Human Evolution and the Environment of Evolutionary Adaptedness

Human Evolution

"Nothing in biology makes sense except for in the light of evolution." This famous quote from Theodosius Dobzhansky illustrates my feelings towards the utility of evolution for understanding children and youth. Certainly, genes without environment are nothing. But the environment must act on a child through the expression of that child's genes. Genes that were shaped by evolution.

But that shaping happened thousands, if not millions, of years ago. Evolution acts to solve today's problems tomorrow. For example, our inherited sweet/fat/salty cravings were presumably of great help to our ancestors, even if they are no longer very helpful in modern Western society. So one of my keen interests is trying to better understand the past conditions that led to our current genes. These past conditions, that include evolutionary pressures from many different times and locations, are generally summarized under the umbrella of the Environment of Evolutionary Adaptedness, or EEA. If we can better understand the EEA, we can better understand the reasons why our mind/genes work the way that they do.

I am currently work on two projects regarding the EEA and childhood. The first has to do with infant and child mortality. In a survey of dozens of hunter-gatherer and historical cultures, there is a remarkable consistency in the infant and child mortality rates. Roughly 1/4 of all infants and HALF of all children died in the past! This is a tremendously important factor for anyone interested in the evolution of our species. From my perspective, these high levels of mortality mean that it really matters for children to be adapted to childhood. In other words, children aren't just incomplete adults- they are adapted to thriving and surviving each of the stages of childhood that they must pass through. This idea is largely the foundation of evolutionary developmental psychology, where the prevailing sentiment is that children are adapted to being children- youth is not wasted on the young!

Youth isn't wasted on the young

The second project has to do with breastfeeding. What struck me about human breastfeeding is that it is not intuitive. Indeed, it can be extremely difficult for some women to succeed at with their infant. This is in part due to the fact that the physical design of the human breast appears to require a more complicated sucking action than other mammalian breasts. But it's also due to the fact that the correct technique for feeding an infant is not instinctive for mothers. It has to be learned, or taught. What does this tell us about the human EEA? To me, it very strongly suggests that since breastfeeding is absolutely vital for infant survival (see previous point!), mothers must have had ample, reliable opportunities to learn and/or be taught the correct way to breastfeed their infant. This means that women must have lived in stable, cooperative groups for most, if not all, of our evolutionary history.

breastfeeding classes

Created November 2010