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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| American anthropology | 5/15 | https://en.wikipedia.org/wiki/American_anthropology | reference | science, encyclopedia | 2026-05-05T14:59:05.969182+00:00 | kb-cron |
Once some useful behavior spreads within a population and becomes more important for subsistence, it will generate selection pressures on genetic traits that support its propagation ... Stone and symbolic tools, which were initially acquired with the aid of flexible ape-learning abilities, ultimately turned the tables on their users and forced them to adapt to a new niche opened by these technologies. Rather than being just useful tricks, these behavioral prostheses for obtaining food and organizing social behaviors became indispensable elements in a new adaptive complex. The origin of "humanness" can be defined as that point in our evolution where these tools became the principle [sic?] source of selection on our bodies and brains. It is the diagnostic of Homo symbolicus. According to Deacon, this occurred between 2 and 2.5 million years ago, when we have the first fossil evidence of stone tool use and the beginning of a trend in an increase in brain size. But it is the evolution of symbolic language which is the cause—and not the effect—of these trends. More specifically, Deacon is suggesting that Australopithecines, like contemporary apes, used tools; it is possible that over the millions of years of Australopithecine history, many troops developed symbolic communication systems. All that was necessary was that one of these groups so altered their environment that "it introduced selection for very different learning abilities than affected prior species." This troop or population kick-started the Baldwinian process (the "ratchet effect") that led to their evolution to genus Homo. The question for Deacon is what behavioral-environmental changes could have made the development of symbolic thinking adaptive? Here he emphasizes the importance of distinguishing humans from all other species, not to privilege human intelligence but to problematize it. Given that the evolution of H. sapiens began with ancestors who did not yet have "culture," what led them to move away from cognitive, learning, communication, and tool-making strategies that were and continued to be adaptive for most other primates (and, some have suggested, most other species of animals)? Learning symbol systems is more time-consuming than other forms of communication, so symbolic thought made possible a different communication strategy, but not a more efficient one than other primates. Nevertheless, it must have offered some selective advantage to H. sapiens to have evolved. Deacon starts by looking at two key determinants in evolutionary history: foraging behavior, and patterns of sexual relations. As he observes competition for sexual access limits the possibilities for social cooperation in many species; yet, Deacon observes, there are three consistent patterns in human reproduction that distinguish them from other species:
Both males and females usually contribute effort towards the rearing of their offspring, though often to differing extents and in very different ways. In all societies, the great majority of adult males and females are bound by long-term, exclusive sexual access rights and prohibitions to particular individuals of the opposite sex. They maintain these exclusive sexual relations while living in modest to large-sized, multi-male, multi-female, cooperative social groups. Moreover, there is one feature common to all known human foraging societies (all humans prior to ten or fifteen thousand years ago), and markedly different from other primates: "the use of meat... . The appearance of the first stone tools nearly 2.5 million years ago almost certainly correlates with a radical shift in foraging behavior to gain access to meat." Deacon does not believe that symbolic thought was necessary for hunting or tool-making (although tool-making may be a reliable index of symbolic thought); rather, it was necessary for the success of distinctive social relations. The key is that while men and women are equally effective foragers, mothers carrying dependent children are not effective hunters. They must thus depend on male hunters. This favors a system in which males have exclusive sexual access to females, and females can predict that their sexual partner will provide food for them and their children. In most mammalian species the result is a system of rank or sexual competition that results in either polygyny, or lifelong pair-bonding between two individuals who live relatively independent of other adults of their species; in both cases male aggression plays an important role in maintaining sexual access to mate(s).
Human reliance on resources that are relatively unavailable to females with infants selects not only for cooperation between a child's father and mother but also for the cooperation of other relatives and friends, including elderly individuals and juveniles, who can be relied upon for assistance. The special demands of acquiring meat and caring for infants in our own evolution together contribute to the underlying impetus for the third characteristic feature of human reproductive patterns: cooperative group living. What is uniquely characteristic about human societies is what required symbolic cognition, which consequently leads to the evolution of culture: "cooperative, mixed-sex social groups, with significant male care and provisioning of offspring, and relatively stable patterns of reproductive exclusion." This combination is relatively rare in other species because it is "highly susceptible to disintegration." Language and culture provide the glue that holds it together. Chimpanzees also, on occasion, hunt meat; in most cases, however, males consume the meat immediately, and only on occasion share with females who happen to be nearby. Among chimpanzees, hunting for meat increases when other sources of food become scarce, but under these conditions sharing decreases. The first forms of symbolic thinking made stone tools possible, which in turn made hunting for meat a more dependable source of food for our nonhuman ancestors while making possible forms of social communication that make sharing between males and females, but also among males, decreasing sexual competition: