Re: Sabretooths

Op 25-12-2007 16:37, in artikel fkr83b$i59$1@xxxxxxxxxxxxxx, Mario
Petrinovich <mario.petrinovic1@xxxxxxxxxxx> schreef:

On sabretoooths being semi-aq.:

Then their stocky built (not very good for catlike life) implied
to me that they might be aquatic.

And short tails?

I forgot about that.

Heavy weight also often correlates with tail reduction.

Then the fact that they could survive injuries that normal cat
wouldn't survive without living in pack. In aquatic situation they could
survive it living solitary.

Why IYO?

I simply got such an impression. You can move in water even if
injured. Injured people feel best when in water. Scientiests concluded that
those cats couldn't survive on land if not in pack. Cats are solitary.
Lions live in pack, but only because they live in environment which supports
such kind of living. There is a REASON why they are living in pack.

Yes, their nearest relatives are solitary, so I guess their cooperation is
recent.

Scientists concluded that sabres lived in pack based on the (false
perspective) look onto evidence. But, there isn't a logic behind it. You
cannot interprete evidence without using logic. PA thinking sometimes is so
simple. "Sabres survived injured, hence they lived in pack", this is the
simplest possible thinking,

Those people reason like that, Mario: they don't look further than their
noses.

and, more important, nobody in PA world cares if
it is contrary to the logic, as long as this thinking has the most direct
path (ie. "the most direct is the most scientifical; things that aren't
direct are just speculations"). In PA world logic isn't science, so nobody
cares to waste its time on logical thinking. They have job to do, you know,
and not time for "speculations". -- Mario Petrinovich

Yes, sad.

.... The original ?open plain¹ ideas were obviously hypothetical, but soon
the general impression of human ancestors coming out of the trees and
colonizing the vast plains became set in the minds of most anthropologists,
and different ideas ­ some more improbable than others ­ were put forward to
explain how savannah-dwelling ancestors might have found enough food and
water to survive on the open plains ­ as if the hypothesis had already been
proven. Human characteristics were discussed in an evolutionary setting
that involved a movement from the forests to the open plains, and reasons
for these characteristics always tended to revolve around the ?open plain¹
theme (see Table 2). Even the most far-fetched of these ideas (for example,
honey collection, liver consumption, or food collection at noon on open
plains) have been seriously considered and published in scientific journals.
Such ad hoc explanations are comparable to the hypothetical ?land bridges¹
between Africa and South-America that were popular in geology before the
theory of Plate Tectonics became accepted.
What is striking about these hypotheses is their combined diversity. Some
rely on hunting large game, others on small game, some on scavenging bone
marrow, or brains, or livers, or collecting seeds, or tubers, or honey.
Some of these ?open plain¹ models are more typical of slow-moving animals
(feeding on belowground resources), others of fast-moving mammals (³bouts of
strenuous activity²), and others rely on endurance (following migrating
ungulates, or the dogged pursuit of prey). This diversity of theoretical
models suggests that the ?open plain¹ scenarios are not the result of usual
biological thinking. In evolutionary biology, hypotheses are not just
?possible scenarios¹, but normally the result of solid analyses of
relationships between form and function. Biologists usually do not propose
a scenario to explain the evolution of an animal without a careful
comparison of different features of this animal with similar features
(convergences) of other, not closely related species.

Table 2. Diverse savannah hypotheses of human origins.

Raymond Dart 1960
Osteodonto-keratic Culture ­ Savannah hunting

Robert Ardrey 1961
Man the Mighty Hunter ­ African Genesis ­ Adult men hunting large game

Mikhail Nesturkh 1967
Herd instinct as our ancestors moved to more open territory

Desmond Morris 1967
Mighty Hunter ­ The Naked Ape ­ Fur loss for easier sweating

Clifford Jolly 1970
The Seed Eaters ­ Savannah baboon model

John Napier 1971
Open grassy spaces = ?arenas¹ for practicing new locomotor skills

Hatley & Kappelman 1980
Belowground food resources

Walker, Zimmerman & Leakey 1982
High dietary intake of carnivore livers ­ Scavenger model

Hanna & Brown 1983
Bouts of strenous activity for hunting or digging outside the forest

Peter Wheeler 1984
Savannah foraging at noon, to minimise solar radiation

David Carrier 1984
Dogged pursuit of swifter animals over 1 or 2 days

Sinclair, Leakey & Norton-Griffiths 1986
Bipedal trekking after herds of migrating ungulates

Mark Skinner 1991
Savannah bee brood consumption ­ Tall grass savannah & tropical forest

Richard Wrangham et al.1999
Cooking and bringing food to a processing area

Bramble & Lieberman 2004
Endurance Running over vaste plains

Dennell & Roebroeks 2005
Ability to ingest large amounts of meat ­ ?Savannahstan¹

Richard Wrangham 2005
Delta hypothesis ­ Okavango-like savannah ­ Omnivory


Whereas modern biology sees evolution as a sequence of overlapping niches
(Kemp 2007), the proposed ?open plain¹ lifestyles of these early human
ancestors are discontinuous and have little or no overlap. Frequently they
are incompatible with each other. Moreover, they suppose that humans
collected foods without the typical adaptations that other mammals use when
they collect the same foods. We have no large digging-claws, for example,
we are slow runners (only some 36 km/hr over short, and some 20 km/hr over
long distances), and we are very prone to dehydration by depletion of water
and salts. We are heavily-built creatures with extensive fat tissues and
(in archaic Homo) heavy bones, features that are not seen in cursorial
species. Our cheekteeth lack the seed-grinding adaptations of baboons, while
the human gastro-intestinal tract and digestive anatomy and physiology
resemble frugi-omnivores such as suids, not carnivorous mammals (Stevens
1990). This contradiction has been labelled the ?baboon paradox¹, because
we would expect humans to be more similar to baboons if we evolved on the
savannah as they apparently did (Bender 1999).

The collection of waterside food resources, on the other hand, is compatible
with the presumed lifestyle of early apes, and fits with modern human
food-gathering strategies. Shifting from a fruit-based diet to a diet
including more waterside foods such as coconuts and shellfish does not
require significant behavioural modification. The use of tools to open
hard-shelled nuts and fruits is easily transferable so that the meat of
certain molluscs can also be procured (capuchin monkeys use tools to open
fruit, nuts and shellfish), and shellfish, like fruits and nuts, are sessile
food resources that need only be found and gathered, not chased or hunted.
From such fruit, shellfish, plant and egg-gathering it is not difficult to
envisage the incorporation of waterside catching of insects, frogs, fish or
birds, and the butchering of turtles, crabs, whale or bovid carcasses found
at the water¹s edge. We do not claim to know exactly how this waterside
lifestyle evolved, but we are confident that the limited diving skills of
humans came about as a result of increased time spent foraging under water.
As to how frequently our ancestors may have dived or waded or collected
fruit from trees or foods along the shore at low tide, or how long our
ancestors¹ waterside phase or phases may have lasted, these are all
questions requiring further investigation.

Questioning the Savannah Model

Although the savannah model still dominates anthropological thinking, many
leading palaeoanthropologists no longer follow it automatically (Table 3).
No other than professor Phillip Tobias, Dart¹s mental heir, already an
emeritus himself, recently stated that ³? All the former savannah supporters
(including myself) must now swallow our earlier words in the light of the
new results from the early hominid deposits ... Of course, if savannah is
eliminated as a primary cause, or selective advantage of bipedalism, then we
are back to square one. ?² (Tobias 1995, 1998).
This questioning of the savannah model (Table 3) resulted from two lines of
evidence: firstly, palaeoecological studies showed that the earliest bipedal
hominids were associated not with open plains, but with wooded or forested
environments (e.g., Tobias 1998); and secondly, anatomical studies showed
that australopithecines and early Homo species such as habilis had good
climbing abilities (e.g., Collard and Wood 1999) (some of which persisted
into Homo georgicus and possibly even Homo floresiensis, see Lordkipanidze
et al. 2007, and Tocheri et al. 2007). Rather than abandon the savannah
theory, however, the chronology of events has been rearranged, with Homo
erectus now seen as the first true savannah hominid, descending from earlier
australopithecine and habilis-like species that are now seen as adapted to
mosaic habitats including both forests and open plains (see Langdon 1997).


--Marc

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Relevant Pages

  • Re: Savanna fantasies
    ... different ideas ­ some more improbable than others ­ were put forward to ... explain how savannah-dwelling ancestors might have found enough food and ... collection, liver consumption, or food collection at noon on open plains) ... Diverse savannah hypotheses of human origins. ...
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    ... different ideas ­ some more improbable than others ­ were put forward to ... honey collection, liver consumption, or food collection at noon on open ... What is striking about these hypotheses is their combined diversity. ... Diverse savannah hypotheses of human origins. ...
    (sci.anthropology.paleo)
  • Savanna fantasies
    ... general impression of human ancestors coming out of the trees and colonizing ... different ideas ­ some more improbable than others ­ were put forward to ... collection, liver consumption, or food collection at noon on open plains) ... Diverse savannah hypotheses of human origins. ...
    (sci.anthropology.paleo)
  • Re: Savanna fantasies
    ... general impression of human ancestors coming out of the trees and colonizing ... different ideas ­ some more improbable than others ­ were put forward to ... collection, liver consumption, or food collection at noon on open plains) ... Diverse savannah hypotheses of human origins. ...
    (sci.anthropology.paleo)
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    ... Bones, stones & shells are much more abundant at the ... "Brain-specific lipids from marine, lacustrine, or terrestrial food ... Diverse savannah hypotheses of human origins. ... David Carrier 1984 Dogged pursuit of swifter animals over 1 or 2 days ...
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