Thread: genes and DNA time periods?

My knowledge in this sphere is sketchy but I hope to bring it together.

I am still having issues with understanding the modern concept of a gene (rather than the sixties concept).

Often, in the literature, there are claims made that this gene is 6 million years old, another 3 million. .....

How on earth is this known? You can't carbon date a gene as it is a copy of something. what is going on please?

Can anyone explain how these claims are justified?

Zero

You look for the same gene in related species.

If, for example, humans and chimps evolved into separate species 8 million years ago, we can look at what genes we have in common, or which are different.

If Gene A is the same in both species, we know it came into being more than 8 million years ago.

If Gene B is different between the two species, we know it is younger than 8 million years.

It is not quite this simple, of course, and lots of comparisons between many different species are done to nail this sort of thing down.

thankyou - all clear now