Mothers, babies, and the origins of human society

Posted on January 10, 2011


I am used to reading media coverage of research and wincing about the unexamined gendered assumptions embedded in stories.

So when I began browsing coverage of new research by Boston University’s Jeremy DeSilva, I braced myself. But guess what? somehow, at least the first reporting has managed to avoid cliche and stereotype.

DeSilva developed a way to estimate the size of newborn infants in early hominids, finding that the calculated infant size for Ardipithecus (4.4 million years ago) was similar to modern chimpanzees (3% of the adult body weight), while the estimated size of newborn infants of Austalopithecenes (sometime between 4 and 2 million years ago), at 5% of adult body weight, were close to the ratio seen in modern humans (6%). The abstract of DeSilva’s paper in Proceedings of the National Academy of Sciences concludes that

Carrying such proportionately large infants may have limited arboreality in Australopithecus females and may have selected for alloparenting behavior earlier in human evolution than previously thought.

What this means in simpler terms is that infant dependency has a long history in the human lineage. NPR quotes DeSilva saying

“The whole expression that it takes a village is in part rooted in the fact that we have really big infants that are pretty helpless… If we wanted to get anything done, we have to hand them off.”

NPR flirts with the edges of gender stereotype in commenting on this quotation:

So stable communities developed where some took care of babies while others hunted or did the taxes.

But they don’t take the next step. And bravo for that.

The Cosmic Log blog on also managed to avoid reducing this research to a story of dependent females and independent males, emphasizing that infant dependency “may have played a role in shaping us as social animals”:

bigger babies mean human mothers need more help than chimp mothers to give birth, take care of their babies and carry them around. In prehistoric times, that could have been a factor behind the development of extended family ties and other characteristics of human social organization.

Precisely. The solutions to challenges of survival in the history of the human species were social ones, not individual ones. And it is clear who deserves the credit for advancing this more complex storyline: DeSilva. The Cosmic Log story includes the “it takes a village” image, and continued with more of his remarks, noting that birth mothers

“would have benefited from the help of pair-bonded males, older children or siblings, or a combination of these.”

Scientific American also got the message, and expanded on the point:

Saddled with a large, nursing infant that is unable to walk, Australopithecus mothers could have used assistance from males as well as juveniles in caring for themselves and their babies (grandmothers are thought to have come into the picture only after lifespan lengthened with the emergence of the Homo genus). This new need for extended postnatal care may have driven the emergence of a social structure different from that of chimpanzees…

By leaving open the range of human social arrangements that might have contributed to addressing the problem of caring for more dependent infants, DeSilva encourages us– and the media– to imagine the past differently. And a catchy turn of phrase that still is an accurate encapsulation of his scholarship was one key to getting the story out the way he wanted.

So that’s the good news. But– and you knew there had to be a but, right?– I’ve been waiting since January 3, when this research was initially reported, for articles in mainstream newspapers. So far, nothing in English… which raises the question– if research doesn’t fit into simple stereotypes, no matter how revolutionary it is, can it make it through the news filters?

Posted in: biology, gender