Re: Australopithecus afarensis vs. chimps

From: Marc Verhaegen (fa204466_at_skynet.be)
Date: 07/30/04 

Date: Fri, 30 Jul 2004 21:08:07 +0200

"Andrew Nowicki" <andrew@nospam.com> wrote in message
news:410A49F9.2D3B1017@nospam.com...

>>> its (Australopithecus afarensis) hands were very weak and its legs were
very powerful.

>> Ah??

> O.K. I exaggerated, but it is fair to say that it had relatively weak
hands and relatively strong legs. I looked at a painting of the
Australopithecus afarensis by John Gurche (http://www.gurche.com). It looks
almost like Arnold Schwarzenegger below the neck. Male chimps weigh about as
much as modern humans, but their hands are *much* stronger than human hands.

We can't trust these "reconstructions" (nearly always "humanised"), we need
hard facts.
- A.afarensis had curved phalanges for clmibing trees arms overhead, IOW,
very likely strong hands.
- Apiths had femoral head diameters as in apes, much smaller than Homo
(archaic & modern), IOW, probably weak legs.

>>> Both species could use sticks and stones as tools.

>> Chimps, yes. Apiths probably, but no direct information.

> The material from Turkwel includes several wrist bones (WT 22944), which
Carol Ward describes as very humanlike, specifically lacking any
knucklewalking adaptation. It seems natural that such a dexterous hand could
use sticks and stones.

KWing doesn't contradict tool use & manufacture, see chimps.

>>> The Australopithecus afarensis fossils were found in open habitats: dry
bushland, riparian woodland, and riverine forest habitats.

>> open? dry??

> KE Reed 1997 "Early hominid evolution and ecological change through the
African Plio-Pleistocene" J.Hum.Evol.32:289-322. ...claims well-watered,
wooded paleoenvironments, but a good review:

Yes.

> J.Anat. (2000) 196, pp. 19±60, "Human evolution: taxonomy and
paleobiology," by Bernard Wood and Brian G. Richmond claims the opposite on
page 30: "Paleohabitat. Paleoenvironmental reconstructions suggest that
A.afarensis inhabited a mosaic environment. Evidence from Hadar suggests a
mixture of dry bushland, riparian woodland, probably with seasonal
floodplains, and riverine forest habitats (Johanson et al. 1982; Reed & Eck,
1997). One reconstruction of Laetoli suggests open grassland, with
closed-woodland nearby (Harris, 1987), but others interpret the same
evidence as indicating a much more wooded environment (Andrews, 1989)."

First they say human ancestors became bipedal to run over the savanna (pure
nonsense of course), then they say Lucy was a human ancestors (probably also
nonsense), then they have to conclude Lucy's characteristics were for
running (nonsense: it had curved phalanges). Deep sigh. Poor poor savanna
believers...

> > - Stern & Susman: the small spms had curved phalanges as in apes: they
often climbed trees arms overhead.

> It does not surprise me. I believe that most of their food grew on trees.

1) climbing arms overhead: Monkeys' foods grow in trees, but they don't
climb arms overhead. The monkey that most climbs arms overhead is Nasalis. A
mangrove-dweller. Coincidence?
2) afarensis diet: Thick enamel suggests hard foods as in orangs. Microwear
suggests the diet included aquatic plants. Small anterior teeth suggests
plant diet. IOW, probably only part of their food grew on trees.

>> - Radosevich cs.1992: Hadar AL.333: "The bones were found in swale-like
features ... it is very likely that they died and partially rotted at or
very near this site ... this group of hominids was buried in streamside
gallery woodland."

> My time machine is out of order, so I cannot check it out, but the
"gallery woodland" looks like a reasonable compromise. I doubt that the
bipedal Australopithecus afarensis could compete with chimps in a dense
rainforest. They were more likely to live in a place that was marginal
habitat for the chimps.

1) Not all chimps live in dense rainforest.
2) The most likely habitat of afarensis were swamp forests, of course: these
were probably abundant in the hot & wet Pliocene, and this fits the diet
(wetland plants) & the locomotion (bipedal-suspensory). Where else?
3) Why should they compete with chimps?? There were no chimps at the time
AFAIK: chimps live today. The most chimp-like creature at the time (3 Ma)
was A.africanus, eg, Zihlman cs.1978: "P.paniscus provides a suitable
comparison for Australopithecus [Sts.5]; they are similar in body size,
postcranial dimensions and... even in cranial and facial features."
Ferguson 1989: "A.africanus Sts.5... falls well within the range of Pan
troglodytes, is markedly prognathous or hyperprognathous." Etc.

>>> ...The big question is why the Australopithecus afarensis survived

> > Ah? Where do you see their descendants? gorillas?

> Immediate descendants: Australopithecus africanus. Final descendants:
humans.

?? Where do you get this? It's pure nonsense.
1) How can africanus (3 Ma) descend from afarensis (3 Ma)??
2) Fossils normally leave no direct descendants. Fossils are sidebranches of
lineages leading to living hominids (Pt, Pp, Hs, Gg, Gb).
3) If anything, of all living hominids, afarensis-boisei were more like
gorillas, and africanus-robustus were more like chimps.
4) Homo is partly contemporaneous to apiths, so it does not descend from the
later apiths (nor from the early ones IMO).

>> - Ryan & Johanson 1989: "Incisal dental microwear in A.afarensis is most
similar to that observed in Gorilla." - Johanson & Edey 1981: The
composite skull reconstructed mostly from A.L.333 specimens "looked very
much like a small female gorilla." - Schoenemann 1989 :"A.afarensis is much
more similar cranially to the modern African apes than to modern humans." -
Ferguson 1987: the type spm A.afarensis: "the lower third premolar of LH-4
is completely apelike." - Kimbel cs.1984: "assertion that the lateral
inflation of the A.L.333-45 mastoids is greater than in any extant ape is
incorrect if the fossil is compared to P.troglodytes males or some Gorilla
mates and females. Moreover, the pattern of pneumatization in A.afarensis is
also found only in the extant apes among other hominoids." ... "Prior to the
identification of A.afarensis the asterionic notch was thought to
characterize only the apes among hominoids. Kimbel and Rak relate this
asterionic sutural figuration to the pattern of cranial cresting and
temporal bone pneumatization shared by A.afarensis and the extant apes."

> What is your point? Are you saying that at that same time (3MYA) another,
more advanced hominid lived in Africa and it became our ancestor?

1) Did *I* say anything?? Nothing but quotes AFAICS... :-)
2) I'm saying that IMO apiths have not much to do with human evolution.
Apiths are fossil=primitive hominids. IMO humans do descend from more
apith-like ancestors, but not from one of the apith spp we know. Apiths have
none of the typical Homo features (very long legs, very large brain,
external nose, masticatory reduction).
3) Why in Africa? Not impossible in Africa, but the so-called baboon-marker
suggests human ancestors were not in Africa at that time.
4) IMO, most apiths are closer to one of the Afr.apes than to humans, see
http://allserv.rug.ac.be/~mvaneech/Fil/Verhaegen_Human_Evolution.html .
5) My impression now (not proven at all): Gorilla & Homo-Pan split c 7 Ma.
Since G & P evolved partly in parallel, this suggests allopatry. Homo & Pan
split c 5 Ma (could well have been isopatrically, since Homo took a very
different path). A.afarensis-boisei (E.Africa) evolved in parallel to
africanus-robustus (S.Africa): from more closed (afar//afri c 3 Ma) to more
open wetlands (boi//rob c 2 Ma). The E.Afr.apiths look more like Gorilla
than like Homo-Pan. The S.Africans look more like Homo-Pan than like
Gorilla. IOW, Gorilla could have lived in the central Afr.forests, whereas
Homo-Pan could have lived in the coastal forests along the Indian Ocean (cf.
Kingdon "Lowly origin"). Pan colonised the inland part of these forests,
Homo the seaside part. With the Plio-Pleist.coolings, Homo colonised the
tree-poor coasts along the Ind.Ocean & Med.Sea, got longer legs to wade,
learnt to dive for shellfish (& voluntary breathing control, a preadaptation
to speech), lost his fur, got larger brains, extreme handiness & tool use to
open cocos & shells & to butcher turtles & stranded whales, got reduced
olfaction, reduced biting force (cf. seafood & tool use), lost
grasping=climbing big toes, got full plantigrady etc.etc. This scenario fits
all facts AFAIK. No? :-)

Marc Verhaegen
http://www.onelist.com/community/AAT
http://allserv.rug.ac.be/~mvaneech/Verhaegen.html

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