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Some scientists disagree with new fossil findings
Not everyone is on board with calling the jaws and teeth found in Ethiopia a new species that lived alongside Lucy 3.4 million years ago
by WKSU's JEFF ST. CLAIR


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Jeff St. Clair
 
Lucy looks a little skeptical, and so are several scientists who disagree that fossils found in Ethiopia represent a new species that lived alongside Lucy 3.4 million years ago.
Courtesy of Jeff St.Clair
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The announcement by a Cleveland researcher last week of the discovery of a new potential human ancestor made international headlines, but not everyone in the scientific community is on-board with the finding.

Cleveland Museum of Natural History curator Yohannes Haile-Selassie, says the jaw bones and teeth he found in Ethiopia belong to a new species of early human that lived alongside a more commonly known ancestor.

Kent State University professor Owen Lovejoy was part of the team that back in 1974 discovered the famous specimen known as Lucy.    

He says, not so fast - the new teeth are not that different than Lucy’s.

LISTEN: Owen Lovejoy says new bones belong to Lucy's species

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Owen Lovejoy was part of the original team that analyzed Lucy's skeleton. He believes new fossil teeth and jaw bones found in Ethiopia belong to Lucy's species, not a new lineage of early human ancestors.
Cleveland Museum of Natural History curator Yohannes Haile-Selassie holds casts of upper and lower jaw bones that he thinks belong to a distinct species he calls A. deyiremeda. Others disagree, saying they belong to Lucy's species.
Yohannes Haile-Selassie has made several significant fossil finds in his native Ethiopia, including a new set of jaws and teeth that he says belong to a new species that lived alongside Lucy, on display in Cleveland.

New species designation in doubt
A species is the fundamental taxonomic category we use in biology and it’s a very difficult judgement to make, especially in the fossil record where you’re invariably looking at only a small portion of the animal, in this case it’s a few teeth and jaws.

You’re making the judgement as to whether or not this constitutes a new lineage that lies outside the variation that you’d expect.

And some of us recognize much higher ranges of variation than others.

Here you’re comparing things like molar and enamel thickness and size, and various characteristics of the dentition, and having to make the judgement as to whether these are significantly different than anything we’ve seen in Lucy’s species to justify a new lineage.

Many of us feel that, in this case, it’s probably not justified.  That includes Lucy co-discoverer Tim White at Berkeley, one of Haile-Selassie’s mentors, and William Kimble, director of the Institute of Human Origins at Arizona State University. 

Sharing habitats with Lucy 
Lovejoy says part of his skepticism stems from the behavioral implications of adding a new species side-by-side with Lucy.

If in fact Haile-Selassie’s specimens do represent a new lineage, then it means there were two contemporary lineages that must have had at least something called character divergence, which means they were occupying different niches within the environment.  That would be one of the implications.

When we look at hominids in this particular time range however, they all seem to share the same set of very clear, unmistakable specializations -  upright walking; small canines, which has social implications – so undoubtedly even if Yohannes’ specimens are a separate species, they still had the same social structure as did Lucy’s species.

So it’s a matter of scientific debate.

Theories vs facts in human origins debate
AS Darwin pointed out,  shooting down someone’s theory is a positive thing, as long as you get the facts right.

In this case the facts are still in dispute - that these teeth represent a new species.

Some scientists say they’re within the variation seen within Lucy’s species Australopithecus afarensis, but Haile-Selassie says they’re not.

And we won’t be able to answer the question fully until more specimens are found that can be satisfactorily added to the proposed new species, Australopithecus deyiremeda.

Haile-Selassie needs to build up the hypodigm, the individuals that we define as members of the new species.

But whenever new fossils are found, no matter how much we disagree about it, it always adds to our understanding of human evolution.


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