In ancient times, people used 'angul' (finger), a mutthi (fist), length of human feet for measurements. Later on, these were not used for measurements.
The size of body parts varies from human to human. These cannot be considered as a reference for measurement. We needed a standard system of measurement. Therefore, we have standard units like kilogram, metre, etc.
For example,1kg of rice in India should weigh 1kg in Europe as well.
Therefore, 'angul' (finger), a mutthi (fist) and length of human feet cannot be used for measurement.