I emailed my friend, colleague and font of all knowledge – Gerry Foley – the other week to check if there is any scientific proof of the head weight. I’ve understood for some years that it’s about 10-12 lbs or 4-6kg but wanted to know if this was actually true or not. Incidentally, those weights equate to about 5 bags of sugar or 4-6 litres of water.
Here is Gerry’s response:
“I think the conventional figures are fairly reliable. There was quite a bit of research by earlier anatomists when separated heads were more readily available especially in France. There is obviously a lot of variation between people so absolute accuracy is irrelevant.
If you want to check it out roughly, the mathematics are fairly simple. Human flesh is approximately the density of water – bodies float. The skull is a bit denser than other bits but not much since we can float horizontally in water. So you can assume that a head is made of water and work out its volume as being somewhere between a cube and sphere. The volume of a sphere can be got from Google – I can’t find all the symbols. You can also work out the volume of a cube. Given the variations, in shape and size, this will reassure you 4-5 kg is reasonable.
New Scientists journalists checked by filling a bucket of water and putting it inside a basin. They then up-ended a shaven-headed colleague and dipped his head into the bucket. The displaced water that flowed into the basin was the volume of the head which at 1gr/ml gives you the weight.”
So there you have it.
I recently gave a talk about the Alexander Technique and brought in a 5 litre bottle of water. No one wanted to lift it, even though this is what we balance on our necks. Everyone had back, neck or shoulder pain. It’s crucial that we get a good balance of our heavy heads on our necks otherwise it leads to problems.