*from letter from Charles Darwin
To W. D. Fox 24 [October 1852]
Down Farnborough Kent
From Bitch: What does it mean to be female? (2022), by Lucy Cooke:
“In another of his private barnacle letters (this time to Charles Lyell in 1849) Darwin signs off by eulogizing, ‘Truly the schemes & wonders of Nature are illimitable.’
Truly they are. A century and a half later, state-of-the-art research using DNA markers has confirmed that Darwin was indeed right. Barnacles display a rich diversity of sexual systems – from hermaphrodite to separate sexes to a mixture of both – allowing scientists an exceptional opportunity to study evolution in motion.
Barnacles are masters of hedging their sexual bets. Their ability to adapt their sexual system according to the environment or social situation they land in produces a spectrum of procreative possibility in adulthood. Dwarf males, for example, may or may not develop ovaries depending on whether they land on or near a female. Classifying them as strictly male is therefore tricky. Instead many are considered an indistinct sex better described by modern science as ‘potential hermaphrodite’ that ’emphasizes male function’. In some cases the boundary between a hermaphrodite individual and a female, or dwarf male, is so blurred their sexual expression is considered more of a continuum than a distinct classification of sex.
The barnacle’s rapid evolution from one reproductive system to another reveals the surprising flexibility of sex and its expression in nature. Darwin clearly recognized this – he was way ahead of his time. Which is why it is a shame he chose to exclude his beloved barnacles from his musings on the manifestation of sex. They might have prevented him from presenting sex in such a dichotomous and deterministic fashion. Today barnacles, and creatures like them, are at the forefront of teaching us how sex is no static binary, but a fluid phenomenon, with fuzzy borders that can bend to evolution’s whim with astonishing speed.”
Julia Upton 