The Origin of Our Species

By MICHAEL D. LEMONICK

More than 3 million years ago, a tiny female, part human and part ape, slumped to the mud of an East African lakeshore and died, her bones sinking deep into the soft ground. Eventually, the lake dried. The mud turned to rock and so, gradually, did her bones. She might have rested there undisturbed forever but for the roaring geologic forces that ripped the earth apart over the next 30,000 centuries, finally thrusting the long-buried fossil bones to the surface -- where American anthropologist Donald Johanson would find them in 1974. Named Lucy, after the Beatles song Lucy in the Sky with Diamonds, this long-dead primate, half-a-million years older than any known human- related species, revolutionized scientists' understanding of human origins.

That remarkable discovery is the departure point for In Search of Human Origins, a three-hour Nova mini-series that airs on PBS next week. Over three consecutive nights, beginning Monday, Johanson himself is the tour guide on a journey through the physical and intellectual landscape of human evolution. Starting with the 3-ft.-tall, small-brained Lucy and her kin, he traces the ascent of humankind through some of its milestones: the emergence of toolmaking, the transition from scavenging to hunting and the struggle between the first modern humans and their Neanderthal cousins for control of the earth.

Johanson, though a little stiff at times, is a capable guide, narrating and often participating in a mix of on-location filming, talking-head interviews and dramatic re-creations, both historic and prehistoric. In some of the most impressive segments, actors in ingenious makeup, moving with a quasi-simian gait, bring Lucy and other protohumans eerily to life.

Two things make Origins more compelling than most science programs. The producers avoided the temptation to be encyclopedic and thereby to overwhelm viewers with information. And Johanson doesn't simply present facts. He shows how paleoanthropologists actually work, how they uncover fossils (the hard part) and how they analyze what they've found (the harder part). The earliest hint that his team had discovered an especially ancient human ancestor was a single knee joint plucked from the African dirt. It was old -- carefully dated volcanic ash in nearby rocks proved that. But it took laborious work by anatomist Owen Lovejoy to prove the knee belonged to a biped -- and thus, not entirely apelike -- primate. Lucy turned up nearby a year later, but it took weeks to piece her jumbled bones into a partial skeleton and years before anthropologists could agree on her place in human evolution.

In short, Johanson presents paleoanthropology as a kind of detective story, in which physical evidence is carefully gathered, painstakingly assembled and used to construct a convincing story of what actually happened. (In fact, Lovejoy, Johanson's frequent collaborator, also works with real detectives to solve murders and other crimes.)

The major differences between humans and apes, Johanson notes, are that the former are more intelligent and walk upright. There's one more: humans are intensely and endlessly curious about where and how they began. In Search of Human Origins will do much to satisfy that curiosity.