Researchers have detected preserved metabolic molecules in bones from 1.3 to 3 million years ago, shedding light on prehistoric animals' diets, health, and environments. The findings, from sites in Tanzania, Malawi, and South Africa, indicate warmer and wetter conditions than today. One fossil even shows traces of a parasite that still affects humans.
Scientists led by Timothy Bromage, a professor at NYU College of Dentistry, have pioneered a new method to analyze metabolites—molecules from digestion and other bodily processes—preserved in fossilized bones. These bones, dating from 1.3 million to 3 million years ago, come from animals in regions associated with early human activity, including Tanzania, Malawi, and South Africa. The team examined remains of rodents like mice, ground squirrels, and gerbils, as well as larger species such as antelopes, pigs, and elephants.
Using mass spectrometry, the researchers identified thousands of metabolites matching those in modern species. These clues reveal normal biology, like amino acid breakdown and vitamin processing, and even sex indicators through estrogen-related markers, suggesting some animals were female.
A notable discovery came from a ground squirrel bone in Tanzania's Olduvai Gorge, about 1.8 million years old. It contained a metabolite unique to Trypanosoma brucei, the parasite causing sleeping sickness, spread by tsetse flies. "What we discovered in the bone of the squirrel is a metabolite that is unique to the biology of that parasite, which releases the metabolite into the bloodstream of its host. We also saw the squirrel's metabolomic anti-inflammatory response, presumably due to the parasite," Bromage explained.
Dietary evidence pointed to plants like aloe and asparagus in the animals' environments. For the squirrel, aloe metabolites indicated specific conditions: warmer temperatures, higher rainfall, and suitable soil. Overall, the sites showed wetter, warmer landscapes than current ones, aligning with prior geological data—for instance, Olduvai's ancient freshwater woodlands and grasslands.
Bromage noted the potential: "Using metabolic analyses to study fossils may enable us to reconstruct the environment of the prehistoric world with a new level of detail, as though we were field ecologists in a natural environment today." The study, published in Nature, involved collaborators from NYU, France, Germany, Canada, and the US, supported by the Leakey Foundation and NIH.
This approach builds on collagen preservation in fossils and could enhance understanding of ancient ecosystems beyond DNA analysis.
