Re: Percentage values commonly given for differences in DNA etc, may be meaningless.

Gautam Majumdar (
Fri, 26 Jul 1996 21:21:05 +0100

In article <>, =?iso-8859-
1?q?Ludvig_M=F6rtberg?= <> writes
>All the time we hear percentage values for how much species differ in
>their genetic material. Yet there is unclear what people mean when
>they for example say that humans share 98% or their genetic material
>with chimpanzees. Is it sequence similarities? I have been thinking of
>this and doubt if the "genetics" of an organism can be equated with
>raw DNA sequence. Genome and genetic material may be difficult
>concepts to define. Can they really be measured quantitatively, like
>weight or length? Even relatively?
>Is there really an established way of measuring differences between
>two DNA sequences that gives you a percentage value? If we take for
>example a 100 bases and substitute 2, this may be a 2% difference. But
>what if we insert 5 bases or delete 10, then what?
>Can we really talk about humans as the "third chimpanzee" because we
>supposedly share 98% of our "genetic material"? Do we know what we are
>talking about?
>Ludvig M€rtberg

Also how can we tell the total percentage difference of DNA between
two species without knowing the complete sequence ? Complete
DNA sequencing, as I understand, has been done only for some
bacteria and yeast.

Gautam Majumdar