It's happenstance, not design. Chromosomes are
the length they are because of evolutionary
accident. In some cases there are important
adaptive reasons for why chromosomes would be of a
certain length (for example, on the mammalian Y
chromosome, there are really only a handful of
genes that are important, because females don't
have that chromosome at all, which means that the
Y is really short).
Chromosomes just happen to be different in
number, size, and lengths of the arms. Life
started from single-celled organisms like bacteria
that just have a circle of double-stranded DNA and
no chromosomes. Then each species of life changed
in different ways to get all the different forms
we see today.
Click Here to return to the search form.