The Origins of Modern Humans, Part III: The Fossil Evidence

My third BioLogos post on the fossil evidence concerning the origins of modern humans is up over at BioLogos.  This is the part that will, likely, rattle a few cages.  Comments welcome.

Discovery Institute Promoting New Book: Counting to God

The Discovery Institute is pushing a new book called Counting To God: A Personal Journey Through Science to Belief, a new attempt, by Doug Ell, an attorney (again?) with an undergraduate degree in math and physics,  to meld science and faith. It is purported to be a balanced and fair treatment of evidence for the “Seven Wonders of Science of the New Millennium.” That it is being promoted by the DI makes me wonder how fair the treatment of evolution will be, though, especially since one of the pillars is “New species appear suddenly in the fossil record.” The critiques of Darwin's Doubt (here and here, for example) apparently did not sink in.

In the book, he is said to address scientism (philosophical naturalism) and is quoted in the write-up thus: 

Do you think we live in a meaningless universe, and human beings were created by accident? Or do you think we live in a universe designed and created by a great intelligence, and human beings were designed? Accident or design -- that is the question.

This is a noble question and one that has been addressed by learned philosophers for centuries. And that is the point: it has been addressed by philosophers, not scientists. People can take swipes at evolutionary theory for the next two hundred years and it won't make modern design theory any more robust. You can construct tests to show that something fails to reject the null hypothesis, but you cannot use those results in support of a theory that does not have its own testable hypotheses.

That is where ID fails.

New Investigations at the Sima de los Huesos Cave in Atapuerca: Kind of Neandertal and Kind of Not

Science Daily is reporting on a new paper in Science, about the conclusions drawn from the largest single cache of human remains in one place in Europe, the Sima de los Huesos cave, near Atapuerca, in Spain.  They write:

“With the skulls we found," co-author Ignacio Martínez, Professor of Paleontology at the University of Alcalá, added, "it was possible to characterize the cranial morphology of a human population of the European Middle Pleistocene for the first time.”

About 400 to 500 thousand years ago, in the heart of the Pleistocene, archaic humans split off from other groups of that period living in Africa and East Asia, ultimately settling in Eurasia, where they evolved characteristics that would come to define the Neandertal lineage. Several hundred thousand years after that, modern humans -- who had evolved in Africa -- settled in Eurasia, too. They interbred with Neandertals, but even then showed signs of reproductive incompatibility. Because of this, modern humans eventually replaced Neandertals.

This is the hybrid depression that I mentioned a few posts back.  This model fits the genetics information that was summarized by Dennis Venema in his BioLogos post on palaeogenomics from a few weeks ago.  It still also fits with the idea that modern humans swamped a Neandertal genome that was already subject to selective disadvantage.  Consequently, by around 27-29 ky BP, the last populations of Neandertals are, perhaps represented by Zafarraya, a late surviving Neandertal from the very southern coast of Spain. The idea that this Neandertal represents a refugium has been kicked around for decades. Critically, the earliest moderns in Central Europe predate this “last neandertal” by between five and nine thousand years and the evidence from Lagar Velho, in Portugal, indicates that hybridization was occurring as late as this. 

David MacMillan: Understanding Creationism, Part IV: The Predictive Power of Evolution

David MacMillan's fourth post on being an ex-creationist is over at The Panda's thumb and in this one, he writes about why it is so hard for those with the YEC perspective to understand the evolutionary biological concept of “transitional” fossil. He writes:

Young-earth creationists believe that all life, living and fossil, can be grouped into a series of families – they call them baramins, a made-up Hebrew word for “created kinds” – which all existed together at the same time from the very beginning. They use this completely artificial understanding of our planet’s biosphere in generating their concept of a “missing link”: in order for something to be a “true” transitional form under their model, it would have to be something halfway between two separate created “kinds”. Because they automatically assign every species to a particular created kind and only to that created kind, their “transitional form” is something that could never exist.

The usual parodies of evolutionary transitional fossils, like Ray Comfort’s infamous crocoduck, are openly tongue-in-cheek. But because creationists see all animals as belonging to individual, immutable kinds, they represent evolution as “change from one ‘kind’ to another” claiming that evolution predicts we should see transitions between their “created kinds”: for example, a fossil that is midway between a dog and a cat. Just as with living species, all fossil species are placed within strict “created kinds”, allowing creationists to maintain the illusion that nothing is ever “in-between”.

This is only one aspect of the problem. The other problem, mentioned in Young's third post in the series, is the mistaken belief that evolution is entirely vertical and that there is only direct ancestry and not collateral ancestry. With this understanding, one species directly leads to another species and so on. That Archaeopteryx may not have been ancestral to modern birds must mean that we have a gap in the fossil record. These “gaps” must mean that there are problems with evolutionary biology.  With created “kinds,” the species related to Archaeopteryx simply create gaps of their own.  It is difficult to penetrate this logic. 

The Origins of Modern Humans, The Fossil Evidence, Part II

The second of my BioLogos posts on the fossil evidence concerning the origins of modern humans is up. 

Great Britain Extends Creationism Ban From Public Schools to Academies and Free Schools

Politics.co.uk is reporting that there has been a change to the acceptance of the statutes concerning the teaching of creationism as an acceptable alternative to established biological and geological science.  Since sometime last year, creationism has been banned from state-run schools.  Now the wording has been expanded to include schools that are maintained by the state but run semi-privately.  This includes what are known as "free schools" and "academies."  A running battle has been waged by several groups to try to keep these schools from falling under the sway of the government in terms of being able to teach creationism.  They have lost. Ian Dunt writes:

New clauses for church academies published on June 9th clarify the meaning of creationism and state that it is a minority view within the Church of England and Catholic church.

It then adds: "The requirement on every academy and free school to provide a broad and balanced curriculum in any case prevents the teaching of creationism as evidence based theory in any academy or free school."

Because every free school and academy is required to provide a broad and balanced curriculum in its funding agreement, the explicit statement that creationism is incompatible with it bars the teaching of it as a scientific theory.

So what, exactly, is “creationism?” As far as the state-run schools and academies are concerned:

Creationism, for the purposes of clauses 2.43 and 2.44 of the funding agreement and clause 23E above, is any doctrine or theory which holds that natural biological processes cannot account for the history, diversity, and complexity of life on earth and therefore rejects the scientific theory of evolution. The parties acknowledge that creationism, in this sense, is rejected by most mainstream churches and religious traditions, including the major providers of state funded schools such as the [Anglican] [Catholic] Churches, as well as the scientific community. It does not accord with the scientific consensus or the very large body of established scientific evidence; nor does it accurately and consistently employ the scientific method, and as such it should not be presented to pupils at the Academy as a scientific theory.

This represents a new clarification of the language and is very clear: the government has implicated both young earth creationism and intelligent design in their definition of creationism.  From here on out, it will be only private schools that can teach creationism in any form.  Although there is no analogous model here in the United States, this might be roughly similar to any school taking public money for school vouchers being prohibited from teaching creationism, a model currently being promoted by Zack Kopplin. It is hard to say if such a restriction would ever be placed on US schools in the future, barring a court decision because support for creationism in all of its forms is so high among the populace, as a whole. 

BioLogos Post: The Origins of Modern Humans, Part 1 Is Up!

The first of three posts on the origins of modern humans is up over at BioLogos.  As always, comments are welcome there and here.

July 22, 2014

Yay!

New Gallup Poll on Belief in Human Evolution

On June 2, the Gallup organization released another poll on acceptance of human evolution.  In a random sample of 1028 adults (18 years +), they found the following:

• The percentage of people that accept some form of theistic evolution has dropped since 2012 from 46% to 42%.
• The percentage of people who accept a young earth creation model of human origins is exactly three times that of people who seldom or never attend church: 69% to 23%.
• While the percentage of people who have less than a high school education and who accept the young earth model of human origins is 57%, of those who have a college degree, only 27% accept this model. 

The authors of the poll results hasten to mention that education may not play as large a role as one might think: 

These relationships do not necessarily prove that if Americans were to learn more about evolution they would be more likely to believe in it. Those with less education are most likely to espouse the creationist view and to be least familiar with evolution, but it's not clear that gaining more education per se would shift their perspectives. Many religious Americans accept creationism mostly on the basis of their religious convictions. Whether their beliefs would change if they became more familiar with evolution is an open question.

This tracks with modern-day young earth creationism, for which I do not know a single adherent who is not an evangelical Christian.  I do not know whether or not the relationship is real or not.  I do know that I have several friends who are Ph.D.s who are highly skeptical if not doubtful of evolution.  This is not because they have familiarity with the subject (one is a materials scientist, the other a chemical engineer) but because they think it is inherently anti-Christian.  My pastor, who is quite intelligent, and I engaged in a long conversation about it and yet I am quite certain that he remains unconvinced of its authenticity because, as he has stated since then, it conflicts with his understanding of scripture.

The writers also note:

However, significantly fewer Americans claim familiarity with "creationism" than did so seven years ago. In 2007, 86% were familiar, including 50% who were very familiar. Now, 76% are familiar, with just 38% very familiar. In short, even though the adherence to the creationist view has not changed over time, familiarity with the term "creationism" has diminished.

Given the current news climate and what I perceive to be the increased importance of this subject in Christian circles, I find this unusual. Given that these results are not broken down by age, however, it is possible that the drop is related to the rise of people that are more a-religious and thus do not come into contact with this controversy.  If this is the case, this is disheartening. 

Dennis Venema on Human Evolution and Palaeogenomics

Dennis Venema is doing the genetics end of human evolution.  He has, as with most evolutionary creationists, taken the long view of creation, to the point where he has publicly stated that the modern human genome could not possibly have originated with two individuals.  Knowing what I do of the fossil record (upcoming BioLogos posts on June 16-18), I have no problem with that.  He focuses on palaeogenomics, and writes:

The discovery of Neanderthal remains in the same location that preserved the exceptional Denisovan DNA at last provided a very high quality Neanderthal genome, the analysis of which was published just this year. This new data allowed for several more robust analyses comparing human, Denisovan, and Neanderthal genomes. These analyses produced several noteworthy results: modern mainland Asian populations also have a small amount of Denisovan DNA; humans contributed some DNA variation to Neanderthals; Neanderthals and Denisovans interbred, with DNA variation flowing both ways; and (perhaps most interestingly) Denisovans have DNA variation that suggests they interbred with yet another archaic hominin group, possibly Homo erectus.

While the palaeogenomic data indicate a split time of c. 600 Ky years for modern humans and Neandertals, it is fairly clear from other genetic evidence that there was at least some interbreeding between early moderns and Neandertals all the way up to around 50 Ky B.P. (perhaps as recently as 29 Ky, given the information from the Portuguese burial at Lagar Velho), as well as interbreeding between the newly emerging African moderns and African archaic Homo sapiens. 

The news that the Denisovans have some very archaic DNA in them is not surprising.  IF modern humans and Neandertals split around 600 Ky B.P., the only people running around on the landscape at that point were early archaic Homo sapiens/late Homo erectus.  The salient feature of the name "archaic Homo sapiens" is that it is not a taxonomic name but rather a linguistic "catch-all."  The primary reason for this is because, as I noted in my series on human origins, the earliest members of this group still have some Homo erectus characteristics, while the later ones look more modern.  When these fossils, which all date to between (possibly ) 800 and 400 Ky B.P., were pulled out of the ground, researchers did not know what to call them, so they applied this "catch-all."  Adding to the confusion is that some of the archaic Homo sapiens crania from Africa bear more than a passing similarity to some of the finds in Europe.  All were clearly transitional but what to call them was a mystery.  Researchers such as Bernard Wood, applying systematics to the problem, have suggested that these forms should be given the name Homo heidelbergensis.  Such a taxon would, however, have quite a lengthy geomorphochronocline, stretching its limits, perhaps, to the breaking point. For a refresher on these fossils, you might want to read this post. 

So, if the split between modern humans and Neandertals was around 600 Ky B.P., who would have been the progenitors of these groups?  Modern humans don't appear on the landscape until between 160 and 190Ky B.P.  Neandertals don't appear until maybe 300 Ky B.P.  Here is one possible scenario. Sometime prior to 600k B.P., there was a migration out of Africa by one or more groups of archaic Homo sapiens/late Homo erectus.  This explains the similarities between the Petralona and African Kabwe crania, as well as that of the Gran Dolina remains and the African Bodo cranium.  In Africa, the archaics went about their business being archaic until around 200 ky B.P., when the modern genome began to arise (in response to what?).  In Europe, over time, in the face of not one but two ice ages (The Riss and Würm), one group evolved into the Neandertals, who's remains are found in Europe, the Levant, northern Iraq and very western Russia. Populations in the two areas would have, depending on the level of gene flow in the circum-Mediterranean area, become genetically isolated.

Now here is the really odd thing.  When these groups reunited, so to speak, they discovered that, not only was there an attraction, they were still genetically compatible after some 500 thousand years apart—to a point. Even though they actually produced viable offspring (and the presence of Neandertal genes in modern humans demonstrates that they were), because the Neandertal and modern human genomes were "optimized" if you will, eventually over time, hybrid depression would likely have ensued, reducing the fitness of the hybrid offspring.  This may account for the ultimate demise of the Neandertals, who had a genome that, with the warming at the end of the early Würm stadial, was likely undergoing negative selection pressure.  If, in fact, there was a swamping of the Neandertal genome by arriving moderns through the gates of Europe, this would have sped up the process.

This scenario is bare bones at best but explains much of the fossil data.  It leaves aside the hotly contested notion of whether or not Neandertals were a separate species from the early moderns and, with them, reflected a syngameon, or whether, as Milford Wolpoff contends, they reflect a widely polytypic species that interbred at the peripheries.  That is for another day.