Mark Wahl

¹²C of the sea (20090226)

The article Radiocarbon Dating of the Human Eye Lens Crystallines Reveal Proteins without Carbon Turnover throughout Life by Lynnerup et al published last year describes a mathematical model which predicts the year of a person's birth based on Carbon 14 dating of the eye lens, at least for people born after the bomb pulse. (This technique is already applied to analysis of the teeth and bones.)

Source: Radiocarbon Dating of the Human Eye Lens Crystallines Reveal Proteins without Carbon Turnover throughout Life

The model is however affected by the diet, specifically the lack of marine food:

Consumption of fish would have a significant effect on the ¹⁴C content of the lenses, because the ¹⁴C concentration in the sea is smaller that in the atmosphere (marine ¹⁴C reservoir effect).

This effect is summarized on the page Corrections to radiocarbon dates:

The average difference between a radiocarbon date of a terrestrial sample such as a tree, and a shell from the marine environment is about 400 radiocarbon years (see Stuiver and Braziunas, 1993). This apparent age of oceanic water is caused both by the delay in exchange rates between atmospheric CO2 and ocean bicarbonate, and the dilution effect caused by the mixing of surface waters with upwelled deep waters which are very old (Mangerud 1972).

Another component, the Suess Effect, although not discussed in the eye lens paper, is due to industrial production. The "absolute radiocarbon standard" is tied to a piece of wood that would have been growing in 1890, where there was comparatively little fossil fuel consumption.

The activity of 1890 wood is corrected for radioactive decay to 1950. Thus 1950, is year 0 BP by convention in radiocarbon dating and is deemed to be the 'present'. 1950 was chosen for no particular reason other than to honour the publication of the first radiocarbon dates calculated in December 1949 (Taylor, 1987:97).

Copyright 1999-2011 Mark Wahl. All rights reserved.