Evolution 101


‘Consider Darwin’s original phrase natural selection: everything from Cuckoo Birds that lay their eggs in the nest of other birds, to giraffes whose long necks are good for reaching food in high trees, to humans whose brains make up for their fragile bodies, are selected for, naturally.

An even better phrase would be non-random selection or maybe even non-random elimination. While all genetic mutations are generated by a random copying error or random variation completely beyond the animal’s control, the selection of those traits is not random.

Successful variations that allow you to survive and reproduce are determined by the very specific circumstances of your environment, where elimination – death – might not be far away.

So, the selection of your traits is done by a very specific and sometimes brutal list of criteria. This is why people who say that they don’t understand how all animals could have “evolved by chance” don’t really understand how evolution works.

Here’s another phrase that doesn’t get it right: “evolution is just a theory”. In everyday speech, theory means guess; but in science, a theory is something that was tested time and time again, explains many different observations and is backed up by a mountain of evidence.

Evolution is a theory like gravity is a theory, and you don’t go jumping out your window because gravity is “just a theory”.

Why are we so certain? Emily knows:

Evolution is one of the most tested, most utilised and most widely accepted theories in science. It’s backed up by literally tonnes of fossil evidence which can show us shared traits with species that no longer exist, and help us map out lines of descent for creatures that are around today.

DNA sequencing further tells us about lines of descent and you can measure the commonality of the DNA possessed by two animals to tell how closely related they are, and when they may have split off from a common ancestor.

Radiometric dating allows us to assign dates to various fossils, further helping us map out lines of descent.

Then there’s the simple fact that extinct species are always found in the same rock layers you’d expect to find them. Which is why you don’t see a bunny skeleton in Cambrian rock layers from half a billion years ago. That’s also how we know that Dimetrodon is not a dinosaur.

Closely related species are often geographically distributed near one another. That’s not to mention that we can see evolution happening before our very eyes: whether it be the discovery of a new species that recently moved into a different environment, the development of newly adapted bacteria into superbugs, the evolution of new breeds of rapidly reproducing insects, or the almost constant changes in gene distribution in animal populations all over the world.’

– Green. H., Graslie. E. (2014, October 29) The Evolutionary Epic: Crash Course Big History #5

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5 thoughts on “Evolution 101

  1. Even the most recalcitrant skeptic must surely see evolution at work in our own modern frame of reference, when we realize that prior to 30,000 years ago, dogs didn’t exist – that ancient, Stone-Age hunters brought home orphaned wolf cubs, for use in hunting, tracking, and as sentries, and that every breed of dog that exists today, from St. Bernards to Pekinese, to Chihuahuas, were all descended – through manipulated selection – from that original stock of wolves.

  2. Ross: You don’t believe in evolution?
    Phoebe: I don’t know, it’s just, you know…monkeys, Darwin, you know, it’s a, it’s a nice story, I just think it’s a little too easy.
    Ross: Too easy? Too…. The process of every living thing on this planet evolving over millions of years from single-celled organisms is… is too easy?
    Phoebe: Yeah, I just don’t buy it.
    […]
    Ross: Ok, Pheebs. See how I’m making these little toys move? Opposable thumbs. Without evolution, how do you explain opposable thumbs?
    Phoebe: Maybe the overlords needed them to steer their spacecrafts.

    – Friends (1995) Season 2, Episode 3; “The One Where Heckles Dies” [No. 27]

  3. I’ve yet to find anything more comprehensive than Dawkins’ “The Ancestors’ Tale.”

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