Evidence for evolution, Installment 3b: Neandertals and Mitochondrial DNA

by seattleniceguy 11 Replies latest jw friends

  • seattleniceguy

    This is a continuation of last week's installment in my Evidence for Evolution series. Since this post builds directly on concepts discussed last week, I highly recommend that you read last week's thread carefully before looking at this one. It is here:

    Previous articles in this series are here:
    Retroviral sequences: http://www.jehovahs-witness.com/6/86797/1.ashx
    Cytochrome c: http://www.jehovahs-witness.com/6/87238/1.ashx
    What evolution is not: The role of randomness: http://www.jehovahs-witness.com/6/87711/1.ashx

    Primary sources for this article:
    Hominids and mtDNA: http://www.talkorigins.org/faqs/homs/mtDNA.html
    What is Mitochrondial Eve?: http://www.talkorigins.org/faqs/homs/mitoeve.html
    Paleoanthropological Discovery Timeline: http://www.talkorigins.org/faqs/homs/recent.html
    Overview of Neandertals: http://www.answers.com/topic/neandertal
    Refutation of Common Creationist Arguments Regarding Neandertals: http://www.talkorigins.org/faqs/homs/a_neands.html
    Neandertals Were Not Our Ancestors: http://www.psu.edu/ur/NEWS/news/Neandertal.html

    Because there are a lot of popular misconceptions about Neandertals, throw out everything you think you know about them unless you have actually done research. The reality is probably significantly different than you imagine.

    The first Neandertal was discovered in 1856 in the Neander Valley in Germany (tal = valley in German). Interestingly, this was three years before Darwin published his famous book. As more and more Neandertals were found, we learned that these people, although strikingly similar to humans, were significantly different from modern humans in anatomy. Some of the major differences are:

    • Pronounced brow ridge
    • No chin
    • Slightly larger brain cavity (10% larger)
    • Differently shaped ear labrynths
    • Shorter and considerably stouter than modern humans (bones are 50% thicker on average that modern humans)
    • Barrel-shaped rib cage

    A visual comparison of the skulls of humans with Neandertals should be sufficient to demonstrate the differences.
    Images from the University of Texas (Neandertal http://www.utexas.edu/courses/denbow/labs/homoneand.htm and Homo sapiens http://www.utexas.edu/courses/denbow/labs/homosap.htm).

    Neandertal skull

    Human skull

    At first, some suggested that these were just humans that suffered from some disease or environmental problem. However, a couple things make this a poor explanation. First, there are no diseases that have been observed to create such effect in humans. Second, the traits described above are observed in all discovered Neandertals. To date, we have unearthed more than 400 Neandertal specimens.

    If they weren't modern humans, then, were they just some sort of advanced ape? No. The evidence is clear that they had an advanced stone-tool culture, controled fire, and had advanced weapons. The Answers.com source cited above says:

    There is good evidence that they routinely constructed a variety of stone implements. The Neanderthal (Mousterian) tool case consisted of sophisticated stone-flakes, task-specific hand axes, and spears. Many of these tools were very sharp: some had a cutting edge sharper than a surgeon's scalpel.

    The similarity to humans on one hand but the obvious differences on the other striking. The creationist sites answersingenesis.com and biblestudy.org both assert that he was fully human, and speculate about old age, disease, environmental factors, or closeness to perfection (!?) being the cause of his different anatomy.

    From biblestudy.org:

    Neanderthal man was a direct descendant of Adam. He was therefore closer to the creation than we are.

    Answersingenesis.com says:

    Neandertal fossils are all post-Flood, so these bones are believed to represent just one more group of people which split off from other groups following the Babel dispersion.

    If you take a look at these sites, keep in mind that there are several patently false characterizations of what evolution predicts for Neandertal morphology, as well as blatant fabrications about the science (compare the assertion that "Neandertal fossils are all post-Flood" with the next paragraph).

    The geologic record puts Neandertals in Europe from about 230,000 years ago to about 29,000 years ago. Anatomically modern humans are found in Africa from about 150,000 years ago, showing that humans lived at the same time as this sister species.

    Okay, so aside from disputes about exactly when Neandertal Man lived and how closely he was related to Adam, we are basically in agreement: Neandertals were real, they were clearly different in significant ways from humans, while retaining much of what we consider to be human, and they lived at the same time as modern humans.

    Mitochondrial DNA and Neandertals
    In our last installment, we reviewed mitochondrial DNA, or mtDNA for short. Recall that mtDNA is passed only from the mother, and it changes only rarely (unlike nuclear DNA), so it allows us to trace matrilineal ancestry. On the basis of mitochondrial DNA evidence, we know that all humans are related through a common female ancestor who probably lived about 170,000 years ago. Because this most recent common female ancestor is called Mitochondrial Eve, creationists are fond of suggesting that mtDNA supports the Bible.

    Here's where it gets interesting. Because mitochondrial DNA is much more abundant than nuclear DNA (about 500-1000 copies per cell) and it is much shorter (about 16,500 base pairs compared to 4.8 billion), it is much easier to extract and study. If we could get our hands on some Neandertal mtDNA, we could surely learn a great deal about how they fit in with the human family, if at all.

    First, let's consider what we should expect if Neandertals are related to humans, and especially if they are very recently related, as creationists suppose. If Neandertals were "just one more group of people which split off from other groups following the Babel dispersion" (a mere 4000 years ago, supposedly), we would expect that their mtDNA would be exceedingly similar or identical to ancient human mtDNA, since all humans supposedly bottlenecked through three matrilineal lines which would have interbred profusely. Neandertal mtDNA should also show clear relatedness to modern human mtDNA.

    On the other hand, if Neandertal mtDNA is grouped together with that of other Neandertals but does not show any clear relation to that of modern humans, and especially if it shows no clear relation to ancient human samples, it would mean that Neandertals are not in our ancestry but represent a separate line of hominid, a sister species to humans.

    In July 1997, the first mitochondrial DNA was successfully recovered from a Neandertal specimen. mtDNA was successfully extracted from two other Neandertals, including a baby, in 1999 and 2000, confirming the results from the first. What have we learned from the comparison of the mtDNA from these four Neandertals with humans?

    When the three Neandertals are compared with modern humans, all three of them cluster together, and apart from all modern humans. This conclusion is reinforced by a study by Knight (2003). Knight excluded from the comparison sites in the mtDNA genome which are known to have mutated more than once, and which are therefore poor indicators of phylogenetic relationships. His study strongly confirmed earlier ones showing deeply divergent histories for modern human mtDNA lineages and the known Neandertal ones.
    -- http://www.talkorigins.org/faqs/homs/mtDNA.html

    Further, in 2004 mtDNA was sequenced from four more Neandertal specimens, as well as five early humans. Once again, the Neandertal mtDNA was distinct from the human mtDNA. The team found no evidence of gene flow between the two populations.

    What does this mean? Just as mtDNA from humans points to common ancestor about 170,000 years ago, mtDNA shows that Neandertals do not share that Mitochondrial Eve with humans.

    Neandertals are not closely related to humans (at least not in the sense of being our ancestors). Humans and Neandertals likely diverged 500,000 to 600,000 years ago and then lived chronologically side-by-side, as sibling species which did not or could not interbreed.

    The key to understanding this is that, even if we throw away the dates (since creationists obviously have a built-in problem with dates higher than 6000 years), the evidence is clear that all humans are related through a common ancestor, and that Neandertals represent a completely seperate line. Sister species living side-by-side humans are expected in evolutionary theory, but they obviously present a major impediment to a literal interpretation of Genesis.


    (Edited to correct typing mistakes)

  • AlmostAtheist

    Hooray! The new evolution article is out! (Can I renew my subscription for two years, I don't want to accidentally let it lapse and miss one!)

    Are the skulls of all humans very similar? Or does it vary greatly from race to race? You see people all the time that seem to have the heavy-brow thing going on, more pronounced chin, less pronounced, etc. Is there any human skull (aside from those changed by disease) that looks similar to the Neandertal?

    I wonder why none of these guys survived into modern times? There doesn't have to be a reason, a simple disease to which they are very prone could have wiped them out, or any number of other things. It just seems curious that such a well-developed intelligent population wouldn't have at least some hangers-on.

    Of course 150,000 years from now some other homonid-type may be posting pictures of *my* skull wondering why *my* species doesn't exist anymore. (Who says he has to be a homonid?)


  • Amazing1914


    Once again, excellent! What were the dating methods use for the Neanderthals. C-14 would not be suitable as it is limited to about 50,000 years at best. Was it K-Argon or another? I am curious because I have discussion going on another discussion board. Thanks again, Jim W.

  • seattleniceguy


    I'm not sure what the variance is in human skull characteristics, but in the source cited "Refutation of Common Creationist Arguments," there is the following paragraph:

    Amazingly, a century after scientists knew otherwise, most creationists still believe that Neandertals were merely modern humans, deformed by diseases such as rickets, arthritis or syphilis. Some, but by no means all, Neandertals have been found with signs of health problems such as arthritis. But Neandertals have many distinctive features, and there is no reason why these diseases (or any others) would cause many, let alone all, of these features on even one, let alone many, individuals. Modern knowledge and experience also contradicts the idea that disease is a cause of Neandertal features, because these diseases do not cause modern humans to look like Neandertals.

    I'll have to look into human skull variance, but I would imagine that any differences are very minor.


    I don't know what the dating methods were. The baby Neandertal was only 29,000 years old, which would allow the use of C-14. I may end up researching this more at the library, so I'll let you know if I learn anything on that. My suspicion is that since we have so many fossils, a great number of methods have been used.


  • drwtsn32

    SNG, You're wrong. Neandertals were simply the Nephilim. Plus we know that radiometric dating was thrown way off by the flood, so you can't trust any dates older than a few thousand years. ;)

  • Mary

    Hey SNG.....are you sure you didn't steal the medical records of my former Presiding Overseer??

    Neandertal skull

  • love11
    was three years before Darwin published his famous book

    Wow! That's one I didn't know.

    AHHH... I love hearing facts.

  • Leolaia

    About variation in skull morphology, there is a pretty good discussion of it in James Chatters' book on Kennewick Man, at least as it concerns modern H. sapiens. Basically, the Kennewick Man skull is only 9,000 years old or so and still it falls outside the parameters of modern H. sapiens. Not that there isn't any variation any more, just that the particular combination of traits and features is different from any living human today.

    I saw a program on Nova several months ago that cautioned drawing inferences on differences in Neanderthal morphology; the occipital bun, for instance, has nothing to do with brain function at all...the evidence suggests that for Neanderthals it helped with locomotion by providing a counterbalance, increasing running speed compared with modern humans. Also, occipital buns occur in modern humans in instances of post-natal head-binding....there is no room for the brain to grow but horizontally. There is a remarkable variety of skull shapes in ancient peoples due to the plasticity of the cranium and different head-binding practices. Thus, one should keep in mind post-natal development in skull morphology; not all physical traits are genetic.

    Great thread, BTW, my comments are mostly a digression....

  • seattleniceguy


    Very interesting regarding the occipital bun and locomotion! Regarding whether their unique skull features are genetic, I think that the fact that they consistanly have these features over more than 100,000 years spread out all over Euroasia indicates strongly that it is simple a part of their morphology.

    Of course, morphology aside, the mtDNA data provides the clinching evidence that they are their own species, not just deformed humans.

    Thanks for your points!


  • Whiskeyjack

    Almost missed this class!

    Thanks again, W.

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