examples of relevance of evolutionary principles to human health
• Pathogens evolve
• Traces of our evolutionary history affect our health
• Trade-offs between competing demands
• Symptoms may be defenses, not defects
• Pathogens evolve to resistance from drugs and vaccines. Natural selection tinkers with what is already
there. Symptoms of diseases have adaptive history in giving defense against diseases.
• New infectious diseases are emerging all the time. We may never close the book on infectious disease.
• High calorie foods are readily available, which is part of why our environment is different from our ancestors’.
Traits may have been historically favored (storing fat). So, obesity is reflecting a disease of civilization.
There is a mismatch between current environment and environment to which we are evolutionary adapted.
trends in incidence of infectious vs. autoimmune disorders with respect GDP
– genetic basis… wait, what??
– Barrow Inuit study, 1970
• 42% of 6-35 yr olds myopic
• 5% of 36-88 yr olds myopic
- Alleles pre-disposing people to myopia did not cause myopia in ancestral visual environment
Auto immune diseases are another example of diseases of civilization. Looking at different
diseases, there has been a decrease over the years due to drugs that combat these things and
improved sanitation etc. So, infectious diseases on decline, while auto immune disorders are
increasing. Auto immune disorders – body’s immune system is over reactive (asthma, allergies
Comparing poorer countries to richer countries: the auto immune disorders are more of a
problem in richer countries.
evolutionary basis of diseases of civilization
evolutionary basis of the "hygiene hypothesis"
We are adapted to dirtier environments:
We haven’t had time for human genome to adjust to new environment. Our environment’s are too clean: less
childhood exposure to bacteria and parasites. The increase in auto immune disorders is a consequence to
decreasing infectious diseases. Our immune systems are a lot more active now then they need to be. Our immune
systems are still very active because historically they were challenged a lot more.
You are less likely to have allergies if you…
• have older siblings (especially b