BODY BY DARWIN

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.

ABSENT FRIENDS
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.
A FINE ROMANCE
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.
THE DOWNSIDE OF UPRIGHT
What is the relationship between the fact that we have evolved to walk upright - our bipedalism - and a range of orthopedic illnesses?
DIY EYE
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.
HOPEFUL MONSTERS
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.
A PROBLEM WITH THE PLUMBING
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?
THREE SCORE YEARS - AND THEN?
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?

READ ON DOWN TO ENTER MY BLOG WHICH IS BASED ON THE BOOK AND EVOLUTIONARY MEDICINE IN GENERAL. COMMENTS AND RESPONSES STRONGLY INVITED!

Thursday, 19 March 2015

Polyploidy can drive rapid adaptation in yeast


http://links.ealert.nature.com/ctt?kn=9&ms=NDgyNTU3NjkS1&r=MjA1NzU0NTkxMQS2&b=2&j=NjQyMjc3NTA3S0&mt=1&rt=0


For those of you who can access NATURE online here is a rather important paper. As the authors point out, although polyploidy - usually chromosome doubling - is rampant in nature there is too little known about whether or not it confers fitness on organisms. They conclude that it does. It is important because cancer cells behave very much like the yeast cells studied here, and other microorganisms and there is growing evidence that the genetic mayhem changes in ploidy can release can throw up new mutations - in this case to increase the malignancy of cancer cells in the body.

Polyploidy can drive rapid adaptation in yeast


Nature
 
519,
 
349–352
 
 
doi:10.1038/nature14187
Received
 
Accepted
 
Published online
 
Polyploidy is observed across the tree of life, yet its influence on evolution remains incompletely understood1234. Polyploidy, usually whole-genome duplication, is proposed to alter the rate of evolutionary adaptation. This could occur through complex effects on the frequency or fitness of beneficial mutations2567. For example, in diverse cell types and organisms, immediately after a whole-genome duplication, newly formed polyploids missegregate chromosomes and undergo genetic instability8910111213. The instability following whole-genome duplications is thought to provide adaptive mutations in microorganisms1314 and can promote tumorigenesis in mammalian cells1115. Polyploidy may also affect adaptation independently of beneficial mutations through ploidy-specific changes in cell physiology16. Here we perform in vitro evolution experiments to test directly whether polyploidy can accelerate evolutionary adaptation. Compared with haploids and diploids, tetraploids undergo significantly faster adaptation. Mathematical modelling suggests that rapid adaptation of tetraploids is driven by higher rates of beneficial mutations with stronger fitness effects, which is supported by whole-genome sequencing and phenotypic analyses of evolved clones. Chromosome aneuploidy, concerted chromosome loss, and point mutations all provide large fitness gains. We identify several mutations whose beneficial effects are manifest specifically in the tetraploid strains. Together, these results provide direct quantitative evidence that in some environments polyploidy can accelerate evolutionary adaptation.http://links.ealert.nature.com/ctt?kn=9&ms=NDgyNTU3NjkS1&r=MjA1NzU0NTkxMQS2&b=2&j=NjQyMjc3NTA3S0&mt=1&rt=0

No comments:

Post a Comment