When hominins straightened up
At what point did early humans switch from ape-like shuffling to walking upright? Scientists have long puzzled over that question—and new research suggests it was much earlier than previously thought. Evolutionary anthropologists at the University of Arizona examined footprints discovered in Laetoli, Tanzania, that were made by human ancestors about 3.6 million years ago. Analysis showed that the heel and toe impressions of the ancient footprints closely matched those made by modern humans walking upright, rather than bent over. That suggests early human ancestors lost their ape-like shuffle and adopted a straight-legged gait long before big-brained members of the Homo genus emerged about 2.5 million years ago. “While there may have been some nuanced differences,” study author David Raichlen tells ScienceDaily.com, “these hominins probably looked like us when they walked.” Moving in a crouched position requires more energy than walking with a vertical torso and long stride. Scientists believe our early ancestors adjusted their gait because the changing climate forced them to cover greater distances to find food.