人类大脑、认知与行为进化的整合模型

1、心 理 学 报 2007,39(3:383397 Acta Psychologica Sinica383An Integrative Model of Human Brain, Cognitive, and Behavioral EvolutionDavid C. GearyUniversity of Missouri at Columbia, USAThe evolved function of brain, cognitive, and behavioral systems is to allow organisms to attempt to gain control of the so

2、cial, biological, and physical resources that have covaried with survival and reproductive options during the species evolutionary history. The information generated by these resources ranges from stable (e.g., prototypical shape of human face to unpredictable (e.g., changing facial expressions. Sta

3、ble information is predicted to result in the evolution of modular brain and cognitive systems and implicit, automatic behavioral responses. For humans, these systems coalesce around the domains of folk psychology, folk biology, and folk physics. Unpredictable information is predicted to be associat

4、ed with the evolution of brain and cognitive systems that enable explicit, consciously driven top-down behavioral responses. For humans, the evolution of these explicit systems resulted in the emergence of self-awareness and the ability to consciously simulate control-related problem solving behavio

5、ral strategies. A motivation-to-control theory that incorporates these folk domains and conscious, self-aware problem solving is described.Keywords :evolutionary history, folk psychology, folk biology, folk physics.人类大脑、认知与行为进化的整合模型物种进化的历史进程中,大脑、认知与行为系统的进化机能利于有机体控制社会、生物与自然资源,而有机体所控制的各种资源又会影响自身的生存与繁衍

6、。社会、生物与自然资源可以相对稳定,也可以变化不定。资源的稳定变化所传递的信息会引起大脑、认知以及行为系统做出模块化的自主反应。资源的稳定变化利于人类整合朴素心理学、朴素生物学与朴素物理学,而资源的变化不定所传达出的信息会引起认知与行为系统有意识地进行自上而下的外显行为反应。人类外显行为反应系统的进化导致人类出现自我意识,并具有探索性解决问题的能力。朴素心理能力、意识与问题解决能力可以整合为动机-控制理论。关键词:进化历史,朴素心理学,朴素生物学,朴素物理学。 分类号:B84-069Darwin and Wallace (1958, p. 54 described naturalselecti

7、on as a “struggle for existence”, but perhaps itis better described as a struggle for control. It is notthat individuals necessarily have a conscious, explicitmotive to control other members of their species, suchas potential mates, or other species, such as potentialprey. Rather, the result of natu

8、ral and sexual selection(e.g., competition for mates has been the evolution ofbrain and cognitive systems that are sensitive to andprocess the types of information that have covariedwith survival and reproductive outcomes during thespecies evolutionary history (Geary & Huffman,2002; Geary, 2005.

9、 The operation of these systemsbiases behavior so that it is focused on the corresponding informational features of the ecology(e.g., movement patterns of prey and on attempts toachieve behavioral control of these potential resources(e.g., prey capture. In most species and often forhumans, the proce

10、sses occur below consciousReceived 2006-06-30Correspondence should be addressed to David C. Geary, Department ofPsychological Sciences, 210 McAlester Hall, University of Missouri,Columbia, MO 65211-2500, USA; e-mail: .awareness, that is, implicitly, and automatically; humans can at

11、 times consciously focus on the control of other people and other forms of resource. My proposal is that many of the functional features of brain and cognition have evolved to guide behavioral attempts to organize the world in ways that eliminated predatory risks and enhanced survival and reproducti

12、ve options. The shorthand for these biases is the motivation to control (see Geary, 2005. To illustrate the concept, consider variation in the size and shape of the beaks of different species of finch on the Galápagos islands, often called Darwins finches. Across these species, variation in bea

13、k morphology has evolved in response to the differentfood sources on the various islands (Grant, 1999; Grant & Grant, 2002. The long and thin beak of the woodpecker finch (Cactospiza pallida enables the use of cactus spines to pry insect pupae out of tree bark, whereas the stout and deep beak of

14、 the largeground finch (Geospiza magnirostris enables themanipulation and cracking open of casings around the seeds of the caltrop plant (Tribulus cistoides . The beaks of these finches and associated perceptual384心 理 学 报 39卷biases and foraging behaviors can be understood as evolved traits that enab

15、le them to locate and to gain access to specific food sources. The birds do not have a conscious motivation to control these resources, but their evolved traits nonetheless function in ways that result in resource control. By conceptualizing these adaptations in terms of control, the relation betwee

16、n the trait and the evolved functional link with respect to specific social or ecological pressures is highlighted.In the following sections, I outline the basic components of the motivation-to-control model as related to human evolution. In the first section, the focus is on basic changes in brain

17、volume and organization during hominid evolution, selection pressures that may have resulted in these changes, and the potential relation between the motivation to control and these changes. In the second section, the focus is on the cognitive and affective mechanisms and folk systems (e.g., folk ps

18、ychology that are components of the motivation to control. The final section provides an illustration of the utility of the motivation-to-control model for organizing research on social cognitions and social biases.Hominid Evolution and the Motivation to Control The section begins with an overview o

19、f changes in brain size and organization during hominid evolution, and with discussions of potential selection pressures that drove these evolutionary changes. This discussion is followed by an overview of the basic components of the motivation-to-control model.Brain EvolutionBrain Encephalization a

20、nd OrganizationTo control for the relation between body weight and brain size, the encephalization quotient (EQ is an often used measure of evolutionary change in brain volume (Jerison, 1973. An EQ of 1.0 means that the brain volume of the species is average for a mammal of the same body weight. By

21、creating casts of the inner surface of fossil skulls, brain volume and the structure of the outer surface of the brain can be recreated (Holloway, Broadfield, & Yuan, 2004. The endocasts allow for the study of patterns of evolutionary change in brain volume, organization of the surface of the ne

22、ocortex, and can be used to estimate EQ. Using these techniques, the EQ of chimpanzees (Pan troglodytes and species of Australopithecus that preceded the emergence of Homo are estimated at about 2.0, indicating that their brains are (or were double the size of that of a typical mammal of the same bo

23、dy weight. Since the emergence of australopithecines, about four million years ago, brain volume has roughly tripled and EQ estimates have increased two to three fold such that the EQ of modern humans is about 6.0 (Jerison, 1973; Ruff, Trinkaus, & Holliday, 1997.The brain has also been reorganiz

24、ed in important ways (Holloway, 1973; Tobias, 1987. On the basis of endocast patterns, there appears to have been modest evolutionary expansions in the volume of the frontal and parietal lobes and extensive remodeling; specifically, evidence for more folding and thus more surface area of the frontal

25、 lobes with the emergence of H. habilis about 2.5 million years ago (Falk, 1983; Tobias, 1987. As an example, one area of the frontal lobe that supports human speech and gesture, specifically, Brocas area appears to have expanded relative to australopithecines and had an architecture similar to that

26、 of modern humans. The right prefrontal cortex also appears to have undergone an evolutionary expansion since the emergence of H. habilis (Holloway & de al Coste-Lareymondie, 1982. Evolutionary change in this area of the brain is intriguing because it may support self awareness and mental time t

27、ravel (Suddendorf & Corballis, 1997; Wheeler, Stuss, & Tulving, 1997, important components of the motivation-to-control model. The increase in the size of the parietal cortex is interesting as well (Holloway, 1996. This is because it is coincident with increasingly sophisticated tool use wit

28、h and after the emergence of H. habilis, and is engaged during tool use in modern humans, and because these areas are involved in controlled attention as related to working memory.The most substantive increases in brain volume and EQ, as well as changes in brain organization have occurred since the

29、emergence of modern humans and the immediate predecessor species, H. erectus (Ruff et al., 1997. In fact, recent comparative genomic studies have identified several genes involved in prenatal brain development and organization that appear to have been under intense selection pressures since the emer

30、gence H. erectus (Pollard, Salama, Lambert, Lambot, Coppens, Pedersen et al., 2006 and continuing with modern humans (Evans, Anderson, Vallender, Gilbert, Malcom, Dorus, & Lahn, 2004; Mekel-Bobrov, Gilbert, Evans, Vallender, Anderson, Hudson, et al., 2005; Zhang, 2003. In other words, there is e

31、vidence for the recent and ongoing evolution of these genes and associated brain systems. Selection PressuresThree forms of selection pressure have been proposed as driving evolutionary change in the human brain; climatic (Vrba, 1995, ecological (Kaplan, Hill, Lancaster, & Hurtado, 2000; Wrangha

32、m, Holland Jones, Laden, Pilbeam, & Conklin-Brittain, 1999, and social (Alexander, 1989; Humphrey, 1976. The common theme across these proposals is that the human brain and mind evolved to enable the anticipation and thus improved behavioral coping3期 David C. Geary. An Integrative Model of Human

33、 Brain, Cognitive, and Behavioral Evolution385with unpredictable climatic, ecological, or social change within a lifetime. For reasons described elsewhere, climatic variability is not likely to have been the primary form of selection pressure that drove these evolutionary changes (see Geary, 2005; f

34、or instance, most of the changes in brain volume and EQ in H. habilis and H. erectus do not appear to have been coupled with periods of rapid climatic variation (White, 1995. There is, in contrast, evidence that our ancestors beginning at least as far back as the australopithecines ( 4 million years

35、 ago became increasingly skilled in their ability to extract resources from the ecology through hunting and use of tools (Foley & Lahr, 1997; Wrangham et al., 1999. Increased skill at tool use almost certainly resulted in improvements in the ability to extract resources from the environment and

36、exert increasing levels of ecological control; for instance, through use of fire (Goren-Inbar, Alperson, Kislev, Simchoni, Melamed, Ben-Nun, & Werker, 2004. It has been proposed that improvements in ecological control eventually resulted in a critical change in the pattern of selection pressures

37、 experienced by our ancestors. Alexander (1989; see also Flinn, Geary, & Ward, 2005 termed this change the emergence of ecological dominance: “The ecological dominance of evolving humans diminished the effects of extrinsic forces of natural selection such that within-species competition became t

38、he principle hostile force of nature guiding the long-term evolution of behavioral capacities, traits, and tendencies” (Alexander, 1989, p. 458. Ecological dominance is the ability to efficiently extract biological resources from the ecology and manipulate the ecology in ways that substantially redu

39、ce mortality risks (Hill, Boesch, Goodall, Pusey, Williams, & Wrangham, 2001; Kaplan et al., 2000; the achievement of ecological dominance may have triggered the population expansions and migration of H. erectus into Asia and the Middle East. More important, ecological dominance results in the p

40、otential for the creation of demographic “pumps”, whereby lower mortality rates and increases in the amount of food extracted from the ecology result in an expanding population. As was argued by Malthus in 1798, populations typically expand until they reach a point that exceeds the carrying capacity

41、 of the ecology. When this occurs either some portion of the population must migrate or the population will crash, that is, there will be a sharp increase in mortality. Following the crash, the pressures on the ecology are reduced (e.g., native species recover and this in turn sets the stage for ano

42、ther population expansion. These cycles of expansions and contractions are important because they provide a mechanism for rapid change in our ancestors. During population contractions, social competition for diminishing resources will necessarily increase in intensity (Malthus, 1798 and any trait th

43、at facilitates the ability to compete with other people for control of these resources will evolve rapidly.This is where Darwins and Wallaces (1858, p. 54 “struggle for existence”, becomes in addition a struggle with other human beings for control of the resources that support life and allow one to

44、reproduce (Geary, 1998, 2005. In addition to competition within the social group, a struggle with other groups for ecological control would follow, if ecologies varied in the quantity and quality of the resources such as prey species, water, shelter contained therein. Because ability to control reso

45、urce-rich ecologies is likely to be enhanced with the formation of large competitive social groups (Dunbar & Bever, 1998; Wrangham, 1999, the result is pressures for the evolution of social-competitive competencies that support the ability to form kin-based social coalitions (Geary & Flinn,

46、2001. Members of these coalitions (the in-group cooperate to compete with other kin-based coalitions (the out-group for ecological control. The point is that Kaplan et al.s (2000 and others (e.g., Tiger, 1969 theory of the relation between ecological pressures and hominid brain evolution is consiste

47、nt with Alexanders (1989 and others (e.g., Flinn et al., 2005; Humphrey, 1976 theory of the relation between social pressures and hominid brain evolution. Alexanders proposal implies that ecological pressures were more salient earlier in hominid evolution and social pressures were more salient later

48、 in hominid evolution.Motivation to ControlThe basic thesis is that the brain and mind has evolved to attend to and process the forms of information that covaried with survival and reproductive prospects during the species evolutionary history. These systems bias implicit decision making processes a

49、nd behavioral responses in ways that allow the organism to attempt to achieve access to and control of these resources (see Gigerenzer, Todd, & and ABC Research Group, 1999. Although not typically presented in an evolutionary context, the proposal fits well with the consensus among psychologists

50、 that humans have a basic motivation to achieve some level of control over relationships, events, and resources that of significance in their life (Fiske, 1993; Heckhausen & Schulz, 1995; Shapiro, Schwartz, & Astin, 1996; Taylor & Brown, 1988; Thompson, Armstrong, & Thomas, 1998. The

51、 proposal here and elsewhere is that the human motivation to control is an evolved disposition and is implicitly focused on attempts to control social relationships and the behavior of other people, and to control the biological and physical resources that covary with survival and reproductive prosp

52、ects in the local ecology (Geary, 1998, 2005.386 心 理 学 报 39卷The constellations of traits that enable attempts to control these resources are shown in Figure 1. The base of the figure represents folk modules described in Domains of the Human Mind that direct the individuals attention toward and enabl

53、e the automatic and implicit processing of social (e.g., facial expressions, biological (e.g., features of hunted species, and physical (e.g., manipulation of objects as tools information patterns that have been invariant during human evolution and have been associated with survival or reproductive

54、prospects. These represent the respective domains of folk psychology, folk biology, and folk physics. The center of the figure represents brain and cognitive systems, such as working memory, that function to cope with evolutionarily significant information patterns (e.g., social dynamics that tend t

55、o vary within the life span and across generations. For instance, many forms of social relationship, such as mother-infant attachments and friendships, are found across generations and in all cultures (Bugental, 2000, but the details of any one relationship can vary across individuals and time; the

56、mechanisms are elaborated in Evolution of Control-Related Cognitive and Affective Systems.Figure 1: The apex and following section represent the proposal that human behavioral baises conceptualized reflecting an evolved motivation to control the social, biological, and physical resources that have t

57、ended to covary survival and reproductive outcomes during human evolution. The midsection shows the supporting affective, conscious-psychological (e.g., attributional biases, and cognitive (e.g., working memory mechanisms that support the motivation to control and operate on the folk modular systems

58、 shown at the base.Benefits of ControlIf brain, cognitive, and behavioral traits have evolved in ways that facilitate the identification and control of social, biological, and physical resources, then individual differences in resource control should correlate with individual differences in survival

59、 rates and reproductive outcomes. Biological resourcesinclude food and medicine, and physical resources include the territories that contain biological resources and that support homes, agriculture, pastures, and so on. In modern societies some resources are symbolic (e.g., money, stocks, but are important because control of these resources enhances social influence and facilitates control of quality foods, medicines, and housing. Although humans have psychological mechanisms that obscure the fact that they often use social relati