Paleoanthropologist John Hawks has more news that’s bound to be a disappointment to those who found their ideologies on the presumption that males in general, and human men in particular, are psycho-bio-accountants when it comes to providing paternal care only to offspring they know beyond all doubt is “theirs.”

The value of long-term field studies: Christophe Boesch and colleagues report on adoption in the Taï Forest chimpanzee study population — where more than 30 years of observations have produced 18 well-defined cases of adoption of orphaned individuals. They considered “adoption” to be the provision of maternal care (e.g., carrying, feeding, food sharing, defense) for more than two months. It’s possibly unfortunate terminology, as it leads to headlines like mine. Yet it is really interesting behavior.

It would be nice to say that these cases represent 18 happy endings, but these adoptions did not increase the probability of survival compared to orphaned individuals who did not receive ongoing care. There were a couple of cases where females breastfed orphaned infants “for many years,” but there seem to be several sad stories too.

Sometimes, the care for the orphaned juveniles was given by males:

Remarkably, all adult males of the East Group that adopted young orphans went a step further by investing in unweaned small infants and carrying them dorsally during travel for many months (see Figures 3 and 4 of Porthos with Gia) (Table 3). Since, Taï chimpanzees walk about 8 km per day on average, this represents a notable investment. Porthos’ adoption of Gia lasted for 17 months, until his death due to Anthrax, and he was seen to carry her even in extremely risky situations, such as during encounters with neighboring communities [26]. Furthermore, some males were seen to share their night nest with their adopted infant (Table 3). Fredy, the 3rd ranking male of the East Group, adopted Victor, the son of Vanessa, who died from Anthrax in late December 2008, and shared his nest with him every night, carried him on his back for all long travels, and shared the Coula nuts he opened from December 2008 to July 2009. For example, on February 17th, Fredy cracked 196 Coula nuts for 2h05mn and shared pieces of 79% of them. This gives a measure of the altruistic investment made in an unrelated infant.

That sounds pretty amazing. I think it’s very relevant to human evolution, as orphaning must have been very common with the high mortality rates of the past.

He said it here.

Hawks doesn’t mention it but according to the original author’s abstract, half the orphans were adopted by male chimps.

The proposed driver for this and other prosocial behavior, at least among chimpanzees, would be responses to heavy predation by leopards. That could be relevant for evolution of social behavior in humans as well since leopards have been big predators of primates for many millions of years.

Both Hawks and the original authors are very careful to point out that you really can’t draw simple, straight-line correlations between different species, but to the extent (cough*sociobiology*cough*evolutionary-psychology*cough) you do it’s something else you’re probably going to take into account while spinning yarns about, oh, all sorts of just-so stories. Like about maternal investments in offspring, paternal investments in offspring, the tendencies for animals with complex cognitive behavior being highly influenced by specific genes.

Especially if you’re going to go throwing those genes around by way of justifying explaining antisocial and/or animal-like behavior in humans in general, and men, women, and children in particular.