Posted by Adam on November 30, 1999, at 0:18:04
In reply to Evolution doesn't add up., posted by CC on November 29, 1999, at 23:04:11
>Plus bacteria have means of exchanging genetic material that higher animals don't and have
Are you referring to conjugation? That's a bit like a primative form of sexual reproduction.
Mostly all that gets exchanged are little circular bits of DNA (plasmids) that normally carry
only a couple or maybe just one gene, often a gene that confers resistance to something.Anyway, when you stack the kind of genetic recombination that can happen during the various
processes of sexual reproduction, eukaryotes have it big over prokaryotes. Crossing-over
during meiosis alone can lead to enormous exchanges of genetic material from chromosomes
derived from different parents. Sexuality mixes everything up really well.Bacteria have a doubling time of about 30 minutes. People, for example, take a lot longer.
So you can see bacteria evolving, in the human perception of time, very quickly relative to
us poor primates. But if it takes a million years to get humans as far as bacteria can go
in a decade, it doesn't mean that humans won't evolve. It just takes longer.P.S. In my last post, I guess I said dimethylbenzamine. That's wrong. I'm pretty sure it's
dimethylbenzanthracene. Icky stuff.
> I still don't see how you could ever hope to accumulate favorable mutations. If one mutation in a thousand is beneficial, then there are 999 that aren't. With the bacteria developing antibiotic resistance, if there is one resistant individual in a million that one individual can repopulate the growing medium in ~24 hours. Plus bacteria have means of exchanging genetic material that higher animals don't and have you ever heard of someone developing a different species of bacteria starting with a known one? There are of course biological processes that can correct mutations but how could they tell a good one from a bad one? So if you had a million monkeys and they each accumulated a thousand mutations only one of which was favorable during the period they are able to breed, and they each have ten offspring to ten different mates, how many offspring have accumulated more favorable mutations than bad?
poster:Adam
thread:14368
URL: http://www.dr-bob.org/babble/19991123/msgs/15977.html