快猫短视频

Bryn Nelson (Hachette)

ASK me to name the world鈥檚 best invention, and I will always give the same answer: the toilet. Its ability to whisk waste away to a safe place where potential pathogens and odours can do no harm isn鈥檛 to be sniffed at. But an unusual book has convinced me that toilets make it too easy to waste our waste.

Bryn Nelson鈥檚 Flush: The remarkable science of an unlikely treasure explains the many ways in which a precious natural resource, faeces, can be put to good use. Along the way, Nelson studs the important stuff with delightful facts. For starters, did you know that the average adult defecates about the weight of a pineapple every week? Well, you do now.

Anyone who has followed the recent success of faecal transplants to treat conditions such as irritable bowel syndrome or Clostridium difficile infections will know about their power to heal. But I didn鈥檛 realise that the first known faecal transplant took place in China in the 4th century AD.

Modern medicine was hesitant to embrace these transplants, partly because the idea can trigger disgust. Nelson tells of people seeking the treatment who faced stigma, oddly stronger from doctors providing the treatment than in patients.

In fact, the fight against revulsion is key, says Nelson. At first, I thought he was pushing that argument too much, until I realised how much it was needed 鈥� people have died waiting for faecal transplants to be approved. We have manufactured this disgust in some ways: studies show it is worse in places with widespread modern plumbing and ceramic toilets.

Nelson鈥檚 tone is fairly light as he asks us to confront a taboo subject, but he can go overboard with details of his solid emissions, including their texture, buoyancy and more. Elsewhere, a section on the microbiome 鈥� microbial cells that play a crucial role in health 鈥� gets wearing as he covers the tests he subjected himself to. As a former microbiologist, he may be more interested in the minutiae than I am.

Press on, though, and you find that shifting views on human faeces are revealing their power to explain the past. One anthropologist described how, as an undergraduate in the 1960s, he and his colleagues thought fossilised human waste was so unimportant they used it as a frisbee to see how far they could throw. These days, scientists pore through ancient latrines and human waste to reconstruct the diets and diseases of our ancestors. Some findings give us a sense of how the human microbiome has evolved, but others are just plain interesting.

Take what Nelson calls the 鈥渉oly shit鈥� of Danish bishop Jens Bircherod, found in a latrine from the late 17th century, which revealed the bishop鈥檚 taste for local blackcurrants and peppercorns imported from India.

Then there are other modern uses of sewage, such as monitoring disease and drug detection 鈥� as explored in 鈥淪ecrets in the sewers鈥� (快猫短视频, 20 August, p 42) 鈥� or using faecal matter to replenish soil nutrients. And human biogas, natural gas made from sewage, is being used to power sewage treatment plants.

Nelson has great historic tales of the use of excrement. In 12th century China, for example, catapults launched a mixture of gunpowder, dried human faeces and poison in ceramic containers, which was said to release toxic smoke on impact.

Reading each chapter, I found myself anticipating such tales, which remind us that whatever else we are, humans have always been resourceful 鈥� at least with our faeces.