April 25, 2010
Take a look at a banana.
It has just the right length and just the right thickness to fit snugly in your hand. The surface of a banana is anti-slip, making it easy to hold and to eat. There is a finger-sized tab on the top of every banana, all you have to do is to pull it lightly, and the skin peels away from the edible fruit inside. Banana skin also acts as a comprehensive ripeness indicator: Green – not ripe yet; Yellow – perfect; Black – time to throw it away. Bananas are sweet, easy to chew and good for your digestive system.
These arguments were presented by evangelist Ray Comfort in an attempt to prove the existence of God. Obviously bananas were designed by God, he argued reasonably, how else could so perfect a fruit have come to exist?*
While hardly irrefutable proof of God, his arguments certainly do provide fairly compelling evidence of a supernatural power that in some way influenced the course of nature. In fact, it would have been a brilliant argument if not for one fatal flaw: God didn’t create the bananas; we did.
Bear with me for a moment. I’m not suggesting that we magically made bananas appear out of thin air, I’m merely saying that bananas were developed by humans over the course of hundreds of years through a process called ‘selective breeding’, or ‘artificial selection’.
You have probably never seen a true wild banana before, and if you ever do in future, you might not even recognise it as a banana. In the wild, bananas are small and oval; they have thick, tough skin that is difficult to peel; they are peppered with large, hard seeds that make eating them a thoroughly unpleasant experience.
So, how was it that bananas came to be the way they are today?
Around seven thousand years ago, the first bananas were discovered. In the wild, bananas were not easy to eat. They probably had to be peeled using sharp rocks and whoever was eating them would have had to constantly spit out big seeds. However, not all the bananas were exactly the same as each other. Just like humans, some bananas were thinner than the others, some had different skin colours, some were especially seedy and some were sweeter than the rest.
Now humans were fairly intelligent even back then, and they didn’t fail to notice this diversity in the banana trees. So what they did, was to collect the bananas with the most desirable qualities they could find, and breed them. They found bananas with the smallest seeds, bananas with the thinnest skin, bananas that were longer than the others, and used them to plant new banana trees.
Just like with humans, bananas pass on traits to their offspring. A seed from a sweet banana is more likely to produce a sweet banana, just as a tall parent is more likely to produce a tall child.
Over generations of breeding, bananas with desirable traits were bred and encouraged to grow, while bananas with undesirable traits (i.e. fatter, more bitter and thicker ones) were tossed back into the wild, where their chances of survival were much lower.
As a result, an entirely new breed of banana was produced. These were bananas that had over the centuries been selectively bred so that only those best suited for human consumption were cultivated, spread and became widely available to humans.
Bananas, unsurprisingly, are not the only organisms that have been created by artificial selection. Dogs, for example, are descended from the gray wolf, but most breeds of dogs don’t look anything like a wolf. The answer is that wolves were domesticated by humans some 15,000 years ago and through thousands of years of selective breeding, evolved into the dogs we see today.
For plants, selective breeding can increase the crop yield, make fruits more tasty, improve the plants’ resilience to pests and viruses, increase the tolerance to environmental fluctuations such as temperature and humidity and much more besides.
Through artificial selection, animals can be bred to have specific behaviours (e.g. Despite their origins from pack animals, dogs have been moulded to be reasonably independent, and protective of humans) or to develop certain physical traits (e.g. The Belgian Blue was bred to be exceptionally muscular).
Artificial selection is everywhere. Whether intentionally or accidentally, humans have swayed the course of nature. Most of what we eat has been selectively bred to enhance desirable traits. Many animals we come into contact with every day did not exist before humans domesticated them.
So next time someone asks you why a banana seems to be specially designed for us, you’ll be able to answer them:
*Upon hearing this, my very first impulse was to ask, “Who, pray, invented the coconut, the pineapple, the durian and the whole host of poisonous berries?”