1992-09-09: People of the Lake

People of the Lake (1978)

Mankind and Its Beginnings

by Richard Leakey (1944-) and Roger Lewin (1944-)

In this book, Leakey gives his views on the development of hominids from the very earliest (about 6 million years ago) to the advent of modern types (about 50 thousand years ago). In particular he takes issue with, and effectively refutes, the view that humans are innately hostile and murderous, leading inevitably to warfare as a natural consequence of our genetic makeup.

Leakey’s views are consistent with, and clearly influenced by, the genetic views of Richard Dawkins, expressed in The Selfish Gene (which he credits), and therefor consistent with Dawkins views of the meme as the atomic unit of cultural evolution. The book is rich in material from which a catalog of memes for early hominids might be constructed. In addition, he cites results from studies of modern gatherer/hunter societies to support many non-obvious aspects of early hominid lifestyles.

In addition to the physical characteristics preserved in the fossil record, elaborated at great length, Leakey focuses on the behaviors consistent with the physiology and environment, constrained to end up with modern gather/hunt lifestyles. One of the key developments was reciprocal altruism, where it is genetically advantageous for one individual to help another who is closely related, particularly in situations, such as close social life, in which such efforts are likely to be repaid. Given a primate who must learn a great many facts (memes) about gathering plant foods from its mother or other close associates, and therefor takes several years to become fully productive, genetically derived reciprocal altruism can enhance the survivability of a band (about 25 individuals) by allowing the caregivers (mainly females) to spend more time with the young, while being (partially) provided with food by others, mainly males. Another genetic trait would reduce the bad genetic effects of inbreeding: the outmigration of one sex or the other from its home band to a neighboring band upon reaching sexual maturity. (I assume the females left, so that the males in each band were closely related, while the mature females were not). Both of these traits probably arose by 3 MYA.

The hominids at this stage would already be memetic to the extent that the young would learn memes for finding a wide variety of foods from observing their mothers and other elders; whether the mothers deliberately taught is unknowable. In addition to learning the foods of their mothers, these hominids were adaptable enough to learn new foods as they passed from one area to another, in migrations from africa to eurasia, and from woodland to savanna and forest.

Leakey points out another consequence of reciprocal altruism. In such a situation there is a ‘temptation’ to ‘cheat’, that is to accept help but never to give it. It is to the advantage to givers to be able to detect cheaters, to avoid wasting efforts that will not be repaid, or to be able to coerce cheaters to reform. (This assumes that cheating may arise from unalterable genetic reasons, or from alterable memetic reasons, such as laziness.) The emotions supporting the system must have developed (genetically) as part of its balancing mechanism (p.191-192). The tendency to like people who are not necessarily closely related is essential. We are usually altruistic to people we like, and we like those who are altruistic. When someone refuses to reciprocate, the ‘injured’ party is suffused with moralistic aggression: anger at such outrageous behavior. This has two effects: it prevents further altruism to the nonreciprocator, and it can shock (shame) him back into reciprocating. The emotions of sympathy and gratitude also paly a part. Faced with someone in need, we feel sorry for them, and proportionally to the severity of need. When we receive help, we feel gratitude toward the helper, proportionally to the severity of need, and to the cost to the helper. the greater the gratitude, the more likely we are to reciprocate in the future.

The emotional system supporting the altruistic system is subject to falsification (unconscious or conscious) by ‘cheaters’, who may produce more or less convincing sham emotions that might result in receiving more than they give. These ‘tactics’ can be countered by increased ability to detect sham behavior. There will be a selective pressure to increase the efficacy and complexity of the system, leading to development of emotions of trust and suspicion to modulate the use of the other emotions.

The net result is a set of emotions, co-emotions and counter-emotions: like-dislike, sympathy+gratitude, anger+shame, trust-suspicion. By balancing and reinforcing each other, these can result in a set of emotional responses between individuals, based on experience, that lead to effective and reliable reciprocal altruism. None of this requires speech (though it certainly provides additional channels of communication, both for deception and validation), but more effective gesturing would be helpful. Most emotional states are communicated by facial (and body) expression rather than manual gestures. This mode might have been more effective among those with less facial (or body) hair, and might have been a selective pressure to the (otherwise unexplained) lack of hair among humans compared with other primates.

A summary of the time various traits appeared:

15-12 MYA

  • Ramapithecus, changes in the environment opened a niche for a woodland animal that could survive on tough plant food, probably on the fringes of wooded/savannah areas, spread from africa across mostly dry mediterranean to southern eurasia
  • ability to learn food gathering skills from elders, and to adapt to new food sources
  • females leave bands for neighboring bands on reaching sexual maturity; adult males in a band are more closely related than adult females

12-3 MYA

  • important advantages in being able to walk around on two rather than four legs; upright posture frees the hands for carrying, throwing, manipulating smallish objects and gesturing (no other primates’ lifestyle includes carrying food for sharing)
  • ability to make and use tools, such as carrying bag and digging stick
  • opportunistic use of meat (e.g., scavenging)
  • reciprocal altruism, and supporting emotional and communication systems (loss of body and facial hair?); sharing of food (particularly meat) from males to close males and females (little sharing of plant foods between females)

3-.1 MYA

  • elaboration of toolmaking to stone tools, and to tools to make tools (e.g., stone axes to make digging sticks)
  • control of fire
  • separation of functions among male/female with males dominating hunting, and controlling the sharing of meat
  • increased coordination among hunters raises gestural language; increased teaching/learning of all kinds raises audible language

100-50 KYA

  • development of distinct local cultures, discrimination among ‘clans’, geographic diversification of dialect/languages
  • end of high-level genetic evolution (physical, neurological) among hominids

These stages are a mix of influences, culminating in the modern human type. At this stage, cultural evolution, based on memes, dominates biological evolution, based on genes.

(Not all of these statements are explicit in Leakey, but I think they all are consistent.)


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