What Is The “Gene’s Eye View” Of Evolution?

The gene’s eye view of evolution (sometimes called the “selfish gene” concept because of the popular book written on the subject) is the simple realization that genes – stretches of chromosomal material that code for or influence an organism’s traits – are the smallest things capable of evolution by natural selection.

When Darwin first discovered and studied the process of natural selection, he wasn’t thinking in terms of genes, he wasn’t aware of the concept of a gene. Instead he mainly focused on how natural selection acted on individuals and how that action changed the types of individuals you’d find in a population over time – over multiple generations.

It was common knowledge (long before Darwin) that when two individuals got together to reproduce, their offspring were born with a variety of different traits, some which seem to have come from the mother, some from the father, others appeared to be completely unique.

Darwin’s first big insight was noticing that in each generation, more individuals are often born into a specific environment than could ever possibly grow up and successfully have children of their own.

This is true almost anywhere but it’s most obvious on islands where it’s plain to see that resources are limited. Just as a thought experiment, imagine releasing a group of badgers onto an island. During the first few years the population would quickly expand exponentially until growth is slowed down by the limit of island food produced each year. At this point, a brutal tournament automatically begins – a tournament that Darwin called “the struggle for existence”. When resources are limited, every badger becomes a contestant, whether they like it or not.

Badgers that happen to have better traits than others for survival and reproduction (on our particular island) will tend to survive more often and have more offspring. This fact is so obvious that it’s almost silly to say out loud, but Darwin realized this had huge implications.

It meant that nature, simply by being difficult to survive in, automatically “selects” which individuals get to reproduce, and which do not. Over many generations, the types of individuals you would find on the island will change – they will be shaped by natural selection and will adapt to the specific selection pressures unique to that island.

In the struggle for existence, Darwin studied how whole individuals compete with rivals and cooperate with allies in order to survive. Watching the struggle at the level of individuals is useful but if we look carefully, we find that the contest also plays out at a much finer level – the level OF THE GENE!

Particular traits and specific combinations of particular traits, are really what give individuals an edge over their rivals. Many of these traits are heritable, they’re passed down from parent to child via sperm and egg. Individual heritable traits are in a struggle for existence against different versions of themselves within a population. In our thought experiment, the heritable units that give rise to long claws, are in direct competition with the heritable units that give rise to short claws.

Those heritable units are genes: stretches of chromosomal material that code for or influence an organism’s traits. Before reproduction, a mother’s genes are copied and half of them are shuffled into an egg cell. A father’s genes are also copied and half are shuffled into a sperm cell. These cells fuse after mating and that fused cell then grows and divides to become a new pup. The child contains a unique shuffling of its parents genes, and a unique combination of the traits those genes influence. From time to time, completely new traits arise from genetic mutations.

Suppose that on our island, termites are the best source of protein for our badgers. Genes that happen to give rise to long, thick claws (claws that just so happen to be extra useful for opening termite mounds) these give badgers better access to food. Over time, these genes might completely out compete and eliminate genes that give rise to short, or narrow claws. Genes don’t eliminate their rivals “on purpose”. Their success is an automatic consequence of natural selection on the island.

Genes are the foundational entities “fighting” in what Darwin called the struggle for existence. As badgers fight for space on an island, genes, though they don’t actually have minds or ambitions, automatically fight for space within the badger population. They don’t fight with claws or teeth, instead, they fight with their ability to influence the development of claws, teeth, or any other trait that might help a badger survive and reproduce.

If you look at evolution from a gene’s perspective – a gene’s eye view, if you will – the badger can be thought of as a home or a survival machine built by genes, for genes. If all goes well, the survival machine will make copies of the genes that built it. It will spread those genes into the next generation, using tiny escape pods that we call sperm cells and egg cells.

The gene is the fundamental unit of inheritance, the smallest possible thing that nature can either select for, or against.

The gene is to evolutionary biology, what the atom is to chemistry, what the musical note is to a musician.

Now… It has been argued by some that looking at evolution from a gene’s eye view is too reductive. By analogy, a single musical note in isolation can’t tell us much of anything about a song. It’s only when many notes are played together, and in the right pattern over time… that the richness and emotion of a musical piece… begins to emerge.

The same is true of genes. An individual gene can not build a claw. A claw (and an entire badger) is the result of many genes functioning together as the individual develops. So, why would we ever bother looking at evolution from a gene’s eye view?

Well, to continue the music analogy, when there is a problem with a piece of music… something strange happening in a song, a good musician should be able to zoom in all the way to the level of individual notes if necessary. This level of reductionism is sometimes needed to figure out exactly what’s going on.

Ahh, there we go… much better.

It turns out that there are certain mysteries in evolutionary biology – certain physical traits that plants and animals have or behaviors they display – that do not easily make sense unless we zoom into the level of the gene.

One classic example is the stinger of a honey bee. This structure is covered in backward facing barbs. If you attack a bee and it stings you. The bee will be trapped because of those barbs. If it tries to fly away, its stinger, venom gland, and venom pump will rip out of its body. The stinger stays in you and keeps pumping until every drop of venom is emptied into your skin.

On the one hand, this seems like a great defense because it maximizes the pain you feel, usually stopping you from messing further with the bee. On the other hand, the bee almost always dies from the massive wound left by its missing stinger.

How could such a seemingly counterproductive defence system evolve? You’d think that any bee with a mutation that either makes barbs smaller or makes its body strong enough not to rip when it flies away, these mutations would make the bee better at survival than its suicidal neighbors. Natural selection should promote these individuals, right? However, if we take a gene’s eye view, we find that this conclusion is wrong.

If you are a gene there are two ways to make sure copies of yourself spread into the next generation. The most obvious is to code for a trait that helps your personal host survive and reproduce.

This is called direct fitness. Copies of you will be directly made and passed into the next generation.

Another way to make sure your copies spread is to code for a trait that makes your host help another host survive and reproduce, if that host also carries a copy of you among its genes. As far as the math goes, this is the same as you reproducing yourself.

This is called indirect fitness.

Obviously it’s best for a gene if both hosts reproduce but the world we live in is rough. Teamwork is often the best option.

A real life example of genes that code for indirect fitness can be found in African wild dogs. They are compelled by their genes to help take care of their nieces and nephews, often instead of ever trying to have children of their own.

Natural selection favours mutations that increase a gene’s inclusive fitness.

Bees live in hives, mostly with their sisters and only a few will ever get a chance to reproduce. If you live with your own sisters, an exact copy of any gene you have – even a suicidal stinger gene – is likely to be shared by all or many of your sisters. If on average, one suicidal sting is so much more effective than a normal sting that it saves at least 2 lives that would otherwise be taken by a hive invader (2 lives of bees that also carry copies of the suicidal stinger gene) the math works out in favour of that suicidal gene.

This is because most bees with suicidal stingers will never have to use them. Chances are, one of their sisters will be provoked to fight first and will successfully scare away the attacker. Her life is sacrificed by the gene inside her, so that identical copies of that gene can be spread by her sisters.

Taking a gene’s eye view of evolution allows us to carefully apply mathematics that solve complex mysteries in evolutionary biology. Reductionism, when used properly, can be extremely powerful.

So in summary, what is the gene’s eye view of evolution? The gene’s eye view is the simple realization that genes – stretches of chromosomal material that code for or influence an organism’s traits – are the smallest entities capable of evolution by natural selection.

From a gene’s eye view, we, the organisms of the world, are merely vehicles which they have built. From their view, our function is to make exact copies of them and pass those copies into the next generation. Though you and I are guaranteed to eventually die, our genes, or at least copies of our genes if we reproduce, can live on indefinitely.

In the struggle for existence, genes mindlessly compete with alternative versions of themselves, versions that might code for or influence the development of opposing traits. While I don’t recommend thinking of yourself as nothing more than a gene carrying machine, when trying to solve tough mysteries in evolution, this extreme level of reductionism really can be useful.