|An undergraduate reflecting back on what they learned in introductory human origins and evolution.|
Perpetual chance change is the only way evolution makes sense to me. Without it, natural selection, none of it, makes sense to me. It seems to be true for my students as well. Check out these three examples.
1. “When I learned about evolution in high school, I may have known the biological mechanism (mutations) and natural selection, but I did not know about genetic drift and gene flow. Out of those two, I thought genetic drift was more surprising to learn about. I always thought evolution was driven by natural selection, “survival of the fittest.” While that may produce the most rapid change in organisms, evolution is always happening through genetic drift. Mutations are always occurring and if a mutation is passed down parent to offspring that does not impede the offspring from reproducing then that mutation will appear in the subsequent generations. The mutation does not have to have any inherit benefits, the organism just has to survive until successful reproduction. I liked the catchphrase of genetic drift “survival of that which does not suck too badly.””
2. “One new thing I learned this week was genetic drift. I believe genetic drift was briefly mentioned in my biology class, but I was very confused on what it was and how it played a role in evolution. I was interested to learn about genetic drift, because it opened up my eyes to realize that evolution didn't just occur because of "survival of the fittest" and geographic isolation. Evolution also occurred in part because of random chance. This concept makes total sense, and yet before learning about it, it had never crossed my mind. While Darwin was correct in his principles on the theory of evolution, it is important to remember that there is more to evolution (and more people who contributed to our knowledge of evolution) than just Darwin. APG 201 and learning about genetic drift helped me to realize that this week.”
3. "I was also fascinated to learn about genetic drift because I have always wondered if there is any accidental evolution of traits. It was really interesting to learn that traits can in fact disappear through evolution accidentally even if they weren't necessarily undesirable traits. Evolution is not always carrying forward only hand-picked traits. There are random, unintentional chances in alleles that still happen and contribute to evolution. This is pretty cool because I often find myself (when learning about evolution) wondering how the traits of a species were important to them and what role they had in the evolution of the species. For example, did an animal only evolve brown fur because they can hide better? According to genetic drift, the allele for white fur may have just been bred out unintentionally. I now know that sometimes a trait doesn't have an intentional role in helping the species at all, genetic drift may just have caused this trait randomly.”
In the USA, K-12 evolution education standards are missing GENETIC DRIFT as well as the word NEUTRAL.
I don't know how to understand life's perpetual change without those fundamentals.
If students know about meiosis (which *is* in the standards), then they know about genetic drift. It's just a matter of linking meiosis to evolution.
Genetic drift is a very simple concept and makes natural selection make a whole lot more sense!
I shout about this on Twitter and I get "just be happy anyone teaches evolution in K-12 at all" and "teachers don't know about drift" in response. But evolution without genetic drift is not evolution, and if teachers knew about drift, then they'd be more comfortable teaching evolution. I guarantee it!
Without drift, it's too easy to just replace God with natural selection. And that habit of narrating evolution by giving agency to natural selection is super-duper weird for non-believers let alone for believers! (This a no hatred of religion, faith, or creationism zone.)
Genetic drift paves the way for thinking about and then narrating evolution as the constant change that life/nature/biology is. Everyone gets that time is just constant change and they will get that nature/biology/life is too. They embody it themselves, being different from their parents.
Plus, continuing to teach evolution as only being natural selection (which is what the standards are doing), is also dangerous. That selection-obsessed mindset is tied to racism, sexism, essentialism... all the stuff that we have to remove from our species' shared origin story. Darwin only had selection (not drift, etc) to work with and look what his imagination did with evolution: racism, sexism, essentialism
If we want to get the science right which will also improve its cultural consequences, then we have to teach genetic drift to our kids when they are learning evolution.
Perpetual. Chance. Change. That's all it is.
But it's a big part of how we're going to remove the racism, sexism, etc from our species' shared origin story and finally write one that is worthy of all humankind. A story that we all deserve.
I do not know how to even begin to suggest, or lobby for, these changes to people with actual power over K-12 education standards. If you do, please consider pointing me in the right direction and I'd be so grateful: holly_dunsworth at uri.edu