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Lucy, the 3.2 million-year-old fossil, is a key piece in evolution’s puzzle

By TOM PAULSON
P-I REPORTER

Some 3 million years or so after her descendants arrived in the Pacific Northwest, Lucy represents just how far we have come from those days of wandering the savannas of Africa, scavenging for food, avoiding predators and awaiting the rapid expansion of a brain that today allows us to, among other things, ponder our origins.

 

She wasn’t human. But she wasn’t really an ape, either. She was, for many, a hint of humankind to come.

“Lucy is simply phenomenal,” said Patricia Kramer, an anthropologist at the University of Washington. “You can see yourself in her.”

You can, perhaps, as long as you are among those who can imagine having evolved along with chimpanzees, gorillas and other primates from a common — and now extinct — ancestor many millions of years ago. Not everyone can so easily imagine this, of course, whether because of conflicting religious beliefs or just that vague “sense” we have of human beings as somehow different, special, compared with the rest of creation.

   
   
   

However the metaphysical debate of our place in the cosmos may some day get resolved, there’s little debate within the scientific community today as to the significance of Lucy’s role in human evolution on Earth.

“She occupies a pivotal place on the human family tree,” said Donald Johanson, the American paleoanthropologist who, with his colleagues, discovered the fossil in 1974 near the northern Ethiopian community of Hadar. “We now know that one of the first significant things our ancestors did was to stand up, to walk on two feet instead of four.”

Lucy is still one of the most complete fossils from an early group of hominids (pre-humans) to routinely walk on two feet. This may sound like no big deal to us 21st century bipeds. But scientists say this was a key evolutionary adaptation probably caused by climate change, which forced our ancestors to shift from forest skills to operating on the savannas. It appears to have triggered other critical changes in our physique and behavior that led to modern humans.

More on those changes later. First, why is the fossil named Lucy?

“After the discovery, we kept listening to The Beatles’ song ‘Lucy in the Sky with Diamonds’ in camp and a girlfriend of mine suggested we call her Lucy,” said Johanson, who neglected to mention the much-documented celebratory partying that also took place that night. “The name just stuck. I’m amazed at how this helped to make her into this popular icon for human evolution.”

But it wasn’t just The Beatles who lent Johanson’s discovery such prominence and recognition.

“Lucy forced us to rewrite much of the science,” said Gerry Eck, a retired UW anthropologist who worked with Johanson in Ethiopia on expeditions after Lucy was uncovered. “Evolutionary history is basically a puzzle with a lot of missing pieces. Lucy helped fill in a big piece of the puzzle.”

Technically, Lucy is a fossil member of a class of hominids, or proto-humans, known as Australopithecus afarensis who lived between 3.9 million and 2.9 million years ago.

Scientists use a lot of confusing Latin names for (and frequently argue about) labeling members of the human evolutionary family tree. For simplicity’s sake, human evolution can be broken into three phases — early and very apelike hominids, Australopiths such as Lucy and our genus Homo.

Lucy and her ilk occupied a critical phase in the evolutionary process that scientists believe led to a variety of other pre-modern human species such as Homo erectus, Homo neanderthalensis (the Neanderthals) and eventually to us, Homo sapiens.

Australopithecus is Latin for southern ape. Lucy’s species name A. afarensis means she is the southern ape who hails from Afar, the region in Ethiopia where she was discovered. She stood about 3.5 feet tall, but still had a very small brain. Back in the 1970s, scientists were still arguing over what came first in human evolution — growing a much bigger brain or moving from four-legged to two-legged walking.

Unlike most such ancient fossils, Lucy was more than just a piece of skull, femur or jaw. She was 40 percent intact, including much of her skull and most of her pelvis.

It was her pelvis and leg structure that nailed it: Bipedalism clearly had preceded the boom in brains.

“There was no question that we were bipedal millions of years before our brains got big,” said the UW’s Kramer.

“It was a spectacular find,” Eck agreed. This caused a bit of a fuss, he added, because Johanson was a relative newcomer to the field and, based on Lucy, was introducing a revolutionary new interpretation of how we evolved.

Put brutally simply, here is a quick summary of how Lucy’s bipedalism contributed to human evolution:

 

  • Standing up freed our hominid hands to eventually allow for tool use.  
  • Tool use led to greater success in hunting or otherwise acquiring meat in the diet.  
  • A diet rich in meat provided more of the basic biochemical building blocks needed for brain development.  
  • Someone, at some point, learned how to use fire. Someone started talking. Someone started writing.
  • It’s an absurd abbreviation of our story, of course, and of the scientific evidence. The complete story of human evolution, like the human brain, is too incredibly rich and complex to be so simplistically boiled down to such a short description. What makes Lucy so special is that, to some extent, she represents a stage in our prehistory, our evolutionary development, that we can comprehend.

    There are still many mysteries, many gaps and unresolved issues to this story. Why did the Neanderthals disappear some 28,000 years ago? Did they really disappear or did they interbreed with us? Do the diminutive fossils dubbed the “Hobbits” recently discovered on the Indonesian island of Flores represent a new branch of Homo that lived contemporaneously with modern humans?

    What does it really mean to be human?

    Lucy certainly can’t answer all the questions, but she did answer some of the most significant ones for human evolution. As such, she likely will forever be regarded as a crucial turning point in our ongoing search to understand who we are, how we got here and, perhaps, where we are headed.

    “Lucy really is the link, the common ancestor, between the older, more apelike creatures and the hominids that gave rise to us,” Johanson said.

    “The field of paleontology is still quite young and we are in for an enormous number of further surprises. But Lucy will always be a touchstone.”

    P-I reporter Tom Paulson can be reached at 206-448-8318 or tompaulson@seattlepi.com.
    ————————————————————————————-
    other links (news) :
    SA academic called on to solve fossil mystery
    Independent Online – 4 ore fa
    By Shaun Smillie They died suddenly in an Ethiopian riverbed – killed by a single catastrophic event that claimed babies, and possibly their mothers and
     
    ‘Lucy’s Legacy’ holds treasures for all ages at the Pacific
    Seattle Post Intelligencer – 15 ore fa
    By DOREE ARMSTRONG For such a little girl, she sure has had an enormous impact on the world. The 1974 discovery of 3 1/2-foot-tall Lucy, the oldest and most
    Lucy on display with controversy
    Seattle Times – 2 ott 2008
    Lucy, the world’s most famous fossil, goes on exhibit in Seattle this week. But some scientists say the fragile bones should never have left Ethiopia.
    Ethiopia’s rich heritage: Lucy’s birthplace is globally significant
    Ethiopian Review – 19 ore fa
    By TOM PAULSON SEATTLE, WASHINGTON – It is fitting that one of the most signature discoveries of humankind — a finding that has helped define a big part of

    settembre 30, 2008 - Posted by | - Primati, Africa, P - Paleoantropologia, Paleontology / Paleontologia, x Terziario | , , , , , , , ,

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