Evolution is something I have wanted to write about for a very long time.
It is not because I think I have a particularly unique take on the subject - people much more knowledgeable than me have already written lots about it and I don’t suspect I’d surprise them with anything new.
It is simply because I love the idea so much. In my book, it is the definition of elegance as far as scientific theories go - astonishingly simple once you get it, but at the same time really tricky in trying to consider all the implications it entails.
Evolution is also the first thing that truly humbled me (in the best way possible).
I have always, for as long as I can remember, claimed that I understand evolution. I knew it has to do with mutations, that baby animals are different from their parents and that over time this results in all the different species we now have around.
I never really thought about it much deeper and, if you asked me, I would probably just mouth something vaguely scientific (and, to my credit, probably still at least somewhat true). I never got deeper than the surface-level understanding.
And then, quite recently (more recently than I’d like to admit, probably), I got the push I needed - I have met a creationist.
At that time I already proudly self-identified as the rational one in any group, so, naturally, my first instinct was to jump straight into a discussion.
How big my surprise and frustration were when, after a couple of hours, not only did I not convince the guy, but was actually losing the grip on my own arguments (in my defence - there was alcohol involved, so it might have contributed to that slightly).
The next day was the beginning of what turned out to be a small revelation for me. I of course took straight to reading and watching all I could find on the topic of evolution (funnily enough, Darwin’s original work was not on that list - I have already read it before, but apparently it did not stick too well).
Sadly, I do not remember the exact moment when it clicked for me - I only know that it really was a click. One moment I was skimming on the surface of understanding and the next I plunged right through.
I genuinely think that this might have been the closest thing to a religious epiphany my hopelessly rational brain is capable of experiencing.
Alright.
With this touchy-feely personal account out of the way, let’s finally get technical.
To the best of my knowledge, there are two separate, albeit somewhat overlapping, systems governing the process of evolution - environmental conditions and sexual selection.
The first one makes living things better adapted to said conditions, so that they become more resilient and have a better chance of survival, which in turn leads to their genes being passed forward in time.
Sexual selection on the other hand is a result of one sex (usually females) actively choosing only those reproductive partners that display a specific set of traits. If an individual in a species is not selected, its genes naturally do not get passed on, even though technically it might have survived in the environment just fine.
The reason I consider these two (environment and selecting mates) to be overlapping, is the fact that the traits females are selecting for are, more often than not, related to survival possibilities. In other words - in my view the whole thing can be thought of in terms of two (or more, as we’ll see shortly) tiers, or levels of filters.
The first, lighter filter is the environmental pressure. If an organism passes this test (it does not die before it gets the chance to reproduce), the second ‘filter’ it has to pass is being selected by a member of the opposite sex and producing offspring.
It is worth noting here that, as already mentioned, the second filter is usually, but not always, just a more strict version of the first one. It is, however, also quite common, for example, for females to select for seemingly useless characteristics from the survival’s point of view - huge colourful tails of male peacocks being one of the most prominent instances. This category of traits favoured by sexual selection boils down to using additional resources for purposes irrelevant or often even actively harmful to the chances of survival in order to manifest one’s fitness and strength. It is a way of communicating to the world (and, more importantly - the opposite sex) ‘look how much of valuable resources I am willing to put into unnecessary things and still be able to survive and prosper.’
That is also, by the way, an explanation of the luxury goods market.
Ok, this all seems to make sense, but there is still one crucial component missing - what produces all these traits, that the environment later puts to the test and that females find attractive and select for? How does the organism, or the evolution, know which traits to produce?
Well, the answer is pretty simple - it does not. Neither evolution, nor the organism itself know anything.
This is the exact part that had to “click” for me. So if it doesn’t for you yet - just keep on reading and hopefully, at some point, it finally does. Now back to the technical part.
Even if organisms do understand which traits might be more beneficial than others (like humans do) it does not give them any advantage, since they cannot purposefully change their own genome (at least not to any truly significant degree yet). All the differences present within species (and actually all differences between all living things on Earth) are a result of one thing - random mutations.
Mutations are the actual first step in the tiered process already described - they produce all the differences with each new generation of the organisms. And the beautiful thing is - they do not have to be smart. Since they are only the first step, it is not a problem that they are random.
After organisms randomly mutate, the natural environment allows only the ones fit enough to live, and finally sexual selection chooses from this leftover group those that are deemed worthy of reproduction.
This is the magic (or rather - the science) of evolution.
Once the organism reproduces, the whole process starts again, since there will inevitably be mutations in the offspring - no reproductive process is perfect and these imperfections are exactly what we refer to as ‘mutations’.
Fun fact here - it has recently been observed that different aspects of organisms’ genetic code have different proclivities for mutation - some “less vital” parts of the genome mutate more frequently than other “more vital” parts. This means that even the chance of mutation itself is influenced by evolution - a sort of ‘evolution of evolution’ or ‘meta-evolution’, if you will.
With the technical part done, I would now like to briefly tackle the baffling issue of evolution denialism.
The fact I find so hard to accept about such a position is the sheer ignorance required to hold it.
Obviously, I do understand that fully grasping the brilliance of evolution may not be instantaneous - it definitely wasn’t for me. But to deny it outright is a very puzzling stance to me.
One has to be oblivious to so many common phenomena that it seems almost impossible. GMO, selective breeding of plants and animals, the archeological record, the paintings depicting how various fruits looked a couple hundred years ago, the fact that disease-carrying bacteria and viruses mutate over time and that is partially why they are so hard to cure (so called ‘variants’ of the recent COVID virus being an example that everybody should be familiar with) are only some among many.
I will not go through all of those examples in detail, but I would like to touch upon one of them nonetheless - selective breeding. It is a process by which humans have been using evolution for their own advantage literally for millenia (since around 12000 BCE or for over 14000 years). It is remarkably simple as well - you select which animals are allowed to breed based on their traits that you want to enhance.
You want chickens that are on average bigger and thus give more meat - allow only the biggest ones you can find to have offspring and then repeat with the next generation until you are satisfied.
Maybe you want to have some dogs that are very timid to act as pets and some that are very aggressive to serve as protection for your flock of sheep (which, by the way, are selectively bred to have extra-thick wool) - simply breed the naturally most timid and naturally most aggressive individuals separately.
Or perhaps you want to increase the yield from your crops - then just use the seeds from the ones that give the most plentiful harvest to plant the next generation.
These seemingly primitive techniques are still very much in use along many more direct and advanced ways of genome manipulation. Ask any dog breeder and they will surely confirm - it is literally their job to selectively breed dogs.
I truly do not think that it is possible to argue with the fact that selective breeding is a thing. Which in turn makes it hard to grasp, how people can not see it as the proof of evolution.
Fundamentally, the only thing that is different with evolution is the lack of active agent that selects the traits (although, as was already discussed, it is not even entirely true when one considers sexual selection).
All it takes to make a jump from selective breeding to evolution by natural selection is the acceptance of the fact that the environment itself can act as ‘the agent’. In other words - it requires for one to not believe that the natural conditions of the world allow only for some organisms to reproduce, while making it extremely hard or outright impossible for others.
For the life of me, I just cannot comprehend why that would be something up for debate.