Compare the skeleton of a man and a rat, name the reasons for the differences.

Man and rat are mammals, therefore they have 6 sections of the skeleton, their structure is similar. But, a person has changes in the skeleton associated with:

1) upright posture – 4 bends of the spine and the arch of the foot (shock absorption when walking), massive leg bones, dilated pelvis and chest;

2) labor – the thumb is opposed to the rest;

3) mental activity – due to the increase in the volume of the brain and the area of the PCB, the cerebral part of the skull predominates over the facial one, and not vice versa, as in the rat.