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Path of human evolution continues to be enriched and elucidated by growing trove of fossil evidence

In comments to the media, renowned paleoanthropologist Richard Leakey opined that the evolution debate "would soon be over" thanks to a growing wealth of fossil evidence.  The latest piece of the puzzle comes courtesy of Professor Leakey's wife, Meave Leakey, and his mother, Louise Leakey, who are busy working on the excavation of a site east of Lake Turkana.

I. Two New Branches on the Evolutionary Tree

Located in Eastern Africa, specifically in the north of Kenya and south of Ethiopia, the Turkana Basin has been the site of some of many astonishing and fortunate fossil discoveries that have given mankind a glimpse of its evolutionary ancestors.  In fact the region proved so fruitful that the Leakey family of famed anthropologists raised funds to open Turkana Basin Institute (TBI), a special research institution devoted to studying the region's fossils and human evolution.

The recent discoveries were made by Professors Louise and Meave Leakey, along with other TBI researchers and researchers from the Koobi Fora Research Project (KFRP) -- a evolutionary research team funded by the National Geographic Society.

Lake Turkana Basin
The Turkana basin is located in Eastern Africa. [Orig. Image Source: Google Maps]

Unearthed between 2007 and 2009, the find includes a face, a remarkably complete lower jaw, and part of a second lower jaw.  Researchers believe that the fossils belong to not one, but two genus Homo species, which lived beside mankind's direct ancestor, Homo erectus.

II. Solving a Big Mystery

The find solves the mystery of KNM-ER 1470 -- the research designation given to a mysterious hominid skull fossil found four decades ago.  The KNM-ER 1470 specimen featured a striking long, flat-face -- à la the pop culture depiction of an alien -- and a large brain size.

Researchers were unsure if the fossil was truly a different species or simply an unusual variant of Homo erectus.

Professor Meave Leakey enthuses, "For the past 40 years we have looked long and hard in the vast expanse of sediments around Lake Turkana for fossils that confirm the unique features of 1470's face and show us what its teeth and lower jaw would have looked like.  At last we have some answers."

Complete specimen
The stellar jaw specimen (bottom) fits perfectly on the restored KNM-ER 1470 skull (top).  
[Image Source: Fred Spoor]

The new finds left little doubt among researchers that KNM-ER 1470 was indeed a separate species, and as an added surprise, they also indicated that one of the two specimens dug up during the various excavations was a second relative.

Comments Fred Spoor who led the analysis of the specimens unearthed by the Leakey team, "Combined, the three new fossils give a much clearer picture of what 1470 looked like.  As a result, it is now clear that two species of early Homo lived alongside Homo erectus. The new fossils will greatly help in unraveling how our branch of human evolution first emerged and flourished almost two million years ago."

The KNM-ER 1470 look alike was found in 2008.  Dubbed KNM-ER 62000, the individual is thought to have lived between 1.78 million and 1.95 million years ago (placing it in the early Pleistocene era), according to isotopic dating techniques.  

Hominid Jaw
The semi-complete skull and upper jaw provided promising clues. [Image Source: Nature]

The find included a complete skull with most of the cheek teeth present in the well-preserved upper jaw, allowing researchers to infer the shape of the lower jaw.

Hominid jawHominid Jaw
The KNM-ER 60000 jaw was the best lower jaw specimen recovered to date. [Image Source: Nature]

The skull allowed a 2007 partial lower jaw discovered by Robert Moru, dubbed KNM-ER 62003, to be confirmed as a member of the new species.  Likewise, another jaw discovered in 2009 by Cyprian Nyete -- KNM-ER 60000 -- further enriched the picture.  The 60000 specimen was the most complete hominid lower jaw ever discovered by researchers to date.

III. Much Work Remains

The discovery was truly a breathtaking process, beginning with geological analysis of probable sites for preserved remains, funded by the Leakey Foundation.  With promising dig sites pinpointed, the National Geographic Society provided funding for the successful fieldwork, a half decade ago.  And the Max Plank Society also chipped in, funding the laboratory work on the unearthed fossils.

The finished paper [abstract] on the groundbreaking work was published in the prestigious peer-reviewed journal Nature.  Its authors include Christopher Kiarie (TBI), who carried out the laboratory preparation of the fossils, Craig Feibel (Rutgers University), who studied the age of the fossils, and Susan Antón (New York University), Christopher Dean (UCL, University College London), Meave and Louise Leakey (TBI, Kenya; and Stony Brook University, New York) and Fred Spoor (Max Planck Institute for Evolutionary Anthropology, Leipzig and UCL), who analyzed the fossils.

Leakeys
The Leakey ladies with their outstanding find. [Image Source: National Geographic]

While the terrific find solves many unanswered questions about hominid evolution, it raises yet others.  These species clearly have not survived to the present day, but it is unclear what their true fate is.

Recent sequencing of the Neanderthal genome revealed that humans surprisingly interbred with this co-existing species, allowing some of its genetic material to be preserved even after it was displaced by Homo sapiens and went extinct.  Likewise, these new hominids could have interbred with Homo erectus, contributing scraps of valuable DNA that helped create the creature that we today know as a "human".

There's much work to be done on the eve of this discovery.

Sources: Nature, National Geographic Society



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This article is over a month old, voting and posting comments is disabled

By Jackthegreen on 8/10/2012 8:21:53 PM , Rating: 2
I think you give people more credit than they deserve on this. There will be racist people who cling to the notion of the differences in human races meaning some of them are better than others and who will have a bit more to stand on if we start publicly going over more of the differences in detail. Thankfully those people are becoming fewer with each day, but it will probably take a while longer before those people are enough of a minority that they can't cause problems.


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