Explain how humans influence the evolution of species.

• Through artificial selection

Human beings are able to select and allow breeding of animals or plants with characteristics at the expense of others. This may lead to emergence of bred animals or plants with the desired characteristics and extinction of the others.

• Through pollution

Pollutants such as pesticides and industrial chemicals act as a selection pressure on the survival of organisms in the environment. Organisms often develop characteristics which allow them to survive the pollution. As a result, a new strain of organisms may arise.

• Through genetic engineering

Man has developed a number of techniques through which he may introduce new allelesinto population of organisms. Such organisms usually exhibit characteristics which make them better adapted to the environment than the others an therefore selected for.

• Through man-made major environmental disruptions.

Fire outbreaks, over grazing, over fishing, swamp reclamation and bomb blasts may lead to death of organisms which are sole possessor of certain genes in the population leading to their extinction. On the other hand, some organism may develop characteristic that allow them to withstand these stresses and therefore survive and reproduce leading to evolution of a new strain of organisms.