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It may involve a mutation in the genetics of a group of organisms.

Evolution is understood to be the changes occurring in species which provide them with characteristics which make them well suited to survive in their respective habitat and environment. It may involve a mutation in the genetics of a group of organisms. This a broad definition that you will find mentioned in human evolution class 10 lessons.

As students of Biology, you must also know its different types even though it goes beyond human evolution 10 syllabus.

Evolution of two species occurs independent to each other. However, the same level of similarity will be maintained. It usually occurs in two unrelated species.

It relates to the common understanding of evolution. Here, two species become increasingly different over time. It occurs in closely related species that diversify to adjust to a new habitat.

In convergent evolution, two different species share a common ancestry. Those continue to retain some analogous traits. For instance, whales and fish share common traits owing to their movement in the same medium, water. Do You Know? Even though evolution is an extremely slow process, scientists have identified the fastest evolving animal. Tuatara, also known as ‘Living Dinosaur’, is found in New Zealand and also resembles a lizard.

Even though the mechanism of evolution involves improved abilities in a species, it does not mean that evolution is progressive. Natural selection does not produce perfect organisms suited to the surrounding environment. The surviving species merely possess a conducive range of traits. Hence, evolutionary change does not automatically ensure persistence of particular species. For example – mosses, fungi, shark and crayfish have undergone little physical change over the passage of time. It did not render those unsuited for its surrounding environment. The discourse of progress is not entirely compatible with evolution. With climate and topological changes, the existing favourable traits in an organism may become poorly suited for survival with massive changes in environment. There are other attributes related to this aspect that is beyond the ambit of human evolution class 10 lessons.

There are four forces to human evolution which you will find mentioned in human evolution textbook –

It is the differential reproduction in an organism that develops certain functional traits which help in adapting to the environment. Genetic variation is held to be the main cause of genetic inheritance and natural selection.

The change in allele frequencies occurring only due to chance over time is called genetic drift. Allele frequency chance changes evident in one generation may alter the probability of such transmission in the following generation.

Mutation takes place largely due to error in DNA copying which is classified into somatic mutation and germinal mutation. Somatic mutation impacts all cells apart from gametes. On the contrary, germinal mutation only occurs in such cells that convert to gametes.

Population mating structure includes such parameters that convert in non-random mating among the members of a species. The factors may be behavioural, temporal and physiological, among others. Test Your Knowledge 

(a) remarkable increase in brain size (b) shortening of jaws (c) upright walking (d) loss of body hair

(a) sparse body hair (b) absence of tail (c) arms shorter than legs (d) broadened chest due to flattened sternum Solutions: i. (a) remarkable increase in brain size, ii. (c) arms shorter than legs  

Ans.  Existing environmental conditions leads to adaptation in species. Evolution primarily gives rise to diversity with the help of environmental selection. However, progress in evolution involves complex body designs. Hence, evolution and progress are not similar.

Ans. No. ‘Survival of the fittest’ is a statement referring to the process of natural selection. On the other hand, evolution refers to the ability to survive. In that sense, evolution is the prerequisite to the fittest species.

Ans. Evolution leads to genetic variation affecting the physical characteristics of a species. Such characteristics may make one species have an advantage over another.