Rejecting the metaphysical theory of creation of man and universe, Darwin put forward the theory of evolution .According to this theory, man has evolved and developed from his ape ancestors.
How the man has evolved on earth is still a deep mystery?. Men of wisdom and men of intellect have tried to solve this riddle with their own wisdom and have put forward various theories abbot origin of man. The metaphysical theory is based on the concept of god or Brahma. According to this hypothesis, all forms of life including humans have evolved from God. The materialists and scientists do notagree to his theory of creation of universe. The dominant scientific thought is that life is continuous and evolutionary process. Man has evolved to this phase of modern development by crossing many evolutionary processes.
Life originated on earth between four and three billion years age during Precambrian era. The atmosphere of original or primitive earth was reducing in nature. And there was no presence of oxygen in the atmosphere. In the evolutionary process universe, first formed the simple organic compounds from elements. High temperature, ultra violet rays cosmic rays provided energy for chemical actions to take place. The first organic compounds formed were simple sugars. Glycerol, fatty acids, amino acids purines and pyrimidines were the primordial compounds formed. Coacervate was the first cell formed. Coacervate were cell like structures but not true c ell structure. It lacks nucleic acids. Monera and blue green alga were the first prokaryotic cell structures. Than evolved the blue green alga or cyanobacteria. Cyanobacteria were the first photosynthetic organisms. Due to photosynthesis oxygen evolved in the atmosphere. . Now the atmosphere of earth become oxidizing in nature. Free oxygen formed a protective layer around the earth’s surface which is called ozone layer to
Earth s protective layer absorbed the radiations (ultra violet rays) coming from sun into earth’s atmosphere. The event of photosynthesis and evolution of oxygen as a consequence was milestone in the evolutionary history of mankind. It paved the way for new forms of life on earth. Slowly and slowly with million and billion of years five kingdoms of life evolved. Before Whittaker whole organisms were broadly divided into two categories
Whittaker classified whole life or different forms of life on earth into five biological entities called kingdoms. These kingdoms according to their evolutionary process are:
Man belongs to mammalian group of animals. Mammals evolved from reptiles 210 millions yeas ago in Triassic period .The order primates of kingdom animals contains man , great apes ,monkeys lemurs and tarsiers originated about 65 million yeas ago during cretaceous period. The hominoids i.e. ancestors of apes and man evolved around 24 million ago. Darwin put forward the theory of evolution of man from apes. Man’s ancestors were apes like. “Descent of man and selection in relation to sex” is his masterpiece in which he established the deep evolutionary co relationship of man with animals. There are multitude of similarities between man and apes. Some prominent ones are:
Absence of tail
Larger cranial capacity’
Show social behavior
Fore hands modified for grasping
Show similarities in blood proteins and banding pattern of chromosomes.
The modern man homo sapiens sapiens developed from cro mag non man about 10.000years ago.
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