Human Evolution Celebration Exposed

The evolutionary story of human origins is often told like a cultural myth that is intuitively obvious.  Humans emerged in Africa after their ancestors came down from the trees and walked upright.  They began to hunt with stone tools and used fire.  They migrated north out of Africa and populated Europe, overtaking the Neanderthals who lacked the brain power and culture of their more evolved cousins.  How much of this story is based on actual evidence?  How much is interpolation of what “must” have happened based on an evolutionary view of natural history?
    As part of its celebration of the Darwin Bicentennial, PNAS invited a special series of papers on human evolution, called Out of Africa: Modern Human Origins.  A careful reading of these papers reveals more gap than knowledge, more bluffing than evidence.

1. Richard Klein’s lead editorial:¹  Richard Klein of Stanford summarized the views of Darwin and Huxley and surveyed the history of fossil finds since Darwin.  “In the absence of fossils, Darwin could not have predicted the fundamental pattern of human evolution, but his evolutionary theory readily accommodates the pattern we now recognize,” Klein asserted, but he acknowledged a number of controversies among paleoanthropologists.  The story requires two out-of-Africa migrations – one 200,000 years ago that kept the Neanderthals isolated from the modern human gene pool, and another 50,000 years ago when modern humans overtook the Neanderthals.
       “Many details of Out-of-Africa remain to be worked out,” he admitted, “and disagreement persists, for example, on the extent to which dispersing modern Africans and archaic Eurasians may have interbred and especially on what promoted the relatively sudden Out-of-Africa expansion.”  As to what stimulated the moderns to gain survival advantages to win the fitness game, he proposed two ideas: “Some attribute it to a genetic mutation that promoted the final development of the modern human brain with its seemingly infinite capacity for innovation.  A larger number ascribe the behavioral change to social, economic, or demographic change, perhaps above all to population growth that increased the frequency and density of transformative interactions among individuals and groups.”  It would seem that ultimately the behavioral changes would have also had to have roots in genetic mutations to be passed on.
2. Ian Tattersall on the Out-of-Africa hypothesis:²  Tattersall presented Africa as the “fount of human evolution” but ascribed that evolution to unexplained, unobserved acts of chance.  Whatever happened to make human beings capable of symbolic communication after their physical traits were in place left no trace, he admitted: “The event concerned was apparently short-term,” he said, “because it is essentially unanticipated in the fossil record.”  In a remarkable statement that seems tantamount to a miracle, he said, “The radical reorganization of gene expression that underwrote the distinctive physical appearance of H. sapiens was probably also responsible for the neural substrate that permits symbolic cognition,” he said.  “This exaptively acquired potential lay unexploited until it was ‘discovered’ via a cultural stimulus, plausibly the invention of language.”  As examples of exaptation, he later said, “Birds, for example, had feathers for millions of years before coopting them for flight, and tetrapods acquired their limbs in an aquatic context.”  So why not believe that man had a brain before he thought of thinking?
       If one can believe Tattersall’s story thus far (that modern man’s physical body, intelligence, symbolic cognition, culture and language all appeared suddenly by an unplanned “exaptation” of a previously useless “neural substrate”), then the reader clearly has the credulity to accept the rest of the tale.  It relies on a “relevant fossil record [that] is fairly thin” and the argument that “sparse as they were, the earliest fossils that resembled members of our species came from southern and eastern Africa.”  Does the evidence get better after accepting that premise?  “Beyond this, however, the picture is a little hazy,” he said, but he told it anyway: modern humanness arrived in two stages: a body, then a brain, and migrated north out of Africa twice separated by 150,000 years of stasis.  In case the reader didn’t catch his miracle story, he repeated it in the conclusion:

   Symbolic reasoning appears to be qualitatively different from all other forms of cognition, including its own immediate precursor.  Its neural substrate continues to be strenuously debated; but, whatever it was, that structural innovation was most plausibly acquired as part and parcel of the radical biological reorganization that gave birth to H. sapiens as an anatomically distinctive entity.  In which case (like those feathers and limbs) it remained unexploited, at least in the cognitive context, for a very substantial length of time, until its new use was “discovered” by its possessor.  How this discovery was made remains a matter for conjecture, but a leading candidate for the necessarily cultural stimulus to symbolic processing of information is the invention of language.

3. Tim Weaver on Neanderthal Man:³    Let’s turn our attention to one part of the human evolution story that has abundant fossils: the Neanderthals.  This should provide an opportunity for an evolutionist to backfill the story with ample evidence.  The story is usually told that Neanderthals, with their barrel-chested robust frames, were adapted to living in the ice age cold.  Weaver surprises the reader that it’s hard to establish a correlation with the anatomy and the climate.  In fact, the anatomical differences point to genetic drift rather than adaptation.  “Neither climatic adaptation nor anterior dental loading are well supported, but genetic drift is consistent with the available evidence,” he said.  It’s also hard to connect anatomy with activity patterns, including diet.  Modern humans living in cold climates today seem to share some features with Neanderthals, but “relationships in extant humans between morphology and activities are typically not well established.”
       Weaver described a number of unknowns about Neanderthals.  Here are a few.  We don’t know the extent to which skeletal anatomy reflects life habits as opposed to genetics (although some of the distinctive Neanderthal traits in the few juvenile specimens can help sort them out).  We don’t know if lab experiments on animals have relevance to the real world.  We don’t know which traits vary together (covariance) or which originated separately.  We don’t know the extent of covariance within groups and within individuals; therefore, analysis of a given individual Neanderthal specimen should be “interpreted cautiously”.  We don’t understand how “evolutionary forces” act over long time periods.  We don’t know if the cranial features of Neanderthals had any adaptive significance.  We don’t know if the post-cranial features (below the neck) had any adaptive significance.  We don’t know the extent to which diet affected facial features such as prominent brow ridges.  We don’t know to what extent the skeletons reflect adaptations to cold.  We don’t know the extent to which Neanderthal and modern human populations were isolated from each other.  We don’t know whether the post-cranial differences are secondary consequences of a change in overall body proportions.  We don’t know why both Neanderthals and Pleistocene modern humans were both more robust than those living today.  Lastly, it may well be that the differences between modern humans and Neanderthals tell us less about evolution and more about genetic drift – random gene frequency variations between populations that have nothing to do with adaptation.
       As an example of how difficult it is to give an evolutionary explanation, Weaver described how it’s done.  Let’s say the anthropologist has decided that a certain trait represents an evolutionary adaptation.  How would he or she test the idea?  Say, for example, that Alice is looking at a Neanderthal cranium and proposes that its distinctive shape was a response to cold climate.  One way she could test it would be to see if similar shapes are found in living animals in cold climates.  “This approach implicitly assumes that whatever factors lead to a relationship in the extant species are also important for the extinct species, and consequently, is most robust when similar relationships are found for multiple populations or species.”  A second way Alice could test her idea would be to see if the cranium shape fits the purported function.  “This approach does not attempt to directly model how natural selection would have acted; it simply evaluates the internal consistency of an adaptive hypothesis,” Weaver said.  But it should be noted: “An internally consistent adaptive hypothesis is not necessarily correct, but an inconsistent one can be rejected.”  This could lead to numerous incorrect but unrejected hypotheses.  A third way Alice could test her adaptive hypothesis would be “by explicitly modeling evolutionary forces with quantitative and population genetics,” i.e., to see if genetic drift would fit the evidence just as well.  One advantage is you get some numbers this way: “A strength of this approach is that the dynamics of the evolutionary process are quantitatively incorporated into the testing of hypotheses.”  Sounds good in theory, but in practice, “The value of this final approach and the previous one would increase substantially if we knew more about how evolutionary forces typically act over hundreds to thousands of generations.”

Time and space do not permit reviews of the six other papers on early man.  These discuss the origin of Neanderthals,⁴ the diets of Neanderthals and early modern humans,⁵ the spread of modern humans in Europe,⁶ the spread of hominins in Africa and Asia,⁷ how early African hominins decorated themselves,⁸ and how founder populations might have migrated out of Africa.⁹  Hopefully these three surveys will provide a sample of the state of the art in evolutionary explanations of how we got here.

1.  Richard Klein, “Darwin and the recent African origin of modern humans,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16007-16009, DOI: 10.1073/pnas.0908719106.
2.  Ian Tattersall, “Human Origins: Out of Africa,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16018-16021, DOI: 10.1073/pnas.0903207106.
3.  Timothy Weaver, “The meaning of Neandertal skeletal morphology,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16028-16033, DOI:10.1073/pnas.0903864106.
4.  J. J. Hublin, “The origin of Neanderthals,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16022-16027, DOI:10.1073/pnas.0904119106.
5.  Richards and Trinkaus, “Isotopic evidence for the diets of European Neanderthals and early modern humans,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16034-16039, DOI:10.1073/pnas.0903821106.
6.  John F. Hoffecker, “The spread of modern humans in Europe,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16040-16045, DOI:10.1073/pnas.0903446106.
7.  G. Philip Rightmire, “Middle and later Pleistocene hominins in Africa and Southwest Asia,” Proceedings of the National Academy of Sciences, September 22, 2009, vol. 106 no. 38, 16046-16050, DOI:10.1073/pnas.0903930106.
8.  d'Errico et al, “Additional evidence on the use of personal ornaments in the Middle Paleolithic of North Africa,” Proceedings of the National Academy of Sciences, September 22, 2009 vol. 106 no. 38 16051-16056, DOI:10.1073/pnas.0903532106.
9.  DeGiorgio, Jakobsson and Rosenberg, “Explaining worldwide patterns of human genetic variation using a coalescent-based serial founder model of migration outward from Africa,” Proceedings of the National Academy of Sciences, September 22, 2009 vol. 106 no. 38 16057-16062, DOI:10.1073/pnas.0903341106.

09/02/2009).  These capabilities lie fallow, with no purpose or use, for millions of years.  Suddenly, those innate capabilities are “exapted” by a “cultural stimulus” like the immediate and unforeseen invention of language.  Tattersall calls this “plausible” – do you?  This is so wacko it makes New Age look downright philosophical.  Whenever the credibility seems to be unraveling, the Darwin Party Rescue Committee runs in with a new load of millions of years to add in, as if time heals all.  It doesn’t.  It makes it worse.  Now, we are supposed to believe that upright-walking, full-brained human beings couldn’t think of a word to say to each other for 150,000 years.
    Some Darwinian reading this might object to calling it “deep dark secrets.”  This is published in a scientific journal available online and in libraries.  That’s right, but who really reads this stuff?  Mostly the faithful Darwin Party members.  What the public sees is the highly-sanitized, carefully-packaged fluff on the Science Channel and Discovery Channel and National Geographic TV.  There, handsomely-paid animators make the miracles seem plausible.  They can throw in whatever is needed to cover the difficulties – a little Lamarckism, some scantily-clad actors with ape-face makeup, some carefully scripted interviews with scientists made up and lighted to enhance their image of credibility, whatever.  The public is led to believe this represents the consensus of all scientists who “know” these things because the evidence is so overwhelming and convincing.  Boy, would it be fun to remake some of those shows with Barnum and Bailey circus music and Tinker Bell zapping apes and turning them into rocket scientists.  It could hardly be any more comedic than reading the words of these scientists quoted above and understanding what they just said.  (Need more?  Browse the Chain Links on Early Man for an endless supply of laughs.)
    This entry is already long after examining only a third of the papers in this series.  The eminent, scholarly, honorable National Academy of Sciences just published all this nonsense with pride.  That means that there is a gold mine of quote material to expose the Darwin myth for what it is.  Let’s get it out there and deprogram the dupes.  Let’s expose the Charlietans and their miracle myth.  Let’s shame the deceivers out of business.  Turn on the lights!