So as you are cutting through the outer plate, you can feel it because it's hard, slightly less hard when you get to the middle part, then you know when you are at the inner place, you know where you have got to be careful because you do not want to start to hit the brain.

  So you have got control of this. You will be cutting from a wider outside circumference, and you would cut carefully, and you would double end as you cut around, and you would change direction and you would cut from the other side. And when you get where you want to be, you cut out and lift out very carefully the bits of bones you don't want in there.   Despite the crude nature of the surgical instruments, signs of healing around the holes showed how adept these early surgeons were at performing delicate operations.

  They knew how to do it. They knew it worked. And they were very successful at this because they nearly all healed.

  Evidence of surgery, industrial scale flint mining, and a new understanding of the new Cursus has revealed a people capable of complex reasoning and planning, who express their ceremonial beliefs in precise solar-aligned monuments.