The researchers caution that it's impossible to draw broad conclusions about Neandertal life histories from this one sample, such as whether Neandertals weaned their children earlier or later than modern humans who lived at the same time, or whether Neandertal children grew up faster, as some earlier studies have suggested—questions that could heavily bear on why Neandertals could not keep up with modern humans in the survival sweepstakes. But the new technique could eventually provide some answers, says co-author Tanya Smith, an anthropologist at Harvard University. "Now that we've established an accurate and precise approach, we hope to examine additional fossils to determine at what age Neandertals actually weaned their infants."
Anthropologist Shara Bailey, an expert in ancient human teeth at New York University in New York City, says that "the barium method is novel and appears to be even more powerful" than previous approaches, adding that despite small sample sizes, "the authors present a strong argument for the utility of this method for extrapolating weaning history." Julia Lee-Thorp, an archaeologist at the University of Oxford in the United Kingdom, agrees that the work with children and monkeys represents a "very solid validation" of the method, although she cautions that the amount of barium that children absorb through their guts and into their teeth could decrease as they get older and this could skew the results...."