"Rainbows within rainbows"

Gender-normative views across species unsupported by data, biologists argue

Blue-breasted fairywrens, Malurus pulcherrimus, female on left, male on right, Dryandra Woodland, Wheatbelt region, Western Australia (Photo by: Auscape/UIG via Getty Images)

Prevailing theories of evolution hold that, as a general rule, “males have evolved to be promiscuous and females have evolved to be choosy — they should only mate with the best male,” according to Zuleyma Tang-Martinez, a researcher at the University of Missouri — St Louis. But this understanding, heavily supported by theory and data across species, is now under attack by scientists such as Tang-Martinez who argue that biologists may have been applying this theory too broadly — in effect, projecting their own beliefs onto nature.

“You get this back-and-forth: science is reinforcing societal mores, and the mores are reinforcing what the science is saying,” explained Tang-Martinez. In a paper she published in April 2016, Tang-Martinez displayed evidence of females defying the normative rules of sexual selection theory — among birds, for instance, the seemingly monogamous fairy wren will see only five percent of its clutches fathered by a single male. Further evidence includes female lions capable of mating 100 times a day with various partners, and similar patterns of female promiscuity across many species of primates. “It is dangerous to come up with simple explanations for all species,” Tang-Martinez concludes.

Joan Roughgarden, a researcher at the Hawai’i Institute of Marine biology, agrees. Joan, who was formerly known as Jonathan, published Evolution’s Rainbow in 2004, a book that examined the multiplicity of expressions of sexual identity in nature. “The living world,” Roughgarden argued, “is made of rainbows within rainbows within rainbows.”

Read the full story at BBC News.

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