There’s a dirty little secret in paleoanthropology: What we know about human evolution is that we don’t know much of the story.
Let’s be clear: That Homo sapiens evolved from earlier hominin species isn’t in question. Although the fossil record is incomplete, we have more than enough to see that, in broad terms, our big-brained, long-limbed, built-for-distance-walking species evolved from arboreal ancestors with smaller brains, larger teeth and broader chests. We can also say, more confidently than even a few decades ago, that our family tree isn’t a tall pine, with a single trunk progressing upward to a lone pinnacle (us). Instead, the story of hominin evolution is a gnarly tree with multiple branches, some of them tangled through interbreeding.
“Our provisional family tree shows typically several hominids were living at the same time,” says paleoanthropologist and best-selling author Ian Tattersall. “It’s only very recently that we’ve had the planet to ourselves. ‘Normal’ is having more than one hominid running around.”
In the opening decades of this millennium, researchers have unearthed several breathtaking fossils from the caves of South Africa to the mountain valleys of the Republic of Georgia. At the same time, advances in sequencing ancient DNA have allowed us to determine not only when one species branched from another, but also whether they reunited, briefly, in isolated examples of interbreeding.
“In the 45 years I’ve been doing this, the human fossil record has expanded enormously,” Tattersall says. “In 50 years, what we believe now will look just
The Root of the Matter