New View of How Humans Moved Away From Apes

A nice article in the New York Times by their science correspondent Nick Wade. He reports on recent work on hunter-gatherer societies building on 2008 insights into human social organization by Bernard Chapais. Kim Hill and colleagues point out that the previously-thought pattern of females moving away from family groups, leaving male cross-generational coalitions in charge, is not by any means the rule in hunter-gatherer societies, where just as often it is the young males that move out. They call the phenomenon bilocality. This means that social groups are far less genetically related than thought so that cooperation between non-kin, as opposed to kin selection inclusive fitness cooperation of selfish genes, is the key to how humans moved away from the ape model. here's a bit of the article:

"Anthropologists studying living hunter-gatherers have radically revised their view of how early human societies were structured, a shift that yields new insights into how humans evolved away from apes.

Early human groups, according to the new view, would have been more cooperative and willing to learn from one another than the chimpanzees from which human ancestors split about five million years ago. The advantages of cooperation and social learning then propelled the incipient human groups along a different evolutionary path.

Anthropologists have assumed until now that hunter-gatherer bands consist of people fairly closely related to one another, much as chimpanzee groups do, and that kinship is a main motive for cooperation within the group. Natural selection, which usually promotes only selfish behavior, can reward this kind of cooperative behavior, called kin selection, because relatives contain many of the same genes.

A team of anthropologists led by Kim S. Hill of Arizona State University and Robert S. Walker of the University of Missouri analyzed data from 32 living hunter-gatherer peoples and found that the members of a band are not highly related. Fewer than 10 percent of people in a typical band are close relatives, meaning parents, children or siblings, they report in Friday’s issue of Science.

Michael Tomasello, a psychologist at the Max Planck Institute for Evolutionary Anthropology in Germany, said the survey provided a strong foundation for the view that cooperative behavior, as distinct from the fierce aggression between chimp groups, was the turning point that shaped human evolution. If kin selection was much weaker than thought, Dr. Tomasello said, “then other factors like reciprocity and safeguarding one’s reputation have to be stronger to make cooperation work.”"

Big brains and spineless penises How DNA deletions may have produced uniquely human traits.

In my chapter LESS IS MORE I suggest that loss, or deletion of working genes has been very important in human evolution. Good examples are the way in which deletion of a part of the CMAH gene, rendering it useless, had been an important, if drastic, defence against malaria back in the days of Homo erectus. The gene MYH16 appears to have been deleted at about the same time which may explain our more gracile head and jaw musculature. Now this team have winnowed through the human genome to discover over 500 deleted chunks of DNA from non-coding regions - regions that are not inside working genes. The thought is that these deletions are in regulatory parts of the genome - parts that control the ways genes express themselves - how much designated protein they make. Deletions in these areas would be like taking the brakes out of a car - and could have led to greater gene expression. They cite a deletion near the tumour suppressor gene GADD45G, for instance, that could have "removed the brakes from cell division and promoted the expansion of brain tissue". "A second deletion near the human androgen receptor gene correlates with the loss of sensory whiskers and penile spines which might have resulted in different copulatory behaviour in early humans.

Elephants know when they need a helping trunk in a cooperative task

In NOT A CHIMP I refute the idea that genetic proximity logically begets cognitive similarity. Convergent evolution in birds, dogs, primates and humans has resulted in remarkable cross-species abilities on social tasks that require the ability to infer something about the content of other minds, or the nature of a task from a partner's perspective, where species have diverged from one another tens or even hundreds of millions of years ago. Here Asian elephants show the same remarkable degree of convergent cognitive evolution on a task that requires cooperative pulling on ropes in order to reach a reward. It is reported by Frans de Waal and here is the abstract:

"Elephants are widely assumed to be among the most cognitively advanced animals, even though systematic evidence is lacking. This void in knowledge is mainly due to the danger and difficulty of submitting the largest land animal to behavioral experiments. In an attempt to change this situation, a classical 1930s cooperation paradigm commonly tested on monkeys and apes was modified by using a procedure originally designed for chimpanzees (Pan troglodytes) to measure the reactions of Asian elephants (Elephas maximus). This paradigm explores the cognition underlying coordination toward a shared goal. What do animals know or learn about the benefits of cooperation? Can they learn critical elements of a partner's role in cooperation? Whereas observations in nature suggest such understanding in nonhuman primates, experimental results have been mixed, and little evidence exists with regards to nonprimates. Here, we show that elephants can learn to coordinate with a partner in a task requiring two individuals to simultaneously pull two ends of the same rope to obtain a reward. Not only did the elephants act together, they inhibited the pulling response for up to 45 s if the arrival of a partner was delayed. They also grasped that there was no point to pulling if the partner lacked access to the rope. Such results have been interpreted as demonstrating an understanding of cooperation. Through convergent evolution, elephants may have reached a cooperative skill level on a par with that of chimpanzees."