This is an interesting story about prions and how natural selection can act to select the more aggressive ones. I apologise for another geeky type science post but I thought I would share a few more examples of how evolution can help doctors understand a disease
I have an interest in cancer pathology and applying Darwinian evolution to cancer cells is a neat way of understanding it. It can explain why cancers can become resistant to chemotherapy. Say chemotherapy is used to kill 99% of cancer cells, the remainding 1% is resistant - it then exapands (pathologists use the term clonal expansion) giving a tumour that no longer responds to treatment.
The best known example of evolution in medicine is the selection of bacteria that are resistant to antibiotics. This is why GPs are constantly being told not to prescirbe antibiotics unless its necessary and why patients are told to make sure they finish the course - to minimse the chance of further resistance to anitbiotics developing. In one lecture we were shown a picture of rows of children suffering from TB; this was before antibiotics. Nothing really could be done for them. Hopefully we will design a bunch of brand spanking new antibiotics quickly so this situation does not arise again.
Huntingtons disease is a gentic disorder that laregly escapes natural selection, as the disease generally presents after a person has reproduced, this can explain why early-onset Huntingtons is very rare.
I love the theory of evolution, i think it is an elegant explanation of how life came about and how it became as diverse as it is today. Evolution underpins biology and biology underpins medicine. All the examples above make more sense when explained by the theory of evolution, which is why I think its important that medical students have at least an appreciation of its power