Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution. tement.
Evolution: The term ‘evolution’ means ‘unrolling or unfolding’. It has been derived from Latin word evolve = unfolding). It is defined as the process of gradual and orderly change from one condition to another. Such gradual and orderly changes are taking place in all the living as well as non-living things.
Therefore, evolution may be:
- Inorganic
- Organic
1.Inorganic evolution: It explains the changes that are taking place in non-living objects.
2.Organic evolution: It explains the gradual and orderly change in living organisms with time since the beginning of life. The process of evolution is continuous and it will never come to an end.
How Evolution Occurs: Evolution is a very complex and extremely slow process. There is an inhibit tendency to variation during reproduction because of errors in DNA copying and as a result of sexual reproduction. The random changes in gene frequencies occurring by chance and not under the control of natural selection are called genetic drift. Genetic drift is an evolutionary force operating in small populations. Gene frequency in small populations changes by chance. In small populations some genes may be best or reduced and other may increase by sheer chance irrespective of their selective advantage or disadvantage. Fossils provide one of the most acceptable evidences in support of evolution as we can study the evolutionary past of individuals in the form of their fossils. Study of fossils helps us to know about evolution/link between two species. We must ascertain the evolutionary order by dating the fossils. For example, if we dig earth to locate fossils, we would find that “those fossils closer to surface will be more recent origin than fossils that we find in deeper layers we can date fossils by detecting ratio of different isotopes of same element.”