There is no real progress in the concept of evolution. Evolution is just the production of diversity of life forms and shaping of this diversity by the environmental selection. The only progress in evolution appears to be that more and more complex body designs of organisms have emerged over the ages. This will become clear from the following examples.
When a new species is formed, it is not necessary that the old species will disappear (or get eliminated) from earth. It will all depend on the environment. Also it is not as if the newly formed species are in any way better than the older ones.
It is simply that genetic drift and natural selection processes have combined to form a population having different body design which cannot interbreed with the older population. It is a common belief that chimpanzees are the ancestors of human beings. It is, however, not true that human beings have evolved from chimpanzees.
Actually, both chimpanzees and human beings had a common ancestor long time ago. The two offsprings of that ancestor evolved in their own separate ways to form the modern day chimpanzees and human beings.
Again, it is not as if the body designs of older organisms were inefficient. This is because many of the older and simpler forms of organisms still survive on earth. For example, one of the simplest and primitive life forms called ‘bacteria’ still inhabit some of the most inhospitable (or unfavourable) habitats such as hot springs, deep-sea thermal vents and the ice in Antarctica. Most other organisms cannot survive in such harsh environments.
Human evolution has been studied by using the various tools of tracing evolutionary relationships like excavating (digging earth), carbon-dating, studying fossils and determining DNA sequences. There is so much diversity of human body and features on the earth that for a long time people used to talk about different ‘races’ of human beings.
The human races were even identified on the basis of their skin colour
and named as white, black, yellow or brown. It is now known that the so called human races have raft evolved differently. In fact, there is no biological basis for dividing human beings into different ‘races’. All human beings (whether, white, black, yellow or brown) are a single species (called Homo sapiens).
It has now been established by research that the earliest members of the human species (Homo sapiens) came from Africa. So, irrespective of where we have lived for the past few thousand years, we all come from Africa. In other words, our genetic footprints tell us that we have African roots. About hundred thousand years ago, some of our ancestors left Africa while others stayed back. Those who left Africa slowly spread across the whole earth.
Mendel’s experiments tell us the mode of inheritance of traits from one generation to the next and Darwin’s theory of evolution tells us how organisms develop from simple to more complex forms. But neither tells us anything about how life originated on earth (or began on earth). We will now discuss the origin of life on earth briefly.
A British scientist J.B.S. Haldane suggested in 1929 that life must have developed from the simple inorganic molecules (such as methane, ammonia, hydrogen sulphide, etc.) which were present on the earth soon after it was formed.
He said that the conditions on earth at that time (including frequent lightning) could have converted simple inorganic molecules into complex organic molecules which were necessary for life. These complex organic molecules must have joined together to form first primitive living organisms. Haldane also suggested from theoretical considerations that life (or living organisms) originated in the sea water.
The theory of origin of life on earth proposed by Haldane was confirmed by experiments conducted by Stanley L. Miller and Harold C. Urey in 1953. They assembled an apparatus to create an early earth atmosphere which was supposed to consist of gases like methane, ammonia and hydrogen sulphide, etc., (but no oxygen), over water.
This was maintained at a temperature just below 100°C and electric sparks were then passed through the mixture of gases (to simulate lightning) for about one week. At the end of one week, it was found that about 15 per cent of carbon (from methane) had been converted into simple compounds of carbon including ‘amino acids’ which make up protein molecules found in living organisms.