Tracing evolutionary relationship

Asked by Jaziya | 19th Feb, 2010, 06:04: PM

Expert Answer:

Study of comparative embryology revels the following facts:

i) All vertebrates show common general pattern of development such as unicellular zygote, multicellular cleavage stage, single layered blastula and double layered gastrula.

ii) Early embryos of different vertebrates show striking similarities at one or the other stage.

iii) The embryos of man, lizard and frog show fish-like gill slits even though none of them have gills in the adult stage.

iv) The heart of man in the embryonic condition passes through two chambered and three chambered stages and finally becomes four chambered.


The appearance of gill arches as in fish, three chambered heart as in amphibian and a distinct tail like retiles, in the embryos of man makes one believe that there is ancestral relationship between fish, amphibian, reptile and man. Thus the study of embryology throws light on the possible ancestry of different organisms.


Kindly post each query separately.

Answered by  | 20th Feb, 2010, 06:53: AM

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