ANCESTRAL SPECIES?: New fossils from South Africa represent a previously unknown member of the human family, dubbed Australopithecus sediba. The remains include two partial skeletons, one of which preserves a largely complete skull, shown here.
Image: Photo by Brett Eloff courtesy of Lee Berger and the University of the Witwatersrand
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Scientists working in South Africa have unveiled fossils of a human species new to science that they say could be the direct ancestor of our genus, Homo. Discovered in Malapa cave—just 15 kilometers from the sites of Sterkfontein, Swartkrans and Kromdrai, which have yielded a number of important human fossils—the finds comprise two partial skeletons that are nearly 1.95 million years old. The researchers have given them the name Australopithecus sediba.
The pair—an adult female and juvenile male that may have been mother and son—appear to have fallen into the cave through a hole in the cave ceiling, perhaps while attempting to access a pool of water inside. So exceptional is the preservation of the skeletons, particularly the male, that the discovery is being likened to that of the famous Lucy fossil from Ethiopia and the Turkana boy from Kenya. But the startling mix of primitive and advanced traits evident in the remains is sparking debate over where on the family tree the new species belongs and raising important questions about the dawning of Homo.
The study of human origins has come a considerable way since German quarry workers discovered in 1856 the first fossil to be recognized as an early human (it was a Neandertal). Investigators have traced our roots back to perhaps seven million years ago, close to the point at which the human lineage diverged from that of our closest living relative, the chimpanzee; they have recovered extensive remains of australopithecines such as Lucy and her ilk, creatures that are transitional between apes and us; and they have unearthed fossils representing quite an array of species documenting the evolution of Homo. Considering the virtually nonexistent fossil trails of our cousins the chimps, bonobos and gorillas, the human fossil record is extraordinary.
There are, however, significant gaps in researchers' knowledge of how we came to be. One such blind spot is the origin of Homo. Most experts agree that Homo evolved from a species of Australopithecus—either A. afarensis (Lucy's species) or A. africanus. Connecting the dots between one of these australopithecine species and Homo has been difficult, though, because the oldest known Homo remains are so few and fragmentary.
Scientists’ best guess has been that Homo habilis, which lived between perhaps 2.3 million and 1.5 million years ago, signaled the debut of Homo and subsequently gave rise to H. erectus, the first hominin (member of the human lineage) to spread out from Africa across the globe and the one that is thought to have spawned later human species, including H. sapiens. But H. habilis is a relatively poorly understood species because the known specimens preserve few bones from below the head. In fact, some researchers wonder whether some of the fossils assigned to H. habilis might in fact belong to other species. "H. habilis has been on shaky footing for a long time," observes paleoanthropologist Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research.
Into this morass falls A. sediba. In the paper describing the fossil remains, which will be published in the April 9 issue of Science along with a second paper detailing the geological context and age of the finds, Lee Berger of the University of the Witwatersrand in Johannesburg and his colleagues suggest that A. africanus gave rise to A. sediba, which in turn gave rise to the genus Homo. Intriguingly, the team hints that A. sediba might even be more closely related to H. erectus than H. habilis is, thus potentially relegating H. habilis to a side branch of the family tree, rather than a coveted spot on the line leading to us.
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25 Comments
Add CommentAbsolutely fantastic! What an exciting find. I can't wait to hear more as the excavation and research continues.
Reply | Report Abuse | Link to thisNo DNA to analyze found?
Reply | Report Abuse | Link to thisDNA would be the bee's knees alright. But where ever these fossils fit in, to be sure, that bush by the stream is looking a whole lot thicker than ever before.
Reply | Report Abuse | Link to thisYour man Charles Darwin would be tickled pink.
I do so love the discovery of a new species, and a new transitional fossil-it gets so that it seems there's a new one every day.
What is it that those silly people say about transitional fossils? That there isn't any?
Though I continue to be disappointed at how inconclusive these 'finds' seem to be I, like most people, expect the next one to be the missing link that answers all questions.
Reply | Report Abuse | Link to thisBut quickly now my time draws near, so hurry on and nail the one that makes our time past clear...skause
This is no doubt an amazing find of a fossil and wherever it finally falls on the human or pro-human family tree when all the work and conclussions are worked-out this is absolutely fascinating.
Reply | Report Abuse | Link to thisWhen you say "transitional" , what do you mean exactly? Is this fossil species a direct mutation from another species? If so which one? What aspects of this fossil are considered transitional? I'm still learning biology so please be patient with me. Alex
Reply | Report Abuse | Link to thisskause: Don't look for one missing link to answer all questions. Evolution entails many links. In human evolution many links are no longer "missing", and in science every new discovery raises as many questions as it answers.
Reply | Report Abuse | Link to thisGreat stuff: it's good to be allowed to share in the excitement at these finds.
Reply | Report Abuse | Link to thisOn the interpretation: it seems that those are right who just keep saying ....the bush, the bush, the bush....
In that vein, unlike others above, I'm not confident that further finds will make everything clearer - they could make it worse.
The discovery of the SA fossil confirms exactly my speculation
Reply | Report Abuse | Link to thisabout the loss of estrus and the evolution of Man.
http://abcnews.go.com/Technology/ardi-fossil-brings-us-closer-common-ancestor-humans/story?id=8716359&page=1
The TEETH reveal that the creature lived in a promiscuous
chimp-style group, where the females mated with all males when the
females ovulated.
Then, when estrus was lost, with the "Eve", the way was opened
for monogamy and all other of the things which make us human,
including language.
http://blogs.myspace.com/index.cfm?fuseaction=blog.view&friendId=83327275&blogId=474343872
Amazing!
Comments?
Arne
...those long arms! Does that imply that he lived partly at least an arboreal lifestyle?
Reply | Report Abuse | Link to thisAbsolutely fantastic
Reply | Report Abuse | Link to thisIf we have to rethink the whole family tree every time a bone fragment is found maybe we should not turn speculation into theory.
Reply | Report Abuse | Link to thisI am prone to believe that there may have been numerous early hominids that evolved at the same time around 5 million years ago. Competition and adaptation continued to play a role until migration out of Africa. My theory doesn't explain what occurred to those that never left Africa and how early man continued to evolve in spite of never leaving the African environment???
Reply | Report Abuse | Link to thisTransitional. Everything is transitional. You are a transition from your parents and your parents parents. And your children and their children will be (or are) transitional to you.
Reply | Report Abuse | Link to thisOur new hominid is certainly a glimpse at a time when other uprights walked the plains of Africa; a glimpse like a snapshot of you when you were nine - a moment in time between eight and ten. this particular fossil may not represent a direct transition from an earlier ancestor to our own species, but it certainly would represent some form of collateral ancestry.
Much like your cousin is not in a direct line between your grandparents and you but is representative of the available gene pool of the time. Follow me?
This is why I prefer referring to the human bush. This fossil, no matter where it falls, makes the human bush much thicker than before. And it is likely to get thicker yet.
It's been said that our now robust history as told through the fossil record, makes it clear that we are not unlike other animals in this regard. We are not so far removed - singled out - from our ancestors.
It's great to know Where and When,Why and How to go is more interested..NIRVANA.....
Reply | Report Abuse | Link to thisHi, me again. I have another question for all you hardcore biologists out there: is there much(or any) skepticism among biologists about the Darwinian Evolution?
Reply | Report Abuse | Link to thisMaeve Leakey cracks me up. Her contempt for australopithicines in general, and how they can't touch Daddy's "Homo" lineage, never ceases to amaze me.
Reply | Report Abuse | Link to thisFacts and data, Ms. Leakey, facts and data. We should let the comparative anatomical studies do the talking, not your pet theories.
Hi Alex- I don't presume to speak for all biologists, but I think I can safely say that there is virtually no aspect of what Darwin described that is questioned. Evolution happened and is happening. The question isn't whether evolution occurs, it's how evolution occurs that we're exploring.
Reply | Report Abuse | Link to thiscoolmoss - That may be the established view, that genetically expressed features of identified species serve to functionally transition from one species to another.
Reply | Report Abuse | Link to thisHowever, I suggest that the concept of transitioning incorrectly infers a direction to evolution, i.e., as in 'hominids developed until they finally produced modern humans.' There is no destination or design objective to evolution, only the selection of characteristics, through survival and reproduction, that generally enhance survivability in the current environment.
The transitional view is based on a historical perspective of current species' characteristics. No future transitional development objective has been determined. If, for example, in the current environment lower intelligence promotes reproduction, intelligence levels will be reduced in the future.
This may seem like a trivial point, but I think the transitional view infers information that is not indicated by the evidence.
I think that the refutation of direction for evolution denies:
Reply | Report Abuse | Link to thisa. Ecology as a whole and
b. Culture and Society and its driving force in human evolution due to the breading and kinship vectors.
c. If Evolution has no direction -how do we explain the progress of complexity and organization that has and does continue on this Path.
Check Terrance McKenna on the conservation of novelty and the vortex at the end of time. sure.
After all , a chic is always following some guy and a guy is always following some chic and if you consider Evolution as breeding, as i do, then this is an evolutionary direction.
Reply | Report Abuse | Link to thisApparently they are using the term "transitional" to refer to any of the links between us and the earlier animal forms. If two species of humans evolved at the same point in time, one of the species may have evolved into yet another species, eventually evolving into modern humans. The other species may have died out without being in the chain between us and the earlier animals.
Reply | Report Abuse | Link to thisAll of these diverse hypotheses regarding the different "lines" leading to Homo Sapiens Sapiens are a sentient example of mankinds thinking in evolutionary terms.
Reply | Report Abuse | Link to thisOne's thought, or perhaps several, may end up being correct.
I personally think that all of our "cousins" discovered thus far, and those yet undiscovered but have yet to be, all take their place in the evolutionary tree.
If they were in fact a successful adapting species, they perhaps would have ended the line by stagnation, or being driven out or "one upped" by a more successful strain, or cousin, as is clearly still happeniong today.
Homo Sapiens Sapiens is not done evolving. Evolution is alive and flourishing. Certainly if still takes place today. If and when we take to space and the stars our spacer cousins will evolve dramatically to fit their new environment.
Tommybird,
Reply | Report Abuse | Link to this"I can safely say that there is virtually no aspect of what Darwin described that is questioned".
And that is the problem with biology. Genuine scientists are supposed to question their hypotheses. Biologists do not. In fact, they do not even properly define their hypotheses. Darwin's theory had two main hypotheses. The main one was that evolution is the result of branching descent from common origins. That is accepted by everyone except creationists and IDers.
Darwin's second hypothesis was his explanation of how evolution happens, Natural Selection. That was where Darwin was wrong.
If biologists applied the rigorous tests that scientists are supposed to apply, they would be shocked at the logical gaps in Darwin's explanation. If they carefully followed Darwin's argument, they would recognise that at its heart, Natural Selection relies on a little piece of magic. Briefly, Darwin decided that external conditions had no direct effect. What drove evolution were variations that improved the internal qualities of individuals and favoured them in a struggle for existence. Species (and individuals within species) became adapted to particular conditions not because of any effect from the conditions, but because they were favoured in those conditions. Sounds plausible, right? Read it for yourself in ch. 3 of Origin, but when you read it, remember that Darwin started from a rejection of the effect of external conditions. For more detail, check my blog:
http://ideasintuitionandthinking.com/blog
The crazy thing is that most biologists now accept that external conditions have major effect, but continue to use rules and assumptions that are based on Darwin's decision to reject the effect of external conditions.
If biologists reverse Darwin's decision, they have to reverse all the rules and assumptions that flowed from it.
Biologists apply the rule that there is no direction or purpose in evolution because, if you exclude the effect of external conditions, you exclude the only factor logically capable of providing direction or purpose. If you accept the effect of that factor, you accept that all major evolutionary change has purpose (survival in the prevailing conditions) and direction (adaptation to those conditions).
That change is not the result of selection by some imaginary entity or indefinable process. It is the result of the simple process of deselection of individuals unable to survive in those conditions.
I wonder just how much of the controversy (between researchers)each of these exciting new find brings is due to the competition for limited funding. Paleontology does not, after all, help develop new commercial shiny gadgets or drugs to help us through our dreary days. Perhaps the thrill of discovery that we all share could be increased if collaboration could somehow replace such competition.
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