i'm looking more for a specific example. is there an essential sequence of genetic material that all (or most) life has in common (maybe not exactly the same, but significantly similar)?
A biochem book that I have borrowed (I never had a biochem course!) shows that histone H4 changes 30 times more slowly after species branching events than does cytochrome C, and 100 times more slowly than hemoglobin. So plant and animal histone is very nearly identical - 3%, maybe, difference in amino acids. Cytochrome C is more like 45% different. Is this more like what you're after?
Re my post above: Enard, et al.,
Science, 296, pp 340-343, (2002). It's online with free registration at
Science | AAASTheir data, along with some they quote, has humans 1.08% divergent in some measure of our DNA from chimps, and 2.98% from orangutans. The common house mouse,
Mus musculus, is 2.5% different from
M. spretus and 4.5 from
M. caroli.
The article is actually about how gene expression is very different in human vs. other ape brains, which may be why we (claim to be/are) smarter than them. It's worth a read.
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