Re: Isotope Analysis

2 Jul 1996 13:03:24 GMT

Thomas Clarke ( wrote:
: Does anyone perform isotope analysis of hominid fossils?

: I recently read an article in _Nature_ discussing how
: O16/O18 ratios in whales teeth were being using to help
: resolve the issue of the point in whale evolution when the
: animals became independent of freshwater. It seems that
: freshwater and seawater have different O18 contents
: (I think due to differential evaporation rates, isotope
: ratios in ice cores have climatic implications).
: so that the teeth which are in isotopic equilibrium with body
: fluids can indicate when fresh water ingestion stopped in
: the fossil record.

: It seems to me that similar analysis might me useful in
: determining hominid diet shiftss. Other markers might
: be useful - fluorine?

There is work being done in this area. Note that one implication of the
whale data is that adaptation to salt water took quite a while. Hence the
AAH was primarily adapted to fresh or at most brackish water. Given the
number of examples of fresh water aquatic species that are only
behaviorally and not skeletally different from their terrestrial
relatives, a fresh-water AAH is not a good null hypothesis. On the other
hand, a fresh-water AAH only _behaviorally_ adapted to an aquatic
environment is not what the AAH folks envision.

Wild Ass Speculation: the behavioral features used as evidence for the AAH
were acquired during a sea-going phase of modern H. sapiens evolution
during a period about 40-80KYr ago in the area of Indonesia, New Guinea,
and Australia.


Harry Erwin, Internet:, Web Page:
49 year old PhD student in computational neuroscience ("how bats do it" 8)
and lecturer for CS 211 (data structures and advanced C++)