Title: Darwinian
1Darwinian
Medicine
- An Evolutionary Explanation
- for Modern Disease
Clint Morehead
2Darwinian Medicine
- In 1980, evolutionary biologist Paul Ewald
proposed an evolutionary approach to the study of
medicine - He suggested that we consider evolution in the
treatment of infectious diseases
Paul Ewald
3Darwinian Medicine
- It has not been until very recently that the use
of evolutionary theories to treat disease has
been acknowledged.
Why?
- Lack of General Education
4Darwinian Medicine
Branches
- Anti-viral and anti-bacterial resistance
- Real-time evolution
- Why we even suffer from disease at all
- Millions of years of hominid evolution
5Evolutionary Explanation for Disease
Question Why hasnt the Darwinian process of
natural selection eliminated the genes that make
us susceptible to diseases?
6Evolutionary Explanation for Disease
To answer this question, we must understand
hominid evolution.
7Evolutionary Explanation for Disease
- Homo sapiens and their predecessors evolved
for millions of years as hunter-gatherers
- 10,000 years ago, they adopted agriculture
- Mismatch between design and environment
8Evolutionary Explanation for Disease
Hunter-Gatherers
- Studies of modern and ancient bands
- Fished for salmon and other fishes
- Hunted wild game
- Gathered fruits and berries
- Exercised while hunting and searching for
shelter - Provided nearly all essential nutrients and
protein
9Evolutionary Explanation for Disease
Shift to Agriculture (a novel environment)
- Paleopathological studies of Dickson Indian
mounds show that when they adopted agriculture - 50 increase in enamel defects (malnutrition)
- Risked crop failure/starvation
- 4X increase in iron deficiency
- 3X increase in bone lesions (infectuous
diseases) - Life expectancy dropped from 26 to 19 years
10Evolutionary Explanation for Disease
Atherosclerosis and Cancer
11Atherosclerosis
- Second leading preventable killer among
Americans (behind smoking) - MetS obesity, type-II diabetes, high
cholesterol, high blood pressure
12Atherosclerosis
Evolutionary Perspective
- Diet
- We have evolved to crave sweets and fats (today,
these products are in abundance) - We eat more starches and lack essential
nutrients - Meat comes from livestock rather than game
13Atherosclerosis
Evolutionary Perspective
- Thrifty genes
- Because food supply was never consistent
- To regulate intake and utilization of fuel
sources - Efficient storage
- Today, people who exhibit this phenotype are
those who become obese
14Cancer
- Not a novel disease
- The genome has defenses against damage (p53
gene) - Has spread for 2 main reasons
- Our ability to survive long after reproductive
period - Our tendency to interfere with our bodys biology
(smoking, sunshine, sex, diet, physical
inactivity) - High levels of oxidative stress and accumulation
of mutations over ones lifetime
15Cancer
Statistics
- 80 of all cancers occur at a post-reproductive
age - 25 of men over 70 have prostate cancer
- Average risk of a 25-30 year-old dying of cancer
is 50X less than a 65-70 year-old
16Recap and Conclusion
- Many modern diseases can be understood better
from an evolutionary perspective
- Mismatch between our design and our environment
- Knowing this could lead to more insightful
treatments and measures of prevention
17References
- American Heart Association. Metabolic Syndrome.
http//www.americanheart.org/ presenter.jhtml?iden
tifier4756. A description and statistics
regarding the metabolic syndrome. - Diamond, Jared. The Worst Mistake in the History
of the Human Race. Discover Magazine. May 1987.
pp. 64-66. - Greaves, Mel. Cancer The Evolutionary Legacy.
Oxford Oxford University Press, 2000. - Haffner S.M., Lehto S., Ronnemaa T., Pyorala K.,
Laakso M. (1998). Mortality from coronary heart
disease in subjects with type 2 diabetes and in
nondiabetic subjects with and without prior
myocardial infarction. N Engl J Med. 23
339(4)229-34 - Kagawa Y, Yanagisawa Y, Hasegawa K, Suzuki H,
Yasuda K, Kudo H, Abe M, Matsuda S, Ishikawa Y,
Tsuchiya N, Sato A, Umetsu K, Kagawa Y. (2002)
Single nucleotide polymorphisms of thrifty genes
for energy metabolism evolutionary origins and
prospects for intervention to prevent
obesity-related diseases. Biochem Biophys Res
Commun. Jul 12295(2)207-22. - Onelife. http//www.onelife.com/evolve/index.html.
A discussion of human evolution. - Nesse, Randolf N. and George C. Williams. Why We
Get Sick The New Science of Darwinian Medicine.
New York Vintage, 1994.