Re: Morgan and creationists
HARRY R. ERWIN (herwin@mason2.gmu.edu)
3 Jul 1996 16:13:43 GMT
Paul Crowley (Paul@crowleyp.demon.co.uk) wrote:
: In article <4rbme2$28m@portal.gmu.edu>
: herwin@mason2.gmu.edu "HARRY R. ERWIN" writes:
: > : > The following null hypothesis is probably testable:
: > : >
: > : > "The lineage leading to H. sapiens experienced a phase extending over
: > : > three chronospecies during which it was adapted to aquatic foraging
: > : > behavior."
: Given the length of the phase you specify and your definition of
: "aquatic foraging" (finding food below the surface and having
: sensory systems adapted to working under water) you've not set
: yourself a hard task. What grounds do you have for ruling out
: intertidal foraging? Was there something preventing early
: (aquatic?) hominids from leaving the water? I have to say that
: your primary objective seems to be the setting up of a strawman.
1. I rule out intertidal foraging because that is usually associated with
shell middens. We find those going back perhaps 100,000 years in Africa
and 60,000 years in New Guinea, but no further. Besides, intertidal
foraging is an easy behavioral adaptation and could have been gained and
lost many times. Since it seems to take several million years to develop
the ability to drink saltwater, any intertidal foragers in the hominid
ancestry had to maintain terrestrial behavior.
2. Yes, I'm setting up a strawman ("null hypothesis") to gain an
understanding of how it can be falsified. That's what scientists do. It
can't be a weak strawman, though, or it doesn't rule out the interesting
cases.
: In any case, you are engaged in a deeply fundamental exercise of
: self-deception. You have not got a working/alternative hypothesis.
: Or if you have you are not willing to subject it to the same sort
: of tests. Without one, a null hypothesis has no function.
You misunderstand. Read Popper. I do have a number of working hypotheses,
but I can't judge their validity until I've tested enough null hypotheses
to narrow things down quite a bit.
I've had to deal with this issue recently in preparing my dissertation
proposal.
: How about this (2):
: "The lineage leading to H. sapiens experienced a phase extending over
: three chronospecies during which it was adapted to woodland foraging
: behavior." ^^^^^^^^
This doesn't work as a 'null hypothesis.' It's not probably false.
: Or this (3):
: "The lineage leading to H. sapiens experienced a phase extending over
: three chronospecies during which it was adapted to littoral foraging
: behavior." ^^^^^^^
This is hard to falsify. Hence it is not a good 'null hypothesis.'
: Or this (4):
: "The lineage leading to H. sapiens experienced a phase extending over
: three chronospecies during which it was adapted to savanna foraging
: behavior." ^^^^^^^
The lineage leading to modern Homo sapiens has been adapted to savanna
foraging behavior for at least 1.85 MYr. The direct evidence is the
Nariokotome skeleton. There is indirect evidence of the use of fire to
maintain the the savannah ecosystem in East Africa extending back to about
3 MYr BP (Lee Talbot, 1995). Hence this is not a good 'null hypothesis'
except for the period prior to that.
: In each case you are back to the same old and unanswered (by you)
: problems: "What food did it eat?" "What nocturnal refuge did
: it find?" "How did the mother/infant dyad avoid and escape
: predators while foraging during the day?".
It's easier and more scientific to answer the following questions:
1. What food did it not eat?
2. What nocturnal refuges did it not use?
3. What tactics did it not use to avoid predators while foraging?
: Tests? How about putting groups of h.s.s. in environments which
: model as closely as possible those proposed. Make sure that are
: populated with appropriate species: say, leopards, chimps and
: gorillas -- all habituated to man so that the instinctive fear of
: modern h.s.s. is counteracted. The men and women should go around
: naked and have *no* technology (except for dire emergencies) beyond
: that of early hominids:- clubs and the crudest of stone tools.
: Ideally they should have babies and small children; if this is not
: possible they must somehow emulate them, possibly with animals or
: with very attractive and noisy bundles of food. They would have to
: forage for food and find shelter as though they were early hominids
: carrying their "babies" and caring for their "small children".
Ah, but we see a major adaptive shift in the hominid lineage with early H.
erectus. The developing consensus is that shift coincides with the
permanent occupation of the savannah biome. And one change we see at that
point is a reduction of skeletal features associated with climbing.
: The winning scenario would be that with the best "survival" ratio.
: Where would you place your bets - on the woodland, littoral or
: savanna groups?
Prior to H. erectus: woodland.
Australopithecus, Ardipithecus, 'Sivapithecus,' Dryopithecus, etc., are
all associated with the forest and closed woodland biomes. Why we get
bipedal locomotion in the woodland biome is then the interesting
scientific question.
1. It's not to adapt to the savannah or other relatively open biome. Even
when we have lots of bipeds early on, we don't see them moving into open
biomes. They stay in treed biomes.
2. It's not because it's mandatory to move between trees. Pan trog. and
Gorilla (almost) never bridge. Pan paniscus bridges but not to any great
(quantitatively measured) extent.
3. It's not because the hands are occupied with tool-using.
Either the early hominids were bipedal on the ground because they were
preadapted for it in the trees, or bipedal locomotion was selectively
advantageous over quadrupedal locomotion in their detailed niche.
The following is a working hypothesis. The most obvious way bipedalism is
advantageous (given the quantitative studies on locomotor efficiency) is
sensory. You can see further in environments where you have to move on the
ground if your eyes are far off the ground. That means you can move
further away from a tree on the ground and safely get back. That means you
have a selective advantage over knuckle-walkers in the _forested_-savannah
biome. Knuckle-walkers can live there, and you can live in the forest
biome, but the rule of relative advantage applies, and both species can
survive.
By the way, complex ecosystems (the ones that survive as an ecosystem for
long periods) are characterized by multiple ecological vicars. More than
one species in the system can make use of a resource. That implies the
hominid ancestor had such vicars prior to the invasion of the littoral.
When it did invade the littoral, it would have been accompanied by some of
its vicars. What happened to them?
--
Harry Erwin, Internet: herwin@gmu.edu, Web Page: http://osf1.gmu.edu/~herwin
49 year old PhD student in computational neuroscience ("how bats do it" 8)
and lecturer for CS 211 (data structures and advanced C++)
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