Transcript Evolutionary Analysis 4/e

Evolution and
Human Health
I.
Motivation
Evolutionary principles can contribute to understanding
of origin and treatment of human disease
Evolutionary perspective can supply the WHY of disease
to complement the HOW of disease
II. Influenza A virus
Hemagglutinin
The five antigenic sites, regions
recognized by the immune
system, are highlighted with
colors.
A phylogenetic analysis of frozen flu samples
Neutral evolution??
(deleterious muations eliminated)
(neutral fixed)
A phylogenetic analysis of
frozen flu samples (1968-1987)
From Fitch et al. (1991).
Drift vs. Selection
331 nucleotide substitutions
58% silent
42% replacement
18 codons in hemagglutinin gene
majority were replacement
Amino Acid Replacements
In antigenic sites In nonantigenic sites
Surviving lineages
(into 1980’s)
33
10
Extinct lineages
31
35
Predicting which lineages of flu will survive
to cause future epidemics
Next flu strain: one with the most mutations in the 18 codons
Batting average: 9 of 11 = 0.818
Origin of the Pandemic Flue strains
A phylogeny of flu viruses, based
on the nucleoprotein genes
A phylogeny of flu virus hemagglutinin genes:
The 1968 human flu appears to have acquired its
hemagglutinin gene from a bird flu strain
Branches from the nucleoprotein phylogeny revealing
cross-species transmissions
Human flu can infect pigs
Bird flu can infect pigs
Pig flu can infect people.
Evolutionary analysis of the
nucleoprotein gene from the 1918 flu
Founder of clade??
III. Antibiotic resistance
An assessment of the costs of antibiotic resistance to bacteria,
over the short term and over the long term
Conclusions: Be very careful with use of antibiotics
IV. Virulence
Virulence??
1. Coincidental
2. Short-sighted
3. Trade-off
A trade-off between the virulence and transmission to new hosts
The virulence of vectorborne
versus directly transmitted diseases
The virulence of intestinal bacteria, as a function of
tendency toward waterborne transmission
V. Fever as an adaptation to the host or to the pathogendetermining the proper treatment
Live Bacteria
Fraction surviving
over time (infected)
Does the antifever medicine acetaminophen
have any effect on the course of chickenpox?
Do antifever medicines have any effect on the course
of the common cold?
Do antifever medicines have any effect on the course
of the common cold? Antibodies
VI. Parental care, step children and stress (the princess and the evil
stepFATHER):
Darwinian Psychoanalysis
Stress, cortisol levels, illness,
and reproductive success
for stepchildren versus
genetic children in Dominica
Biological children have higher reproductive success
during early adulthood (ages 18-28 for women, 20-30 for men)
than do stepchildren
Homicides in Canada
Summary
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Flu
Antibiotic resistance
Virulence
Fever
Parental care, stress and illness, &
reproductive success
Monocytes