A monkey descending a tree trunk often keeps its head up, moving almost like a cautious climber backing down a ladder.

A new study explains how climbing down trees helped shape upright posture in early primates and changed the course of evolution.

Dr. Stephanie Poindexter is a biological anthropologist at the University of Buffalo specializing in primatology. Doctor Poindexter conducts field, lab, and desk-based research into how primates use ...