Meet the New Human Family. By: NEIMARK, JILL, Discover, 02747529, May 2011,
Vol. 32, Issue 4
Meet the New Human Family
Once we shared the planet with other human species, competing with them and interbreeding
with them. Today we stand alone, but our rivals' genes live on inside us -- even as their
remarkable stories are only now coming to light.
A SINGLE, UNFORGETTABLE IMAGE COMES TO MIND when we ponder human origins:
a crouching ape slowly standing and morphing into a tall, erect human male poised to conquer
every bit of habitable land on this planet. We walk this earth -- we, this unparalleled experiment
in evolution -- reflexively assuming we are the crown of creation. Certainly we are rare and
strange: As biological anthropologist Owen Lovejoy of Kent State University says, "The chances
that a creature like us will ever happen again are so small that I can't even measure them."
But that ascent-of-man picture is looking as dated as the flat earth. A series of scientific and
technological breakthroughs have altered much of our fundamental understanding of human
evolution. In the new view, the path to Homo sapiens was amazingly dilatory and indirect. Along
the way, our planet witnessed many variations on the human form, multiple migrations out of
Africa, interspecies trysts, and extinctions that ultimately wiped out all hominid species except
one. "Human evolution used to seem simple and linear," says paleoanthropologist William
Jungers of the State University of New York at Stony Brook. "Now, you look at almost any time
slice and you see diversity. We may be special and we may be lucky, but we're far from the only
Unexpected fossil finds keep showing us an ever-expanding variety of human and prehuman
species. Probably the most stunning of these recent discoveries is Ardipithecus ramidus, an
ancestor who displayed a fantastical mosaic of ape and human traits. A. ramidus apparently
climbed trees but also walked upright some 4.4 million years ago -- more than half a million
years before the long-accepted origin of bipedalism.
Our ideas about later human evolution, meanwhile, have been shattered by the remains of a tiny,
novel human species with a small but intricately folded brain. Called Homo floresiensis and
nicknamed the "hobbit" people, this species found in Indonesia rewrites the scientific story of
how humans migrated out of Africa and came to populate the whole world. The hobbits
overlapped in time and space with Homo sapiens, showing that even in relatively recent history
more than one human species shared our planet -- a situation evocative of the colorful world of J.
R. R. Tolkien's Middle-earth, but undeniably real.
The emerging field of paleogenetics has brought perhaps the most surprising news of all. Using