Evidences of evolution :
1. Morphological Evidences :
- Various similarities like structure of mouth, position of eyes, structure of nostrils and ear pinnae and thickly distributed hairs on body are seen in animals.
- Whereas similarities in characters like leaf shape, leaf venation, leaf petiole, etc. occur in case of plants.
- This indicates that there are some similarities in those groups and hence it proves that
- their origin must be same and
- must have common ancestors
2. Anatomical Evidences :
- There doesn’t seem any superficial similarity between human hand, foreleg of ox, flipper of whale and patagium of bat.
- Similarly, use of each of those structures is different in respective animals.
- However, there is similarity in structure of bones and joints in organs of each of those animals.
- This similarity indicates that those animals may have common ancestor.
3. Vestigial Organs :
- Degenerated or underdeveloped useless organs of organisms are called as vestigial organs.
- In living organisms, sudden development of new tissues or organs for living in changing environment is not possible.
- Instead, existing organs undergo gradual changes.
- Such organ, though non-functional in certain organisms, it may be functional in other organisms i.e. it is not vestigial in other organisms.
- Appendix, which is useless to human, is useful and fully functional organ in ruminants.
- Similarly, muscles of ear pinna, which are useless to human, are useful in monkeys for movement of ear pinna.
- Various vestigial organs like tail-bone (coccyx), wisdom teeth, and body hairs are present in body of human being.
4. Palaeontological Evidences :
- Large number of organisms get buried due to disasters like flood, earthquake, volcano, etc.
- Remnants and impressions of such organisms remain preserved underground. These are called as fossils.
- Study of fossils is an important aspect of study of evolution.
- Carbon consumption of animals and plants stops after death.
- Only the decaying process of C-14 occurs continuously.
- In case of dead bodies of plants and animals, instead of remaining constant, the ratio between C-14 and C-12 changes continuously as C-12 is non-radioactive.
- The time passed since the death of a plant or animal can be calculated by measuring the radioactivity of C-14 and ratio of C-14 to C-12 present in their body. This is ‘carbon dating’ method.
- It is used in palaeontology and anthropology for determining the age of human fossils and manuscripts.
- Once the age of fossil been determined by such technique, it becomes easy to deduce the information about other erstwhile organisms.
- It seems that vertebrates have been slowly originated from invertebrates.
- Carbon dating method is based upon the radioactive decay of naturally occurring C-14 and it is developed by Willard Libby.
- Nobel Prize -1960.
- Published in the journal ‘Radio Carbon’
- Some plants and animals show some morphological characters by which they can be related to two different groups; hence they are called as ‘connecting links’.
- Ex. In Peripatus, characters like segmented body, thin cuticle, and parapodia-like organs are present.
- Similarly, these animals show tracheal respiration and open circulatory system similar to arthropods.
- This indicates that Peripatus is connecting link between annelida and arthropoda.
- Similarly, duck billed platypus lays eggs like reptiles but shows relationship with mammals too due to presence of mammary glands and hairs.
- Lung fish performs respiration with lungs irrespective of being fish.
- These examples indicate that mammals are evolved from reptiles and amphibians from fishes.
6. Embryological Evidences:
- Comparative study of embryonic developmental stages of various vertebrates shows that all embryos show extreme similarities during initial stages.
- Those similarities decrease gradually.
- Similarities in initial stages indicate the common origin of all these animals