The truth about testicles: are we facing spermageddon?

When it comes to fertility, testosterone and reproductive fitness, manosphere misinformation is rife - which can lead to a lot of heartache. Meet the man who wants to change all that “I think you can tell it’s for a lay audience,” says Michael Carroll, holding up his book, Your Nuts, its cover illustrated with two walnuts in a string bag. The book has arrived in tandem with worldwide concerns about falling birth rates.

“Spermaggedon” is a chunky piece of this puzzle, part of a wider debate about whether and why we’re heading for species-icide. Are people deciding not to have kids because of climate anxiety and economic precarity? Or is this an unchosen fertility cliff edge, created by forever chemicals and our lifestyles? This is not a drill, says Carroll, a biologist and reproductive scientist at Manchester Metropolitan University. “There’s compelling evidence to support a historical decline in…