Citation:

"The carbon isotope ecology and diet of Australopithecus
africanus at Sterkfontein, South Africa"

Nikolaas J. van der Merwe, J. Francis Thackerayc,
Julia A. Lee-Thorp and Julie Luyt
Journal of Human Evolution
Volume 44, Issue 5 , May 2003, Pages 581-597

Abstract

The stable carbon isotope ratio of fossil tooth enamel
carbonate is determined by the photosynthetic systems of plants
at the base of the animal's foodweb. In subtropical Africa,
grasses and many sedges have C4 photosynthesis and transmit
their characteristically enriched 13C/12C ratios (more positive
delta-13C values) along the foodchain to consumers. We report
here a carbon isotope study of ten specimens of Australopithecus
africanus from Member 4, Sterkfontein (ca. 2.5 to 2.0 Ma),
compared with other fossil mammals from the same deposit. This
is the most extensive isotopic study of an early hominin species
that has been achieved so far. The results show that this hominin
was intensively engaged with the savanna foodweb and that the
dietary variation between individuals was more pronounced than
for any other early hominin or non-human primate species on record.
Suggestions that more than one species have been incuded in this
taxon are not supported by the isotopic evidence. We conclude
that Australopithecus africanus was highly opportunistic and
adaptable in its feeding habits.

And a brief extract from the paper's discussion section:

We can conclude that Australopithecus africanus at Sterkfontein
had a well established C4 dietary component, which may well have
included all of the available C4 food sources: grasses,
particularly seeds and rhizomes; C4 sedges (which have starchy
underground storage organs); invertebrates (including locusts
and termites); grazing mammals; and perhaps even insectivores
and carnivores. Whatever the sources were, different individuals
of this early hominin species differed widely in their consumption
of C4-based foods.

Tom Billings