Cutting Tools
The diagram below shows the development of cutting tools in the Stone Age 
The diagram illustrates the evolution of the cutting tool during the period from 1.4 million years ago to 0.8 million years ago in the Stone Age.
It can be seen that a number of upgrades were made in the shape and size of the tool so that it could become a more effective cutting instrument.
1.4 million years ago, the tool was relatively primitive and resembled a natural stone, which suggests that little crafting was done. From the front and side view, Tool A had an oval shape, rough surface and blunt edges, hence presumably the inferior version compared to Tool B.
After 0.6 million years, the tool was upgraded into a spear-shaped instrument with the tip and edges being much sharper. While tool B was 10 centimeters long - the same length as Tool A, the surface of Tool B was crafted to be smoother and the overall width to be larger. Therefore, these features rendered this version more superior in terms of cutting effeciency.