Scientists announce discovery of 3.6 million-year-old relative of 'Lucy'

Jun 21, 2010
Researchers recovered only the second partial skeleton of science's best-known early human ancestor, Australopithecus afarensis. It's 400,000 years older than the famed hominid "Lucy," which is the same species, and it's male. Here, a small fragment of the specimen's lower arm bone is shown. Credit: Yohannes Haile-Selassie, Cleveland Museum of Natural History

(PhysOrg.com) -- Within the coarsening base of an ancient mudstone exposure in the Afar Region of Ethiopia, researchers say they found evidence that provides new information about the best-known early human ancestor, Australopithecus afarensis.

Yohannes Haile-Selassie--curator and head of physical anthropology at the Cleveland Museum of Natural History--and an international team of scientists dug up a 3.6 million-year-old partial skeleton of the same species as the famed hominid "Lucy." It's only the second partial skeleton of A. afarensis to be recovered; it's 400,000 years older than Lucy and it's male. But just as important, the fossil remains provide conclusive proof that A. afarensis could walk upright freely without the use of its hands.

"The KSD skeleton is long sought fossil evidence," said Haile-Selassie. [KSD is shorthand for 'Korsi Dora,' the name of the locality where the skeleton was found.] "It complements the Laetoli footprints and incontrovertibly shows A. afarensis was an obligate bipedal since its first appearance in the fossil record."

The new skeleton's scientific designation is KSD-VP-1/1. Researchers recovered the skeleton as part of the paleontology-focused Woranso-Mille Project that has been ongoing in the region since 2004.

The researchers report the finding in this week's Proceedings of the National Academy of Sciences early online publication. The National Science Foundation is a major funder of the work.

Previous examinations of Lucy, who lived 3.2 million years ago, led some scientists to conclude A. afarensis was not fully adapted to upright walking. The newly recovered fossil, nicknamed "Kadanuumuu" and pronounced "kah-DAH-noo-moo," clears up the debate.

"Kadanuumuu" appears to be in good agreement with fossilized footprints dated to about 3.6 million years ago and discovered in Laetoli, a site in Tanzania in eastern Africa. The footprints show that early human ancestors habitually walked upright; there are no knuckle-impressions or signs of abducted toes.

The misinterpretation concerning Lucy's ability to walk upright resulted largely from her small frame, said Haile-Selassie referring to her estimated 3 1⁄2 feet. But "Kadanuumuu," whose name means "big man" in the Afar language, is 5 to 5 1/2 feet tall and the proportion of the length of his legs to his arms compares favorably to modern humans.

Long legs are a tell-tale human characteristic of bipedalism. "Generally speaking, the skeleton clearly shows that the emergence of advanced bipedality is not associated with the first appearance of our genus Homo," said Haile-Selassie. "But rather it has deep roots going back to more than 3.6 million years ago."

"Kadanuumuu" also has most of the same skeletal parts as Lucy and others never previously known, including a significant portion of the rib cage and a nearly complete adult shoulder blade.

"'Kadanuumuu's' shoulder was also a major discovery," said Haile-Selassie. "It shows that our ancestor's shoulder blade and rib cage were much more similar to those of modern humans than previously had been thought."

Before now anthropologists concluded evolutionary ancestors had shoulders more like those of chimpanzees. But "Kadanuumuu" surprised researchers by revealing a shoulder very different from chimpanzees, which are thought to be the closest living relatives of Homo sapiens.

"This tells us that chimpanzees have evolved a great deal since we shared a last common ancestor with them," said Haile-Selassie.

Renowned Ethiopian fossil hunter Alemayehu Asfaw found the first element of "Kadanuumuu" in February 2005 at Korsi Dora, about 210 air miles northeast of the Ethiopian capital Addis Ababa.

The specimen was exposed on the surface and further investigation resulted in the recovery of more elements. Excavations between 2005 and 2008 uncovered an upper arm, a collarbone, neck bones, ribs, pelvis, sacrum, a thighbone, a shinbone and the shoulder blade. Excavations took more than five years to complete.

Publication of more results will continue as researchers complete more detailed analysis of Kadanuumuu. Scientists from Case Western Reserve University, Ohio; Berkeley Geochronology Center, Calif.; Addis Ababa University, Ethiopia; and Kent State University, Ohio contributed to this research.

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User comments : 9

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deatopmg
Jun 21, 2010
This comment has been removed by a moderator.
SteveL
3 / 5 (2) Jun 22, 2010
5 years to excavate a partial skeleton? Was this a union job?

Still, it's interesting that whenever we think we know something with a certainty - something new comes along and forces us to re-think, or at least hopefully to re-consider our "facts".
GSwift7
3 / 5 (2) Jun 22, 2010
Not sure they meant it that way. It could mean that the excavation was done over a period of five years, or it could mean that they found the rest of the remains more than five years after the first fragment was found.
Donutz
not rated yet Jun 22, 2010
Still, it's interesting that whenever we think we know something with a certainty - something new comes along and forces us to re-think, or at least hopefully to re-consider our "facts".


You need to be careful when talking about 'certainty'. Very few things in science are really considered 'certain', but when reported and re-reported, some of the nuances can be lost. Also, people in an argument will tend to state things with more certainty than they would in a discussion.
kevinrtrs
1 / 5 (3) Jun 23, 2010
I would like to be a fly on the wall when the researchers discuss how to determine the age of a particular find.
What process do they follow and what are the factors that influence their ultimate pronouncement?
I wish someone/corporation would make a documentary showing how people arrive at these spectacular ages. Maybe the Discovery channel would launch an HD program in one of their "How it works"?

Ethelred
5 / 5 (2) Jun 23, 2010
I would like to be a fly on the wall when the researchers discuss how to determine the age of a particular find.


The usual technique with fossils of that age is potassium argon dating of ash layers above and below the fossils. Other techniques include looking at the other fossils in the same layer with know dates of existence.

I wish someone/corporation would make a documentary showing how people arrive at these spectacular ages.


The book on the original discovery of Lucy describes the dating techniques that were used in a fair amount of detail. You should be able to find a copy at your local library. Assuming that you live in an area that actually has science books that cover such things. In some areas the book would be burned.

Ethelred
Skeptic_Heretic
1 / 5 (2) Jun 23, 2010
I would like to be a fly on the wall when the researchers discuss how to determine the age of a particular find.
What process do they follow and what are the factors that influence their ultimate pronouncement?
I wish someone/corporation would make a documentary showing how people arrive at these spectacular ages. Maybe the Discovery channel would launch an HD program in one of their "How it works"?


You could always read a book. Or perhaps go to school. Maybe learn something that might, *gasp* conflict with your church teachings.
deatopmg
1 / 5 (1) Jun 24, 2010
I'll say it again and hopefully the lout who removed it will get the point - did it have an arched foot like us or flat feet? This is important to know because it is an indication of the lineage and when an arch evolved.
Ethelred
5 / 5 (1) Jun 25, 2010
It is rather difficult to tell as they don't have a foot.
http://www.cmnh.o...muu.aspx

That is far less complete than Lucy. Nothing of the head, not even a tooth.The most important part of the find seems to be the scapula.

Ethelred
Skeptic_Heretic
not rated yet Jun 25, 2010
I'll say it again and hopefully the lout who removed it will get the point - did it have an arched foot like us or flat feet? This is important to know because it is an indication of the lineage and when an arch evolved.
A Afarensis has no examples of the constructed foot available as far as I am aware. Speculation based off of potential contemporary foot prints from local A Afarensis finds indicate that they did, however these footprints cannot be accurately placed with A Afarensis and many think they are not from the same species and perhaps not from the same time.