Long Thumbs Linked to Larger Brains in Primates

Big hands often correlate with big feet, but long thumbs are linked to larger brains-at least among primates. Researchers believe these findings suggest brains and manual dexterity co-evolved in mammals.

“We imagine an evolutionary scenario in which a primate or human becomes more bright, and with that comes the ability to think about action planning, to consider what you are doing with your hands, and realize you are more efficient doing it a certain way,” said Dr. Joanna Baker, lead author of the research from the university of Reading.

“Those with longer thumbs or greater ability to manipulate objects in ways their minds envision were likely more triumphant.”

Both large brains and manual dexterity are considered crucial in human evolution.Opposable thumbs are a key feature, enabling a greater ability to grip and manipulate items-including tools.