chromosomes closely, with one exception: the Hazaras. We, therefore, wished to compare Genghis Khan's Y profile with the star cluster. It is not possible to examine his remains directly, but history provides an alternative. The Hazaras of Pakistan have a Mongol origin [START_REF] Qamar | Y-chromosomal DNA variation in Pakistan[END_REF], and many consider themselves to be direct male-line descendants of Genghis Khan. A genealogy documenting these links has been constructed from their oral history [START_REF] Mousavi | The Hazaras of Afghanistan[END_REF]. A large proportion of the Hazara profiles do indeed lie in the star cluster, which is not otherwise seen in Pakistan (fig. 2), thus supporting their oral tradition and suggesting that Genghis Khan carried the star-cluster haplotype.

The Y chromosome of a single individual has spread rapidly and is now found in ∼8% of the males throughout a large part of Asia. Indeed, if our sample is representative, this chromosome will be present in about 16 million men, ∼0.5% of the world's total. The available evidence suggests that it was carried by Genghis Khan. His Y chromosome would obviously have had ancestors, and our best estimate of the TMRCA of starcluster chromosomes lies several generations before his birth. Several scenarios, which are not mutually exclusive, could explain its rapid spread: (1) all populations carrying star-cluster chromosomes could have descended from a common ancestral population in which it was present at high frequency; (2) many or most Mongols at the time of the Mongol empire could have carried these chromosomes; (3) it could have been restricted to Genghis Khan and his close male-line relatives, and this specific lineage could have spread as a result of their activities. Explanation 1 is unlikely because these populations do not share other Y haplotypes, and explanation 2 is difficult to reconcile with the high Y-haplotype diversity of modern Mongolians [START_REF] Zerjal | A genetic landscape reshaped by recent events: Y-chromosomal insights into Central Asia[END_REF]. The historically documented events accompanying the establishment of the Mongol empire would have contributed directly to the spread of this lineage by Genghis Khan and his relatives, but perhaps as important was the establishment of a long-lasting male dynasty. This scenario shows selection acting on a group of related men; group selection has been much discussed [START_REF] Wilson | Re-introducing group selection to the human behavioral sciences[END_REF] and is distinguished by the property that the increased fitness of the group is not reducible to the increased fitness of the individuals. It is unclear whether this is the case here. Our findings nevertheless demonstrate a novel form of selection in human populations on the basis of social prestige. A founder effect of this magnitude will have influenced allele frequencies elsewhere in the genome: mitochondrial DNA lineages will not be affected, since males do not transmit their mitochondrial DNA, but, in the simplest models, the founder male will have been the ancestor of each autosomal sequence in ∼4% of the population and X-chromosomal sequence in ∼2.7%, with implications for the medical genetics of the region. Large-scale changes to patterns of human genetic variation can occur very quickly. Although local influences of this kind may have been common in human populations, it is, perhaps, fortunate that events of this magnitude have been rare.

  unpublished observations), including RPS4Y and M48, to define the lineage C*(xC3c) (Y-Chromosome-Consortium 2002), also known as haplogroup 10, derived for RPS4Y and ancestral for M48. Sixteen Y microsatellites were also typed, but DYS19 was excluded from the network analysis because it is duplicated in haplogroup C. The central star-cluster profile is 10-16-25-10-11-13-14-12-11-11-11-12-8-10-10, for the loci DYS389I-DYS389b-DYS390-DYS391-DYS392-DYS393-DYS388-DYS425-DYS426-DYS434-DYS435-DYS436-DYS437-DYS438-DYS439. Circles represent lineages, area is proportional to frequency, and color indicates population of origin. Lines represent microsatellite mutational differences.

Figure 2

 2 Figure 2Geographical distribution of star-cluster chromosomes. Populations are shown as circles with an area proportional to sample size; star-cluster chromosomes are indicated by green sectors. The shaded area represents the extent of Genghis Khan's empire at the time of his death[START_REF] Morgan | The Mongols[END_REF]).

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 1 Department of Biochemistry, University of Oxford, Oxford; 2 Department of Medical Biology, Harbin Medical University, Harbin, China; Dipartimento di Biologia, Universita ´di Ferrara, Ferrara, Italy; 4 Wellcome Trust Centre for Human Genetics, University of Oxford, Headington, United Kingdom; 5 Institute of Genetics, Chinese Academy of Sciences, Beijing; 6 Biomedical and Genetic Engineering Labs, Islamabad; 7 Institute of Immunology, Academy of Sciences, Tashkent, Uzbekistan; 8 McDonald Institute, University of Cambridge, Cambridge, United Kingdom; and 9 Institute of Biotechnology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia

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Acknowledgments

We thank all DNA donors, for making this work possible; Ed Southern, for encouragement and comments on the manuscript; Jaume Bertranpetit, for helpful discussions; Ian Wilson, for modifying BATWING to allow 16 different mutation rates to be used; Askar Mousavi, for information on the Hazaras; Christine Keyser, for information about the genetics of ancient Mongolian populations; and Felipe Ferna ´mdez-Armesto, for historical discussions. This work was supported by a Joint Project from the Royal Society and the National Natural Science Foundation of China and a Collaborative Research Initiative Grant from the Wellcome Trust; T. Z. was supported by the Wellcome Trust.