Francis Collins on Genetics

There has been a lot of discussion of Francis Collins' clear battle with the basics of the Second Law of Thermodynamics (and what seems to be a misinterpretation of the concept of entropy).

Still, I thought that this was an excellent post on Collins' site dealing with mitochondrial DNA and the Y Chromosome. It really is a great point, and I think means more to them than it would coming from someone like P.Z. Myers.

Collins writes:

Every woman alive today received her mitochondria from her mother. And the number of mothers who provided the mitochondria is less than or equal to the number of women alive today. Some mothers had more than one daughter, anid other women had no children at all. (See figure 1.) If we trace the passage of the mitochondria back one generation to the mothers, we have fewer women than today. If we trace back another generation, we find an even smaller number, and with each previous generation this number decreases. Eventually this traces back to a single woman from whom all women alive today received their mitochondrial DNA. Using careful measurements of genetic diversity, scientists estimate that this woman, called the Mitochondrial Eve, lived between 150,000 and 200,000 years ago. However, this does not mean that Mitochondrial Eve was the only female alive at the time. Indeed, based upon study of diversity in the genome as a whole, geneticists estimate that thousands of others lived at the same time.

It's an excellent point. Of course, we're already done with New Earth Creationism at this point, because we're talking 150,000 years, and not 6,000.

Collins then goes on to explain that the story with Y-Chromosome Adam is similar, expressing that we can track genetic progression based on mutation:

For example, all Y-chromosomes of individuals outside of Africa carry a particular Y-chromosome mutation called M168. Hence, all of these variant Y-chromosomes are descended from the single male in which this mutation occurred. Some men of African descent have the M168 mutation and some do not. This is evidence that a small group of humans left Africa and, through succeeding millennia, spread around the globe.

This, I think, is fantastically interesting, though I'm curious whether it is possible that the M168 mutation could have occurred multiple times, or what the likelihood of such an event would be.

I'm sure that biologists have thought of it before, I'm just curious to see what the answer would be.

Collins lists the standard time-table as around 50,000 years as the general amount of time appropriated to populate the earth as it is now.

I've often wondered how New Earth Creationists reconcile a 6,000 year old earth with nature of the population. It seems that if the earliest humans date back 150,000 years, or even (as Collins writes) took 50,000 years to spread and populate the planet, shouldn't the number be one utterly unreachable in a 6,000 year mark?

At the end of his piece, Collins makes a note of a bottleneck where the population was thinned out, but it still seems like there should be a significant change in the numbers.

Not being a mathmatician, or a geneticist, or a physicist, all of the things that I'm proposing are purely theoretical, but it's a thought.

Anyway, Collins' conclusion is an interesting one and, in my opinion, objective.

Mitochondrial Eve and Y-chromosome Adam lived at different times, were probably separated by thousands of years and quite possibly were in different locations. Thus, a pictorial diagram tracking all men’s Y-chromosome DNA would not trace back to the spouse of Mitochondrial Eve.

It's an interesting point, though not totally undermining the fundamentals of any religious faith. It's certainly an interesting to consider that the earliest matriarch and the earliest patriarch came in completely different historical periods.