Question

Why it is said that evolution is a progressive development of plants and animals.

Answer 1

Evolution is a gradual change in the characteristics of a population of animals or plants over successive generations which accounts for the origin of existing species from ancestors unlike them. Life forms evolved as a result of natural selection where different adaptations to become the fittest to thrive in the varying environments led to different life forms gradually. Plants and animals evolved from first-cellular forms of life that appeared on earth around 2000 million years ago. Single cellular organisms then evolved into multicellular organisms. Around 500 million years ago the first invertebrates were formed and active. Plants that originated in the ocean invaded the land first and then the animals that evolved from fishes in the ocean which started invading the land. Later plants on land evolved from bryophytes and pteridophytes to gymnosperms and angiosperms while animals evolved progressively from fishes to amphibians, reptiles, birds and mammals and so on. The entire process of evolution which started long back is still going on is a progressive development according to the changing life conditions.