Human adaptations Evolutionary medicine

1 human adaptations

1.1 constraints
1.2 trade-offs , conflicts
1.3 competition effects

human adaptations

adaptation works within constraints, makes compromises , trade-offs, , occurs in context of different forms of competition.

constraints

adaptations can occur if evolvable. adaptations prevent ill health therefore not possible.

dna cannot totally prevented undergoing somatic replication corruption; has meant cancer, caused somatic mutations, has not (so far) been eliminated natural selection.
humans cannot biosynthesize vitamin c, , risk scurvy, vitamin c deficiency disease, if dietary intake of vitamin insufficient.
retinal neurons , axon output have evolved inside layer of retinal pigment cells. creates constraint on evolution of visual system such optic nerve forced exit retina through point called optic disc. this, in turn, creates blind spot. more importantly, makes vision vulnerable increased pressure within eye (glaucoma) since cups , damages optic nerve @ point, resulting in impaired vision.

other constraints occur byproduct of adaptive innovations.

trade-offs , conflicts

one constraint upon selection different adaptations can conflict, requires compromise between them ensure optimal cost-benefit tradeoff.

running efficiency in women, , birth canal size
encephalization, , gut size
skin pigmentation protection uv, , skin synthesis of vitamin d
speech , use of descended larynx, , increased risk of choking

competition effects

different forms of competition exist , these can shape processes of genetic change.

mate choice , disease susceptibility
genomic conflict between mother , fetus results in pre-eclampsia




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