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, 8 April 2015

Distance running may be an evolutionary ‘signal’ for desirable male genes

In my chapter on the perils of bipedalism - called The Downside of Upright - I deal with theories developed by Harvard professor of evolution Dan Lieberman, and assorted colleagues, which posit that the ability for endurance running first evolved with Homo erectus, in the African savanna, some 2 million years ago. Lieberman points out that while these human ancestors were actually poor sprinters (in fact even Usain Bolt today could be outrun by a rabbit), they would have been able to literally run prey animals to death in the stifling heat, because they could dissipate heat through sweating whereas prey species could not pant and deep breathe at the same time - quickly exhausting them to the point where a bang over the head from a rustic club would have been more than enough to finish them off.

Now a group of scientists from the University of Cambridge have explored a possible link between exposure to testosterone in the womb, prowess at endurance running, and attractiveness to females. Such prowess "may have been used by females as a reliable signal of high male genetic quality during our hunter-gatherer past, as good runners are more likely to have other traits of good hunters and providers, such as intelligence and generosity." they say. One of the study's authors, Danny Longman, expands: “The observation that endurance running ability is connected to reproductive potential in men suggests that women in our hunter-gatherer past were able to observe running as a signal for a good breeding partner. It was thought that a better hunter would have got more meat, and had a healthier – and larger – family as a consequence of providing more meat for his family. But hunter-gatherers may have used egalitarian systems with equal meat distribution as we see in remaining tribes today. In which case more meat is not a factor, but the ability to get meat would signal underlying traits of athletic endurance, as well as intelligence – to track and outwit prey – and generosity – to contribute to tribal society. All traits you want passed on to your children.”

A copy of the full paper can be downloaded from the following DropBox link:
The whole paper which is available from the open access journal PLoS 1.

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