Read the following statements and justify the same in your own words with the help of suitable examples. a. Human evolution began approximately 7 crore years ago. b. Geographical and reproductive isolation of organisms gradually leads to speciation. c. Study of fossils is an important aspect of study of evolution. d. There is evidence of fatal science among chordates.
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Answer:
(a) It is true that human evolution began 7 - 10 million years ago. Theories like the 'The Origin of Species' by Charles Darwin suggested that humans emerged from the apes who lived in the African regions which was confirmed by the study of the 3-4 million old Australopithecus fossils.
(b) Geographical and reproductive isolation of organisms gradually leads to speciation. ... (2) Therefore, the individuals from one species cannot reproduce with individuals from other species. (3) When they are separated by a distance or geographical barriers they are said to be isolated geographically.
(c) Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. ... Paleontologists can determine the age of fossils using methods like radiometric dating and categorize them to determine the evolutionary relationships between organisms.
(d) It is believed chordates have originated from invertebrates. (ii) It is difficult to find out from which invertebrate group the chordates were developed. (iii) Chordate ancestors were soft bodied animals, hence they were not preserved as fossils. (iv) Thus, there is evidence of fatal science among chordates.
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