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Q.Describe any five evidences of evolution.
Uttarakhand UbseUttarakhand Board Intermediate (Class 12) 2018Subjective· 5mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →Five evidences: (1) Homologous & analogous organs (divergent vs convergent evolution); (2) Vestigial organs (appendix, ear muscles); (3) Fossils (horse series, Archaeopteryx); (4) Embryological similarity (gill slits in all vertebrate embryos); (5) Molecular evidence (shared DNA, genetic code, cytochrome-c).
Concept
"Evolution" is descent with modification — modern species have arisen from ancestral forms over long periods. Several independent lines of evidence support this.
Five evidences of evolution
- Morphological and anatomical evidence (homologous & analogous organs):
- Homologous organs have the same basic structure/origin but different functions — e.g. the forelimbs of man, whale, bat, cheetah all have the same bone plan (humerus, radius-ulna, carpals…) but do different jobs. They show divergent evolution from a common ancestor.
- Analogous organs have different structures but the same function — e.g. the wings of an insect and a bird, or the eyes of octopus and mammals. They show convergent evolution.
- Vestigial organs: reduced, non-functional structures that were functional in ancestors — e.g. the vermiform appendix, nictitating membrane, muscles of the ear, and tail vertebrae (coccyx) in humans. Their presence indicates an evolutionary past.
- Palaeontological evidence (fossils): fossils in successive layers of sedimentary rock show a gradual, ordered change in life forms over geological time — e.g. the evolution of the horse (from small Eohippus to modern Equus) and Archaeopteryx, a fossil linking reptiles and birds (a connecting link).
- Embryological evidence: the early embryos of fish, tortoise, chick, pig and human look remarkably similar and all pass through comparable stages (e.g. gill slits, a tail), suggesting they share a common ancestry (though Haeckel's strict "biogenetic law" is now modified). …
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