On Fri, 22 Feb 2013 22:11:10 +0000, John Williamson wrote:

If bacteria multiply by division, how else could they change/evolve.?

Random mutations, which is why life was stuck at the single cell stage
for billions of years. It wasn't until a random mutation or accidental
gene transfer from prey to predator started the whole sex thing off
that evolution *really* took off.

With just cloning a single mutation is just as likely to be terminal or
benefical in the next generation. If it's terminal all the beneficial
mutations in the line before are terminated as well.

Once you have sex and the mix 'n match a mutation might not be terminal
in the next generation and you also gain the beneficial mutations of the
other individual. It also allows a beneficial mutation to spread through
the population.

Interesting BBC World Service Discovery short series, part 1:

http://www.bbc.co.uk/iplayer/episode...ual_Nature_1_3

--
Cheers
Dave.