Evolution by Stages

Evolution involves the gradual changes from simple to more complex forms. Humans are believed to have developed from simpler forms. The evolution is hypothesized to have begun in the oceans billions of years ago. Darwin gave the theory of evolution. In his book -The Origin of Species, Darwin has mentioned that evolution has occurred through a series of natural selection. The theory emphasized the following points:

  • Struggle for Existence
  • Variation
  • Survival of the Fittest
  • Natural Selection

Evolution is the result of the interaction between the following five processes:

  • Mutation
  • Genetic Recombination
  • Chromosomal Abnormalities
  • Natural Selection
  • Reproductive isolation

Stages in Human Evolution

The following are the stages of human evolution:

1.Dryopithecus

These are considered to be the ancestors of both men and apes. They lived in Africa, China, Europe, and India. The genus Dryopithecus means oak wood apes. When Dryopithecus was alive, the tropical lowlands which it inhabited were densely forested, so the members might have been predominantly herbivores.

2.Ramapithecus

Their first remains were discovered from the Shivalik range in Punjab and later in Africa and Saudi Arabia. They lived in open grasslands. Two pieces of evidence confirm their Hominid status:

  1. Robust jaws, thickened tooth enamel, and shorter canines.
  2. Use of hands for food and defence, and extrapolations of upright posture.

3.Australopithecus

The fossil of this genus was first discovered in 1924 in South Africa. They lived on the ground, used stones as weapons, and walked erect. They were 4 feet tall and weighed 60-80 pounds.

4.Homo Erectus

The first fossil of Homo Erectus was found in Java in 1891. These were named as Pithecanthropus Erectus. These were considered as the missing link between the man and apes. Another discovery made in China was the Peking man. This specimen had large cranial capacities and are believed to have lived in communities. Homo erectus used tools made of quartz. Tools made of bones and wood are also discovered. There is evidence of collective huntings. There is also evidence of the use of fire. The Homo Erectus is believed to dwell in caves.

5.Homo Sapiens Neanderthalensis

The Homo Erectus evolved into Homo Sapiens. During evolution, two sub-species of Homo Sapiens were identified- Homo sapien Neanderthal and Homo sapiens sapiens. The cranial capacity of Neanderthal grew from 1200 to 1600 cc. Few small hand axes had also been discovered. This species of hominids were capable of hunting big games such as mammoths.

6.Homo Sapiens Sapiens

The remains of Homo Sapiens were first discovered in Europe and were named Cro-Magnon. In these, the jaws are quite reduced, the modern man’s chin appeared, and the skull was rounded. Their cranial capacity was about 1350 cc. They gathered food through hunting. Art first appeared during this time.

This is how evolution took place.

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