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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.

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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Precisely defined vagueness
By drycrust3 on 8/10/2012 3:05:29 AM , Rating: 4
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.

With all this wealth of species genomes one would expect there to be some sort of measurement standard which defines whether or not two genomes are or are not of the same species, but this statement makes it obvious that no one can decide where to draw the line.
Looking at the fact that Neanderthal genes are in our genes, then it is obvious that they are the same species as us, but in this age of precise definition of standards we find loose and vague ideas define what is and isn't a species, not the degrees of similarity or difference of the genomes.

RE: Precisely defined vagueness
By mooty on 8/10/2012 7:40:25 AM , Rating: 4
Defining exact "boundaries" for species is mostly nonsense. Even trying to exactly define what a species is impossible. We mostly define species because it's easier to talk about thing that way, not because belonging to a species is an inherent property of a living being.

It is also nonsensical to try to pinpoint exact dates when one species evolved to another one. It's a gradual process, it's never one day a raptor, next day a chicken thing.
There are even a couple of species, sometimes called "ring species" that live on the globe that if you for example start from a certain population, and start to go west, the animals living close to each other are perfectly able to breed, however they are gradually changing, so much so that when you close the circle they are so different, that they normally would be called a different species.
And if you go down to the level of bacteria, the water becomes much-much murkier.

It is therefore pointless to define some kind of standard measurement that would tell you exactly if two species are different or not.

RE: Precisely defined vagueness
By MozeeToby on 8/10/2012 10:46:30 AM , Rating: 5
[...] this statement makes it obvious that no one can decide where to draw the line.
That's because there is no line. The idea of distinct species is a human concept, used to make the science of taxonomy possible, that does not mean it has any bearing on reality. That's what many creationists don't understand, that there are no dividing lines between species.

Think about it like this, you have two colors, one is definitely red and one is definitely orange. Now smear the spectrum between them and ask 1000 people where red becomes orange. You'll get 1000 different answers. Oh, they'll cluster around the same general area, but it's impossible to draw a line and say "this is the very last shade of red in the spectrum". And even if you did, you could zoom in and create a color between your hypothetical "last red" and "first orange" because (baring going into quantum physics) there's always going to be a color between the two.

More practically, there are species who cannot interbreed, but both can breed with a third species without any problem. Actually, there are "ring species" that are made up of half a dozen or more populations, each of which can breed with it's two neighbors and no others, but the breeding relationships form a complete circle. So, where do you draw the line?

RE: Precisely defined vagueness
By Ringold on 8/10/2012 3:22:53 PM , Rating: 1
That's because there is no line.

I can't be the only one that has certain people come to mind and think "this explains a lot, actually."

More seriously though, this has all been quietly noted in some realms of science for a long time, but political correctness strikes fear deep in to the hearts of researchers as it could, possibly, reopen bigoted debates on racism if genetic differences started reappearing in a more public debate.

RE: Precisely defined vagueness
By Argon18 on 8/10/2012 3:52:54 PM , Rating: 2
why would it "reopen bigoted debates on racism"? why couldn't it open intelligent constructive dialog on human race differences?

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.

RE: Precisely defined vagueness
By Jeffk464 on 8/11/2012 3:20:33 PM , Rating: 1
reopen bigoted debates on racism if genetic differences started reappearing in a more public debate.

Uhm, there are genetic differences between red hair and brown hair, between brown eyes and green eyes, etc. Your genes created everything about you so how can they not play a role?

RE: Precisely defined vagueness
By Jeffk464 on 8/11/2012 3:21:38 PM , Rating: 3
You can't deny reality because it doesn't fit in with what you want to believe.

By foolsgambit11 on 8/11/2012 6:34:55 PM , Rating: 1
Tell that to the religious....

RE: Precisely defined vagueness
By MEZTEK on 8/13/2012 10:50:18 AM , Rating: 2
Your discussions of no or little genetic boundaries and that cross species breeding via a common third species is unheard of. This ring of species concept intrigues me. Now, that the other two HOMO species are gone, what can Humans breed with, APES? Are Apes within our ring? Is that possible? If Humans no longer have a breeding ring, then are we not a distinct and unique species?

RE: Precisely defined vagueness
By trumpeter001 on 8/12/2012 4:05:34 PM , Rating: 3
Everyone overcomplicates this much more than is necessary.

We have used Kingdom, Phylum, Class, Order, Family, Genus, and Species (KPCOFGS) to define life for years. Species is the end of the line. In order to differentiate life of the same genus, they are separated into species.

A Mastiff is a different species than a Great Dane, but they can still bread and share genetic code.

In the end it does not make a difference, it is all just a system to classify what we discover. It does not change who we are.

RE: Precisely defined vagueness
By Belard on 8/15/2012 5:26:42 AM , Rating: 2
Well said

To Drycrust3: Neanderthal of course, have been around longer than modern mankind. But they were not as advanced as humans, they never really evolved. While man came, killed them off and learned how to do so much more.

Yes, there was interbreeding between the two (who knows why. Animals will have sex with anything. bestiality, etc. Even a dolphin will attempt to mate with humans... not recommend to be swimming naked with! They are horny bastards) But of course, there would never be offspring from that!

The lighter/fair skin tone comes from the Neanderthal genetics (very little) when the last modern man left Africa and made their way to Europe.

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