It's tempting to pin the rise of humanity to become the world's dominant species on our ability to out-think, out-hunt and out-technology the competition. But new research suggests that softer skills are the reason for our success: specifically our abilities to work together and share, especially when it comes to raising children.
According to Anthropology Professor Karen L. Kramer of the University of Utah, it's our abilities to have more children and share work, childcare and food that are the most crucial differences between us and the rest of ape-kind.
Kramer points out that although the human population explosion is linked to the industrial revolution, humans were already a very successful species, numbering more than a billion with a presence in almost every land environment on Earth.
The study builds on Kramer's varied research of Mayan farming communities in the Yucatan Peninsula in Mexico as well as Savanna Pumé hunter-gatherers in Venezuela. Her findings from these societies show that sharing childrearing duties can increase the number of children a community can raise, as well as actually speeding up rates of maturation and childbearing – essentially having children at an earlier age.
Her research also suggests that children sharing food with their parents and siblings is a factor in humanity's success.
In her time spent with Maya communities, Kramer compared the contributions individuals made to their families and community compared with their consumption. Her findings showed that Maya children aged between 7 and 14 do between 2 and 5 hours work each day, and those aged 15 to 18 do 6.5 hours a day – as much as adult parents.
Where older children tended to help with food growing and preparation, as well as household duties, younger children were more likely to help with childcare. "If mothers and juveniles did not cooperate, mothers could support far fewer children over their reproductive careers," Kramer explains in a press release. "It is the strength of intergenerational cooperation that allows parents to raise more children than they would otherwise be able to on their efforts alone."
Among the Savanna Pumé hunter-gatherers, meanwhile, Kramer found that cooperation between different age groups helped to reduce risks in what are high-mortality conditions. Challenges for the Savanna Pumé include seasonal undernutrition, but the sharing of food allows mothers to bear children at a younger age, which is beneficial to survival in a high-mortality environment.
All told, Kramer finds that human mothers that live through their reproductive career can, with help, raise twice as many young as any other great ape mother. "Humans are an astonishingly successful ape," she concludes.
So if the global outlook seems bleak from time to time, perhaps we can take solace from the knowledge that we got where we are by being nice to one another.
The study, How There Got to Be So Many of Us: The Evolutionary Story of Population Growth and a Life History of Cooperation, has been published in The Journal of Anthropological Research published by the University of Chicago Press.
Source: University of Chicago