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evolutionary biology

Photo of the female penis structure of the cave insect Neotrogla aurora.
Abstractions blog

Why Evolution Reversed These Insects’ Sex Organs

Among these cave insects, the females evolved to have penises — twice. The reasons challenge common assumptions about sex.

Abstractions blog

Complex Animals Led to More Oxygen, Says Maverick Theory

For decades, researchers have commonly assumed that higher oxygen levels led to the sudden diversification of animal life 540 million years ago. But one iconoclast argues the opposite: that new animal behaviors raised oxygen levels and remade the environment.