The diagram illustrates the development of cutting tools in stone age and it compares the tool from 1.4 million years ago to one from 0.8 million years ago.
The first part shows the front profile of the tool during the period. It could be seen that 1.4 million years ago the tools were less sharp as compared to one in 0.8 million years ago. Moreover the later was wider as compered to the older. Similarly back profile of the tool also changed to being wider as the the front profile but it was not as sharp from the top as compared to front.
On the other hand it clearly shows that side view of the tool changed over the passage of time as it went from thick and non-pointy to slimmer and sharp from both top and bottom.
There were many changes except the size which remained same at 5 cm through out the time.