“I, I, I is the refrain of my whole life, which could be heard in everything I said.”
Albert Camus – The Fall
This is the first instalment in what will hopefully become a series of blogs (six or so) about the evolution of cooperation. I mentioned before that science is made more interesting by paradoxes. Cooperation is the ultimate paradox of evolution. How does “survival of the fittest” end up with people helping each other? And we do see cooperation in nature. Below are two examples. The first is a moray eel allowing a cleaner fish to eat the debris from its mouth. In the second picture are the extremely cooperative bees. A worker bee will sacrifice its life for the hive, and nearly all worker bees sacrifice all opportunities for reproduction for the good of the hive.
Natural selection favours genes that make more copies of themselves than other genes do. This gene level view of evolution is commonly known as the Selfish Gene Theory and is the cause of more misunderstandings than nearly any other biological concept. In this post I will try and debunk a couple of myths about The Selfish Gene Theory and then let it shine as a theory that explains things that are hard to understand without it.
Surprisingly, the Selfish Gene Theory is not particularly about genes being selfish. The main idea of the Selfish Gene Theory is that evolution acts at the level of genes and not the level of the individual or the group. What this means is that a gene will only become more common if the function of the gene increases the average number of copies of that gene. If a gene increases the success of the body that holds it, at the expense of the genes own interest, it will rapidly disappear from the population. The Selfish Gene Theory is about the level of selection (as genes are the level of selection, only they can be said to be truly selfish). It is not about genes wanting to be selfish or being able to make conscious ethical decisions. I will often use phrases like “genes want to make copies of themselves”. This is not true as genes don’t ‘want’ anything. They are molecules without the ability to think. However, it makes for easier reading if I talk about what genes ‘want’ rather than the passive act of genes spreading. Genes don’t ‘want’ to make copies of themselves, the genes that do make copies of themselves will become more common. Selfish Gene Theory is also not about people being selfish or suggesting that people should be selfish. In fact, it provides one of the best explanations as to why humans or any other organism may not be selfish.
The purpose of a scientific theory is to explain how the world works. The Selfish Gene Theory helps us understand why organisms are often not selfish. That sounds backwards but it is true. Only when we really accept that genes are selfish can we understand why individuals may not be selfish. A gene does not really care if the body it is in lives or dies. As long as it creates more copies of itself it will become more common. Therefore, if a gene makes the organism it is in help organisms with that same gene, this gene may well become more common. This is called kin selection and is an example of selfish genes creating unselfish individuals.
A sibling falls into a river. You know you can save them, but at the cost of your own life. There are clearly ethical discussions either way, but in terms of creating the most copies of your genes what should you do? Put another way, will a gene that makes you more likely to dive in to the river become more common? On average, you share half your genes with your siblings. So if you save your sibling, there is a 50% chance that you have saved a copy of the “save your siblings” gene. Your death comes at a cost of 1 copy of the “save your siblings” gene but saves on average 0.5 copies of the gene. This gene will be removed from the population fairly rapidly as it is running on a loss. If you buy 50p for a pound, it doesn’t take long to run out of money.
What if 3 siblings fall into a river? You can save them all, but at the cost of your own life. The gene for this behaviour will become more common. You save 1.5 copies of the gene (on average 0.5 copies in each sibling), and only lose 1 copy (like buying £1.50 for £1). This is kin selection and it means the gene will spread. If a behaviour increases the number of copies of itself by helping relatives (who may well have that gene) it will spread, even if this is bad for the body that the gene is sitting in.
So, kin selection is an explanation for why family members may help each other, even at their own expense. It relies on the fact that as long as a gene makes more copies of itself it will spread. It doesn’t matter if the copies are in the same body or in different bodies. Finally, I will add that Richard Dawkins did not suggest the Selfish Gene Theory (as he always makes sure to point out). It was developed by some of the great biologists of the 20th century, W.D. Hamilton, John Maynard-Smith, George C. Williams (probably the best beard in biology) and others. This is then my little dedication to some of the scientists that have inspired me and enriched my life so much.