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Creationist site deliberately(?[i]) Ignores cited Evidence that African people Not Descendant from Adam & Eve or Noah

Post of the Month: February 2012


Subject:    | Genetics?
Date:       | 08 Feb 2012
Message-ID: |

Christopher, a Christian exploring the evidence, asks:
> Recently, I have been looking at the following article:
> I am not even a layman in the field myself, and would like to know if
> anyone would be willing to address this? Is the reasoning sound? Are
> there any well founded rebuttals against it?

Garamond replies:
Well, let's see what we have here.

The first sentence from your link reads:

"It comes as a surprise to most people to hear that there is abundant evidence that the entire human race came from two people just a few thousand years ago (Adam and Eve), that there was a serious population crash (bottleneck) in the recent past (at the time of the Flood), and that there was a single dispersal of people across the world after that (the Tower of Babel)."

This cites a 2003 article in the Journal of Creation[1], which in turn cites Dorit et al. Science 1995[2], and after quoting Dorit Nelson states "These results are quite consistent with a recent human origin and a global flood.".

Dorit's abstract reads:

"DNA polymorphism in the Y chromosome, examined at a 729-base pair intron located immediately upstream of the ZFY zinc-finger exon, revealed no sequence variation in a worldwide sample of 38 human males. This finding cannot be explained by global constraint on the intron sequence, because interspecific comparisons with other nonhuman primates revealed phylogenetically informative sequence changes. The invariance likely results from either a recent selective sweep, a recent origin for modern Homo sapiens, recurrent male population bottlenecks, or historically small effective male population sizes. A coalescence model predicts an expected time to a most recent common ancestral male lineage of 270,000 years (95 percent confidence limits: 0 to 800,000 years)."

So you might be a little surprised that Dr. Robert W. Carter approvingly cites C. W. Nelson who approvingly cites R. L. Dorit, who thinks our most recent common ancestral male ancestor lived 270,000 years ago.

Nelson then goes on to quote Reich et al Nature 2001, allowing Nelson to conclude "This study concluded with the possibility that 50 individuals may have founded the entire population of Europe. This evidence is also quite consistent with a historical global flood." Here is the abstract of Reich:

"With the availability of a dense genome-wide map of single nucleotide polymorphisms (SNPs)1, a central issue in human genetics is whether it is now possible to use linkage disequilibrium (LD) to map genes that cause disease. LD refers to correlations among neighbouring alleles, reflecting 'haplotypes' descended from single, ancestral chromosomes. The size of LD blocks has been the subject of considerable debate. Computer simulations2 and empirical data3 have suggested that LD extends only a few kilobases (kb) around common SNPs, whereas other data have suggested that it can extend much further, in some cases greater than 100 kb4, 5, 6. It has been difficult to obtain a systematic picture of LD because past studies have been based on only a few (1-3) loci and different populations. Here, we report a large-scale experiment using a uniform protocol to examine 19 randomly selected genomic regions. LD in a United States population of north-European descent typically extends 60 kb from common alleles, implying that LD mapping is likely to be practical in this population. By contrast, LD in a Nigerian population extends markedly less far. The results illuminate human history, suggesting that LD in northern Europeans is shaped by a marked demographic event about 27,000-53,000 years ago."

Before your eyes began to glaze over, did you notice the bit about the Nigerian population data? If not, go back and read that abstract again.

Quoting from the Reich article (it's paywalled, ping me if you'd like a copy):

"The short extent of LD in Nigerians is more consistent with the predictions of a computer simulation study assuming a simple model of population expansion."

In smaller words, the population bottleneck was not observed in the Nigerian population. Why? Quoting again from Reich (citations omitted):

"What was the nature of the population event that created the long-range LD? The event could be specific to northern Europe, which was substantially depopulated during the Last Glacial Maximum (30,000±15,000 years ago), and subsequently recolonized by a small number of founders. Alternatively, the long-range LD could be due to a severe bottleneck that occurred during the founding of Europe or during the dispersal of anatomically modern humans from Africa (the proposed `Out of Africa' event) as recently as 50,000 years ago. Under the first hypothesis, the strong LD at distances >= 40 kb would be absent in populations not descended from northern Europeans. Under the second hypothesis, the same pattern of long-range LD could be observed in a variety of non-African populations. Regardless of the timing and context of the bottleneck, the severity of the event (in terms of inbreeding) can be assessed from our data. To have a strong effect on LD, a substantial proportion of the modern population would have to be derived from a population that had experienced an event leading to an inbreeding coefficient of at least F = 0.2 (Fig. 3). This corresponds to an effective population size (typically less than the true population size) of 50 individuals for 20 generations; 1,000 individuals for 400 generations; or any other combination with the same ratio."

Neat, huh? Not much support for a worldwide flood, though (assuming your world is larger than Europe and includes Africa).

So, what are we to make of C. W. Nelson? There comes a point where incompetence is so gross that I'm not able to distinguish it from lying, and Mr. Nelson has long blown past that point.

An honest approach would have looked at how coalescent theory is applied to multiple species, not just humans. Doing so would have found population bottlenecks as far back as the technique can reach but no common date to a worldwide flood. This is more than sufficient to lay to rest the idea of such a flood. Nelson could have written that article; he chose not to do so.

To answer your question: the very research Nelson and Carter cite in support of their work only does so if you believe their summary of that research. Read it yourself. If you find an article is paywalled, post a request here and you may find a pdf in your inbox.

[1] C. W. Nelson, "Genetics and Biblical demographic events", TJ 17(1):21- 23, April 2003.

[2] Dorit, R.L., Akashi, H. and Gilbert, W., Absence of polymorphism at the ZFY locus on the human Y chromosome, Science 268(5214):1183-1185, 1995

[3] Reich, D.E., Cargill, M., Bolk, S., Ireland, J., Sabeti, P.C., Richter, D.J., Lavery, T., Kouyoumjian, R., Farhadian, S.F., Ward, R. and Lander, E.S., Linkage disequilibrium in the human genome, Nature 411 (6834):199-204, 2001.

[i] Dr. Carter was contacted , he replied, then asked that that reply be removed, and as of 2012/03/13 has not modified his cited claim.

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