You’ve got to feel sorry for the female seed beetle. Whenever she mates with a male, she has to contend with his spiked, nightmarish penis (remember this picture?). And despite the damage that it inflicts, one liaison just isn’t enough; female seed beetles typically mate with many males before they lay their eggs. Surely, she must benefit in some way?

The most likely idea is that she somehow ensures that her eggs are fertilised by sperm from males with the “best” genes – those that either make for particularly fit and healthy young, or that are a compatible match for the female’s own genes. Perhaps these sperm outrace their weaker peers, or maybe the female has a way of selectively