Given diagram illustrates the evolution of cutting instruments in the Stone Age
Overall there is an improvement in the symmetry of the instrument along with increase in the sharpness of edges
About 1.4 million years the the front view of the cutting instruments had unequal sides with one side being more straighter than the the other. This improved with passsage of time, within the next 0.6 million years the forepart not only became much more symmetrical but also more tepered. This change definitely shows that more effort was put into its design as compared to its previous version.
The side view of the cutting apparatus shows that it turned more slender with the span of time. The back also shows certain changes, for example the older device backside was more coned shaped. This turned into a new design which is very similar to a droplet, having more broader lower half and more sharpened upper half.
