These include soil concentration and length of burial.
This shows also contemporaneity of hominid bones and animal bones buried at the same site.
Nitrogen decreases in buried bone and affects nitrogen concentrations. With regard to relative dating Comparative geology includes correlations with soil pollen content.
Therefore nitrogen disappears rapidly under and may be absent. Studies of the fossil fauna assemblage, comparison with other sites, and the different layers at the same site.
Also the correct ecological information of the sites. Firstly the relationship of geological, faunal, archaeological sequences at the site in terms of chronological age in years BP.
Secondly, the remains have to have contemporaneity with deposits.
The fluorine becomes fixed in the bone and is not readily removed which provides the method. dating fossil mankind requires correct placing in the Pleistocene and Holocene periods.
The addition of new mineral matter, such as lime or iron oxide, changes the latter and leads to an increase in weight.
Either from the same site or some other area if they have been preserved under comparable conditions. Fats, protein (collagen) and the fatty composition are lost quite rapidly. Under some conditions, such as permanently frozen soil or exclusion of air and bacteria, the protein may persist for tens of thousands of years.
As soon as bones are buried their composition is subject to chemical changes, some of which are slow, some fairly rapid. The appearance and texture of bone is not a reliable guide to how much organic matter it contains.
It is convenient to assess the residual organic matter in fossil bone or dentine by determination of the nitrogen content.
As bone protein or collagen decays it becomes fossilised and broken down into amino-acids. This depends on the composition of the percolating ground water which is of two kinds.