Biochemical investigations helped us in establishing molecular homology. Homology is also seen amongst the molecules. For example, the proteins found in the blood of man and ape are similar. Following are other shreds of evidence of evolution from biochemical investigations:-  (i) The Protoplasm: The basic substance of living body contains nearly the same elements compounded from roughly the same proportions of proteins, carbohydrates, fats, water am other substances. (ii) Enzymes and Hormones: In a particular group of plants or animals, similar enzymes hormones occur. This is specially true of some of the digestive enzymes in animals. In almost all the green plants belonging to diverse groups photosynthetic enzymes are the same. The indicates seemingly a common ancestry of all green plants. (iii) Metabolites: The presence of characteristic chemical substances, such as aromatic volatile oil in the members of Rutaceae and Labiatae, resins in conifers and so on, suggests that the members are closely related. (vi) Blood Groups: The blood of human has been classified into four well known groups ‘A’, ‘B’, ‘AB’ and ‘O’ on the basis of antigen-antibody reaction. Red blood cells may carry antigen ‘A’ or ‘B’ or both ‘AB’ or ‘O’ (none) and person’s blood group is named accordingly.