Read the following statements and justify the same in your own words with the help of suitable examples.:
Human evolution began approximately 7 crore years ago.
The ice age began on the earth approximately 7 crore years ago. Due to adverse climatic conditions, dinasaures became extinct and also the forest cover declined rapidly. The evolution and diversity of mammals started during this period.
Lemur like animals (ancestors of monkey) started evolving during this period.
The tails of these monkey like animals started gradually diminishing about 4 crore yeras ago.
The body and brain increased in volume. The monkey like ancestors gave rise to two evolutionary links apes and human like animals.
The human kept on evolving. The brain volume increased. He started walking upright. He began to use his hands excessively for manipulations.
Thus, the human evolution began approximately 7 crore years ago. But the true wise and intelligent man was evolved only about 50,000 years ago.
Geographical and reproductive isolation of organisms gradually leads to speciation.
Every species survives in specific geographical conditions which can provide for food and habitat specific to that particular species. The reproductive ability and reproductive period of every species is also specific.
Therefore, the individuals from one species cannot reproduce with individuals from other species.
When the get separated by distance, they are said to be isolated geographically.
Even though the ancestor species of these subspecies may be same, there is a genetic variation between the two subspecies.
Therefore, this isolation leads to speciation.
Study of fossils is an important aspect of study of evolution.
Fossils offer good palaeontological evidence of the evolutionary process.
Study of fossils helps us to understand the characteristics of the organisms that existed in the past.
Carbon dating is a technique which helps us to estimate the age of the fossils.
Thus, study of fossils helps us to unfold the secrets of evolution.
Hence, study of fossils is an important aspect of study of evolution.
There is evidence of fatal Science among chordates. Among different chordates, there are embryological evidances.
In the early stages, young embryos of fish, amphibians, reptiles, birds and mammals show remarkable similarity.
As these embryos grow further, they acquire different patterns.
The initial similarity in the embryos of vertebrates indicates that there must be a common ancestor for all the vertebrates.
Thus, we can conclude that there is an embryological evidence for vertebrate evolution.