With sleepless nights and puzzling crying spells, caring for a newborn may seem like a mind-numbing endeavor. But the mental faculties needed to keep a helpless, fussy baby alive may just be the source of our intelligence.
Humans’ extraordinary intellectual abilities may have originated in part in an evolutionary feedback loop related to caring for helpless infants, researchers hypothesize in a study published in the . Procedures of the National Academy of Sciences. In the loop, large-headed babies are born relatively early in their development to ensure they can fit through the human vaginal canal. The underdeveloped newborns then rely heavily on their parents’ knowledge for survival. Over generations, this selects for smart parents, prompting children to have fatter and fatter noggins and thus earlier births.
“Human babies are born much more immature than the babies of other species,” said study co-author Celeste Kidd, a brain and cognitive sciences researcher at the University of Rochester. “Giraffe calves, for example, can stand up, walk around and even flee from predators within hours of birth. In comparison, human babies can’t even carry their own head.”
The authors caution that the theory doesn’t explain all of humans’ exceptional smarts, which is off the charts when compared to our closest relatives. There are many other factors that likely contributed, such as social learning, nutrition, language, and the general development of reasoning skills seen in other primates. “The model is not intended to be a complete account, but rather a piece of a much more complex evolutionary and reproductive history in which multiple traits are interrelated,” write Kidd and her co-author, Steven Piantadosi, a cognitive scientist also at Rochester. .
To support their hypothesis, the pair created a mathematical model of basic elements of childcare and intelligence development to see how they might relate. The model took into account things like infant and adult head size, adult pelvic size — which may have been constrained by evolutionary pressures for bipedalism — childbirth survival, intelligence and overall mortality. The researchers found that the model predicted runaway selection for higher intelligence.
Next, the researchers looked for correlations in other primates, particularly looking at weaning age, which may act as a proxy for maturity at birth, with the more immature newborns weaning at an older age. The researchers found a clear link with intelligence: the older the weaned parent, the smarter the primate.
While the hypothesis may be only one factor in the evolution of human intelligence, the authors speculate that it offers a satisfactory explanation for why humans became super smart and not other creatures, such as some insects and reptiles that have had much more time to develop. to develop. The key may be the link between live births and cerebrums, the authors say. More research and extensive analysis will be needed to validate the author’s hypotheses.
Procedures of the National Academy of Sciences2016. DOI: 10.1073/pnas.1506752113 (About DOIs).