Darwin’s theory of descent by natural selection may, to some anyway, seem far-fetched and even a little overwhelming. I think most people who embrace science with an open mind would admit that there is a point when learning specific theories where the jaw drops and the mind expands. This is especially so with evolution. Perhaps one of the greatest insights that evolutionary theory can bring to the human mind is the idea of bottom up development, in all it’s autonomy and parsimony. The idea that natural forces, given cetain conditions, can create greater and greater complexity over time is a fascinating and mind expanding idea. Richard Dawkins calls this consciousness raising and Daniel Dennett calls the bottom-up development process a “crane”. Once our consciousness has been raised to the point where we can identify the crane in nature (natural selection) this can extend into many other areas, including physics and specifically the origins of the universe.
Cranes and consciousness raising aside, evolutionary biology represents a powerful affirmation of the power of science as a knowledge gathering and testing tool. Science proceeds by through a rigourous approach to testing hypothesis and a ruthless discarding of those that can’t withstand such scrutiny. Ideas are evaluated on their own merits and will rise or fall given the evidence. A theory should make testable predictions about further discoveries. Evolution, as it happens, makes tonnes of predictions which can be tested in multiple lines of inquiry.
For instance, when Darwin published On the Origin of Species 150 years ago he knew there were many as yet untested ideas that could potentially falsify his theory. Inheritance and natural selection fit with what he saw in the anatomy of plants and animals and the fossil record, as incomplete as it was in 1859. What his theory lacked was the gene and specifically DNA. The requisite discoveries in genetics and molecular biology came much later and when they did, evolution was a stronger theory. By the end of the 19th century, pre-eminent physicist of the day Lord Kelvin calculated the age of the Earth to be 100 million years old. This was seen by many as a death blow to evolution as long periods of time were necessary for the kind of changes needed for evolution to explain the diversity of life on the planet. Time was also necessary if continental drift were to have occured as postulated in the 1920s. With the promise of radioactive dating techniques providing an answer, the age of the Earth wasn’t settled until the 1950s when it was settled at about 4.56 million years. Another separate endeavour supported evolution, as did the discovery of DNA, also in the 1950s. These are just some of the lines of evidence that support evolution and they provide a great example about how evidence from separate inquiries triangulate and point to one hypothesis over another.
Science steps on people’s toes, no question. Far from being a weakness of science, this is its principal strength – science can inform and sometimes challenge and dismiss our intuitive/non-rational ideas of the world. It is innately human to find meaning where there is none and to draw false cause-effect inferences from the data in the natural world. These flaws combined with biases, emotions, flaws in reasoning and other perceptual/cognitive foibles prevent human minds from discovering true cause and effect mechanisms around us. Science is a methodology to control for all these flaws and shortcomings so that we can accurately interpret nature. Evolution is a powerful theory that is still denied today by people (creationists) who claim the authoritative writings of their holy book contradict evolution, therefore evolution is wrong. This kind of flawed logic, reasoning and bias is why science so important. Human beings are not in the business of truth testing – our default brain mechanism is belief protection through confirmation bias. Because of this, Galileo, Newton, Einstein and Darwin have all had to battle established and cherished beliefs in presenting their now celebrated works. Science protects ourselves from our own faulty belief creation mechanisms.
Darwin insisted that theory comes to and from the facts, not from political or philosophical beliefs, whether from God or the godfather of scientific empiricism.
-Michael Shermer in Why Darwin Matters.
As one final point, evolution is powerful because it unites all living things via a tree of descent back to a common ancestor. A single unifying theory of all nature is not only humbling – it’s also a good starting point to dismantle all the xenophobic distinctions and cultural, ethnic, racial and religious vendettas that still seek to divide us.