In 1974, the paleoanthropologist Donald C. Johanson led an expedition to Ethiopia to look for fossils of ancient human relatives.

In an expanse of arid badlands, he spotted an arm bone. Then, in the area surrounding it, Dr. Johanson and his colleagues found hundreds of other skeletal fragments.

The fossils turned out to have come from a single three-foot-tall female who lived 3.2 million years ago. The scientists named her species Australopithecus afarensis, and the skeleton was dubbed Lucy.

Continue reading “A 3.2-Million-Year-Old Mystery: Did Lucy Fall From a Tree?” →

To help his readers fathom evolution, Charles Darwin asked them to consider their own hands.

“What can be more curious,” he asked, “than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions?”

Darwin had a straightforward explanation: People, moles, horses, porpoises and bats all shared a common ancestor that grew limbs with digits. Its descendants evolved different kinds of limbs adapted for different tasks. But they never lost the anatomical similarities that revealed their kinship.

Continue reading “From Fins Into Hands: Scientists Discover a Deep Evolutionary Link” →

An eye is for seeing, a nose is for smelling. Many aspects of the human body have obvious purposes.

But some defy easy explanation. For biologists, few phenomena are as mysterious as the female orgasm.

While orgasms have an important role in a woman’s intimate relationships, the evolutionary roots of the experience — a combination of muscle contractions, hormone release, and intense pleasure — have been difficult to uncover.

Continue reading “Scientists Ponder an Evolutionary Mystery: The Female Orgasm” →