Re: AAT is dogma
alex duncan (aduncan@mail.utexas.edu)
12 Aug 1995 19:39:55 GMT
Subject: Re: AAT is dogma
From: alex duncan, aduncan@mail.utexas.edu
Date: 10 Aug 1995 20:59:23 GMT
In article <95222.113649NDR102@psuvm.psu.edu> Nicholas Rosen,
ndr102@psuvm.psu.edu writes:
>The Danakil/aquatic hypothesis seems potentially vulnerable to a
>black eye or two, if not to absolute falsification. Suppose that a
>human ancestor postdating the alleged aquatic interlude were shown
>to be as hairy as a chimpanzee. Suppose that skeletons of australo-
>pithecus ramidus or something very similar were found elsewhere than
>at Danakil, and definitively dated to the the time when Danakil was
>an island. These would go along way toward falsifying the Danakil/
>aquatic hypothesis.
Well, we've got problems then. A. afarensis is known from as old as ~4.0
Myr from Fejej in Ethiopia. (Note: A. ramidus may well not be as old as
White et al. claim. There are capping volcanics dated to about 3.8 Myr,
and basal volcanics dated to around 4.4 Myr. White et al. use a single
normally magnetized paleomag. sample to suggest A. ramidus comes from the
older end of the time range, but there is also a normal zone around 3.8
Myr. A. ramidus may then be either around 3.8 Myr old, or 4.4 Myr old.)
The hominid mandible fragments from Tabarin (4.25 - 5.15 Myr) and
Lothagam (around 5 Myr) will have to be reevaluated in light of the new
discoveries. Until recently they've been placed in A. aff. afarensis,
but only because that was the closest thing available.
As exploration continues in older sediments, I expect we will see more
wide spread hominid discoveries in the period from 4 - 5 Myr ago. If the
fossil record has taught us anything about hominid evolution, its that
multiple temporally overlapping hominid species are the norm rather than
the exception.
>On the other hand, if australopithecine fossils were found in the
>Danakil Alps, and dated to the interval when the region was an island,
>and no other fossils dating to that period were found elsewhere, the
>hypothesis would be strengthened, although not absolutely proven. In
>short, the Danakil/aquatic hypothesis seems at least as open to
>testing as its rivals, and I think it deserves investigation. I am
>aware that hair doesn't usually leave fossil traces, but something
>might happen, as it did in the case of the Iceman.
I fail to see exactly how this would work. Australopithecines are
clearly adapted to living in a terrestrial/arboreal environment. They
show no skeletal features that one can cite as evidence of living in an
aquatic environment. If they are found on a paleoisland, then that must
mean they were living ON the paleoisland.
By refusing to make any predictions about what an "aquatic" hominid would
look like that differ from what we predict based on the
arboreal/terrestrial model, Ms. Morgan has provided an unfalsifiable
hypothesis.
Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086
512-471-4206
aduncan@mail.utexas.edu
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