When it comes to discussing the changes in the brain size and body mass in humans over the previous two million years starting from Australopithecus, it is worth noting that the brain became considerably larger, which is majorly associated with the improvements in tool technology.
However, some researchers indicate other factors that contributed to such changes.
Brain shape and size became considerably different together with the social structure of ancient people that also changed and became more complex.
Besides, people started to communicate with the help of symbols.
As such, throughout the entire period of human development, the brain kept expanding.
The skull of Australopithecus resembled the skull of a chimpanzee, which indicates that the brain of Homo sapiens is distinguished by many differences when compared to the brain of our ancestors.
Simultaneously, the average size of the human body mass also increased over this period.
However, there is a dramatic difference between the appearance of contemporary Homo sapiens and that of Australopithecus.
In fact, throughout the period of a hundred thousand years, the body mass of humans decreased dramatically, while the average brain size increased accordingly.
As a result, the increase in the brain size was linked to the decrease in the body mass, which is why it can be assumed that these two processes were interrelated, being provoked by the evolution of humanity.