Don’t you hate it when someone drops over without warning? That’s how I feel about head lice, who have been constant visitors at our place for more than two decades.
Just ask my five kids, they’ve all been through it (the common factor – their mum being in charge of treatment).
But just why do head lice love human hair so much? The answer lies in a bit of history and science, it would appear. Let’s investigate.
What are head lice?
Head lice go by the official name of Pediculus humanus capitis, and are also known as ‘heirloom parasites’.
They are wingless, six-clawed, white-brown or red-brown insects that spend their entire lives on the human scalp feeding exclusively on human blood. Like vampires, really.
Head lice are extremely fertile and one female can lay up to 120 eggs in her lifetime (and I thought five kids was a handful).
They live for approximately five weeks, so they’re mighty productive during that short time. It’s also difficult to kill all the eggs, and it just takes one to kick off another infestation.
Nits, which are actually the eggs of head lice, hatch just six to 10 days after being laid, and so the infestation continues.
If you think about it, our heads are their version of planet earth. Why, just the other day I saw a kids’ play adapted from Tristan Bancks’ Nit Boy book built exactly on this premise. It was funny, poignant and had me itching five minutes in.
When did humans first get head lice?
Head lice are called heirlooms because, like family treasures themselves, we pass them on. They’re part of our shared human inheritance and they go back as far as the 5th century AD.
Yes, scientists found mummified head lice on an ancient Egyptian nit comb. It's proof that scratching heads and nit denial goes back to The Nile.
But lice were around way before that. They are thought to have separated from body lice, a similar but distinct species around 100,000 years ago. Probably around the same time people began wearing clothing. Clearly some lice evolved to hand onto smoother fibres of fabrics and materials and others decided to remain on the scalp.
Head lice have even been immortalised in poetry tapping into grand themes of equality, like the 1786 poem by Scottish poet Robert Burns, To A Louse, On Seeing One on a Lady's Bonnet at Church.