Bizarre topic
  • This is going to sound weird, but it's something I've kind of wondered about for a while. Maybe some of you science types will have some insight.

    There was an article about Neanderthals on a website today, and it reminded me of something I've observed before. First, let me mention that scientists seem to agree that 1-2% of modern European DNA comes from Neanderthals. Many modern African populations do not share this Neanderthal ancestry. Scientists also seem to think that Neanderthals were white and possibly red-haired. One of the features of Neanderthal skulls is the large occipital protuberance in the back of the head. I think I've seen explanations for this feature having to do with balance perhaps?

    I've always thought that the distinction made by many scientists of the early lineages of hominids was artificial. I mean, obviously different populations of human type creatures interbred successfully. It seems to me that it's possible that all of these different early hominids were just variations on the same species. 

    That brings me back to the occipital bun. I've noticed that many Kenyan runners (like Wilson Kipsang) seem to have this occipital protuberance that is a trait of the white, red-headed, robust Neanderthals. I wonder if you presented the skull of a modern Kenyan (sorry to sound morbid) and the much differently shaped (flat back of head) skull from a white Ukrainian guy I know--if you presented these to a scientist and told him these were ancient skulls from different parts of the world, would he try to claim they were from two distinctly different hominid species? They are obviously not. They're just people. And maybe it's possible that's what these "different" populations millions and hundreds of thousands of years ago were. Just people.

    I'm certainly not a scientist, so anyone knowledgable about this stuff please feel free to set me straight.


  • Are you talking about the external occipital protuberance? It's a feature present on all human skulls, at least all that I have seen in teaching Human A&P for many years (though it may vary in size). It's the attachment site for the nuchal ligament, which helps to stabilize the head.

    I actually spent most of my academic career studying variability in cranial anatomy, in frogs/tadpoles rather than humans. The reality is that variation is always going to be present within a species. We refer to it as intraspecific variation, as opposed to interspecific variation which is variation between species. Using imaging and advanced statistical techniques I could distinguish "skulls" of tadpoles down to the level of "families" from different masses of eggs of the same species, so the question becomes where do we draw the line between variation within a species an variation sufficient to recognize different species. This gets to the greater question of what is a species? This has long been a topic of debate among evolutionary biologists.

    It's harder for paleontologists and anthropologists to answer this since they don't have living specimens to work with, and sample sizes tend to be very small when it comes to fossils. I'm not an expert on the characters used to differentiate Neanderthals from early Homo sapiens, but I'm sure there is a lot more to it than just a few aspects of the skull.
    Helping runners run | Main Site: www.runblogger.com | Personal Site: www.theblogologist.com
  • Yes, I'm talking about an external occipital protuberance, commonly called an occipital bun when referring to Neanderthals. This is what Wiki says about it:

    "Occipital bun is a prominent bulge, or projection, of the occipital bone at the back of theskull. Occipital buns are important in scientific descriptions of classic Neanderthal crania. While common among many of humankind's ancestors, primarily robust relatives rather than gracile, the protrusion is relatively rare in modern Homo sapiens.Some scientists suspect occipital buns might correlate with the biomechanics of running. Another theory attributes them to enlargement of the cerebellum, a region of the brain which mediates the timing of motor actions and spatial reasoning.There are still many human populations which often exhibit occipital buns. A greater proportion of early modern Europeans had them, but prominent occipital buns even among Europeans are now relatively infrequent."

    So what I think is interesting is that this feature is not as prominent in modern Europeans (who have some Neanderthal DNA) as it seems to be in some modern Africans who probably have no Neanderthal DNA. I'm not sure what to make of the mention of running in the article, since no one would think of Neanderthals as runners, but it's interesting nevertheless.

    It seems to me that there is much that scientists still do not understand about how our species evolved, and about our early history. Again, it's my feeling (since many groups interbred) that the Neanderthals, Denisovans, Homo erectus, etc. were all just variations on one species.

  • Ability to interbreed and form hybrids does not necessarily make two lineages the same species, it happens a lot in nature. You might be interested in this: http://evolution.berkeley.edu/evosite/evo101/VADefiningSpecies.shtml.

    I took a class in grad school taught by a guy from the Smithsonian who is one of the leading minds on species concepts. It's a topic that has been debated for a long, long time. Complex and very interesting!
    Helping runners run | Main Site: www.runblogger.com | Personal Site: www.theblogologist.com
  • This topic certainly can get bizarre. This guy theorises that humans evolved as hybrids.

    http://www.macroevolution.net/human-origins.html#.UrboF5kayc0

  • I think Mr. McCarthy may be the most sophisticated troll I've ever seen. Oink.
  • Here's an interesting quote from Peter's article: 

    "There are lots of other places where the boundary of a species is blurred. It’s not so surprising that these blurry places exist—after all, the idea of a species is something that we humans invented for our own convenience!"

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