Cover

Humanity's first steps

Anthropology’s latest findings are redefining the human tree

Mark Nichols September 20 1999
Cover

Humanity's first steps

Anthropology’s latest findings are redefining the human tree

Mark Nichols September 20 1999

Humanity's first steps

Cover

Mark Nichols

Where exactly did the human tree take root? David Begun, a University of Toronto anthropologist, caught the scent of that mystery this summer while standing beside an abandoned iron mine in northeastern Hungary. In the mine's light-grey rock were four “specks” that turned out to be teeth in the fragmented skull of a European ape called dryopithecus. Begun thinks that ape, which lived about 10 million years ago, may have been a distant precursor of humans—an intervening creature that migrated south and led to the first upright beings on the steppes of Africa millions of years later.

This is a highly controversial idea since most scientists believe apes with early hominid traits developed in Africa— not Europe—eight to 10 million years ago even if they don’t have the fossil evidence to prove it. Still, Begun’s hypothesis has injected another new idea into a discipline that has been suddenly energized by several new discoveries this decade. Where anthropologists once envisioned a steady progression in which each stage of human development led to the next, they now see a twisting route, with evolutionary dead ends— and with pre-humans represented by more than one species at the same time. The human tree is “much more complicated than it used to be,” says University ofToronto anthropologist Mario Gagnon. “It’s a bushier kind of tree now.”

Reminders of a man-ape connection never fail to arouse the ire of Christian fundamentalists—and prompted Kansas authorities last month to ban evolution from state school curriculums. But there is little scientific doubt that human history ultimately goes back to a tree-dwelling ancestor that gave rise to diverging lines of chimpanzee and hominid descendants. Scientists now believe the human journey was set in motion by a combination of genetic mutations and environmental change. When shifts in the Earths surface seven or eight million years ago transformed forested eastern Africa into grassy plains, the early hominids there had a crucial advantage—a limited ability to walk on two feet. “The prairies created a need to abandon the trees,” says Geoffrey Sperber, an Edmonton paleoanthropologist. “On two legs, they could run, handle weapons and hunt—it was a pivotal moment.” But it did not happen suddenly. Fossil discoveries show a succession of early hominids—some more graceful than others but known collectively as Australopithecines—lived in East Africa from about 4.5 million years ago. One was the celebrated Lucy, a young female whose skeletal remains, more than three million years old, were found in Ethiopia in 1974. Then, about 1.8 million years ago, a species appeared that for the first time clearly resembled modern humans. This was Homo ergaster, a tall, slender, highly mobile creature that walked fully upright and was the first human to spread out of Africa. The remains of a descendant, Homo erectus, was found as far east as Java and China—the celebrated “Peking Man,” unearthed in the 1920s.

Anthropology’s latest findings are redefining the human tree

Those discoveries convinced some scientists that modern humans evolved independently in different parts of the world. But by the 1980s, genetic research had come up with a theory in which the first modern humans emerged genetically fully formed in the cauldron of Africa—and then expanded into the rest of the world. That hypothesis—the “African Eve” theory—has Homo sapiens originating in Africa within the past 200,000 years, then gradually replacing the descendants of the earlier out-migration—including the heavy-browed European Neanderthals who disappeared about 40,000 years ago during an ice age.

Though humankinds origins seem clearer today, much remains theoretical. Some experts even question the accuracy of the fossil trail. “There is so much information that we simply don’t have,” observes Bernard Wood, a paleoanthropologist at George Washington University in Washington D.C. That includes the identity of humankind’s ultimate ancestors. But sometimes, as with discoveries like the Hungarian ape skull, that search can feel tantalizingly close.