Today is February 12th. Darwin day. Charles Darwin was born on this day in 1809. Before Darwin one could be an atheist but not an intellectually satisfied or fulfilled one. After Darwin one could be an intellectually satisfied atheist. Although Evolution as an idea for the history of life on earth had been banded about for ages – even being mentioned by Aristotle and Lucretius (in his famous poem ‘De Rerum Natura‘ – on the nature of things) – it was Darwin who put forward a coherent mechanism by which evolution could occur. This he called ‘Natural Selection’.
Natural Selection, as the mechanism of evolution, is a very simple process. Deceptively simple even. It is its simplicity that people find difficult to reconcile with the complexity of life they see around them. They see something like the human eye with all its intricately interlocking parts, or the human brain or the biochemical basis of the immune system and they say: ‘There is no way this came about by a purposeless process! There was a designer. A master planner. It has design written all over it‘. Wrong! So wrong! All wrong! Evolution by Natural Selection is able to explain the rich diversity of life found here on planet earth. And you don’t need a designer. The reason we are awe-struck is because we only see the finished product. We never see how we get there.
It works as follows. All living things produce offspring. These offspring differ from their parents and are never the same from each other and their parents (even twins have differences). These differences arise from gene mutations which occur from radiation or chemicals, gene transpositions – where pieces of DNA are randomly excised and put back into the sequence somewhere else. There is also shuffling of chromosomal DNA during mitosis and meiosis phases of cell division. And there is the shuffling that occurs from sex: DNA from both parents combining to form a child that shares traits from both but as an individual is unique. The result of all the above processes is variation. All creatures, great and small, differ from each other and are never the same.
The result is a population of organisms that differ
Variation is the raw material of natural selection.
And in the harsh world of survival some variants are more likely to survive and bear children than others. This is because they may have a physical attribute that gives them some advantage; no matter how slight, in life’s lottery. They may have longer legs thus enabling them to run faster, or sharper teeth, or stronger muscles or more beautiful feathers – thus attracting more mates. They may acquire a biochemical mutation that allows them to manufacture Vitamin C or they may be able to see in colour thus allowing them to identify fruits. The thing is most mutations are harmful. But given time, and the sheer number of organisms that are born – throw in the struggle for resources and mates, and you have a process that can lead to better adaptability and more complexity.
These ‘better’ variant creatures than have children with those same qualities, and they too than go through the same sieving process. Offspring with qualities that give the bearers an advantage, no matter how small, in the survival stakes, are more likely to reproduce and pass on those same qualities in their genes. Creatures with variations not so good, perish. This is natural selection and over time-spans of hundreds of millions of years and over hundreds of millions of generations, natural selection works like a sieve. The world becomes populated by species that are good at surviving. Species that are supremely adapted to their particular niches. This is evolution by natural selection and it is one of the most powerful, yet also one of the most simplest ideas, that anybody has ever had.
Some people doubt that such a simple process could account for the rich diversity and complexity of life on earth – but you must understand, that our ideas of what is possible are off by millions of years because our brains are incapable of comprehending the vast amounts of geological time that is available for evolution to work its magic. A good example is mountains. Mountains when they are fully risen like the Himalayas are awe inspiringly tall and daunting. Yet their origin is humbling. All mountains start off as small little mounds or hillocks! Every year they rise a few centimetres. But over millions of years, when you add the centimetres together – you achieve great heights. The finished product looks amazing and you wonder how it can be. But it can be, because of time, and time, and time and time and more time.
Slowly, gradually, inch by inch, life evolves. It becomes better adapted to its way of life. Until you see today, feats of biological engineering that leave you awe struck and dumb with wonder.
And do you know what the most amazing thing about it is? There is no plan. No cosmic designer. No ultimate purpose or aim. Life is the result of an algorithm – the algorithm of evolution by natural selection. Life is the result of a tautology – it exists because it exists because it exists.
I am still stunned when I look about myself and think – all these people, all these humans, going about their daily lives – all this life, and all the result of a blind process. I feel immensely privileged to be alive at a moment in time where I am able to know and comprehend this most profoundest of truths.
I am an intellectually satisfied and fulfilled atheist.
Please keep resolving to keep evolving…
Happy Darwin Day.