Apes did not have to be aquaphobes.
Apes did not have to be aquaphobes.
That
was probably quite accidental. The first apes
(gibbon-like IMO) found themselves on an
island surrounded by fast-flowing water. So,
like many flightless bird species on small
oceanic islands, there was selection against
a near-universal ability which was likely to
get them into trouble.
Apes could well have evolved in another
location, retaining the standard mammalian
ability to swim and never acquired a fear of
water.
What difference would that have made for
ape and hominin evolution?
But would hominins have ever evolved?
They split from chimps when there was a
small rise in sea-levels, or a change in the
course of a major river, creating an off-
shore island. If the mainland chimps could
have swum across, that population might
never have achieved the genetic isolation
necessary for a new species.
Apes did not have to be aquaphobes. That
was probably quite accidental. The first apes
(gibbon-like IMO) found themselves on an
island surrounded by fast-flowing water. So,
like many flightless bird species on small
oceanic islands, there was selection against
a near-universal ability which was likely to
get them into trouble.
Apes could well have evolved in another
location, retaining the standard mammalian
ability to swim and never acquired a fear of
water.
What difference would that have made for
ape and hominin evolution?
I doubt if it would have had much effect on
that of apes, per se. Gibbons would not be
as split up into so many different species,
with few significant differences. Likewise,
there would probably have been fewer
fossil species of ape in Europe and Africa
around 10-12 ma.
But would hominins have ever evolved?
They split from chimps when there was a
small rise in sea-levels, or a change in the
course of a major river, creating an off-
shore island. If the mainland chimps could
have swum across, that population might
never have achieved the genetic isolation
necessary for a new species.
As it was, even a small body of water was
enough to allow the (proto-)hominins to
maintain genetic isolation. They would
have needed a larger one before they
started to descend from the trees and live
on the ground. That would not have been
possible in the presence of large mainland
omnivores, and we can assume that a few
individuals of those species would swim
to visible islands from time to time.
Did this process happen, or begin to
happen, several times before it was finally
successful? IMO that's just about possible
and, if various fossil apes before the
australopiths (e.g. Sahelanthropus, Orrorin)
are shown to be bipedal, or other bipeds
are found, they could have come from
earlier proto-hominin populations. They
would have been even more rare on the
mainland African landscape than
australopiths later became, and so could
have wandered around for a while in
relative safety. The local fauna would not
have known what to make of them.
Apes avoid water because their ancestors were islanded.
Humans are aquatic
because their ancestors were islanded.
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