MadSci Network: Evolution |
Has human evolution stopped? A fascinating question. Some leading and respected scientists, including Richard Dawkins, have entertained the notion that human evolution may have ceased because we are now curing more diseases, and thus maintaining and extending human life. People who once would have died young from, say, appendicitis, are now able to live on, reproduce more, and pass on to their offspring what would once have been a genetic liability. Charles Darwin never used the phrase "Survival Of The Fittest" except to complain about it. The phrase was coined by Herbert Spencer, and preceded Darwin's publications. "Natural Selection" was Darwin's preferred term and is more accurate. It is not always "fitness," in the physical sense, that contributes to reproductive success. It may be camouflage, colourful sexual attraction (many birds), or just finding a suitable evolutionary market niche (jellyfish). It could be argued that many men "survived" the Second World war because they were to "unfit" for combat, but such an example is too short-term for the true evolutionary scale. Evolution, via natural selection, takes eons for its effects to become apparent. Humans have barely changed, phsiologically, since Cro-Magnon times. The fact that we are now taller than some of our ancestors (judging by their door frames and suits of armour) has more to do with our improved nutrition and hygiene than it does with evolution. Also remember that medical science is still only influencing a small proportion of the world's population. Most inhabitants of the third world are still sadly afflicted with the diseases of our ancestors. Also, cultural (as opposed to natural) selective forces are now much more actively at work in all human, and domestic-animal, societies. So, evolution (via natural selection) is still at work, though painfully slowly, and it will take much more than just 100 years of medical science, with limited reach, to stop it. I would welcome other views on this subject. Brian
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