Tuesday, November 24, 2009

Nov. 24, 1974: Humanity, Meet Lucy. She’s Your Mom

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1974: Paleonanthropologist Don Johanson and graduate student Tom Gray discover the skeleton of Lucy, the first recognizably human member of the primate family tree.
One morning toward the end of his second field season in Hadar, Ethiopia, Johanson decided to put his paperwork away and go bone-hunting with Gray. After several fruitless hours, they stopped in a gully that had been searched twice before, yielding nothing.
This time, Johanson noticed a fragment of arm bone. Near it were pieces of ribs, legbones, vertebrae and skull — all, amazingly, from the same skeleton. Thus was born specimen AL 288-1, whom the world would eventually know as Lucy.
Johanson’s team found hundreds of fragments, assembling them into the skeleton of a female Australopithecus afarensis who lived 3.2 million years ago and stood 3½ feet tall, with an emphasis on stood. Though Lucy’s long fingers and toes hinted at the arboreal origins of humanity’s ancestors, her pelvis and knees were clearly suited for walking on the ground.
Scientists hailed A. Afarensis as the oldest human primate. To the public, Lucy was the mother of man.
“Lucy captivated people of all ages in a way I don’t remember before her. She was a game-changer in every respect. For much of the public, she brought human evolution into view for the first time,” said William Jungers, a Stony Brook University paleoanthropologist. “Anyone with even a remote interest in human evolution had not just a tooth or a skull to think about, but an entire body.”
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More than 40 percent of Lucy’s skeleton was recovered, a remarkable amount in a field accustomed to drawing species-wide conclusions from bone fragments that could fit in the palm of a hand. Even today, Lucy’s one-of-a-kind completeness makes her extraordinarily valuable as a reference frame for other hominid fossils, from 4.4-million-year-old Ardipithecus ramidus to the Indonesian hobbits who died out just 13,000 years ago. “Lucy is more relevant than ever now,” said Jungers. “We can compare so many different body parts to hers, and get a sense from her of what’s primitive” and what’s new.
On a cultural level, the leading role played by Ethiopian scientists in excavating and subsequently studying Lucy signaled a shift in the world of anthropology, said Rick Potts, a Smithsonian Institution paleoanthropologist. “It wasn’t just a matter of an American researcher going into some other country and claiming the fame,” said Potts. “Since then, there’s been a great movement towards cooperation.” Humanity’s heritage was shared.
But the greatest cultural effect was among the public. Paleoanthropology had been a dry and esoteric field, but Lucy — named after the Beatles’ “Lucy in the Sky, With Diamonds,” which was on heavy rotation at camp in Hadar — wasn’t just another skeleton. She was an individual who touched their imaginations, even their hearts. Lucy: The Beginnings of Humankind, written by Johanson and Maitland Edey, became an international bestseller, kicking off what sometimes seems like a never-ending parade of books and documentaries about humanity’s origins.
Naming skeletons is now de rigueur among paleoanthropologists, but it’s hard to imagine any finding having as profound an effect as Lucy. It’s not, however, hard to imagine the discovery of earlier human ancestors.
Lucy is now considered “rather more humanlike” than originally thought, with many as-yet-unidentified steps linking her to the last common ancestor of chimpanzees and humans, said Arizona State University paleoanthropologist William Kimbel, who analyzed Lucy’s bones as a student and continues to gather A. afarensis fossils in Ethiopia.
In October, researchers described Ardipithecus ramidus, or Ardi, a hominid who predates Lucy by more than a million years. It’s not yet clear whether Ardi was a member or an offshoot of the lineage that led to Lucy and ultimately humans. But if not Ardi, then some other fossil will almost certainly take Lucy’s place as the oldest hominid.
“Lucy once represented the beginning of the human story. Now she’s only halfway through it,” said Potts. This, of course, is the nature of science. “In August, I was on a panel with Johanson. He was asked how he felt about Lucy being supplanted. He said, ‘Lucy likes having ancestors.’”
Source: Various
Images: 1) Detail from Lucy’s World, with Lucy in the center holding a child/Viktor Deak and Reuben Negron
2) Wikipedia

Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecosystem and planetary tipping points.
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