Science notes recap - 12.11.2025 - Thursday

 December 11th - Thursday - Science - 

Scott Forbes

Vaccines, Pathogens, and Evolution

     Vaccines have saved millions of lives by allowing our immune system to mount a defense against a pathogen before we ever encounter it. When Charles Darwin voyaged in the HMS Beagle in the middle of the nineteenth century he not only started us down the road of understanding evolution, but his book “The Origin of Species (by means of Natural Selection)” - published in 1859 - remains the most important publication in biology.

     The first true vaccines appeared in, about, 1800, when a doctor injected a child with the Cow Pox virus and then exposed the same child to a Small Pox virus. People had observed that those who had suffered with Cow Pox rarely got the much deadlier Small Pox. I used a silly example, in class, of a picture of the actor Brad Pitt from the movie “Troy” where he played the, nearly, invincible warrior Achilles.  In one scene you can clearly see the actor’s Small Pox vaccination scar. Myself, and my siblings, were born at a time when children were still vaccinated against Small Pox. We stopped vaccinating against it in 1972 and it was declared eradicated! 

     Pathogens like bacteria and viruses have a tremendous advantage when it comes to getting around our defenses. Both bacteria and viruses can reproduce very quickly and thanks to evolution there are, occasional, mutations when they reproduce. As mutations drive evolution a virus or bacteria may acquire a survival advantage through a small mutation and be able to infect a person when the same strain of pathogen could not infect a person as easily before the change. Keeping up with the mutations - changes - in pathogens is an ongoing challenge.

     Darwin observed variation in Finch Beaks in the Galapagos Islands and realized that variation among the species made it possible for the species, as a whole, to survive when the food source varied between insects and seeds. While evolution doesn’t change an individual over its lifetime, variation through mutation helps ensure both survival of bird species or variety in pathogens.

     Studying vaccination also is a vehicle for understanding good science processes and how unfounded ideas, those based on wild conjecture - like the idea that vaccines cause Autism - can take hold in society. Though it has been shown through rigorous study that vaccine are both safe and effective for preventing disease and there is absolutely no link with vaccinations and Autism, the idea persists.