In our evolutionary past, these would also have been strong indicators of youth.
By definition, any human behavior has to be in some way a product of our evolutionary past.
The focus on this part of the human anatomy has finally been followed by a much later observation testifying to our evolutionary past.
In particular, some parts of embryos reflect their evolutionary past.
Or at the very least, different species who share the same evolutionary past.
"Fear, of course, was absolutely necessary to survival in our evolutionary past," he said.
The information that comes from deep in the evolutionary past we call genetics.
If so, this may explain another key step in the butterfly's evolutionary past, its development of mimicry.
Our evolutionary past doesn't tell us what choices we should make today; old strategies don't always work in a new environment.