Washington: A team of scientists has found the first direct evidence in the fossil record that Homo erectus ate a more diverse diet than its relative Homo habilis.
Ungar, University of Arkansas graduate student Kristin L. Krueger and colleagues at Rutgers University and Berkeley made the discovery.
“This is the very first evidence from the fossils themselves of a broadened subsistence base in our family tree. Homo erectus seems to be where it started,” Ungar said.
The researchers examined the dental microwear of teeth from several specimens of Homo habilis found at Olduvai Gorge between 1995 and 2007 excavated by a team from Rutgers University led by Robert J. Blumenschine.
The specimens collected for this species and for Paranthropus boisei brought the sample sizes in line with those of other hominins. Sample size matters because small numbers mean less confidence that the results represent the variation within a species.
“By adding 5 new Homo habilis specimens we now have 10 for Homo habilis and 8 for Homo erectus and we can actually separate them out in terms of the dental microwear,” Ungar said.
The researchers used a technique developed by Ungar and his colleagues that combines engineering software, scale-sensitive fractal analysis and a scanning confocal microscope to create a reproducible texture analysis for teeth.
“If we compare Homo erectus to Homo habilis, we see a marked increase in variation in the former,” Ungar stated.
The H. habilis fossil teeth show lots of light scratches but little pitting, indicating that it ate plant material. The variation in the H. erectus teeth suggests that this species probably ate a broader range of foods.
“This represents a change to a more human-like diet. It indicates a broader resource base. The evidence suggests that Homo erectus represents a new phase in human evolution,” Ungar added.
The findings have been reported in the Journal of Human Evolution.