Chemistry after death - The chemistry of almost everything (11/31)

Uploaded by OUlearn on 03.09.2009

I've always liked happy endings with all the loose ends tied up.
I thought that's what death did,
close everything down once and for all
but chemically speaking it seems it's not quite that simple.
I think it's a taboo.
I think the chemistry of human decomposition is a taboo.
Not many scientists work on it.
It's quite hard to find a scientist that's interested in it.
It's not clean and tidy, it's not pleasant, but we all come to it.
When the crypt of a church in Spitalfields in London
had to be cleared to allow building work to start,
a team of archaeologists, historians and scientists
began working together to sift the evidence.
What could the contents of the crypt tell them
about how the people had lived and died?
Key to the research was establishing when changes had occurred.
During life or as a result of chemical changes after death?
I think you've got to understand the processes that are involved.
It isn't just a random soaking up of elements that are sitting there
queuing up to come into the bone.
They've got to be there in the first place.
Like the high lead in lead coffins
and perhaps other elements coming out of wooden coffins.
But they're overlaying what was there in the diet.
And I've got to try and tease one apart from the other.
This is a child's face here, turned bright green.
We find from the records that they'd put copper pennies across his eyes
after his death in order to keep the eyes closed
and as the body has decayed, as it's become more acid,
the copper has been mobilised and has been taken up via the bone.
Gone right through inside the bone and you get this bright green skull.
This looks like a perfectly normal skeleton of a child from the time
and we had no indication that there was anything peculiar about it
until we started doing our analyses and x-raying it.
Then we saw that there were some very remarkable differences.
One day the radiographer came to me really quite perturbed,
'I think the machine's gone wrong!'
And she showed me the x-ray
and here you see the picture she'd taken
and the lower part of the skeleton
she hadn't been able to get the x-rays to penetrate.
They were completely white.
We realised we had to take this further to try and identify
what was causing the very opaque part of the bones.
By using the electron microprobe you can actually map
the different elements in different parts of skeleton.
This must be the edge of the bone
so this is just the sample stage at the top.
And this is the surface of the top of the bone down below.
So we can move a little bit further into the bone.
It's imaging quite nicely.
So we'll go right into the middle, choose a nice bright area.
Then if we start the x-ray spectrum inquiry...
So the lead is right over the top.
The lead is enormous.
The main component of the surface of this bone is the lead.
It was only when we realised that it was all the lower bones
that were much more opaque than the upper bones
and that this could have been because the child had been lying in a coffin
that was slightly tilted and the lower part was in the coffin liquor
which is the liquid that forms in the coffin as the body decays
and would have been a means of transporting the lead
from the lead of the coffin into the bones of the individual.
There is nothing supernatural about death.
There is nothing that suddenly comes from elsewhere
that is different from the way our bodies ordinarily function.
Death occurs because we lose the possibility of oxygenating our cells.
A particular kind of chemical reaction is stopped.
It is a very natural phenomenon.