Evolution 101

Throughout my young academic career, I’ve noticed young students might not always understand evolution. So here is my brief explanation of what evolution is.

Contrary to many popular beliefs, evolution doesn’t have a “goal” nor does it try to make things “more complicated”. It is also not linear.

So this picture. All wrong!

Evolution is actually very random. That’s why it takes so long! The world is 4.5 billion years old. To put evolution into perspective, mammals (mammals that give live birth and have milk glands) are about 250 million years old, arthropods (creepy crawlies like insects and spiders) are about 500 million years old. If evolution had a “goal” or was trying to make things “more intelligent” then we would have spiders doing calculus, or probably inventing ways to live on Mars. This is also why we have something called “vestigial traits”. This means we have features that we no longer use, for example goose bumps. Goose bumps don’t have a use for us anymore, why do we still have them? What about wisdom teeth? If evolution had a purpose, we would have lost these features long ago.

This is a scribble by Darwin in his journal of what he hypothesized evolution to look like. Random, all over the place, and not linear.

Here is a simplified version of evolution: a living thing has a mutation in its DNA that is not harmful (many mutations are) and passes on its DNA to its descendants. Now these descendants will pass on this mutation to their descendants and so on. Mutations can make features disappear – like fur all over a primates body – or appear – like a large brain. Then, behaviourally, that living thing can change to suit this new mutation, like walking on two legs due to a large brain. But again this is all random and takes a very long time for a “good” mutation to occur and the population to accept it – what if no one wanted to mate with a fur-less primate!

Evolution is driven by natural selection. This means that certain traits or mutations that randomly appear may help the living thing to survive, or otherwise the living thing will die. This is also why we may tend to see evolution as always being successful – It’s harder to find find evidence of the living things that didn’t survive for very long if they didn’t change with the environment.

A classic example of evolution is the Darwinian finches. These finches were living their lives on the Galapagos islands just enjoying life. But as the population of birds grows, the resources becomes scarcer. So some birds have smaller beaks than average and decide “hey I’ll start eating the smaller seeds” and start mating with birds with smaller beaks, then perhaps this become a mutation in the DNA. And there you go some birds eat smaller seeds, some birds eat large nuts, some birds ended up dying because they just couldn’t change.

Is evolution still occurring today? Can we evolve living things in the lab/ourselves?

Yes and Yes!

Evolution is never finished, like I mentioned it’s random. Therefore no start line, no finish line.

I evolve animals all the time in the lab. But because evolution is so slow and random, I use animals that can develop and reproduce quickly (some people use plants or microbes). Evolution depends on something passing on it’s genes to the next generation, therefore a quick life cycle is important for me to investigate evolution in real-time. I also eliminate other factors that make evolution more random: I control temperature, competition, which individuals get to mate, which descendants live on, etc.

We also evolve living things through domestication. Fruits, vegetables, pets, farm animals, we’ve evolved all of these living things to suit our needs. We can make fruit sweeter, dogs more docile, cows produce more milk all through evolution!

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