Re: What Came Before Monkies?

needgod.com wrote:
Who can tell me what animal did an Ape evolve from? I understand early
man is thought to have evolved from the great Ape about 130,000 years
ago.

Okay, here's the thing. If you pay attention you can learn not only the
answer to this but to a ton of other related questions you might
someday be moved to ask people who know something about biology.

Let's put aside your curious notions about the timetable and your
confusion about what constitutes an ape, and tell you how to answer
questions about descent.

Do you remember when you had to learn about 'kingdom, phylum, class,
order, family, genus, species' in school? Guy named Linnaeus
(pre-Darwin) came up with this scheme, and classified living organisms
into a very neat relationship tree. It's still used today, with
refinements and some greater understanding. (Why is it still used?
Because it works. Because life really is arranged into a nested
hierarchy, i.e. a tree-shape, and this tree shape reflects the
common-descent life ancestry. The *labels* are kind of arbitrary, but
the divisions and shape are real.)

So whether you accept common descent or not, you can figure out what
people who accept common descent are going to answer when you ask
questions like the one above, just by learning what the Linnaean tree
has to say.

We're Homo sapiens. That's our genus and species.

Like chimpanzees, we're of family Hominidae. That means our most
recent common ancestor was with chimps. Since we have changed more in
gross physical characteristics than they did, the common ancestor
probably looked a good deal like a chimp.

We're of the Primate order. The next most recent ancestors (after
chimps) were common to the other primates. (Since Linnaeus, we've had
to put in a bunch of other sub-headings between order and family,
because we know a lot more about the order of division. So there are
superfamilies and suborders and and so on. To divide this up, our
next-most-common ancestors are the rest of the great apes, before which
it was the small apes (gibbons), before which it was the old-world
monkeys (e.g. baboons), before which it was the new world monkeys,
before which it was lemurs and tarsiers.) Our common prosimian ancestor
would have looked kind of like a monkey; our common primate ancestor
would have looked a bit like a lemur, and would have lived something
like seventy million years ago.

We're of the class Mammalia. That means that all primates, as a group,
are descended from a common mammalian ancestor with the other mammals
-- dogs, bison, shrews, dolphins, cats and rats and elephants, lions
and tigers and bears. It goes back a ways -- something like two
hundred million years (I may be off a bit, but that order of magnitude)
-- to find the common ancestor of all the mammals. Again, there are
subclasses and superorders in between. Our common mammilian ancestor
looked a little like a rat -- though that's just my opinion from seeing
drawings of it -- and lived about two hundred million years ago.

We're of the chordate phylum (the vertebrate subphylum), which means
we're more closely related to vertebrates like fish and lizards than we
are to invertebrates like beetles and spiders. (Once again, we know
more than Linnaeus did, so we can classify this in substantial detail:
mammals came from an offshoot of reptiles, while birds came from
another; amphibians split off earlier, skates and rays before that, all
jawed fish still earlier than that, and jawless fish earlier still.)
This goes back to only a little after the Cambrian, which you may have
heard of. The "Cambrian explosion" didn't differentiate among the
chordates, though, as far as I know. The earliest chordates were
fishlike, and lived about four hundred million years ago.

We're in the animal kingdom. We're more closely related to starfish and
worms than to pine trees and flowers. The common ancestor of all
animals lived something between half a billion and a billion years ago,
and was a fairly nondescript single cell.

There's one higher level than kingdom recognized today -- domain.
Plants, fungi, and animals are all eucaryotes, which are one domain;
single-celled organisms that don't have nuclei are prokaryotes, which
form the other domain (and the vast majority of living organisms on
earth, measured by weight, even today). We split off from the
prokaryotes something like a billion years ago. The earliest eucaryotes
would of course also have been single-celled.

May I recommend
http://www.talkorigins.org/origins/postmonth/may03.html

eyelessgame

(All time estimates may be wrong by a bit. They're intended to
illustrate, not be definitive reiterations of official research.)

.

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