Humans Evolved Weak Muscles to Feed Brain's Growth, Study Suggests
Weak muscles evolved even faster than smart brains in people.
We humans may be weaklings by nature.
The upshot, says biologist Roland Roberts, is that "weak muscles may be the price we pay for the metabolic demands of our amazing cognitive powers."
Scientists have long noted that the major difference between modern humans and other apes, like chimps, is our possession of an oversize, energy-hungry brain. (Related: "Human Origins Project.") It was the development of that brain that drove the evolution of our early human ancestors away from an apelike ancestor, starting roughly six million years ago.
But the question of just why and how we evolved such big brains, which consume 20 percent of our energy, has long bedeviled science.
"A major difference in muscular strength between humans and nonhuman primates