Oldest Human-link Skeleton Found

[LadyTevar]

No one's said anything about this, though it's been out for a few days.

MSNBC.com

World’s oldest human-linked skeleton found
‘Ardi’ predates Lucy by a million years, changes scientific view of origins


WASHINGTON - The story of humankind is reaching back another million years with the discovery of “Ardi,” a hominid who lived 4.4 million years ago in what is now Ethiopia.

The 110-pound, 4-foot female roamed forests a million years before the famous Lucy, long studied as the earliest skeleton of a human ancestor.

This older skeleton reverses the common wisdom of human evolution, said anthropologist C. Owen Lovejoy of Kent State University.

Rather than humans evolving from an ancient chimplike creature, the new find provides evidence that chimps and humans evolved from some long-ago common ancestor — but each evolved and changed separately along the way.

“This is not that common ancestor, but it’s the closest we have ever been able to come,” said Tim White, director of the Human Evolution Research Center at the University of California, Berkeley.

The lines that evolved into modern humans and living apes probably shared an ancestor 6 million to 7 million years ago, White said in a telephone interview.

But Ardi has many traits that do not appear in modern-day African apes, leading to the conclusion that the apes evolved extensively since we shared that last common ancestor.

A study of Ardi, under way since the first bones were discovered in 1994, indicates the species lived in the woodlands and could climb on all fours along tree branches, but the development of their arms and legs indicates they didn’t spend much time in the trees. And they could walk upright, on two legs, when on the ground.

Formally dubbed Ardipithecus ramidus — which means root of the ground ape — the find is detailed in 11 research papers published Thursday by the journal Science.

“This is one of the most important discoveries for the study of human evolution,” said David Pilbeam, curator of paleoanthropology at Harvard’s Peabody Museum of Archaeology and Ethnology.

“It is relatively complete in that it preserves head, hands, feet and some critical parts in between. It represents a genus plausibly ancestral to Australopithecus — itself ancestral to our genus Homo,” said Pilbeam, who was not part of the research teams.

Scientists assembled the skeleton from 125 pieces.

Lucy, also found in Africa, thrived a million years after Ardi and was of the more humanlike genus Australopithecus.

“In Ardipithecus we have an unspecialized form that hasn’t evolved very far in the direction of Australopithecus. So when you go from head to toe, you’re seeing a mosaic creature that is neither chimpanzee, nor is it human. It is Ardipithecus,” said White.

White noted that Charles Darwin, whose research in the 19th century paved the way for the science of evolution, was cautious about the last common ancestor between humans and apes.

“Darwin said we have to be really careful. The only way we’re really going to know what this last common ancestor looked like is to go and find it. Well, at 4.4 million years ago we found something pretty close to it,” White said. “And, just like Darwin appreciated, evolution of the ape lineages and the human lineage has been going on independently since the time those lines split, since that last common ancestor we shared.”

Some details about Ardi in the collection of papers:
# Ardi was found in Ethiopia’s Afar Rift, where many fossils of ancient plants and animals have been discovered. Findings near the skeleton indicate that at the time it was a wooded environment. Fossils of 29 species of birds and 20 species of small mammals were found at the site.

# Geologist Giday WoldeGabriel of Los Alamos National Laboratory was able to use volcanic layers above and below the fossil to date it to 4.4 million years ago.

# Ardi’s upper canine teeth are more like the stubby ones of modern humans than the long, sharp, pointed ones of male chimpanzees and most other primates. An analysis of the tooth enamel suggests a diverse diet, including fruit and other woodland-based foods such as nuts and leaves.

# Paleoanthropologist Gen Suwa of the University of Tokyo reported that Ardi’s face had a projecting muzzle, giving her an ape-like appearance. But it didn’t thrust forward quite as much as the lower faces of modern African apes do. Some features of her skull, such as the ridge above the eye socket, are quite different from those of chimpanzees. The details of the bottom of the skull, where nerves and blood vessels enter the brain, indicate that Ardi’s brain was positioned in a way similar to modern humans, possibly suggesting that the hominid brain may have been already poised to expand areas involving aspects of visual and spatial perception.

# Ardi’s hand and wrist were a mix of primitive traits and a few new ones, but they don’t include the hallmark traits of the modern tree-hanging, knuckle-walking chimps and gorillas. She had relatively short palms and fingers which were flexible, allowing her to support her body weight on her palms while moving along tree branches, but she had to be a careful climber because she lacked the anatomical features that allow modern-day African apes to swing, hang and easily move through the trees.

# The pelvis and hip show the gluteal muscles were positioned so she could walk upright.

# Her feet were rigid enough for walking but still had a grasping big toe for use in climbing.

The research was funded by the National Science Foundation, the Institute of Geophysics and Planetary Physics of the University of California, Los Alamos National Laboratory, the Japan Society for the Promotion of Science and others.

[The Spartan]

I saw a commercial for a special on the Discovery channel today for Ardi. It airs a week from Sunday at 9pm ET.

[Johonebesus]

It was found about fifteen years ago, but it took that long for the discoverers to clean and analyze the remains. I believe there have been several upright anthropoids that are about as old found in the past few years, so this new description isn't really so very revolutionary at this point. Some argue that gorillas and chimps evolved knuckle-walking independently, so that the common ancestor of all three was bipedal, with hominids retaining the basal condition.

[Jeremy]

I wonder how similar the Ardipithecus genus is in adaptions to Mandrillus and Papio.

[hongi]

Rather than humans evolving from an ancient chimplike creature, the new find provides evidence that chimps and humans evolved from some long-ago common ancestor — but each evolved and changed separately along the way.

This is news?

[Ypoknons]

This is news?

Heh. That's typical newspaper reporting for fossil finds. I haven't read any scientific publications, but getting a good picture of what was happening a million years before Australopithecus gives us more insight to what our common ancestor looked like. And it's still puzzling where bipedalism came from, since Ardi already has a reasonably advanced form of it, hence the theory Johonebesus mentioned. Ardi's huge curved arms pretty much make it arboreal, but again, Australopithecus also has slightly curved arms so that's no huge surprise. Of course, if the ancestor lived in the forest, good luck finding a fossil.

[Winston Blake]

Rather than humans evolving from an ancient chimplike creature, the new find provides evidence that chimps and humans evolved from some long-ago common ancestor — but each evolved and changed separately along the way.

This is news?

It sounds like it was news to the journalist, who then assumed that this was a momentous change in anthropology, rather than merely a momentous change within their own skull.

This older skeleton reverses the common wisdom of human evolution, said anthropologist C. Owen Lovejoy of Kent State University.

Rather than humans evolving from an ancient chimplike creature, the new find provides evidence that chimps and humans evolved from some long-ago common ancestor — but each evolved and changed separately along the way.

“This is not that common ancestor, but it’s the closest we have ever been able to come,” said Tim White, director of the Human Evolution Research Center at the University of California, Berkeley.

The lines that evolved into modern humans and living apes probably shared an ancestor 6 million to 7 million years ago, White said in a telephone interview.

But Ardi has many traits that do not appear in modern-day African apes, leading to the conclusion that the apes evolved extensively since we shared that last common ancestor.

Second bolded part: actual novel result.

First bolded part: journalist's inability to separate the novel result from perfectly ordinary facts.

[Zor]

We actually studied Ardi in my Physical Anthropology course this week. A rather interesting critter.

Zor

[Lagmonster]

So, do you have anything to *say* about it, Zor?

[Zor]

So, do you have anything to *say* about it, Zor?

Well in the video scientists think that it changes how they thought how bipedality and human social charecteristics came about. Africa was more forested in Ardi's day and as such, scientists are now thinking more along the lines of moving towards perminant mates with males able to carry food to provide it to specific females in exchange for sex.

Zor

[NDR-113]

It is relatively complete in that it preserves head, hands, feet and some critical parts in between.

Like what? All they talk about is the head and hands.

Africa was more forested in Ardi's day and as such, scientists are now thinking more along the lines of moving towards [permanent] mates with males able to carry food to provide it to specific females in exchange for sex.

Whoa! How do they get all that from one pre-hominid fossil and several other smaller ones?

[Edi]

It is relatively complete in that it preserves head, hands, feet and some critical parts in between.

Like what? All they talk about is the head and hands.

Africa was more forested in Ardi's day and as such, scientists are now thinking more along the lines of moving towards [permanent] mates with males able to carry food to provide it to specific females in exchange for sex.

Whoa! How do they get all that from one pre-hominid fossil and several other smaller ones?

In addition to Ardi, there was a crapload of fossils of the environment which gave them a very good idea of what the living conditions were like then. Read some of the publications on this, even the light stuff like the Time Magazine article on it.

[ArmorPierce]

So, do you have anything to *say* about it, Zor?

Well in the video scientists think that it changes how they thought how bipedality and human social charecteristics came about. Africa was more forested in Ardi's day and as such, scientists are now thinking more along the lines of moving towards perminant mates with males able to carry food to provide it to specific females in exchange for sex.

Zor

I thought that was previously discounted as the main reason because chimps are able to walk upright whilst carrying food at present.

http://www.youtube.com/watch?v=l0tAQcpLILQ