On Fri, 10 Nov 2006 22:41:53 -0600, skip wrote:
>
> Steven> The world seems to be flat, the sun appears to rotate around the
> Steven> Earth, and mushrooms look like they are more closely related to
> Steven> plants than to animals, but none of these things are actually
> Steven> the case.
>
> Where can I read about mushrooms as animals?
Mushrooms, like all fungi, aren't animals. The old divide of the
living world into animals and plants has been obsolete in biology for
decades. Biologists today generally follow Woese's "Six Kingdoms":
Eubacteria ("ordinary bacteria")
Archaebacteria ("extrophile bacteria")
Fungi
Plantae (plants)
Animalia (animals)
Protista (eukaryotes that are neither fungi, plants or animals -- a
grab-bag of "things left over" such as protozoa and algae)
Notice that, although to the naked microscope eubacteria and
archaebacteria seem very similar, their biochemistry is radically
different -- more so than (say) an oak tree and you or I.
Based on molecular and DNA evidence, fungi and animals are more similar
than fungi and plants. (Remember that animals include many thousands of
species that don't walk or crawl or fly, beasties like corals, sponges and
other creatures that look superficially plant-like.) Both animals and
fungi rely on plants to convert solar energy into chemical forms that they
can digest.
The best evidence is that the animal kingdom (including, naturally, human
beings) and fungi split during the Mesoproterozoic Era, approximately
1500-2000 million years ago. The common ancestor ("concestor") of animals
and fungi split from plants not long before that, where by "not long" I
of course mean "many hundreds of millions of years".
Richard Dawkins' excellent book "The Ancestor's Tale" is worth reading for
more about this. But keep in mind that biology is in a constant state of
flux these days, with new molecular discoveries virtually every day, so
dates are naturally uncertain and subject to revision. (Aside: this
willingness, even desire, to revise old beliefs in the light of new
evidence disproves the Creationist canard that evolution is a matter of
faith rather than science -- but I digress.)
See also http://en.wikipedia.org/wiki/Fungi for more about fungi including
mushrooms, although regrettably little on their evolutionary relationship
with other species. Follow the references there to discover more.
http://en.wikipedia.org/wiki/Kingdom_%28biology%29 discusses the
biological kingdoms -- again, treat Wikipedia as the start, not the end,
of your reading :)
--
Steven.
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