The Role of Terrestriality in Promoting Primate Technology

Abstract

Abstract“Complex technology” has often been considered a hallmark of human evolution. However, recent findings show that wild monkeys are also capable of habitual tool use. Here we suggest that terrestriality may have been of crucial importance for the innovation, acquisition, and maintenance of “complex” technological skills in primates. Here we define complex technological skills as tool‐use variants that include at least two tool elements (for example, hammer and anvil), flexibility in manufacture or use (that is, tool properties are adjusted to the task at hand), and that skills are acquired in part by social learning. Four lines of evidence provide support for the terrestriality effect. First, the only monkey populations exhibiting habitual tool use seem to be particularly terrestrial. Second, semi‐terrestrial chimpanzees have more complex tool variants in their repertoire than does their arboreal Asian relative, the orangutan. Third, tool variants of chimpanzees used in a terrestrial setting tend to be more complex than those used exclusively in arboreal contexts. Fourth, the higher frequency in tool use among captive versus wild primates of the same species may be attributed in part to a terrestriality effect. We conclude that whereas extractive foraging, intelligence, and social tolerance are necessary for the emergence of habitual tool use, terrestriality seems to be crucial for acquiring and maintaining complex tool variants, particularly expressions of cumulative technology, within a population. Hence, comparative evidence among primates supports the hypothesis that the terrestriality premium may have been a major pacemaker of hominin technological evolution. © 2012 Wiley Periodicals, Inc.

If at first you don't succeed… Studies of ontogeny shed light on the cognitive demands of habitual tool use

“…Social transmission seems to be mainly vertical, through association, tool recycling, food and tool transfers, and watching. Other modes of transmission, although not predominant, might nevertheless be crucial as for example suggested by the finding that habitual tool use only occurs in populations with increased opportunities for social learning owing to enhanced social tolerance [97], prolonged parental feeding or association [25], exposure to artefacts [108] and/or perhaps rare cases of opportunity teaching [35,115]. Re-use of tools may be important for the accumulation of technological complexity [13,108].…”

Explaining brain size variation: from social to cultural brain

“…Variation among great ape species in innovation and problem-solving biases illustrates this. Thus, bonobos bias their innovations, including those involving tool use, more toward solving social problems, chimpanzees more toward solving subsistence problems, and orangutans more toward enhancing physical comfort [50][51][52][53]. These divergent biases are found in the wild, but also in captivity, where conditions are uniform across the species concerned.…”

‘Captivity bias’ in animal tool use and its implications for the evolution of hominin technology

“…These animals also have more time available to observe the behaviour of others, adding further impetus to the positive feedback loop suggested earlier. Suggestions that terrestriality in captivity promotes tool use among typically arboreal primates [2] may also rely, in part, on freedom from vigilance, as the captive environment provides security for these animals on the ground. A terrestriality effect cannot explain captivity bias seen in non-arboreal species, however, including elephants, gorillas and rodents.…”