Thursday, July 16, 2015

Does evolution work for dominant species?


That one word explains everything about life on Earth. From the simplest of bacteria to the most complex of organisms Evolution is the one tool which has made it all.

This brings up the question does evolution still work when a species becomes the dominant one on the planet?

Dominance may be defined as when a species begins to have the largest fraction of the population of life in a given area. Humans are definitely the largest population (I am ignoring bacteria here) of multi cellular life on the planet in my opinion.

Evolution works on the thumb rule of limited resources. With limited resources, species have to contend for food. This causes them to evolve by natural selection, as in those unable to gather enough food die out as a result of having no children. This puts evolutionary pressure on the species to evolve and get better at gathering food and creating children or die out. What this means is that everything that a species does is somehow allowing it to be better at producing more children. Everything in this world results from that on drive.

Humans on the other hand are unique. They are undoubtedly the dominant species on this planet. How does evolution affect us? Does it even count? A species which becomes dominant implies that it has a method or some tool which allows it to produce a lot more children than the other species. They can actively control the population of other species and cause artificial selection within them. That is how animal husbandry began and how it works.

For a dominant intelligent species however, the number of children per individual is not dependent on the traits of the individual, unless the traits interfere in actual child creation.

Social service and community concepts work against natural selection by giving everyone an equal chance to produce an equal number of children irrespective of what makes them better. That eases the evolutionary pressure on the dominant species to evolve.

The very attribute that made them dominant now stops their evolution. Let us take another theoretical example.

Imagine a world that is inhabited by lizards, say. Now these lizards are of many different species and of many different regions. Each has evolved to be perfect in it's surroundings. Now there arises a species of lizards which goes on to become the dominant species in the planet. The dominating lizards, lets call them God for lack of a better word. The dominating feature allows them to have unparalleled advantage over every other species on the planet. Let us say that they are the only lizards that can fly, walk and swim.

Now how does this pan out for Gods? Anywhere they go on the planet they dominate the local populace. This leads to them having a population explosion because they can get their food too easily. With that the evolutionary pressure is gone. They stop evolving at the same rate as the rest of the species. A sick God is still a God. A handicapped God is still a God. Hence a God will always have more children than a normal lizard.

So what might happen next? Evolution is still in play but it is in slow motion for the Gods. They do not evolve until they are forced to do so by competing lizards (Titans lets say). Thus if a titan species does not come along, Gods will be stuck where they are. If the titan species does come along, natural selection will proceed at the normal pace.

This might be thought of as a local maxima. Thankfully due to the nature of evolution, The population of lizards will not get stuck there. There will be change, and it might be drastic. The dinosaurs were the dominant species on the planet for quiet some time. Presumably they were wiped out by an asteroid impact. The next best species, humans, which were Titans came out unscathed. The dinosaurs might be thought of as a local maxima. Evolution overcame that and created humans which can read blogs like this one.

All in all evolution may be slowed down for dominant species until one of the other species can compete with them, but it never really stops. Have other theories? Comment.