Re: Predation & AAT Theory
J. Moore (j#d#.moore@canrem.com)
Tue, 26 Sep 95 11:26:00 -0500
Pa> Jim is right to focus on predation as a vital issue. But he has said
Pa> nothing about nocturnal predation; this matters as both crocs and lions
Pa> are mainly nocturnal. Even gorillas go upstairs to sleep. What did
Pa> transitional/early-bipedal hominids do? If you say they used trees,
Pa> then it's hard to see how they could have become bipedal so quickly.
They undoubtedly did sometimes use trees, probably during the day
as well as at night, not just for defense. I can't see how this
impedes them from becoming more bipedal, any more than getting out
of the water for most of each 24-hour period would've kept the
proposed aquatic transitional population from doing so.
However, early hominids didn't necessarily have to resort to
trees, even at night. Chimps in open forest and savannah have
been observed to spend the night on the ground. If they can do
it, so could our ancestors.
Pa> Jim is wrong about "no non-infested waters". (1) Crocs are reptiles and
Pa> need heat: at some point you can move 50 miles north or 100 feet higher
Pa> and you won't find them; (2) they can't climb: so the hominids could
Pa> have inhabited lakes in hilly areas. The East African lakes: Edward,
Pa> George, and Kivu are croc-free, possibly because crocs can't climb
Pa> waterfalls, but more probably because the lakes aren't warm enough.
Pa> Their equivalents 5mya could easily provide an environment suitable for
Pa> an aquatic ape.
So produce some theory based on this possibility. BTW, your "not
warm enough" theory doesn't fit crocodilian behavior.
Pa> Most AAT'ers seem to prefer a hot marine one. The hominids could have
Pa> inhabited rocky coasts with little sloping access to the sea. In any
Pa> case, a heavily-crevassed littoral rock shelf could have provided
Pa> numerous predator-free havens. Marine crocs only seem to be a danger in
Pa> swamps or when they have good cover; they are hardly a threat in clear
Pa> waters. To get safety at night the hominids could have slept on boulder
Pa> islands (steep-sided if necessary).
Are you aware that in just this two paragraphs, you've provided more
analysis of the problem of predation from the AAT perspective than
Morgan has in three books? You are incorrect, however, about
crocodiles not being a threat in clear waters -- any water is good
cover for a crocodile; muddy may be better cover, but an animal
which can and does stalk prey underwater is tough to guard against.
The rock shelves you mention would seem to leave these hominids with
little choice but to dive into pounding surf, like sea lions, which
seems more than a bit dicey. They would also have little opportunity
to get non-marine food, which leads one to the question of why
hominids didn't evolve very large, heavily lobulated kidneys, as seen
in virtually all marine mammals.
Pa> Predation was probably a problem, but I'm sure we're bound to get our
Pa> assessment of it completely wrong. It's far too easy to exagerate the
Pa> dangers and misunderstand how a local population copes with it. Given
Pa> how dangerous sharks are supposed to be, it's hard to believe that
Pa> millions swim daily and unconcernedly from tropical beaches.
The business about our modern world and habits and its application
to ancient ancestors has been done to death and dealt with. It
does not apply. I hope I don't have to point out the many reasons
why yet again. ;-( Please check the archives for my posts on predation
if you want to get into this.
You do at least know about the expensive shark nets used on
South African and Asutralian beaches, don't you?
Pa> Our extremely weak sense of smell seems a most unlikely attribute in a
Pa> continuously terrestrial animal which was both heavily predated and a
Pa> predator. Any explanation for this, Jim?
Pa> Paul.
That we are like our primate relatives. We are predisposed, like
the primates we are, to depend mostly on our eyesight. This would
be a feature which in some environments would tend to be
developed (like in open areas), and in other environments to be
atrophied (like in an aquatic habitat). Many AATers seem quite
astonished that we should resemble our primate relatives in
matters like this.
BTW, it would seem that we were not particularly "heavily predated",
any more than chimps are for instance, and our predation was heavily
dependent on eyesight, just like chimps.
Jim Moore (j#d#.moore@canrem.com)
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