determining the age of genes

Can anyone suggest a reference or provide a description of how scientists determine the age of genes? I can see how the use of morphological features and fossil evidence can be used to aid in determining the lineage of organisms, but a wholly different approach is used for DNA. I have some background in molecular biology, but struggle with this concept.

Thread moved here from the Proposed New Topics forum.

Usually one of the best methods is how frayed the bottom hem is. various wear patterns and holes can help determine the age as well. I tend to prefer Levis over Lee . Lees just dont fit me right. Like the crotch is to high or something. I do happen to have some very old LUCKY;s that I cherish. I do not know if the faded amount can be used to determine the age because so many manufactures and designers are artificially aging them.

Hi. I'm new here. U can call me Cookie refered me to this place.To all of my knowledge, there is no objective way to determine the age of genes. The age of genes can only be approximated by first determining the first organism to possess that particular gene, then estimating when that organism evolved.This message has been edited by Eis_baer, 12-04-2006 01:24 PM

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Howzit Eis You're right that there is no objective method to determine gene age, however, i'm not sure of the technique you postulated.Nowadays a common method used in age estimation is to use Coalescence theory.For Eoasa:
This is a ref that might help Estimating Allele AgeI struggle with it too. Hell, I expect more than 99% of people would struggle with it This message has been edited by U can call me Cookie, 04-12-2006 12:33 PM

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"The good Christian should beware the mathematician and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of hell." - St. Augustine

Hey cookie. The reason I joined is because I've been bored stiff at work and I figured this forum wouldn't likely trigger any red flags in the IT department. So you'll be seeing a bit more of me around these parts.This message has been edited by Eis_baer, 12-04-2006 01:24 PM

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The Molecular clock is an interesting phenomenon. The simple idea is as follows. First we take two organisms which we are fairly confident that we know the date of their most recent common ancestor and we use this as a callibration of our clock. We can get a rough idea on the average rate of change of the genes we are looking at.For example, if we look at the human/chimp divergence (warning: I believe it is normally wise to pick something that happened much longer ago) we can estimate then that 5 million years results in a change of magnitude x within the tested genes. We might then try and compare how much the genes have changed in other species. For example, if two species have variation in the genes which is three times greater than x then we can estimate that the common ancestor is dated at about 15 million years ago.This method has proved useful, here is an interesting paper that employs the technique and discusses what is involved:

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Here we present divergence-time estimates for mammalian orders and major lineages of vertebrates, from an analysis of 658 nuclear genes. The molecular times agree with most early (Palaeozoic) and late (Cenozoic) fossil-based times, but indicate major gaps in the Mesozoic fossil record

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"First we take two organisms which we are fairly confident that we know the date of their most recent common ancestor and we use this as a callibration of our clock."Any idea how this would work with bacteria, archaea or microeukarayotes? With the lack of morphological complexity, I am wondering how one is determined to be ancestral to another and how that plays into inferences of gene age (eg rRNA).Thanks for the reference.

This is completely off topic but that has got to be the most frightening sig image I have ever seen - good job