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Fourth Human Species?


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A human finger bone was found in an Siberian cave, well known for its Neanderthal remains, only this finger's DNA is not Neanderthal. This human may have been in Siberia long before Neantherthal. Perhaps we should be looking for the missing link, some place besides Africa? There appears to be agreement we came out of Africa, but our understanding of that migration is changing.

 

http://www.nature.co...ll/464472a.html

 

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Edited by Athena
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Perhaps we should be looking for the missing link, some place besides Africa?

 

We've found many transitional forms that bridge the gap between anatomically modern humans, and our more distant ancestors, any of which fits the bill for what used to be popularly called "the missing link" (or at least is a fair example of a close cousin of an actual direct ancestor). And from those, the case is about as solid as it can get that we're descended from African australopithecines (whether of a known or unknown species), which gave rise to early members of African-based Homo such as H. habilis (which so closely bridges the gap between Australopithecus and Homo that some specialists contest which genus it actually falls into.) While the finer details of the ancestry linking the various later species of Homo is interesting, I'd suggest that the more interesting and less certain mystery is that of those ancestors bridging the gaps between African australopithecines and their own knuckle-walking quadrupedal ancestors. "Missing Link" is a bad term, and I think it'd be helpful if you explained just what you interpret the phrase to mean.

 

Anyhow, based on genetic evidence, this new "Denisovan" lineage would have split off from the ancestor of the neanderthals after the common ancestor of those two lines split off from that of our own ancestry, though it's still a very interesting find, especially as it seems that the Denisovans may have interbred with the ancestors of some modern populations of humans, just as it's strongly suggested neanderthals did with those ancestors of a wider population of all modern humans outside of Africa.

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AzurePheonix, maybe we should we have a system for clarifying who is a scientist who sits with the gods and who is not. I am just a mortal, and for most of my life the term missing link was used to mean the species that is the transition from animal to human. Science has come a long ways since I was in high school. Give me some time to catch up, okay?

 

 

Here is another recent find of a species that could be a transition to the naked ape (humans).

http://www.guardian....-human-ancestor

 

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Edited by Athena
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Personally I dislike the term transitional species, it assumes a stoppage of evolution that doesn't happen. Every species is a transitional species. Primitive species would be a better word. Missing link is even more confusing because it assumes a clear cut line of what is human and what fossils are not and there should be a single fossil that will show an 'in-between'. It would be wrong to assume that our common ancestry with apes looked more like Modern apes than modern humans. Obviously that would be hairy and walk on all fours, it doesn't mean that it would look a lot like apes now except superficially.

 

I'm not sure why you say scientists who sit with the gods, but the reason people used the term missing link was a bash at evolutionary theory saying that we had no intermediary fossils, which is just untrue.

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I believe the term missing link is primarily due to the fact that no direct intermediary fossils, that is a fossil form that is in the direct ancestorial chain between one major form and another have been identified. In other words with respect to major divisions in discernible forms, the fossil record contains no known direct primitive species in the sense you mean. It is true that there are no known direct line intermediary fossils mutually agreed by experts. In the same way, these researchers seem to be overselling the idea that this human finger and the differences in the DNA represents a separate human species unless one chooses a less restrictive sense of what it means to be a separate species. A better term would be a different DNA line than that of the line of modern humans. Either way I don't see how this has any implications regarding common ancestor relationships from millions of years ago.

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I believe the term missing link is primarily due to the fact that no direct intermediary fossils, that is a fossil form that is in the direct ancestorial chain between one major form and another have been identified. In other words with respect to major divisions in discernible forms, the fossil record contains no known direct primitive species in the sense you mean. It is true that there are no known direct line intermediary fossils mutually agreed by experts. In the same way, these researchers seem to be overselling the idea that this human finger and the differences in the DNA represents a separate human species unless one chooses a less restrictive sense of what it means to be a separate species. A better term would be a different DNA line than that of the line of modern humans. Either way I don't see how this has any implications regarding common ancestor relationships from millions of years ago.

 

Really? Maybe you should look here before you say there are no known intermediary fossils

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I believe the term missing link is primarily due to the fact that no direct intermediary fossils, that is a fossil form that is in the direct ancestorial chain between one major form and another have been identified. In other words with respect to major divisions in discernible forms, the fossil record contains no known direct primitive species in the sense you mean. It is true that there are no known direct line intermediary fossils mutually agreed by experts. In the same way, these researchers seem to be overselling the idea that this human finger and the differences in the DNA represents a separate human species unless one chooses a less restrictive sense of what it means to be a separate species. A better term would be a different DNA line than that of the line of modern humans. Either way I don't see how this has any implications regarding common ancestor relationships from millions of years ago.

 

In the logic of cladistics you're actually right about the first part. On a branching cladogram there are no 'transitional' forms, just common ancestor nodes that only exist theoretically. But I think that's a bit silly of a position to try to apply to the fossil record and there are clearly fossil forms that bridge 'gaps' in evolving fossil lineages (the term here would be anagenetic evolution). As for the rest of it; you're right that delineating two species is tricky business. I think the evidence that this population was interbreeding with both Neanderthals and with modern humans (it's actually mostly closely linked to modern Melenesians, wildly, which must indicate something about migration patterns in Asia at the time) should suggest strongly that none of these three is a separate species to begin with (and there is also strong evidence that Neanderthals contributed to the genomes of modern Eurasians, but not Africans, supporting admixture, see The famous Green et al. (2010)). And, finally, you're right that this has nothing to do with ancestry of millions of years ago, but rather ancestry of about 500 ka, when a Neanderthal/Denisovan lineage split from that of modern humans, but continued gene flow with it intermittently. AzurePheonix laid that bit out well, I defer.

 

A good, if long, FAQ on some of the key points of the paper, incidentally: The Denisova genome FAQ[/

Edited by CDarwin
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Really? Maybe you should look here before you say there are no known intermediary fossils

 

Are these unambiguous and true intermediary fossils? How can we be sure that there is a direct relationship? As I research the information about these examples I find there are very few researchers who claim any of these examples are direct intermediaries. I was quite careful in my previous description but you have offered a straw man in response since these examples are not confirmed direct intermediaries. This is not to say that direct intermediaries never existed, or that common descent is false, it is to be accurate about what is actually known about the fossil record.

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Then please define what you mean by intermediary. If you wish to see something that looks half man half ape then you are surely mistaken about what it means to be an intermediary species. All an intermediary species means is an ancestor. Even the term itself in assuming there is a beginning form and an end form that is just untrue. There is nothing in evolutionary theory that predicts ancestors must look like a mixture of two cherry picked species that arose from it. Also, if these are not intermediaries, what are they. Just some hominids that happen to be dated in a timeline that would fit well with our current ideas of human evolution? This is a nice time-line for hominid species evolution. And if you scroll down on this page you will see a graph that shows the gradual rise in cranial capacity in these hominids to support that they were evolving toward more intelligence.

 

Here are some other sites that have timelines supporting this theory.

 

 

http://www.wsu.edu:8001/vwsu/gened/learn-modules/top_longfor/timeline/timeline.html

http://www.wsu.edu/gened/learn-modules/top_longfor/timeline/03_index.html

http://www.archaeologyinfo.com/species.html

http://www.berfingen.info/athemyst/hominid1.html

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Whoo folks, see if you can get a copy of Professor Satyan L. Devadoss's lectures on "The Shape of Nature". His passion for math makes his DVD's inspirational. He can speak for several hours about knots and it is this mathematical knowledge of knots, that helps us understand mutations. With an understanding of genes and the math of knots, we can understand evolution and discuss this reality without the value judgment argument you all are having. I can not believe you are arguing over the use of the terms link and transition. Like what is the big difference between those terms, and who gives a rats ass?

 

What thie discovery of different human species, does to our consciousness is far more important than if we are looking for a missing link or a transition. Actually in math it would be a transition. This information is as dynamic as discovering the earth circles the sun, instead of the other way around. That science was a terrible blow to religion. Today, if all humanity came from Adam and Eve, what was the DNA of Adam and Eve? How does this work mathematically? Now that is a discussion worth having. What happens to religion if science proves, as it did with the orbits of the planets, that Adam and Eve looked nothing like our pictures of them in Eden, but had natural fur coats that they could not take off. That would be awful! Than the figs leaves covering them would look totally rediculous and we would to rethink the whole story.

Edited by Athena
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Whoo folks, see if you can get a copy of Professor Satyan L. Devadoss's lectures on "The Shape of Nature". His passion for math makes his DVD's inspirational. He can speak for several hours about knots and it is this mathematical knowledge of knots, that helps us understand mutations. With an understanding of genes and the math of knots, we can understand evolution and discuss this reality without the value judgment argument you all are having. I can not believe you are arguing over the use of the terms link and transition. Like what is the big difference between those terms, and who gives a rats ass?

 

Actually the difference between terms is a huge deal. You can't have any sort of meaningful argument without knowing that both sides are using the same meaning of a word. A perfect example is when people say evolution is just a theory; they don't realize that scientists don't use theory/conjecture meaning and causes all sorts of disputes. So I, as well as many others, give a rat's ass about the difference between terms.

 

 

What thie discovery of different human species, does to our consciousness is far more important than if we are looking for a missing link or a transition. Actually in math it would be a transition. This information is as dynamic as discovering the earth circles the sun, instead of the other way around. That science was a terrible blow to religion. Today, if all humanity came from Adam and Eve, what was the DNA of Adam and Eve? How does this work mathematically? Now that is a discussion worth having. What happens to religion if science proves, as it did with the orbits of the planets, that Adam and Eve looked nothing like our pictures of them in Eden, but had natural fur coats that they could not take off. That would be awful! Than the figs leaves covering them would look totally rediculous and we would to rethink the whole story.

 

 

We have no way of knowing what ancestors had higher cognitive power. I have to disagree with the statement that science is a terrible blow to religion. The bible never said that the solar system was geocentric, that was an assumption of the people of the time. Even if it had the bible has all sorts of metaphorical statements which could just as easily mean that Earth is important for the life that is present, not that everything actually revolves around it. It's obvious that Adam and Eve isn't a literal reality, but again religion is all about metaphor.

 

 

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Then please define what you mean by intermediary.

 

Intermediary means direct line ancestor not some distant presumed cousin.

 

If you wish to see something that looks half man half ape then you are surely mistaken about what it means to be an intermediary species.

 

You're begging the question, I have not asked for such an example.

 

Also, if these are not intermediaries, what are they.

 

The evidence is inconclusive. They are similar in many ways but there are also significant differences that are inconsistent with direct line ancestors. At best they are in different lines and are not directly related.

 

Just some hominids that happen to be dated in a timeline that would fit well with our current ideas of human evolution?

 

Yes they are at least this. They may be more, but it is unclear.

 

In any case this finger and DNA analysis does not seem to establish a forth human species. The authors seem to be overstepping their bounds particularly since instead the evidence actually shows clear signs of interrelationships with modern genetic lines. I am not sure how this adds anything to our understanding of human ancestry. Should we be surprised to find cut off lines races? Are there not different lines in human races today? An interesting question would be how different is this line from the most diverse current line? Is this information available?

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Well then I would have to ask what evidence is needed for you to believe that a hominid is our ancestor? Do you believe that none of species discovered could be our ancestors, or that they could be but you need more evidence to be convinced? Then again I would ask, what evidence is needed? Of course there will never be proof beyond a shadow of a doubt that these are our ancestors, just like any thing there will always be doubt. But saying that there are no intermediary fossils is stretching it by a large margin.

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(...) And if you scroll down on this page you will see a graph that shows the gradual rise in cranial capacity in these hominids to support that they were evolving toward more intelligence.

(...)

 

in this graph from your link

 

brainsize.gif

 

the winner is a Neanderthal.

 

800px-Sapiens_neanderthal_comparison.jpg

from http://en.wikipedia.org/wiki/Neanderthal_anatomy

Edited by michel123456
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You wrote:

"you will see a graph that shows the gradual rise in cranial capacity in these hominids to support that they were evolving toward more intelligence."

 

The graph shows that Homo reached the most intelligence with Neanderthals. The gradual rise stopped about 100.000 years ago.

Edited by michel123456
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It was a blanket statement, cranial capacity isn't the end all be all of intelligence; if it were whales and elephants would be far more intelligent. Not that it isn't possible that Neanderthal wasn't more intelligent, so it still doesn't affect my statement whatsoever.

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This site has something interesting to say about the possibility the modern humans are the cause of the extinction of others http://blogs.nationa...eanderthal.html

 

Evidentaly having a smaller brain could have been an advantage. Neanderthals may have matured more slowly, being older when they started repoducing and living longer than modern humans. Our small brain is an indication we may have reproduced faster. It is believed both Neanderthal and modern humans had a common ancestor with a large brain.

 

However, looking at the pictures of the Neanderthal skull and modern human skull, I am wondering if the brains developed differently. It seems to me the back of Neanderthal skull is larger but perhaps of the frontal area of the modern human brain is larger? This site discribes what is thought to be differences in the brains. http://neurophilosop...2006/08/07/499/ The ability to think is not just about brain size, but also which areas of the brain are developed.

Edited by Athena
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