The father of the science of evolutionary medicine, Randolph (Randy) Nesse, has a favorite aphorism: “Medicine without evolution is like engineering without physics.” In the same way that it would be impossible to imagine building the Rosetta spacecraft, sending it 300 million miles to rendezvous with Comet 67P, and successfully deploying the Philae lander, chock-full with sampling instruments, without physics and specifically Newtonian mechanics, it proves similarly impossible, for instance, to get to the root of the horrifying scourge of Alzheimer's disease unless we ask deep and fundamental questions, informed by evolution, about what the alleged poisonous plaques of beta-amyloid protein are doing in the brain in the first place. Is amyloid pure pathology or does it have an vital evolved function in the brain? In this sense, Nesse has frequently claimed that the value of evolution to medicine is that it while it may lead directly to changes in medical practice or indeed to new therapies, more fundamentally its value lies in explaining why things are as they are. That is why Nesse argues that evolutionary biology should be the foundation and cornerstone for medicine as it should be for all biology. This book is an attempt to put yet more flesh on the bones of Nesse’s idea that evolution is the “physics” of medicine. I describe the evolutionary background to seven areas of human disease that are causing deep contemporary medical concern to explain why they exist in the first place—why things are how they are - and how evolution might help us to combat them. I hope it will leave readers with a new respect for evolution as the prime mover for the structure and function of human bodies, even if it does, on occasions, cause them to break down and drives us into ER!

Each chapter is built around the sometimes harrowing but always inspiring personal stories of people trapped in the disease process in question. Each chapter provides an evolutionary explanation for why the disease has come about, and each chapter shows how medical researchers, using powerful insights gained from thinking about disease in an evolution-informed way, are charting our way out of it.

How a modern version of the hygiene hypothesis - called the "old friends" hypothesis - explains why the Western world is riddled with allergic and autoimmune diseases, and what we can do about it.
How evolutionary theory explains why the battle between the different selfish genetic interests of mothers, fathers, and fetuses causes low fertility and can lead to diseases of pregnancy like recurrent pregnancy loss, preeclampsia and gestational diabetes.
What is the relationship between the fact that we have evolved to walk upright - our bipedalism - and a range of orthopedic illnesses?
Creationists have always used the example of the "irreducible complexity" of the human eye as the bedrock of their argument that God designed the human body, not evolution. Modern developmental biology, however, not only strongly rebuts creationism but explains the astonishing secret of how the recipe for eyes actually unfolds from within the developing eye itself, not from external influences, and is leading to cures for eye diseases like retinitis pigmentosa and macular degeneration.
How does cancer evolve so remorselessly towards malignancy that it is proving almost impossible to cure? Cancer evolution can be so extreme and drastic it is forcing us to re-write the rules of evolution by resuscitating a heresy from the 1940s.
Why are coronary arteries evolution's answer to feeding our powerful, muscular hearts with the food and oxygen they need and how has this led to the continuing pandemic of coronary heart disease?
Research into curing Alzheimer's disease has become hopelessly bogged down and billions of dollars have been wasted trying to turn the "amyloid hypothesis" into therapy. Can we use evolutionary thought to better explain why dementia comes about in a way that might lead to fresh hope for a cure?


Wednesday, 24 June 2015

Why is my hangover so bad? It’s not just the booze giving you a hangover – it’s the microbes in your stomach

I've written a lot about our gut microbes - what scientists call our microbiota - and research built upon observations that a healthy gut microbiota seems protective of allergic and autoimmune diseases. it is also obvious that our gut microbes can "talk" to our brains and influence our behaviour (it's what Richard Dawkins termed the extended phenotype). This hilarious piece by Tim Spector, professor of genetic epidemiology at King’s College London, extends this line of thinking to the link between gut microbes, our reaction to over-indulgence in alcohol, and our needs for a drink. Spector starts the story: "Last year, a US study explored for the first time what binge drinking did to our microbes. Twenty-five healthy volunteers who were not regular drinkers were given a wine glass of vodka. There was a wide variety in response: those with the worst symptoms and changes in blood tests had the highest levels of toxins coming from the cell walls of their gut microbes. These toxins (called LPS) had somehow leaked out of their intestines, as a result of the inflammation the alcohol had produced. Within their guts the alcohol produced a brief, but large increase in the microbe species that were pro-inflammatory, stimulating the immune system as if it were under attack and contributing to the general sick-feeling so typical of hangovers." Then the bugs start talking: "So, drinking too much alcohol actually causes toxins to be released from our microbes, as well as growing more microbe-loving alcohol species. Studies have also shown that when mice are fed these toxins, they seek out more alcohol than normal mice, suggesting that the microbes, via their toxins, could actually be encouraging us to seek out even more alcohol and – worryingly – even lead to addiction." When bacteria-free mice were given booze they did not suffer from hangovers - the bugs that produce those symptoms were absent - and there were no signs of the liver damage alcohol breakdown products can cause. There was more good news! "Going back to their normal binge-drinking mice, the scientists tried feeding them a high-fibre diet (enriched with pectin found in apples) as well as alcohol shots, and compared this to a low-fibre diet. The high-fibre-fed mice amazingly had virtually no obvious side-effects from the alcohol on their livers. Similar preventive effects were seen on mice given probiotics containing beneficial microbes such as lactobacillus, found in cheese and yoghurt. Even saturated fat counteracted the harmful effects of the alcohol on microbes." Tim's conclusions? "Now when you wake up feeling unwell after a night out, you can blame your microbes as well as your pushy friends. But the microbes could also be part of the solution. If you are still keen on binge-drinking occasionally, at least start the evening with a slab of smelly cheese or a glass of high-fat natural yoghurt and let your microbes reduce some of the pain and suffering. Perhaps salt-and-microbe crisps could be the drinking partners of the future?"!!

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