The Fragmented Field of Paleoanthropology

Humans, chimps, and all of the organisms leading back to their supposed most recent common ancestor are classified by evolutionary scientists as "hominins." The discipline of paleoanthropology is devoted to the study of the fossil remains of ancient hominins. Paleoanthropologists face a number of daunting challenges in their quest to reconstruct a story of hominim evolution.

First, hominin fossils tend to be few and far between. It's not uncommon for long periods of time to exist for which the...