The majority of museum specimens, including ancient and modern mammals, are male, according to a historical survey published in the Proceedings of the National Academy of Sciences suggests.
Speak Atlantic‘s Rachel Gutmann, researchers led by the University of Copenhagen Graham Gower analyzed hundreds of bison and brown bear fossils collected in the field or borrowed from museums in Europe and North America. In the end, the team identified 74% of the bison and 64% of the bears as male.
In addition to assessing prehistoric species, Gower and his colleagues studied modern specimens held at the American Museum of Natural History in New York, the Smithsonian’s National Museum of Natural History, the Natural History Museum in London, and the Royal Ontario Museum. Of 19 mammalian orders represented, 17 were predominantly male; bats, an order constituting bats, and Pilosa, an order comprising anteaters and sloths, were the only groups in which females outnumbered males.
As reported by Hakim Bishara for Hyperallergic, scientists attribute this surprising sex bias to a range of factors, including the generally larger size of male mammals, herd distribution, sex-specific geographic ranges, individual animal behavior and human collection preferences.
To study bison specifically, the team relied on findings from a 2017 study Current biology to study. This paper, centered on an analysis of 95 sets of mammoth remains, found that 69% of the exhibited specimens were male – a trend explained not by unequal sex ratios at birth, but by the behavior of male mammoths.
Mammoths, like bison, traveled alone, in herds led by a single male, or in small groups of only males. (Those who could not establish their own herd often resorted to roaming with other potential herd leaders, according to Phys.org‘s Bob Yirka.) Separated from matriarchal herds, male mammoths and bison often engaged in risky activities with high mortality rates.
“They were more likely to do stupid things, like die in tar pits,” Gower said. Dark Atlasby Sabrina Imbler. Tar pits and similar death sites – from bogs to crevices and lakes – then inadvertently preserved animal remains for thousands of years.
The dominance of male specimens among brown bear fossils, meanwhile, may stem from the fact that these solitary creatures traversed larger tracts of land than their female counterparts. As Gutmann writes for Atlantic, “If you’re a paleontologist digging up a 12,000-year-old slice of rock, … you’d be more likely to come across a wandering male than a homebody female.”
Human collecting habits also contribute to biased museum sex ratios. According to Gutmann, hunters who donate animal specimens largely target males because they are larger, have showy features such as horns and manes, and, unlike mammal mothers, are not responsible for the good. – to be offspring.
Uneven representation among museum specimens could produce skewed search results. Hayley Lanier, an assistant curator of mammalogy at the Sam Noble Museum at the University of Oklahoma who was not involved in the study, recounts the Atlantic that “part of this bias speaks to a larger problem that we have also seen in medical science, which is that we tend to select one sex” as the main model of how living things function, thus ignoring the differences between the sexes in areas such as diet, size and behavior.
Lanier says, “I think these biases really leave us with an incomplete understanding of how the world works.
To remedy the imbalance described in the study, the authors suggest that museums continue to diversify their collections, adding specimens of different sexes, ages and geographical origins.
Talk with the Atlantic, Trina Roberts, a researcher at the Natural History Museum of Los Angeles County who also was not involved in the new research, concludes, “If what museums are trying to do is create a better, more complete record of biodiversity on Earth, and we know that there are biases like the one this document highlights, it is important that we continue to collect.