Monogamy in Ardipithicus ramidus

I was aware of the Russian study demonstrating the ease with which foxes could be domesticated. I began to think that somehow a process of self-domestication had taken place as a precursor to the selection inclusion of the dominance and submissive mentalities. So, when I examined the momentous publication of the Ardipithecus ramidus fossils in 2007, I pounced on their interpretation by the international team’s theoretician, Owen Lovejoy. Due to the near equal size of males and females in addition to the reduced size of the male canine teeth—indicating reduced aggression—this 4.4 million year old hominid species was judged to have evolved a monogamous mating system. Lovejoy reasoned that one of the principal reasons that apes had then been going extinct in deteriorating climates was decreasing birthrates, a problem that was greatly exacerbated by the wasted energy in male competition over females with no male participation in child-rearing. His theory was that by means of sexual selection, females evolved the inclination to choose less dominant males who would provision them, and who then out-procreated those who did not. Here was my old friend sexual selection playing a key role in the initiation of the hominid family!

The evidence for monogamy

Of course there is lots of criticism of this hypothesis. No one is neutral on the subject of monogamy. Monogamous social systems in nature are not particularly cooperative due to the need for “mate guarding,” and terrestrial females, especially when pregnant, are vulnerable to predation when the males are away. However, two important studies fortified the monogamy theory. Edward Wilson is the pioneer in using the super-cooperative insects, such as ants and bees, as the closest animal model for the cooperation characteristic of humans. Although ants are famous for having developed extreme social systems with sterile castes, a researcher named William Hughes in England (2008) demonstrated by means of ancestral genetic studies that the founding colonies of all these so-called eusocial insects were monogamous. The second finding was even more eye-opening.

Robin Dunbar discovers monogamy
Robin Dunbar

One of the most quoted articles for many years after he wrote it in 1993 was a paper by Robin Dunbar at Oxford in which he correlated brain size in primates to the size of their group. The straightforward thinking was that, the bigger the group, the smarter the individual had to be in order to successfully negotiate the ever more complex hierarchies within them. Extrapolating from the size of the expanding brains of more recent hominid species, Dunbar calculated that their groups attained a size of 150 members. However, much to his initial chagrin, he later learned by studying the brain size in other animals, notably in birds, that large brain size most correlated with monogamy. He reasoned that the ability to “synchronize” the feeding of offspring takes brain power, and he acknowledged a large emotional component in this process.

When I read Dunbar’s paper published in 2007, I had the last piece in my lifelong puzzle. Monogamy was the answer, not political alliances. The founding mothers of the hominid family had reversed the decline in apes by evolving females with the ability to select more submissive males who were willing to stick around and help with provisioning their mutual offspring. Finally this domestication process achieved the right balance for the selection of dominance and submissive mentalities via selection inclusion to produce the entities of authority and obedience in groups—the theory I had been patiently nurturing since my prison work decades earlier.

I had long thought that group selection occurred within groups, not between groups. Those subgroups of pair-bonded mates whose collective dominance and submissive mentalities interacted to both inhibit and react aggressively against cheating and freeloading simply out-produced those subgroups without this kind of bonding. By means of a process of passive selection of bonds protective of monogamy, the rules of the jungle were quite rapidly replaced by those of justice and morality required to maintain this most productive of all social systems.

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