How Evolution Works

I’m no biologist, but we need to talk a little bit about evolution and how it works. It’s not as bad or ridiculous as some people make it out to be. And it may actually fit better with the scriptures than you previously thought.

Don’t Knock It Before You Learn About It

Back in the day when I didn’t accept evolution, I definitely didn’t understand it either. I thought it was evil and should be avoided. But once I made an effort to figure out what it was all about, I started to kind of like it, and, well… I started a blog about it.

I’d guess it’s pretty much the same for others. Most people who reject evolution probably don’t really understand how it works. But once you kind of understand how evolution happens, it makes WAY more sense. It stops being the evil monster it once was, and becomes a good old friend you would want to hang out with and go exploring with.

It’s All About Families

“[I]n evolution, surviving descendants are the only currency that matters.”- Carl Safina

The Church, as you know, is really big on Family History. We have Sunday school classes about it at church, and apps about it on our phones. You can probably trace your ancestry back a couple hundred years, and maybe even much further. Families are central to God’s eternal plan for His children, and much of the gospel is focused on the family as we labor to strengthen the bonds between us that can last forever. The gospel is all about families.

This is an example of a human family tree. The gospel is all about families because through living the gospel, our family relationships can endure eternally.

Much like the gospel, evolution is all about families too. It’s about how families of living things multiplied, spread, and diversified throughout the history of the world. It’s about common ancestors, family trees with tons of branches, and inherited traits. Evolution tells us that all organisms on our glorious, green planet are descended from a common ancestor, and have reached their various levels of complexity and diversity through small changes accumulating over a very long time. Darwin called it descent with modification.

Charles Darwin, while formulating his thoughts about evolution and natural selection, sketched this tree of life. It illustrates that all living things are descended from a common ancestor, and that we’re all like branches on a tree.

In fact, it’s not wrong to permanently think of evolution in terms of descent. Instead of saying we evolved from ape-like animals, say we descended from ape-like animals. We’re just a branch on their family tree among many other branches. We kind of look like apes because we are descended from someone who looked like an ape. Just like you look kind of like your great-great grandparents because you are descended from them.

Many people ask, “If we evolved from chimps, then why are there still chimps?” First of all, we didn’t evolve from chimps, but from ancestral apes that were not chimps. And second, that’s like asking, “If some Americans came from British people, why are there still British people?”, or “If I descended from my great-grandparents, then why do I still have 2nd cousins?” Chimpanzees are still around because they are our cousins! We share a common ancestor that looked kind of like us both. Some of this ancestor’s descendants went on to become chimps, and others went on to become humans. We didn’t evolve or descend from chimps, just like you didn’t descend from your cousin. Now don’t you see why that’s a silly question to ask?

Truthfully, all of our features as humans can be traced back to ancestors in the fossil record; from our mammalian hair, to our four limbs, to our toothy jaws, to our backbones, to the very nature of the tiny cells that make up our bodies. We, and all organisms around us, are products of billions of years of slow descent with modifications. We’re all one big happy family!

This is what’s called a phylogenetic tree. That’s another fancy term for “family tree.” This shows how all organisms are related and share traits that were inherited from common ancestors. We’re all part of the same huge family. You’re related to fruit!

Living Things Only Reproduce “After [Their] Kind”

A common scriptural weapon used to battle evolutionary claims is the idea expressed in the creation account that each living thing only multiplies and produces seed “after [its] kind” (Genesis 1:11-12,21,24-25). In reality, these scriptures actually support evolution, because evolution NEVER claimed nor will claim that any species or “kind” gave birth to a different species or kind. Ever.

An organism will always be the same species as its parents, and will always be the same species as its children. It’s always been that way. One species never can give birth to another species. That’s not how biology works. That’s not how evolution works.

Imagine you got amazingly good at filling in your family tree and you traced your ancestry back 10,000 generations. That ancestor would be an archaic Homo sapien. Perhaps a bit different, but still the same species as you. If you went back 75,000 generations, your ancestor would be a Homo erectus. A different species, but not too different looking, and still your ancestor. 15,000,000 generations back and your ancestor would be a monkey-like, rodent-resembling creature that lived in trees and had a tail (Plesiadapis). Definitely a different species, but still your ancestor! The farther back you go, the less like you your ancestors appear to be; yet each of these individuals looked like its parents and its kids, and was the very same species as they were. There was never one generation where they changed species; but rather, each generation underwent very gradual, imperceptible modifications over millions of years. Small changes over a long period of time can add up to dramatic changes in comparison, and that’s exactly what happened to your ancestors and to the ancestors of every organism alive today.

Natural Selection

“[B]y small and simple things are great things brought to pass.” (Alma 37:6)

Now, how do these small changes occur? How does evolution happen?… It happens by natural selection.

Every living thing on earth has DNA. When things reproduce, they share some of their DNA with their offspring. When this happens, little mutations in the DNA can occur (think descent with modification). If these mutations are favorable for survival, the offspring will be more likely to survive than those who don’t have the mutation. And if they’re more likely to survive, they’re more likely to pass on those mutations to their own offspring. And in that way, these little modifications persist and can even become dominant in populations. Nature selects (think natural selection) for those favorable-for-survival modifications or traits to continue, while at the same time selecting for those traits unfavorable for survival to cease and eventually die out.

Whew… Now I know that was some pretty science-packed lingo back there, so let’s consider some families of multicolored rabbits in a snowy area. Some rabbits are born with white fur, and others are born with dark fur. Those cute little bunnies with white fur are hard to see among the white snow, and so they aren’t eaten as often as the small, adorable bunnies with dark fur, who stand out against the snow. Nature selects (think natural selection again) for the white-fur bunnies to survive and for the dark bunnies to die out. The white bunnies live to have families of their own, and pass on their white fur traits to their inheriting kiddos. The dark-furred bunnies all became food for other animals, and thus did not get the chance to have their own dark bunnies. And so, over time, this population of once-diversely-colored rabbits shifts or evolves to a population of predominantly white rabbits.

Also, natural selection happens when nature separates or isolates groups of animals from each other, like when continents are ripped apart by plate tectonics, or when animals get stranded on islands and have to start fresh, away from their mainland homies. While separated, these populations can’t mix with each other, and so each will evolve in their own way, independently. And when mass extinctions naturally wipe out entire families, that leaves ecological niches wide open for others to fill, which then allows nature to select for the traits that best fill those roles (see The Four Beasts post for more about ecological niches).

That’s natural selection. And it can and does happen for any trait that increases the chance for survival. It’s not so much “survival of the fittest” as it is “survival of the good enough for the circumstances.” Given sufficient time, small and simple changes can cause great and big changes to come to pass.

Don’t worry! We’ll talk a lot more about natural selection on this blog, because when it comes to reconciling evolution with the scriptures, it’s kind of a big deal.

Is There Any Evidence For Evolution?

Oh yeah. There’s a ton! The natural world is literally full of evidence that evolution did and does occur.

Scientists can see the evolutionary and familial splits happening among living animals today. Instead of just one species of killer whale, there are several groups that look relatively the same, but eat different things, live different lifestyles, and never reproduce with each other. The same goes for giraffes, where there are something like 9 different groups or subspecies of giraffe that never mix. These animals have essentially already split from their common ancestors and are taking their own evolutionary paths. If we could live long enough to see the eventual outcomes of these family lineages, we would probably see dramatic changes across them.

Five types of killer whale. They look very similar, and some of their territories even overlap; but they do not interbreed. They are already on different branches of the evolutionary family tree.

There’s even proof of evolution in you! For example, think of people who can move or wiggle their ears. They can only do so because they’ve retained an ancestral trait from an old mammalian ancestor who could move its ears around with ease. Lots of our furry friends can still move their ears, but most “normal” humans can’t any more. I’ve always wanted to be able to do this, but alas, nature selected my ancestors for whatever reason to not pass it on to me.

Also, our hands are just like the hands of our tetrapod cousins. Yes, every tetrapod, or land vertebrate animal has (or had, in the case of the extinct ones) the same bones in its arms and hands- five fingers, radius, ulna, and humerus. And that includes us! Even whales have the same bones in their flippers. And why do we all share these characteristics? You guessed it: because we’re all descended from the same tetrapod animal, who had the same bone structure. Pretty darn cool.

Arm and hand bones of several tetrapod species. Notice that they all have the same bones and general structure! The only weird ones are the birds. Birds only have 3 fingers because somewhere along their ancestry, some of their fingers fused together.

There is SO MUCH MORE evidence for evolution out there, so go out and look for it and be amazed.

Conclusion

Evolution isn’t evil, folks. It all about families. Descent. Modifications. Inherited traits. Nature doing its thing and selecting. Kinds only give birth to their own kind, and this has never changed, since the beginning of life on earth. Evolution still happens today and will continue to happen as living things continue to thrive and reproduce.

We are ALL in this together- the bacteria, plants, animals, fungi, you name it. We are all one family. And God loves us all, and He put us here. The fact that we got here in our different bodies through evolution does not change that all-important fact.


Sources and Notes:

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