Evolution and Human Health – Chapter 14 - Flu virus evolution - Antibiotic resistance - Cancer as set of evolving population - Adaptative reasoning and humans

- Pathogens and dietary/lifestyle choices cause disease - Immune systems of hosts select for resistant pathogens - Humans further select for resistant pathogens via drug development and use - Physiological traits and behaviors can be understood by considering evolutionary concepts and evolutionary history Key Concepts

Antigenic sites: Sites that the host immune system recognizes to form a memory and design antibodies.

Viruses from the freezer: Hemagglutinin evolution

Flu strains with novel antigenic sites enjoy a selective advantage Evolutionary history of influenza A is surprisingly linear!

Phylogeny of Influenza viruses based on nucleoprotein DNA sequences Nucleoprotein enables a virus to infect a particular host and therefore is most likely to ‘capture’ the history of particular strains. However, some strains within clades have alleles at other loci (hemagglutinin or neuraminidase) that were obtained from unrelated strains. Flu strains trade genes

Prior to 1968 Flu Epidemic There was no human strain With H3…..where did it come from?

Cross-Species Transmissions (tree based on nucleoprotein) Bird to Pig

The source of the 1918 pandemic flu remains unknown. Reid et al., 2004

Humans further select for resistant pathogens via drug development Bacterial Resistance To Antibiotics Time Societal change in antibiotic use Based on Austin et al., 1999

The cost of resistance can be overcome by selection. Schrag et al., 1997

Evolutionary History of Cancer Shibata et al., 1996 Colorectal adenocarcinoma from 43 yr patient

Adenoma samples are older and show higher levels of genetic diversity

What is the Evolutionary Significance of Fever? Fever represents a condition that is induced by a pathogen for the benefit of the pathogen. Higher temperature of host would increase reproduction/growth of the pathogen. Fever represents a condition that is induced by a pathogen for the benefit of the host. Higher temperature of host would allow the immune response to be more effective.

Behavioral fever Increases survival of iguanids after Injection of Aeromonas What happens if you prescribe aspirin?

Should Patient’s Allow Fevers to Run their Course? - Fever may be adaptive against some but not all pathogens. - Fever may carry significant costs in some cases, but low costs in other cases

Evolution and Parenthood: Parents Invest in Ways to Increase Their Fitness

Flinn and England, 1997 Stress, cortisol levels, illness, and reproductive success

Stepchildren vs Genetic Offspring

Stepparents kill stepchildren at a higher rate than biological parents kill biological children Daly and Wilson, 1988a,b