Re: Bipedalism in different substrates

From: Pauline M Ross (pmross_at_ross-software.co.uk)
Date: 07/22/04 

Date: Thu, 22 Jul 2004 12:49:05 +0100

On Thu, 22 Jul 2004 00:21:08 GMT, "Bob Keeter" <rkeeter@earthlink.net>
wrote:

>> [Pauline]They increase the overall size of the foot, which enables slow
>> fish-style motion (like fins). They don't help at all with frog-leg
>> kicks or crawl-style power kicks.
>
>Have you ever been scuba diving or snorkeling? Have you ever tried to do a
>"crawl-style" power kick with swim fins on? Honestly now!

Well, exactly. Frog-leg and power kicks are two forms of human
swimming motion which are not helped at all by flippers, in fact
flippers would be counter-productive. Neither would webbed feet be any
use.

>> [Pauline]Chimps, bonobos and gorillas all wade bipedally in the wild, that's
>> well documented. I'm sure Algis can give you the references if you
>> want. In shallow water, they also have the option of wading
>> quadrupedally.
>
>As with the swim fins, you have made a pretty definitive statement in that
>first sentence. So. . . I will just ask that you show me the evidence for
>it or state that its an opinion.

I found the references in Algis's published paper on the subject;
here's what he said:

"Galdikas, Ellis and Sommer & Amman have all either commented about
orang-utans (Pongo) wading or have published photographs showing such
behaviours and Ashley Leiman of the Orangutan foundation made this
statement “Since 1986 I have visited Tanjung Puting National Park in
Indonesia, on numerous occasions. During this time I have frequently
seen orangutans wading bipedally in the swamp and river.”
Gorillas have also not traditionally been linked with water but Ellis
(1990:p57) provides anecdotal evidence in captive gorillas that they
can swim. Also Doran & McNeilage (1998:p121) and Parnell (2001:p294),
studying Western Lowland Gorillas in the field, provide evidence of
splash displays and feeding in the marshy swamps of Mbeli Bai. Parnell
(2000, personal communication) observed several bouts of bipedal
wading in these animals and wrote…[*].
Even chimpanzees, which have long been considered the most hydrophobic
of all the apes, turn out to be surprisingly fearless in water when
they are sufficiently driven by hunger to get their feet wet. Angus
(1971:p51) and Nishida’s (1980) both provide anecdotal evidence of
chimpanzee locomotion in water. In addition to this there has recently
emerged some significant photographic footage of chimpanzees wading
bipedally in fairly deep (chest high) water from a research student,
Jess Tombs, working at a chimpanzee sanctuary in the Conkouati reserve
lagoon (See Tutin et al. 2001).
Finally, in bonobos too (the least studied of the great apes) there
seems to be growing evidence that they are less fearful of water and
show a greater tendency to wade than their chimpanzee cousins.
Uehara (1976), de Waal (1996:p185), de Waal & Lanting (1999:p79-82)
all document anecdotal evidence of bonobos moving in water in the
wild."

[*] there seems to be a quote missing here.

You can look up the details of the primary references cited on his
website www.riverapes.com

> If you can infer environment by an indirect
>characteristic (such as hairlessness), why can I not infer diet from a
>direct characteristic like isotope concentrations? 8-) If my inference is
>faulty, where does that leave yours? 8-)

Of course you can infer diet from isotopic analyses. What the research
tells us is that hominids had (on average) a sizeable C4 component in
their diet (from 0 to 60%, mean 40%). The C4 component must have come
from grasses and sedges, or animals that fed on grasses and sedges, or
both. It is perfectly reasonable from that to infer that they ate some
meat, especially once you get past 2.5 Mya when the stone tools
confirm that.

What you *can't* do is infer that they ate mostly or entirely meat.
Just because they show the same C3/C4 ratio as hyenas does *not* mean
that they had the same diet as hyenas. The C3 component comes from
fruit, nuts and leaves, or animals that fed on these, or both. In the
case of hyenas, it is reasonable to presume that they got their C3
component from feeding on browsers and frugivores. In the case of
hominids, it is reasonable that the C3 component came mostly from
fruit, nuts and leaves, as it does in our closest cousins and most
other primates and (probably) the LCA.

>> >[Bob]8-) Did you read the article on the 2my old blood samples from the
>> >Sterkfontein stone tool? ;-)
>>
>>[Pauline] Yes, that will be terrific if it holds up. But we already knew that
>> stone tools (at 2.5 Mya) were used to butcher carcasses of
>> medium-sized animals, so that in itself isn't news.
>
>Oh, but I think that the idea of scraping wood, bone and horn might open up
>some very large cans of Lumbricus terrestris.

Well, I've always assumed that once they had stone cutting tools, they
were going to use them to cut (or shape) all sorts of things,
including wood and bone. It will be nice to get confirmation of that,
but I don't think it produces any radically new ideas. 

-- 
Pauline Ross
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