So much for the homebody males of prehistory, then? Not so fast, says Copeland. The first set of complaints is, "simply applying a variety of statistical tests to our data, and pointing out, as we had already done in our original study, that determining male versus female from isolated hominin teeth is difficult," she says, by e-mail. Her team had already acknowledged that, she says.
As for the second critique by Balter and colleagues, "There is nothing in their data set as presented that contradicts ours," she says. "Since they didn't make any attempt to determine whether the hominin individuals that they measured were large and possibly male or small and possibly female, their data neither support nor refute our suggestion of female dispersal."
Just so you know disputes about what fossils can tell us aren't all that unusual among researchers: Consider the case of the 600-million-year-old "whoopee cushion" creature, Vernanimalcula guizhouena, reported in 2004 in the journal, Science. They were the oldest known "bilateralian" creatures in the fossil record, ones with a top and bottom, a front and a back.
Only the width of a human hair across, these flattened circle-shaped organisms (hence their nickname) possessed a mouth, throat and gut, researchers announced after its discovery in China. Researchers have tied it to the origins of eyes, bloodstreams, swimming and cancer.
Unfortunately, a team led by Stefan Bengtson of the Swedish Museum of Natural Historyreports in the current Evolution & Development journal that the Vernanimalcula guizhouena remains reported in the past are likely just mineral deposits, not fossil creatures. Bengtson and colleagues have been criticizing the original find, it turns out, since its discovery, making this an eight-year dispute.
So does that mean we have another eight years of arguing about Australopithecus molars ahead?
Maybe not, Copeland says. "The good news is that we have now established a method and the background data that can tell us whether or not individuals grew up in the same valley where they died." With technology improving, the team should be able to test more teeth, including ones still stuck in their owner's skull that are much easier to assign a gender. "We have the method, and we will soon have the tools, that will help us to determine once and for all whether human ancestors were indeed â??mama's boys'," she says.