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Author | Topic: New Human Fossil Shows Unique MtDNA | |||||||||||||||||||||||||||
Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 3.8 |
Don't get too excited, it's just a finger-bone. It does have apparently non-sapiens mitochondrial DNA though. It is being interpreted as a new species.
quote: Full article here. This raises the interesting idea of multiple human species inhabiting Pleistocene Asia alongside one another. Mutate and Survive "A curious aspect of the theory of evolution is that everybody thinks he understands it." - Jacques Monod
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hooah212002 Member (Idle past 792 days) Posts: 3193 Joined: |
Funny thing: the first article I saw about this was something somewhere about how it debunks evolution. I've yet to really read more on it as anything I've seen so far appears to be nothing more than hype.
"Some people think God is an outsized, light-skinned male with a long white beard, sitting on a throne somewhere up there in the sky, busily tallying the fall of every sparrow. Othersfor example Baruch Spinoza and Albert Einsteinconsidered God to be essentially the sum total of the physical laws which describe the universe. I do not know of any compelling evidence for anthropomorphic patriarchs controlling human destiny from some hidden celestial vantage point, but it would be madness to deny the existence of physical laws."-Carl Sagan "Show me where Christ said "Love thy fellow man, except for the gay ones." Gay people, too, are made in my God's image. I would never worship a homophobic God." -Desmond Tutu
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Coyote Member (Idle past 2096 days) Posts: 6117 Joined: |
the first article I saw about this was something somewhere about how it debunks evolution.
Debunks evolution? Some folks interpret any change in evolutionary theory or improvement of our database as evidence that we were wrong before, and most likely wrong again. The Dishonesty Institute is well known for this. It's nothing more than religious apologetics. What this find seems to show is that there is a new mtDNA type back some 50,000 years or more. Given the number of specimens we have that are so old, this is not surprising. This is a new field, and these results have only been coming in the past few years. About ten years ago I submitted a bone that was dated to about 4,800 years ago and repeated extractions could not find usable mtDNA. (A tooth from the same site yielded good results at 5,300 years ago.) Techniques have improved so much in that short time that 50,000+ years is becoming possible, and the Planck folks are about the best there is right now. Look to see a lot of new and exciting data, and changes in existing data, in the years to come. That's the way science works, whether the religious apologists say yea or nay. Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.2 |
How does non-sapiens mtDNA imply it's a new species? We know, for a fact, that mtDNA lines die out from time to time why not interpret this as an extinct mtDNA line rather than a distinct species?
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Huntard Member (Idle past 2285 days) Posts: 2870 From: Limburg, The Netherlands Joined: |
Wouldn't sapiens MtDNA need to contain certain genetic markers that identify it as sapiens MtDNA? I mean, it's not like it can be made up out of any random combination, could it?
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
It is less closely related to H. Sapiens mtDNA than Neanderthal DNA. I don't see how this could be an extinct H. Sapiens mtDNA lineage and still fit in with a common ancestry model. We would still expect extinct human mtDNA lineages to be more similar to other humans, as currently extant human mtDNA lineages are.
TTFN, WK
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.2 |
Having been off and read the Nature letter, I tend to agree. It's still possible although unlikely that this simply represents a unusual mtDNA:
quote:
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RAZD Member (Idle past 1395 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Folks,
I find it curious that they take the divergence date as fixed, based on one piece of evidence, rather than subject to validation with more information:
quote: This divergence date is based on many assumptions, and one of them is that there is a steady rate of changes when we know that this is not so. To my mind this could easily be one or the other of these candidates. Or a Yeti ... The NATURE letter is at Fossil finger points to new human species | NaturePublished online 24 March 2010 | Nature 464, 472-473 (2010) | doi:10.1038/464472a Enjoy. Edited by RAZD, : nature article link we are limited in our ability to understand
by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.2 |
I find it curious that they take the divergence date as fixed, based on one piece of evidence, rather than subject to validation with more information Er, they don't. They take both the Neanderthal/Human and Denisova/human/neanderthal splits as subject to large (non-overlapping) margins of error. But, if you read the letter, their main argument for seperate species status is the construction of the cladogram which groups the Devisova hominid on a seperate branch to all the human and neanderthal samples.
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RAZD Member (Idle past 1395 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Mr Jack,
They take both the Neanderthal/Human and Denisova/human/neanderthal splits as subject to large (non-overlapping) margins of error. I also note that the Nature letter was much less emphatic about the genetic divergence dates, so that is more likely a result of reporters not understanding the science than that the scientists were emphatic about the dates. I just find the whole issue of generating dates from genetic information to be a little untested at this time to say with any assurance that the divergence dates are known with any reliability. To me, all we have is relative information, much like the relative information on dating provided by sedimentary layers: we know what sequence is involved to a fairly good degree, but absolute dates are not derived from this kind of data.
But, if you read the letter, their main argument for seperate species status is the construction of the cladogram which groups the Devisova hominid on a seperate branch to all the human and neanderthal samples. Which doesn't rule out erectus and heidelburgensis, which we also know left africa for europe and asia, especially erectus (java man). I'm not aware of any DNA evidence of erectus or heidelburgensis, so assuming a new species seems pretty premature at this point. Enjoy we are limited in our ability to understand
by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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Coyote Member (Idle past 2096 days) Posts: 6117 Joined: |
I'm not aware of any DNA evidence of erectus or heidelburgensis, so assuming a new species seems pretty premature at this point.
One other piece of information: the fossils do not (yet) suggest another species in that time period. Paleontologists have been digging like mad for close to 200 years, and the mtDNA is the first clue to another species here. And I would still like to see what the mtDNA or DNA of Florensis might be. The mandible I saw pictured looks like it has some nice teeth to work with. If the Planck guys can do a finger bone a tooth should be easy! Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.2 |
I just find the whole issue of generating dates from genetic information to be a little untested at this time to say with any assurance that the divergence dates are known with any reliability. To me, all we have is relative information, much like the relative information on dating provided by sedimentary layers: we know what sequence is involved to a fairly good degree, but absolute dates are not derived from this kind of data. Hmm.... it has problems to be sure. But I think it's pretty sound in many cases; certainly good enough to make tentitive judgements from. When the conditions are right (primarily not parasites, not domesticated) it pases both external and internal tests of reliability - although the margins of error remain large.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.2 |
And I would still like to see what the mtDNA or DNA of Florensis might be. The mandible I saw pictured looks like it has some nice teeth to work with. If the Planck guys can do a finger bone a tooth should be easy! Sadly not. The Florensis bones were recovered from waterlogged conditions - where DNA doesn't survive long.
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sfs Member (Idle past 2524 days) Posts: 464 From: Cambridge, MA USA Joined: |
The authors of the paper go out of their way to avoid using the word "species" to describe their individual. They talk about "types" or "forms" of hominin, but do not commit themselves to any conclusions about species status. (Note: they have also sequenced the nuclear genome of this sample, which will no doubt reveal much more about the relationship with sapiens and neandertals, once they get around to publishing.)
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