When bone mineralizes, blood vessels exchange nutrients with surrounding tissue. Metabolites — small molecules from diet, disease, and environment — become trapped in microscopic niches where vessels once ran. The assumption in paleontology was that these molecules degrade over geological time. Fossilized bone preserves structure: morphology, isotope ratios, crystal lattice. Not chemistry.
Timothy Bromage and colleagues at NYU tested this assumption by applying mass spectrometry to fossilized animal bones from Tanzania, Malawi, and South Africa, dated between 1.3 and 3 million years old. They found thousands of preserved metabolites — many closely matching those in living species. A ground squirrel bone from Olduvai Gorge, 1.8 million years old, showed chemical markers for Trypanosoma brucei, the parasite that causes sleeping sickness. Other fossils revealed dietary compounds, estrogen-related metabolites indicating sex, and plant molecules suggesting aloe and asparagus species in the ancient environment. Control tests on modern mouse bone confirmed that nearly half of dietary metabolites appear in bone tissue, and the fossil metabolites were separable from soil contamination — bones preserve individual histories while soils blend collective signals.
The finding introduced palaeometabolomics. But the method — mass spectrometry — has existed for decades. The fossils were excavated years ago and sat in museum collections. What prevented the test was the assumption that organic chemistry doesn't survive fossilization. The assumption was load-bearing: it determined what questions were worth asking, which determined what instruments were pointed at which specimens, which determined what was found. An assumption that prevents the experiment that would refute it is self-protecting — not through circular evidence but through circular absence. The test that would have disproved the assumption fifty years ago was never run because the assumption made it seem pointless.