Adaptation

• Adaptations are favourable, heritable variations or changes that enable an organism to increase its chances of survival.

• Such variations are the result of genetic recombinations or mutations.

• Adaptations can be either permanent (i.e., heritable from generation to generation) or temporary (i.e., within an organism's life span. It can again be a short term or long term adaptation).

• Short term adaptations are temporary in nature and appear in response to a particular condition, season or stage of the life cycle.

For example, when skin is exposed to sunlight for a considerable period of time, it starts turning black in colour. It is due to the formation and accumulation of melanin pigment. It protects the body tissues from harmful radiation.

• Long term adaptations are permanent changes that have occurred over many generations, in response to some significant changes in the environment. These adaptations have now become genetic characteristics of the species.

For example, in the course of human evolution, forelimbs have become free from the task of locomotion and have opposable digits. This adaptive feature has enabled man to use his forelimbs for various activities like holding, examining or throwing an object, making and using of tools and so on.