Genetic Evolution is More Complex Than You Think

Genetic Evolution Is More Complex Than You Think

A little while back I remember learning about something within genetic evolution that really surprised me. Genes that are immediately next to each other on a chromosome tend to stick together during cellular division. Physics is at play in the way that chromosomes line up and pull apart during cellular division and the separation of genes in both eggs and sperm. This can have a strange effect on how some genes get passed along. Imagine you have a gene that is crucial for survival, such as a gene that codes for whether lungs develop and a gene that is somewhat negative for survival, like a gene that makes your immune response a little less effective. If these two genes are immediately next to each other on a chromosome, then they will likely be passed along together, because it would be hard for them to be separated. If you don’t get the lung development gene, you also don’t get the weak immune system gene, but you don’t develop in the womb. If you get the lung development gene, you also get the weak immune system gene. The genes are passed along in the standard evolutionary process, but one gene seems actively harmful to survival.
I share this story because it demonstrates that genetic evolution is more complex than I had ever thought. I hadn’t considered the way that physics could influence which genes are passed along. Scientists could spend time trying to find exactly why a weak immune system gene is beneficial for survival and what competitive advantage that gene gave to a species for it to be favored by evolution. However, the real answer would just be that the gene was stuck next to a more important gene, so it kept getting passed along. An inadvertent deletion that would have inactivated the weak immune system gene may have also damaged the lung development gene, making it more likely that evolution would favor the two genes being passed along without errors together.
Looking at more complexity within genetic evolution, Yuval Noah Harari in his book Sapiens writes, “a microorganism belonging to one species can incorporate genetic codes from a completely different species into its cell and thereby gain new capabilities, such as resistance to antibiotics.” We think of evolution as a chain, with organisms and species slowly evolving as random typos provide advantages or disadvantages to a species. But this is too simple of a model as Harari’s quote shows. A microorganism can take in genetic information from outside, completely transforming that organism in a single generation.
Science also knows, however, that this kind of genetic adoption is not limited to microorganisms. There is evidence that sweet potatoes evolved when a virus infected a potato plant and inserted its DNA into the plant. The potato adopted DNA from a different organism and started down a new evolutionary path toward becoming the modern sweet potato. This sounds like a very niche and strange thing, but it is something humans are now exploring through CRISPR technology that may be able to cure many genetic disorders.
Genetic evolution is not a simple chain. It is much more complex than we think, and there is likely more we will discover that will demonstrate how complex the system truly is.
An Over-Hasty Food Chain Jump

Climbing the Food Chain Too Quickly

Evolution usually takes a very long time. Genetic and epigenetic factors tend to be the driving forces behind evolution, and changes to the genome or expressions of genes are usually quite slow. Over thousands to millions of years certain traits in species change, certain genes end up with errors that turn out to be beneficial for survival, and species slowly evolve. In most ecosystems across Earth’s history, predators, prey, and everything living have co-evolved in a slow but steady manner.
However, evolution does seem to have its shocks. This can be seen in theories of punctuated equilibrium, where things are stable with small changes occurring at relatively constant frequencies punctuated by periods of rapid and dramatic changes. Perhaps a volcano erupted and changed the landscape of an ecosystem. The genetic changes that were previously advantageous might not be advantageous now, and perhaps a whole new set of genetic mutations become advantageous. Or perhaps an invasive species has moved into the ecosystem and is upending a balance that evolution and natural selection had settled upon, reshaping the ecosystem and what traits are the most beneficial for the survival of all creatures.
In his book Sapiens, Yuval Noah Harari describes the quick ascension of humans as a force toward punctuation in the history of evolution on planet Earth. We are similar to a volcano or invasive species in terms of our destructive and disruptive power. For over a million years humans evolved slowly, positioned in the middle of the food chain, but  relatively rapidly, we rose to the top of the food chain and became the most dominate animal on the planet.
Harari writes, “Other animals at the top of the pyramid, such as lions and sharks, evolved into that position very gradually, over millions of years. This enabled the ecosystem to develop checks and balances that prevented lions and sharks from wreaking too much havoc.” Most apex predators evolved over a long period of time alongside the same prey and other living creatures, allowing animals to find their niches and natural defenses to live in a type of balance within an ecosystem.
Harari continues, “humankind ascended to the top so quickly that the ecosystem was not given time to adjust. Moreover, humans themselves failed to adjust. … Many historical calamities, from deadly wars to ecological catastrophes, have resulted from this over-hasty jump.” When humans went from mid-food chain to the top in only a few thousand years, we created a punctuation in the evolutionary course of the planet. Tool use, advanced social tribes, and coordination and cooperation among humans allowed us to disrupt the slow and steady process of evolution that allows living creatures to steadily evolve together. Other species couldn’t adapt quick enough, and a mass extinction is the end result.
Further, Harari argues that our quick jump in the food chain didn’t allow humans to evolve and adapt – in terms of our psychology – to our new position. We possess fears and insecurities that are tied to our tribal ancestry. We live as if we are still in the middle of the food chain, and not  the top. Our quick ascent was so fast that we still haven’t caught up with exactly what the change means and where we are, and as a result we still live with the same fears that our ancestors had when they were in the middle of the food chain. This insecurity, Harari argues, has contributed to wars, deliberate decimation of other animal species, and various negative things that humans have done to each other and the planet since becoming the most dominant species.

Night Owls By Birth

A chronotype is the scientific term used to describe people who are night owls and early morning people (or larks as they are sometimes called). Most people fall into these two categories, with a small segment of the population who are somewhere outside of either lark or night owl. Between morning people and night owls, the majority of people are generally in the morning person category (even if most people are not waking up at 4 a.m. to write blog posts every day).


In the book When, Dan Pink discusses research which suggest that our chronotypes are often determined before we are even born. He suggests that being a night owl or a lark is beyond our individual control, and not something we can flip like a light switch. He writes, “Genetics explains at least half the variability in chronotype, suggesting that larks and owls are born, not made. In fact, the when of one’s birth plays a surprisingly powerful role. People born in the fall and winter are more likely to be larks; people born in the spring and summer are more likely to be owls.”


To me it seems really strange that we would find a genetic component to whether we like to wake up early or go to bed late. What is even more strange is that there would be an epigenetic factor that shapes whether we are a morning person or night owl based on the time of year of our birth. I can understand why early human civilizations would benefit by having some people who were morning people and some people who were night owls, but it is still surprising to me that it is baked in at a genetic level.


We often look at behaviors like waking up early or staying up late and apply some type of moral lens which does not make sense given this research. Our society generally praises the early risers and is critical of night owls, but for many people, according to the research Pink presents in his book, being an owl or lark is not a choice. We don’t need to be so critical of people with a different chronotype than ourselves, and we don’t have to praise people who have the same chronotype as ourselves either. We can simply accept that some people are going to be up early and others will stay up late, and we can adjust our own schedules according to our chonotype so that we are engaging in appropriate activities at the appropriate time for ourselves based on our chronotypes.


Ultimately, for me, this brings me back to my personal belief that we need to shorten the work day and find more flexibility in how we work. Forcing everyone into the same work schedule doesn’t make much sense if many of us are not built on a genetic level for that work schedule. Also, if our work is knowledge work, where the important thing is what our brains produce and not how many times we swing a hammer, then there is no reason to force that work to be done at a particular time of day, at least not if it can be done at a different time of day with better output that doesn’t slow down and impact other people’s productivity. Respecting chronotypes in this way will likely make us  more productive, if we can find a reasonable way to blend chronotypes and work schedules. This is something I think we should work toward, especially since our chronotypes are more or less set before we are born, and not something we explicitly chose for ourselves.