Monday, September 10, 2018

Mohamed A. F. Noor's "Live Long and Evolve"

Mohamed A. F. Noor, besides being a Trekkie, is a professor in the Biology Department at Duke University. He is the editor in chief of the journal Evolution and author of You’re Hired! Now What?: A Guide for New Science Faculty.

Noor applied the “Page 99 Test” to his new book, Live Long and Evolve: What Star Trek Can Teach Us about Evolution, Genetics, and Life on Other Worlds, and reported the following:
Although Live Long and Evolve uses Star Trek to engage readers, the purpose of the book is to teach fundamental concepts in genetics and evolution. Page 99 introduces the concept of "genetic drift".

The term "genetic drift" appears twice in Star Trek, but it is used inappropriately, both times referring to an individual. Instead, genetic drift is an evolutionary process that occurs in a population of individuals, just like the more familiar "natural selection". With natural selection, often called "survival of the fittest" in popular media, individuals bearing a particular trait or attribute are more likely to survive and pass on their genes to the next generation than individuals lacking this particular trait or attribute. For example, natural selection happens because an individual has keen eyesight for hunting, or a color that matches their tree's bark so they're not easily spotted by predators, or a particular tail ornament that's attractive to females. Because the best-surviving or reproducing individuals have that "fittest" trait, those individuals have more offspring, and more individuals in the next generation will inherit that trait.

Genetic drift also changes the abundance of variants (and their underlying genes) in natural populations, but the changes are random rather than directional. Genetic drift is similar to the concept of "sampling error"—if few samples are studied, then one can have a very different view of a population than was true in the original population. Imagine one wants to know the frequency of heads vs. tails in a coin flip. If you only flip a coin twice, you may decide that the coin "always" lands on heads. If you flip it 4 times, you may decide that the coin lands on heads 75% of the time. However, if you flip it 1000 times, you'll know that very close to 50% of flips result in heads.

The same sampling error happens in natural populations based on the number of individuals. If a population is very large, then the next generation (assuming it is also large) will have similar representation of whatever feature (e.g., red hair, and its underlying genes). However, if the population is very small, then big changes can happen each generation. Those changes resulting from small population size are "genetic drift", and that is the subject of page 99 of my book.
Learn more about Live Long and Evolve at the Princeton University Press website.

--Marshal Zeringue