The Human Genome and Evolution

If you gather genetic sequences from a number of individuals, you can infer the evolutionary history of those individuals back until you reach their most recent common ancestor. When genetic sequences are gathered only from members of the human species, the most recent common ancestor of the sampled individuals will by definition also be a human being. You can only trace human DNA back to a nonhuman species by including nonhuman species in the dataset - which of course has been done, but not by the genographic project.I believe the genographic project is more concerned with population processes within the species over historical time - for example the inference of migration patterns and demographic parameters.Hope this helps,MickThis message has been edited by mick, 06-28-2005 04:41 PM

Hi Tranquility Base,You are thinking of phylogenetic trees that represent the genealogy of individuals (frequently members of different species). But it is also possible to build gene genealogies which reflect the phylogenetic relationships between alleles or even different genes rather than individuals.For example see the phylogenetic tree of opsin proteins on page 623 of this article. Note that the human genes are not clustered together, as we would expect from a species level phylogeny. Instead, the opsin genes responsive to different wavelength of light are clustered together. The nodes on such a tree correspond to the origin of new genes by duplication. Hence the phylogenetic method does actually address the origin of new genes.A bit off-topic but thought it would be of interest.Mick

I couldn't help but notice that all of the data sets you linked to start with the error message "The page cannot be displayed - The page you are looking for is currently unavailable"Did you screw the links up, or is this diagnostic of ID research in general? This message has been edited by mick, 07-08-2005 04:43 PM

Hi EZscience,I thought you might enjoy this article, recently published in Nature, which shows that the biological species concept isn't always very good identifying "kinds" either.To put it briefly, the researchers analysed the genetic structure of Wasmannia auropunctata (little fire ant) populations. By analysing genetic sequences of queens, workers, gynes (winged queens), drones, and sperm collected from mated females, they got some pretty surprising results.All gynes in this species are reproduced clonally, asexually, by the queen. This means that males are unable to pass their genes onto their daughters. All new queens have only maternally-inherited DNA. Males are necessary, however, for the production of workers by sexual reproduction; but workers, of course, don't mate, so none of the males' DNA gets passed on to future generations.On the other hand, all males are produced by sexual reproduction. But some time after fertilization, it is thought the male genome destroys the maternally-derived copies of each gene. Only the genome derived from the father is used to create new cells as the zygote develops. This means that all DNA inside a male is paternally inherited. Females are unable to pass any genes on to their sons.If you think about this situation for a second, you realise that there is no common gene pool to the species. There is a female gene pool and there is a male gene pool, but there is no way for male DNA to get into the female gene pool, or vice versa.According to the biological species concept, the different sexes of the little fire ant are completely genetically isolated from each other and are hence different species. The males are evolving independently of the females.Phylogenetic analysis was consistent with this result: all the males in their sample formed one monophyletic clade, and all the females formed a separate monophyletic clade.Weird eh?This message has been edited by mick, 07-08-2005 05:22 PM

Just to give some details for TB, here is gene number for a variety of species. Gene number appears to increase rather than decrease with time. Genome complexity appears to increase rather than decrease with time (measured by gene density, inverse of amount of non-coding sequence per genome)species, number of genes, gene density
Homo sapiens, ~30,000 genes, 1 gene per 100,000 bp
Rattus norvegicus, ~30,000 genes, 1 gene per 100,000 bp
Mus musculus, ~30,000 genes, 1 gene per 100,000 bp
Drosophila, 13,600 genes, 1 gene per 9,000 bp
a plant, 25,500 genes, 1 gene per 4000 bp
roundworm, 19,100 genes, 1 gene per 5000 bp
baker's yeast, 6300 genes, 1 gene per 2000 bp
a bacterium, 3200 genes, 1 gene per 1400 bp

I think I see what you're getting at. But to show an inverse relationship with time (i.e. gene loss) wouldn't it require humans, mice and rats to be older than bacteria and yeast?I may be mistaken here, but I think the general trend is clear.Mickadded in edit: Yes, the 'time' component necessitates us accepting that the species here appeared at different times, not simultaneously. If they all appeared at the same time, then there IS no time component.For this reason one cannot argue that genes are lost over time, while arguing for simultaneous origin. The hypothesis that gene number declines over time necessitates the belief that species arise from one another (otherwise, what does the decline mean?).MickThis message has been edited by mick, 07-11-2005 12:49 PM