Excerpt from Immune by Catherine Carver, plus links to reviews, author biography & more

However I'd like to suggest this golden goo just has a seriously bad marketing department. Far from being filthy, earwax is an incredible cleaning product that helps solve the ear canal's major logistical challenge: being a cul-de-sac. This anatomical fact means the ear requires a system for escorting any dirt that makes its way into the canal back out the same way. It also means that when the cells that line the canal die, they too must be made to exit – if not they'd pile up, block the canal and leave us deaf. Earwax to the rescue! Earwax is secreted by tiny glands in the skin of the ear canal and includes a mix of cholesterol, triglyceride and another fatty chemical called squalene. This aural concoction of waxy fatty goodness is further enriched with microbe-killing substances like lactoferrin. Its goopy brilliance traps germs, dirt and dead cells and the whole lot is then carried out of the ear on an earwax conveyor belt. The movement is created by the migration of cells from the eardrum outwards and aided by movements of the jaw during chewing. Thus earwax can catch, kill and kick out the multitude of microbes that wheedle their way into our ears. It might not be pretty, but the next time you reach for a cotton bud or an ear candle remember your ear is busy cleaning itself!

Alas, while snot, skin, stomach acid, sobbing and earwax are all great defences, they're not perfect. Fort Knox allegedly has 30,000 soldiers, an array of armoured helicopters and even laser-triggered machine guns protecting its perimeter. Only a James Bond villain has ever even tried to rob it. Sadly the body isn't as secure as Fort Knox, and sometimes bacteria break through the mucus or survive the stomach acid bath, and sneak inside us. But as we'll see in the next chapter, that's where the real immunological fun starts.

Excerpted from Immune by Catherine Carver. Copyright © 2017 by Catherine Carver. Excerpted by permission of Bloomsbury USA. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.