Nehaveigur

The next time you’re in a room full of biologists and you want to start a shouting match, ask them about junk DNA. While everyone agrees on the importance of protein coding genes and the regulatory sequences that control their expression, there is little consensus if the majority of the genome that doesn’t encode proteins does much that’s useful to us.

Evolutionary theory, backed up by genetic sequencing data, suggests that most variation in the non-coding genome is under no selective constraint. A lot of it is made up by viruses and selfish genetic elements that have integrated into our genome over the millennia. Like hobos riding a freight train, they get a free ride, but while the hobos at least evoke nostalgia, those selfish genetic elements contribute nothing. While some of it is transcribed, this likely constitutes noise and doesn’t serve any particular function. If you want to know more about this, written by someone who has thought about it a lot more and writes in a wonderfully combative style, read Larry Moran’s blog.

If most of genetic variation is neutral, and if even slightly deleterious variation can persist and even become predominant in a population, could the same be the case for phenotypic traits too? Are the peaks of the fitness landscape actually table mountains?

Human societies differ in their customs along many dimensions, suggesting that only some of those customs are strongly advantageous or disadvantageous. This point has been made, among others, by Jared Diamond in The World Until Yesterday. Take infant care as an example: In some societies babies are separated from their mothers after birth and reared communally, while in others, mothers carry their babies around as long as physically possible. Neither approach is obviously better than the other. Just like it probably doesn’t matter very much which language a society speaks, a lot of its belief systems and customs don’t matter much to its survival either. This blog post elaborates on this and describes several seemingly maladaptive customs that have persistent for a long time.

All this suggests to me that I should try to be tolerant towards customs and traits that aren’t obviously detrimental. More often than not, there are multiple acceptable ways of doing things. Instead, I’ll focus my energies on fighting against that which is clearly deleterious.