Evolutionary Medicine Flashcards
Tinbergen’s 4 questions
they are used to examine traits, diseases, & behaviors
1. How it works (causation)? (proximate)
2. How does the phenomenon develop (development)? (proximate)
3. How did the phenomenon evolve (evolution)? - Ultimate
4. What is the adaptive function? – ultimate
proximate cause
Mechanism: How does it work? - sickle cell is caused by mutation of hemoglobin
Ontogeny: How does it develop? - RBCs sickle when exposed to deoxygenated blood causing blood clots and hemolysis
Treatment based: after symptoms appear you treat it logically
ultimate cause
Phylogeny: Why did the phenomenon evolve ?- balancing selection so hetero sickle cell carrier protects against malaria
Adaptive value: What is the adaptive function? – sickle cell hosts aren’t suitable for malaria virus (plasmodium falciparum)
Historically medicine uses……
Reductionist approach: at individual levels (cells, genes, tissues, organs), medical history, environment, symptoms
- they treat symptoms through immediate pathways (proximate)
Medical Histories
- medical history of patient
- developmental history (childhood to elderly)
- medical history of relatives
- evolutionary history
- human bio & cultural evolution
- demographic, cultural, ethnic history
- coevolution with diseases
Holistic Medicine approach
used in current day
uses history, genetics, ancestry, evolutionary medicine
evolutionary medicine
examines disease and humans through the ultimate cause lens
why are diseases still prevalent?
- Many pathways are involved in the evolutionary underpinnings of one disease
- Its not survival of the fittest or healthiest but survival of the best reproducer so genes are only concerned with pre and during reproduction period, but post doesn’t matter
- Ex: a certain gene associated with Alzheimer’s may help with cognitive development in kids
7 Fundamental Principles of Evolutionary Medicine
- Natural selection doesn’t enhance health/longevity because it is only concerned with passing on our genes
- Phenotype is a product of genes and environment
- So there are many factors that affect health like toxicity and infection which aren’t genetic - Individual History affects susceptibility to disease
- Not exposed to grass as kid leads to it being seen as an attacker as adult so get allergies - Current and past conditions of our species don’t align
- We evolved exposed to many pathogens but now we don’t because of our man-made environment and things like hand sanitizer - Environment and culture don’t match with the slow rate of evolution or our biology
- Individual variation is based on different contexts/environments
- Some traits better for some environments but now there is tons of migration across the world so you may not live where your ancestors evolved from - No purpose/goal of evolution
- Traits based on environment
8 Pathways affecting Disease Risk (could be one or many for a single disease)
- Evolutionary mismatch
- Obesity and energy storage - Life history associated factors
- Menopause causes drop in estrogen which increases risk for osteoporosis because lifespan is longer now - Excessive and uncontrolled defense mechanisms or immune responses
- Autoimmune diseases, sepsis which is an excessive response to infection - Coevolution with microbes
- HIV, TB - Evolutionary constraints
- Plantar fasciitis is caused by Bipedalism - Balancing selection maintains harmful allele
- Sickle cell - Sexual competition
- Testosterone is linked to decreased immunocompetence, but it doesn’t matter because they have already reproduced
- BRC1 increases likelihood for breast/cervical cancer but you ovulate twice a month - Cladal and demographic histories
- diabetes is prevalent in nonwestern people
- Tay-Sachs in Ashkenazi Jews protects from TB
- People from the Andy’s live at high elevation so they developed increased RBC density to help them breath but this can lead to heart disease and clot problems
