NEAT science

There’s much that still puzzles scientists about Neanderthals, despite all the advances we’ve made in sequencing their genomes and reconstructing how they might have lived. One of those mysteries is the high level of an isotope called nitrogen-15 in their remains.

To understand the mystery, first you have to understand about isotopes. Isotopes are slightly different versions of the same element. To be nitrogen, an atom needs to contain seven protons, but it doesn’t matter how many neutrons it has. Nitrogen-14 (seven neutrons) is much more common than nitrogen-15 (eight neutrons). Plants, for example, are low in nitrogen-15, which tends to accumulate as you go up the food chain — so a mammal that eats a lot of plants has a small accumulation of nitrogen-15, and the animal that eats a lot of that small mammal over its lifetime accumulates even more nitrogen-15. In the end, an apex predator which…

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