Category Archives: Host Parasite Coevolution

Darwin’s place in medicine

Before human intervention the rules of disease were simpler. The competitors: pathogen vs. host. The rules: in order to win, the pathogen must ‘divide and conquer’, attacking the host’s defences and increasing in numbers; the host, on the other hand, must stay strong and defend hard in order to keep a united front, before finally striking back and wiping out the invaders. It was a game of risk, and the winner would ultimately find themselves stronger and better prepared for the next battle. This is because the hosts and pathogens necessarily need to coevolve – that is to adapt to each other simultaneously – in order to stay in the game. This concept was famously captured in a quote by the Red Queen in Lewis Carroll’s ‘Through the Looking-Glass’,

“Well, in our country,” said Alice, still panting a little, “you’d generally get to somewhere else — if you run very fast for a long time, as we’ve been doing.”

“A slow sort of country!” said the Queen. “Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!

However, since modern medicine came along, the dynamics of the game have become more complex; and it is only recently that evolutionary biology has been considered a potential weapon against disease – by trying to predict and manipulate the pathogen’s strategies, in order to stay one move ahead. The application of evolutionary theory to understanding health and disease is known as evolutionary or Darwinian medicine – and it is being used to try and find answers for all sorts of medical ailments, such as: autoimmune diseases, diabetes, anxiety disorders, antibiotic resistance, and cancers (to name just a few). As such, Darwin – the “medical school dropout” – turns out to be having a bigger impact on the world of medicine than he could ever have imagined.

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The Age of the Phage

Phage infecting bacterial cell

We are in the middle of a war that has been raging for several billion years, and its continuation is certain for as long as life exists on our planet. The number of bacteria on earth has been estimated at 4-6 x 1030 cells,equal to approximately 350 – 550 Pg of carbon (1Pg = 1015 grams). That’s a lot of carbon for a little thing. For a long time, bacteria were thought to be the most abundant and diverse organisms on the planet, but for every organism there is a parasite, and the bacteria’s mortal enemy is the phage (or the bacteriophage as it is also known). Phages are viruses of bacteria, and outnumber their hosts 10 to 1. Every day, these viruses kill half the bacteria living in the oceans, and they are infecting bacteria all over the world at a rate of 10 trillion times a second. But we didn’t even know they existed until the 20th century. Read the rest of this entry »


A Whole Host of Horrors

Article by Tiffany Taylor, posted  October 26, 2010 on Science Oxford Online (see original article here:

It’s Halloween: time to turn down the lights, and gather round for a horrific tale of what waits for you in the shadows… luring you into its lair… creatures capable of turning ordinary souls into monsters… and beasts that can control your mind to carry out their evil bidding. This is a true story of some unpleasant parasites that might just be coming, for you.

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The Curse of the Pharaoh… A Mummy with a Message?

Article by Tiffany Taylor, posted August 24, 2010 on Science Oxford Online (see original article here:

In Egypt there are stories of supernatural activities surrounding the tombs of ancient kings. It is said that the hieroglyphics etched into tomb walls frequently carry warnings of ‘Pharanoic hexes’ for those who may wish to steal from or disturb the resting king. So when a number of people present at the excavation of Tutankhamen’s tomb died under mysterious circumstances, was it down to black magic, bad luck or biological bugs?

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