Hand-drawn illustration of two of the seven sampled molars from AustralopithecusDom Jack, MPICThe ape-like human ancestor Australopithecusperhaps best known from the iconic fossil Lucymight not have had much meat on its menu. After examining more than 3.3-million-year-old remains from seven specimens in South Africa, scientists suggest these Australopithecusindividuals were mostly vegetarian.The new work, detailed in a study published last week in the journal Science, sheds light on prehistoric diets using the nitrogen ratios in fossilized teeth.This method opens up exciting possibilities for understanding human evolution, and it has the potential to answer crucial questions, for example, when did our ancestors begin to incorporate meat in their diet? says co-author Alfredo Martnez-Garca, an environmental scientist at the Max Planck Institute for Chemistry, in a statement. And was the onset of meat consumption linked to an increase in brain volume?Scientists suspect that the transition to eating meat allowed our ancestors brains to grow and, consequently, develop the crucial ability to produce and use tools. Exactly when and how that transition happened, however, is still unclear. Lead researcher Tina Ldecke stands beside "Little Foot," anAustralopithecusskeleton thought to be the most complete pre-human skeleton ever found. The specimen was uncovered in the Sterkfontein caves, South Africa, where the studied teeth were also recovered. Bernhard Zipfel / Wits UniversityMeat likely played a significant role in the expansion of cranial capacitylarger brain developmentduring human evolution. Animal resources provide a highly concentrated source of calories and are rich in essential nutrients, minerals and vitamins that are critical for fueling a large brain, study lead author Tina Ldecke, a geochemist at the Max Planck Institute for Chemistry and the University of the Witwatersrand in South Africa, tells Reuters Will Dunham.Ldecke and her colleagues recent work, however, suggests the transition to meat-eating did not happen during the lifetimes of the seven studied Australopithecus individuals, which spanned between 3.3 million and 3.7 million years ago. This conclusion comes despite some evidence that associates some Australopithecus specimens with stone tools.These are still fairly ape-like, small-brained hominins, that already walked upright but had a more ape-like walk, Ldecke tells NPRs Nell Greenfieldboyce. Here, for the first time, we have actual numbers to put on there to say, Ok, not much meat was consumed for these small-brained hominins.The team analyzed nitrogen isotopesforms of nitrogen with different numbers of neutronsin the fossilized tooth enamel from the Australopithecus remains. Because food digestion in animals ultimately expels light nitrogen (14N) from the body, it increases the bodys ratio of heavy nitrogen (15N) to 14N, in comparison to its food. In other words, the higher up the food chain an animal is, the higher its 15N to 14N ratio, according to the statement.Scientists have previously analyzed nitrogen isotope ratios in younger organic remains such as hair, claws and bones, to study human and animal diets. But for the recent research, the team developed a new method to apply this technique to tooth remains that are millions of years old.Tooth enamel is the hardest tissue of the mammalian body and can preserve the isotopic fingerprint of an animals diet for millions of years, Ldecke explains in the statement. The Sterkfontein excavation site, where theAustralopithecusfossils were discovered Dominic StratfordThe researchers then compared the 15N to 14N ratio in the Australopithecus remains to fossilized tooth samples from animals that lived around the same time, including both ancient herbivores and carnivores. Though variable, the Australopithecus ratios were more similar to those of herbivores, ultimately suggesting that these human ancestors depended mostly on a vegetarian diet.This finding, however, doesnt exclude the possibility that Australopithecus feasted on termites, which contain less 15N than large mammal meat does. We see that apes nowadays [fish for termites], so why not our ancestors? says Ldecke to Science News Jake Buehler.Ultimately, the study suggests Australopithecus had not yet started to enjoy a meaty diet at the time. However, the novel method Ldeckes team developed could now be used to track down those human ancestors that did.It means that one can look at other hominins, and try and do the same kind of measurements, and try to get a sense of what they were consuming during life, Bernard Wood, a paleoanthropologist at the George Washington University who was not involved in the study, says to NPR. Moving forward, the researchers plan to continue investigating the origin of meat-eating in our ancestors and whether it triggered an evolutionary benefit.Get the latest stories in your inbox every weekday.Filed Under: Africa, Brain, Chemistry, Evolution, Fossils, Human Evolution, New Research, Paleontology, Primates, Teeth