Presently, it is the mitochondrial dna that are used for this purpose and it shows many intriguing features. Since this depicts the maternal line, the maternal mitochondrial dna (mmdna) points to few differences between female ancestors and us.

The mmdna space may have less variance than would be found with men. Women differ less than men because there are such strong constraints on the female to successfully bear offspring. Men are likely to differ by more than women because women have two X chromosomes and males have an X and a Y. The Y chromosome is shorter and, thus deletions, mutations and so on, contribute more to the variance in the information it carries. So, I think women are closer to one another in gene space than are males.

But, there is another reason for high variance among males: testosterone. Testosterone is a developmental hormone. A human with higher testosterone adapts more to activity patterns. This is an additional reason why males are more different physically from one another than are females. Of course they are, just look at them.

In PaleoTimes males had to cope more with environmental variety than females and testosterone is one of the reasons they are able to do this. Size, muscularity, bone density, facial shape and a host of other traits are affected by testosterone. And these all create a physical plasticity that would let PaleoMales adapt to a wide variety of challenges. A male's body will respond more to physical challenge than a female's. Which is why females needn't worry about becoming too muscular if they work out.

The idea of gene space also opens a window to the breeding of new pathogens in the chaotic region of gene space created when humans and animals live together. In this case, chaos just means that the gene flow in the space may take near points taken far away from one another and far away points can rapidly approach one another. The hog/duck/human gene space in Asia is a hothouse for the creation of new pathogens as the gene space is mixed and churned in regions not formerly near one another.

A new intersection of gene flows from distant regions of the gene space began with the beginnings of agriculture. It existed before that too, but there were fewer paths for flow between species (regions in gene space) when humans lived in small groups and did not live in such close and continuous proximity to animals.

I think that when the gene space is eventually mapped there will be gaps in it, just as there are gaps in the periodic table of the elements. The space of proteins is vast, on the order of 20^200, but only a small part of that space is used in living things. So, there will be many empty regions of gene space, as there are outer space and in protein space.

I also think it will be a self-similar space; larger and smaller regions will look similar. We know from Mandelbrot that the scattering of the galaxies is fractal; the densities are power law distributed. I doubt the gene space will be different from space itself in the distribution of density of "stuff".

I suspect that humans will be somewhat unique in the gene space; off in a region of our own. It will turn out that to say that humans are only 2% different from chimpanzees in gene space will look rather dumb. We are very different and when the right metric for gene space is defined and verified, the distance between us will be very large.

On the Edge The Third Culture you will find a discussion of computation and genes. I enjoyed it.

· Evolutionary Fitness

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Posted by: Arthur De Vany at July 7, 2005 8:05 PM

Posted by: Ari at June 30, 2005 11:15 PM

Posted by: carniverous canuck at June 30, 2005 9:32 PM

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