Friday, June 12, 2009

Parallel convergence

Sit float feeding in warm water -> hominoid, absent tail, air sac

Sit grass feeding on dry ground -> gelada, long tail, no air sac

Sit float feeding in warm water -> LCA toad/frog, throat sac, croak, long
prehensile tongue, rear feet similar to other frogs

Dive & swim in water -> diving frog, no throat sac, no croak, trill, no more
long prehensile tongue, rear feet differs from other frogs
Diving frog
This most-aquatic frog has a unique immunity to the fungi that is killing
amphibians around the world. Breath control.

Dive & swim in water -> human, no throat sac, no croak, speech/click
no prehensile toes, rear feet differs from other hominoids
Diving hominoid
This most-aquatic hominoid has a unique condition (domestication) that is
killing hominoids around the world. Breath control.

Parallel convergence among tetrapods.


Orang-utans: Our Closest Relative?


I find it odd that Lluca was pictured as a flat faced orangutan, considering
that it is the most distant of all hominoids from the current location of the
orangutan populations. Yet if it was merely the westernmost kin of a ring
species of base Pongid-Hominid apes which distributed along the Tethys shores
with localized dietary and predatory adaptations, and varying degrees of
bipedality, it is not so surprising.

IMO the question is not "are humans and orangs most closely related?" but
rather, "why do people insist on placing human ancestors geographically next to
chimps and gorillas, despite the gross differences in morphology?". Two closely
related species living in the same environment do not change drastically their
morphology, see gorillas and chimps.

Since lowland gorillas forage for floating AHV in brackish water, mountain
gorillas forage in highland fog forests for ground THV, savanna chimps forage in
open woodlands, forest chimps forage for small invertebrates in shallow water
and rainforest bonobos forage in the sub-canopy, we know that human ancestors
must have done something different (or in addition) to account for the extreme
morphological changes.

Crocs and hippos dominate the tropical waters of Africa except for small puddles
and highland waters, notably they lack both fur and SC fat, like manatees, they
rely on the sun's warmth in shallow water. Beavers and otters have thick fur and
live in sub-tropical and temperate waters, with the habit of cool water diving.

Humans, unlike all other great apes, fit in between these two groups, sun
basking (ashore and afloat in warm water) and cool-water deep-diving (deeper
than body length).

That this would have developed after the Orangutan had split eastwards and the
African apes split westwards, seems most parsimonious. The human ancestor seems
to have done neither, until they had well adapted to and dominated their new
African and Asian niches.

Rather, human ancestors seem to have paralleled the crab eating macaques (and
possibly Allen's swamp monkey), foraging both at the shoreline and beneath the
water surface, but still retaining the primate ability to climb. (also
paralleling the African clawed frog and marine otters, which can climb but not
as well as treefrogs or stoats.)

Why would human ancestors have generally stopped climbing and hanging from tree
branches and reeds while foraging? Because they brought their sticks with them
into the water to get food, just as chimps bring customized sticks to spear
bushbabies, to gather termites, to collect honey, to dig tubers in the wet
season. Orangutans don't customize sticks, though they use twigs to get neesia
seeds from spiny fruit, using their lips since one hand and both feet are used
to keep them in position in the high forest canopy.

Human ancestors didn't need their hands and feet to keep in position in the
canopy, because the canopy was low at shorelines, and because the food was as
much under the water surface as above, including later ambushed prey.

I can think of an interesting parallel here, whereby the young and old males
both compete individually and cooperate societally,

Gorilla: young lighter males climbing to canopy, older large males actively
ground foraging and in bais shallows

Orangutan: young lighter males climbing to canopy to forage, older larger males
lower (and if no cats) on ground foraging in swamps.

Aquarboreal ape: young males more mobile fruit foraging, older larger males at
tidal waterside peeling mangrove oysters and papyrus.

He: young males climbing coconut palms, older larger males more in water diving
for longer periods.

Hn: young males in waterside trees leaping onto and stabbing thirsty animals
into the water, older larger fatter males backfloating camouflaged with long
spears aimed at the prey's throats and chest as they dash into deeper water away
from the airborne ambush.

Hs: young trim males as paddlers/sailors/fishers, older larger males as ship

A bit simplified but interesting. Not sure what happened to the "harem" and size
dimorphism, seems variable depending on climate, but otherwise a sort of
continuum. I'd think the shoreline would make for weaker harem/dimorphism
societies than the inlands where drought would be more drastic. The very deep
diving elephant seal harems seem to contradict this, but that may be due to
quite different constraints (simultaneous birthing, cyclical food supply) than
an aquatic ape (with hidden estrus and year around birth) which could forage
above, below and along the surface, and travel far inland during the muddy
coastal rainy season.

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