Evolution is all about sex, baby, at least for us big hulking heterotrophs. When it comes to sex, sex organs play a central role in that evolution, regardless of what cultists invested in mythical invisible sky wizards would have you believe. And new research shows size does matter — it’s just that bigger doesn’t mean better:

(MSNBC) — Using data from scarab beetle populations separated by anywhere from 50 years to millions of years, research led by scientists at Indiana University reveals that both male and female genitalia evolve rapidly and in parallel with one another. But between newly evolving species, genitals diverged faster in shape than they did in size.

If a beetle’s wee-wee doesn’t fit in Mrs Beetle’s nu-nu, evolution pronounces a harsh sentence for life and beyond. Remember that the next time you’re staring in a mirror.