Some common misconceptions about evolution
SPECIAL CORRESPONDENT
There is a section of people who firmly believe that all living things seen today are the products of Divine creation and hence cannot accept evolution. But misconceptions abound even among people who believe in evolution.
The New Scientist in its issue of April 16 2008 lists out these misconceptions. Here are some of them.
First is that natural selection explains everything we see today.
There are two fundamental mechanisms of evolution. Natural selection is only one of them. The less realised mechanism is the random genetic drift. The anti-evolutionists fail to recognise genetic drift. Darwin did not know about it either.
Genetic drift
Genetic drift is the random change in the genetic composition of a population due to chance events. It all boils down to how the two alleles, one inherited from each parent, get affected. The smaller a population, the bigger the role of genetic drift.
Genetic drift has played an important role in human evolution. By the time the last ice age ended about 10,000 years ago, human population had shrunk. The migration of humans out of Africa 60,000 years ago was another instance when the population had become smaller.
Survival guaranteed
Second is about the survival of species. The theory of survival of the fittest is widely misunderstood.
Evolution does not always increase the chances of a species’ survival. Mutations, which provide the vital mechanism for natural selection, need to be helpful.
Detrimental mutations are a common phenomenon. Species may not survive if such mutations happen rapidly and if they keep accumulating.
Again, if the rate at which mutations happens is slow, then a species may not be able to cope with changing environmental conditions.
Third is that only the biggest, strongest survives. Fittest does not always go with the most aggressive or strongest species. On the contrary, the ‘fittest’ label may be more appropriate to animals that are the most co-operative like the bees, the best camouflaged or the cleverest.
The ‘lowly’ sponge and the jellyfish with a few simple cell types have persisted from the Precambrian, and have changed very little. It is the same with fungi, mosses, sharks, and horseshoe crabs.
Fourth is about perfectly adapted creatures. Natural selection only produces species that are as good as they could be. They never produce the perfect ones but just the ones that can survive at that instant.
The fitness of an organism is relative to its ever-changing environment. No species has the best of all characteristics. Human eye with its blind spot and inability to see in the dark is not the best.
The pinnacle
Fifth is the notion that man occupies the pinnacle. Till recently scientists believed that “modern invertebrates, fish, amphibians, reptiles, birds, mammals and humans were living representatives of successive evolutionary steps toward a more complex brain,” (Scientific American, December 2008).
But the fact is that complex brains — and sophisticated cognition — have evolved from simpler brains multiple times independently in separate lineages.
This can be seen in molluscs such as octopuses; in bony fishes such as goldfish and, separately again, in cartilagenous fishes such as sharks and manta rays; and in reptiles and birds.
Evolutionary ladder
Evolutionary ladder is the last misconception. Evolution does not proceed in a specific direction and at a rate that will see a continuous improvement of organisms.
This is often stated as climbing an evolutionary ladder. This is simply not the case. Rather, organisms either adapt to environments that are always undergoing change, or risk extinction.
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