Before anyone comes for me, I grew up southern baptist – went to a private christian school & was homeschooled for a few years. The extent of my “science” education when it came to evolution & the origin of the universe was “if we came from monkeys why do monkeys still exist?” and “look at this galaxy that’s shaped like a cross, isn’t god amazing!!” I’m an atheist now and would like to have some sort of understanding of how our world came to be, but trying to figure it out as an adult with no real foundation has been incredibly difficult, and none of it’s making sense. I also know I’m asking a lot as all 3 of those subjects are pretty extensive, so if you know any good videos or books I’d love some recommendations!
In: Biology
Non-scientists tend to get a lot wrong about evolution, and that leaves a lot of questions that can seem to make for contradictions.
A lot of people have the idea that evolution is about trying to build a genetically perfect individual that can be replicated across the population. That’s not right. Evolution doesn’t even operate at the level of the individual, it operates at the level of entire populations. It’s not trying to build a perfect individual, it doesn’t “want” anything, evolution is just observing a tendency of populations to build resiliency over time.
This means that the population will live on, not any particular individual. If you are in a particularly “evolved” population, that means you have a higher chance of taking on whatever environment stresses come at you, but in order to build that resilient population, there have to be a lot of experiments going on with variation, and a lot of those are going to be failed experiments.
Also, in order to be resilient, there may be a lot of characteristics that are hidden away and only come into the picture when the environment changes. It’s the latent *variation* in populations that allows them to adapt to new situations. Keeping those variations means that an organism might not be perfectly adapted to the current situation, but as long as it’s good enough to pass on those genes along with all that latent variation, then the genetic line will survive. Then when things change, it can adapt.
One final bit of this evolution preamble: Don’t confuse *evolution* with *evolution theory*. Many, many people use these terms interchangeably. Evolution is an observable **fact**. You can see that evolution happens with some bacteria and a mild toxin. We see pathogens become antibiotic resistant, etc, etc. There is no more disputing that evolution exists than there is disputing gravity. *Evolution theory* is a scientific model based on the fact of evolution that makes all sorts of predictions, and it’s changed over the years. The first theory was Darwinism, but as time goes on and we learn more, we keep improving the theory (there was punctuated equilibrium for awhile, then that got replaced, up to the modern day theory). This is no different than any other theory, we had Newtonian physics get updated with relativity, for instance.
Okay, so what about abiogenesis? Well evolution doesn’t care about life. It is highly correlated with life, but to evolution, there’s nothing particularly special about life. So if you think about the primordial soup with all these compounds running around in a high energy environment, constantly getting zapped with lightning and all these things going on, you can imagine that this soup is just chaos. There are different compounds forming and breaking all the time.
If any of those compounds happen to be an enzyme that operates on other compounds, then you might start to see the population of different compounds shift. At first, there might be a bunch of compound A and compound B, but in the presence of enzyme E, which turns A into B, the balance of things will naturally shift so there’s not many A and lots of B. What happens if B happens to itself be an enzyme that makes enzyme E? Well now as long as you have a steady supply of A coming in, there’s going to be a lot of B and E floating around. Or you might have an enzyme X that makes more of itself, a self-replicating enzyme.
Both of these things might seem improbable, but if you think about this soup just sitting there getting zapped all the time, once you realize that this process only has to take hold once and suddenly the populations will shift toward these substances that tend to replicate themselves, it doesn’t seem that farfetched. (Think of a terrible dart player playing darts. If they throw a dart, it’s highly unlikely they’ll hit a bullseye. If they throw 100 darts an hour for decades, they’ll almost certainly hit a bullseye a bunch of times.)
In this simple primordial situation, evolution is already in play. The enzymes and self-replicators that are more robust and adaptable will end up “metabolizing” all of the inputs they need more successfully to outcompete all of the other enzymes and self-replicators that aren’t as fast or as stable or adaptable.
>“if we came from monkeys why do monkeys still exist?”
If you came from your parents, why do your parents still exist? A more accurate representation of how evolution works would be like monkeys are our cousins.
The common ancestor species between humans and any other apes is long extinct, but the idea is that one group of thay species was separated from the other, and they were separated long enough that they experienced different pressures from their environments. Random mutations in their genes would occasionally prove either beneficial or hurtful. The beneficial mutations mean that the individual with said mutation would be more likely to survive and pass on that mutated gene. Repeat this millions of times, and then you have a new species.
A more recent example of this is very easy to show with our closest relatives, chimpanzees and bonobos. They live very close together, but about 1.8 million years ago, they were separated by a river changing course. The bonobos were in a very resource rich area, and the chimpanzees were in a resource poor area. As a result, the chimpanzees evolved to be more aggressive, meaning they’d be more likely to secure food for themselves, and live to reproduce, but the bonobos evolved to be more friendly, so they could work together and share food and find mates.
If there were an aggressive bonobo, it would be shunned from the group, but if there were a generous chimp, it would be getting less food.
This is natural selection at work, the driving force behind evolution.
We can also very easily show artifical selection with how we breed plants and animals. We find the ones with desirable traits, and we breed them, so their children have those desirable traits. We haven’t been doing this long enough to create a new species, but we have definitely left our mark on their genetics.
Read The Big Bang by Simon Singh. It’s very appropriate for people with no scientific background and it tells the whole story of how we figured out the Big Bang.
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