The Human Genome and Evolution

I totally agree. I'm not sure where this idea that 'microevolution' and 'macroevolution' are somehow not real scientific terms came from. They may not be overused in the literature but that is probably because they are pretty general terms which cover a number of things. So if a paper is about speciation it will talk about speciation not 'macroeveolution', similarly a paper discussing the genetic basis of large scale morphological changes is more likely to talk about 'large scale morphological changes' rather than 'macroevolution'.It may simply be that the wide usage of these terms as convenient labels for what creationists will or will not accept in terms of eveolution, as opposed to their limited use in current literature, has led to this misperception of these terms as having originated with creationists. It is also possible that many individual creationists have their own idiosyncraticc definitions of these terms, but that is another issue.TTFN,WK

WKCreation vs. evolution aside, the issues of precisely how eyes arose was always going to be more than beak reshapings. Creationists certainly did jump on it but it seems to me that researchers working at the big picture level use the terms.

Isn't that what I just said? I wouldn't assume that all researchers working at that 'big picture' level necessarily use those terms however.My point was that it isn't as commonly used as other terms related to macroevolution, such as speciation. so we find only 92 hits for 'macroevolution' on Pubmed but 4778 for 'speciation'.The reasons for this seem to be partly historical, in that micro- and macro- evolution were terms favoured by the orthogeneticists like Schindewolf and Goldschmidt (and probably Salty) and consequently were not favoured by amany of the originators of the neo-darwinian synthesis, although they were initially introduced (at least in English) by Dobzhansky, who people never tire of quoting. Apparently there is some historical russo-germanic/ anglo-american divide in respect to the usage of the terms.TTFN,WKThis message has been edited by Wounded King, 07-13-2005 05:35 AM

My post was meant to be agreeing with you!

But I was just agreeing with you!! Lets just agree to agree .TTFN,WK

I think we might have to accept there may never be a firm answer to 'why', only speculation. I also suspect that the truth might be far less 'spiritaully satisfying' than many philosophers and theologians would like it to be. The origin of life most likely arose as a coincidence of circumstances and events that, although of extremely low probability, are in fact only seen by observers fortuante enough to have been themselves one outcome of the process. The only alternatives to this type of origin are completely bereft of evidence and require some sort of omnipotent manipulation of the process, typically accompanied by teleological interpretations of evolution that are not acceptable to mainstream scientific thought. I am an organismal biologist, not a molecular biologist. Others frequenting this site are far more qualified than I am to comment on the limits of inferences that are possible from molecular genetics. Howver, I would say that most retrospective inferences from DNA hinge on a series of assumptions of consistency w/r/t rates of change in conserved / non-conserved and expressed / non-expressed regions of the genome. We are often not sure how well all these various assumptions how true across taxa, particularly when considering lineages above the family level. Add to this the newly recognized phenomenon of lateral gene transfer (usually mediated by virses) and you have another monkey wrench in the works that can make inferences more and more tenuous the farther back in time you go. But that is part of the problem - it probably doesn't. Read up on the concept of 'punctuated equilibria' put forward by Gould. Many explosions of taxonomic diversity could have happened relatively rapidly in geological time, while certain species remained relatively unchanged throughout the same period.Hope this helps.EZ

Careful TB,
You are now making some sweeping overstatements.There are very good, very plausible, mechanistic explanations of how eyes and immune systems have evolved that have no dependence whatsoever on the fossil record.I suggest you go here and scroll down below the quote boxes to a series of links on the evolution of the eye, how partly evolved eyes are still useful, and how extant life forms still have partly evolved eyes.You can also go here to read the abstract of a PNAS article entitled "The descent of the antibody-based immune system by gradual evolution".Now you may say that these conceptual constructs do not constitute 'proof', but they are far more convincing and intellectually satisfying to any real scientist than the 'poof - they were created' explanation.

EZAs you're aware these papers simply track either phenotype or where gene and protein-fold families re-appear. They do not address the geneuninely new molecular machinary required (quote from immune system paper): If you assume evolution of genuine novelty occurred it's all childishly simple, I agree.

I'm sorry, but it doesn't appear that you've understood my argument in the least, or else you don't know what it means to be "the opium of the masses" (which is the accurate quote, btw.)You asserted that science was a kind of faith. I define, and I imagine you define, faith as "certainty in the absence of kproof."But the scientific method leads to tenative knowledge even about those things which seem most obvious. I could be looking right at it and the scientific method would demand that my conclusions be tentative.Faith is certainty in the face of the unknown. Science is tentativity in the face of the obvious. How are those things not exactly opposite? So many of you say, but I've never seen anything like that. If you believe this to be true then that's something you take on faith. I'm not prepared to do that.

It seems to me that it is just as true to say that there is no proof that anything happened simply by natural processes. Science can only look at what happened and is unable to come to any conclusion whether there is any metaphysical interference or not. We have to take it on faith either way. Science can only be agnostic and anything beyond that requires faith in something that has been unproven. I would imagine that there are many who have studied philosophy who would disagree with you.

This seems to be drifting off topic more than a little. I'm sure there are more suitable forums for a discussion of the philosophical merits of the scientific method.TTFN,WK

Thanks WK. You are right of course. I do let myself get sucked in. Back to the OP. I think that the clearest answer to my question was given early on by mick. It sounds as if genetic research will not be able to trace human lineage beyond our common ancestor and his comment on the Genographic project is correct as well.

I'm not sure why you would conclude that. We certainly might not be able to trace an unbroken lineage but there is a pretty substantial body of evidence suggesting that humans and chimps shared a common ancestor 5-6 million years ago.Wihtout a great deal of luck in finding preserved specimens and continued refinement of our usage of ancient DNA I doubt that we will ever actually get DNA from whtever species was that common ancestor. We may try to reconstruct an ancestral genome but usually these are based on a larger number of species than 2, maybe an ancestral genome for the great apes could be reconstructed.I guess the real issue is how detailed you want your lineage to be.TTFN,WK

My genographic history has me with a M168 marker that takes me back to a common ancestor about 60,000 years ago. As I understand it everyone goes back to a common male ancestor out of Africa about 70,000 years ago.Are you saying that if they did a study of the genome of a group of great apes they could then use that study to trace our DNA back even further to a common ancestor of both species?As I said at the beginning, I was wondering if through the study of genetic history if we would be able to provide conclusive evidence for how evolution occurred. I do understand that through genetics they have proven that we aren't related to Neanderthal man.

Yes, that is exactly what I'm saying. In fact you don't need to study the whole genome, if all you want is something along the lines of the m168 marker on the Y chromosome then all you need to do is look at Y chromosomes. I would be very surprised if ther weren't some common markers between the chimp and human Y chromosomes, even though they are substantially different. Similarly I wouldn't be surprised to see similar markers forming a number of specific clades throughout the great apes as they do in man today.I was actually making the somewhat more outrageous claim that a sustained and detailed analysis of the genomes of extant great apes could allow us to reconstruct a plausible candidate for the actual sort of ancestral genome that our latest common ancestor would have had, along the lines of work already done for a common mammalian ancestor (Blanchette, et al., 2004).TTFN,WK