Paleontologists Are Trying to Understand Why the Fossil Record Is Mostly Males
Researchers from the University of Adelaide in Australia first identified this strange trend after analyzing ancient DNA in specimens in their own collection, according to Graham Gower, a genomic programmer and a coauthor of the study..........
After analyzing seven samples of ancient bison bone for another study, Gower noticed most were male. This puzzled him, so he asked a colleague if he could look at her samples. By the time he got up to 25 or 30, the bias was clear. “Seventy-five percent of them were male,” he says.
[This bias held up among other museum collections - such as the American Museum of Natural History in New York, the Natural History Museum in London, the Smithsonian Institution National Museum of Natural History in Washington, D.C., and the Royal Ontario Museum.]
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The researchers all toyed with another theory: Were collectors decades ago just more likely to seek out larger, more impressive fossil trophies, which would tend to show a preference for males? This kind of bias is clear in modern ornithological collections, where flamboyantly plumed male birds vastly outnumber their more modest female counterparts. According to Gower, sexual dimorphism—significant anatomical differences between male and female individuals of a single species—is apparent in the skulls of ancient beasts such as mammoths and bison, so it’s possible that male remains were more desirable finds. But analysis of the number of samples that display clear sexual dimorphism didn’t offer clear results.
While these biases certainly generate interesting theories about Pleistocene behavior (and modern human behavior), they create very real problems for science based on museum collections. These specimens are one of the largest sources of data for understanding the anatomy, variability, diet, range, and more of long-extinct animals. And if that’s the case, much of what we know about these creatures comes from a population that’s not reflective of reality. Accordingly, the paper suggests that, when possible, museum curators should choose specimens or seek more balanced collections to represent both sexes, as well as a range of localities, ages, and time periods.
Until then, it’s a lonely world for female mammoth, bison, and brown bear fossils.
https://www.atlasobscura.com/articles/fossil-record-prefers-males
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