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. 

A Review of Darwin's Doubt By Nick Matzke

Over at Panda's Thumb, Nick Matzke has written a review of Stephen Meyer's new book Darwin's Doubt.  To get an idea of what he thinks of the book, Matzke's post is called "Meyer's Hopeless Monster." For example:

As I read through Meyer’s book, though, in case after case I see misunderstandings, superficial treatment of key issues which are devastating to his thesis once understood, and complete or near-complete omission of information that any non-expert reader would need to have to make an accurate assessment of Meyer’s arguments.

He also chastises Meyer for his lack of understanding of unilineal versus collateral ancestry, and notes that this is a common problem with creationists:

Yet another confusion that Meyer exhibits relates to the idea of “ancestor”. As with all creationists, Meyer exhibits no understanding of the fact that phylogenetic methods as they exist now can only rigorously detect sister-group relationships, not direct ancestry, and, crucially, that this is neither a significant flaw, nor any sort of challenge to common ancestry, nor any sort of evidence against evolution. Distinguishing between a close sister-group relationship and an exact ancestor is just a level of precision that we cannot expect in most cases. It’s just a by-product of the method and the data available.

A common problem is the inability to understand that even if a species did not give rise to successor species, it can still be transitional by virtue of the number of derived and retained traits relative to its sister taxa.

The whole review is scathing and his examples devastating to the premises of the book.  Another ID hatchet job.  

“Out-of-Africa Replacement Model”: Piling On

On the heels of the recent DNA arguments supporting hybridization between early modern Homo sapiens and archaic Homo sapiens in Africa comes fossil skeletal evidence.  As the Telegraph reports:

A study on human remains found in the Iwo Eleru cave in Nigeria, West Africa, shows that Stone Age humans in the area shared characteristics with much older human relatives. Palaeontologists leading the study believe their findings provide evidence that modern humans and older subspecies of human might have coexisted and even crossbred in Africa. The findings add weight to theories that ancient species of human lived alongside the anatomically modern humans after they first appeared in Africa 200,000 years ago.

Quoted in the article is Chris Stringer, one of the progenitors of the Out-of-Africa replacement model of modern human origins which was based on mitochondrial DNA studies done in the late 1980s.The article continues:

Professor Stringer said: "The majority view was that once modern humans emerged in Africa 150,000 years ago, it was kind of the end of the story and modern humans took over. "I think the reality is that the ancestral forms didn't just disappear but hung around alongside those that had evolved into modern humans. "Somewhere lurking in bits of Africa were these more archaic people and we are starting to get a picture of that."

I suspect that it is going to get very hard to pin down exactly where Homo sapiens starts. It is becoming more and more clear that anatomically modern Homo sapiens and archaic Homo sapiens went for the occasional “roll in the hay.” If so, as I pointed out earlier, there simply was no “speciation event.” This goes more to supporting the multiregional evolution model, as it applies to Africa, in which there was selection for more modern genes. This model may also apply to Europe, with the mixing of modern humans and archaic humans there. I suspect that this will spur reexamination of the early modern material from there, such as Mladeč, where the material dates from the Early Würm/Late Würm interglacial period.

Speciation and Human Intervention

Brandon Keim of Wired has a story about the blackcap warbler, a species that is slowly splitting in two. He writes:

Blackcap migration routes are genetically determined, and the population studied by Schaefer has historically wintered in Spain. Those that flew north couldn’t find food in barren winter landscapes, and perished. But during the last half-century, people in the U.K. put so much food out for birds that north-flying blackcaps could survive.

About 30 percent of blackcaps from southern Germany and Austria now migrate to the United Kingdom, shaving 360 miles from their traditional, 1,000-mile Mediterranean voyage. Because they’ve less distance to travel, they tend to arrive home first in the summertime and to live in prime forest-edge spots. All this makes the U.K. migrants more likely to mate with each other than with their old-fashioned brethren.

From these groupings, subtle differences are emerging. The U.K. birds tend to have rounded wings, which sacrifice long-distance flying power for increased maneuverability. Now that they don’t need wide bills to eat Mediterranean olives in winter, their bills are becoming narrower and better-suited to summer insect diets. They’re also slightly darker.

These are the first steps toward anagenetic speciation, a process that has been observed in other species¹. As the authors point out, this is fascinating not just because it may be an example of speciation in action, but that it is speciation influenced by humans.


¹Ayala, F. J., M. L. Tracey, D. Hedgecock & R. C. Richmond (1974) Genetic differentiation during the speciation process in Drosophila. Evolution, 576-592.

Pfosser, M., G. Jakubowsky, P. M. Schlüter, T. Fer, H. Kato, T. F. Stuessy & B. Y. Sun (2005) Evolution of Dystaenia takesimana (Apiaceae), endemic to Ullung Island, Korea. Plant Systematics and Evolution, 256, 159-170.

Stebbins, G. L. & D. L. Hartl (1988) Comparative evolution: latent potentials for anagenetic advance. Proc. Natl. Acad. Sci. USA, 85, 5141-5145.

Stuessy, T. F., G. Jakubowsky, R. S. Gómez, M. Pfosser, P. M. Schlüter, T. Fer, B. Y. Sun & H. Kato (2006) Anagenetic evolution in island plants. Journal of Biogeography (J. Biogeogr.), 33, 1259-1265.

Just to name a few...

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New Global Model for Speciation

ScienceDaily has a report on work done that is adding support to the idea that geographical isolation need not be present for speciation to occur. The article notes:

In a new study just published in Nature, Les Kaufman, Boston University professor of biology and associate director of the BU Marine Program along with a team of researchers from The New England Complex Systems Institute, have collaborated and found a way to settle the debate which deals with the origin of species independent of geographic isolation.

They demonstrated, using a computer model, how diverse species can arise from the arrangement of organisms across an area, without any influence from geographical barriers or even natural selection. Over generations, the genetic distance between organisms in different regions increases, the study noted. Organisms spontaneously form groups that can no longer mate resulting in a patchwork of species across the area. Thus the number of species increases rapidly until it reaches a relatively steady state.

"Our biodiversity results provide additional evidence that species diversity arises without specific physical barriers," the study states.

The computer simulations, the authors, note showed the distribution of species formed patterns similar to those that have occurred with real organisms all around the world.

This is a boost for the sympatric speciation model, although it is likely that both take place all over the world in different populations.



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