Ways of determining chronometric age

[ThomasFuhlery]

At least I think that's the field I'm looking for.

I need to know if there is a way, through collagen collecting, DNA testing with PCR, etc., what is the defining characteristic in a piece of a BONE that would tell that it is human, i.e., is it possible to tell the # of chromosomes, or some other method?

And also: what are some ways of determining chronometric age in such a sample (besides C-14, Potassium-Argon, etc.)?

Thanks!
An Interested Layman

 

[mgb_phys]

Usually it is easiest to tell if it is human from the shape and size, especially if you you know the area you find it in. DNA doesn't always survive very well depending on the conditions. C14 is the main way of ageing human remains, at least for modern humns in the last 50,000 years.

You can also get a lot of useful information about where the person was born and grew up as well as their diet from isotope ratios.

 

[jim mcnamara]

Stratigraphy is also a primary means of dating old bones and fossilized remains.

 

[mgb_phys]

Stratigraphy is also a primary means of dating old bones

And most accurate if you have good stratigraphy.
There was a sensational result for an abbey in Whitby ( Yorkshire UK) showing monks with syphalis which C14 dated to before contact with S. America.
The monk's diet was mostly fish which pick up geological C from the sea - so the C14 dates looked centuries older than they should be.

 

[ThomasFuhlery]

Interesting!

My question was meant to refer to an otherwise unidentifiable *piece* of bone -- and the testable characteristics that might confirm that it is human.

Also -- can anyone tell me more about diet information from isotope ratios (or another method?)

And one more thing. What would you expect the range look like on a good sample of modern bone (like 20 yrs. old) with C14? (example: "___ B.P. + or - ___ @ ___ sigma").

thanks again

 

[mgb_phys]

Archeologists are very good at spotting human bone, even fragments, from the shape. And context helps, if you dig it out of grave it's human, if you dif it out of a midden and it has butchery marks it's pig!
I don't know if there are human specific antigens that you can easily detect, it may be that they are enough to determine human/pig in a site in europe but might be a problem if it either human/chimp in say africa.

Any oxygen in your bones came from the air/water but most other elements especially Carbomn must have come from your food - and so depending on if your food was eating grass which fixed CO2 out of the air or was eating shellfish that took CO2 from the sea you can tell a differenc ein isotopes.

Your last point - I don't think you could use C14 for anythng less than 100 years old just because the amount of decay would be so small. Samples newer than 1950s are also a real problem because of the effects of atmospheric atomic weapons tests.