TOP ARTICLE | It's Still Evolving

Darwin's theory that all species of life have evolved over millions of years from common ancestors through the process of natural selection has profoundly altered scientific opinion regarding the development of life. In the process it's also produced a philosophical revolution that reverberates to this day. Today, which is the 200th anniversary of Charles Darwin's birth and this year the 150th anniversary of his Origin of Species, we need to ask ourselves again why the 19th century naturalist is considered one of the greatest scientists of all time, ranking with Galileo, Newton and Einstein.
Because, in the main, what Darwin proposed was not absolutely new stuff. The idea that species change had been speculated since antiquity by the Greeks, Romans, Chinese and Muslims. But such notions were never robust enough to compete with the concept of fixed forms created by some divine edict or the Platonic notion of ideal types permanently distinguished from one another. Nor were any of them ever rigorously formulated to stand up to later scientific scrutiny.
Some scientists who were nearer contemporaries of Darwin, though, fared better. In the early 19th century, Jean-Baptiste Lamarck presented his hypothesis of the transmutation of species, which was the first fully formed theory of evolution. According to him, the habits of a creature would inevitably lead to a modification of its anatomical structure. For instance, in order to reach for higher leaves a shorter necked giraffe would stretch towards them and, thus, over time, automatically acquire a longer neck. Once this addition was acquired it would be handed on to the next generation, and so on. Smart idea. But unfortunately for Lamarck, acquired characteristics are not passed on. End of theory.
Even up to just a year before Origin appeared, Darwin received a paper from a fellow naturalist and thinker, Alfred Russell Wallace, which so uncannily paralleled his own views on the subject that it immediately prompted him to co-publish an article with Wallace in the Journal of the Linnaean Society.
What all this actually establishes is that by 1859 the scientific atmosphere was saturated with the possibility of evolution and it was only a matter of time before someone stumbled upon the truth. The facts which would have supported the theory were already known and had been widely discussed before, yet no one seems to have recognised their significance. At least not entirely. The truth of the matter is that others failed to see what Darwin saw, not because they were short on facts, but because they were seeing them in a different way.
It's like the optical illusion where the profiles of two silhouetted faces on two sides of a drawing form the outline of a white vase in the middle. Sometimes we see one aspect of it and sometimes the other. Darwin's predecessors and contemporaries were generally gazing only at the faces on the edge till Darwin pointed out the vase in the middle which was actually staring them in the eye all the time. Is it any wonder then that when Darwin's friend and colleague T H Huxley first read the Origin of Species in 1859 he was so dazzled by its obviousness that he said to himself: "How stupid not to have thought of it before!"
Geologists in the 18th century had already shown that the Earth was not only millions of years older than what the Bible said but also subject to continuous physical change due to natural processes and not because of sudden historic cataclysms as theologians supposed. Also, in the 18th century Thomas Malthus had observed that plants and animals produce far more offspring than can survive so that favourable variations would tend to be preserved, and unfavourable ones destroyed. And, by the time the century ended, so much fossil had been discovered and examined that it was generally acknowledged rocks contained a whole record of previously existing life forms.
Coupled with the presence of functionless organs, a shared embryonic development pattern and the evidence of a common body plan that all animals seemed to have, astute minds before Darwin were able to come up with some pretty clever evolutionary theories of their own. These even included a modified descent from earlier archetypes. What the theories lacked, however, was a mechanism responsible for the change. That's where the genius of Darwin triumphed over everyone else.
Darwin proposed natural selection. This is the process by which only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated. Or, to give Lamarck a total makeover, those giraffes who had even a minimal advantage of height due to individual variation would be able to reach slightly higher leaves and get to eat a little bit more. They would, thus, have a better chance of surviving and, over time, producing more of their kind while the slightly shorter giraffes wouldn't.
The amazing thing about this remarkably deep insight is that when Darwin thought of it there was no mechanism available to explain how natural selection itself would work. That would have to wait for the 20th century and the development of genetics and discovery of DNA to prove him right again and again on virtually every count.