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Carbon-14 datings works because once an organism dies, it stops exchanging carbon with its environment, so C14 stops coming in. Carbon dating any living organis
by jerf 7y ago
Carbon-14 datings works because once an organism dies, it stops exchanging carbon with its environment, so C14 stops coming in. Carbon dating any living organism will come back with "it died 0 years ago/hasn't died yet", give or take whatever details make it more complicated in reality than it is in theory, as it always is.
- iguy 7y agoIs there any dead carbon, like perhaps in the teeth? Have never heard of it being done, but would be neat.
- hobofan 7y agoTeeth mostly consist of hydroxyapatite, which doesn't contain any carbon. Not 100% sure, but for someone that just died, you might be able to do it with their brain, as brain cells are hardly ever renewed. For a living human I don't think there is any way that's non-invasive.
- garmaine 7y agoThat thing about brain cells not regenerating is a myth, btw.
- hobofan 7y agoCould you provide a source for that? I recently tried to read up on the topic and everything I found stated that brain/nervous cells are generally barely regenerated and can stay with you your whole life. Granted, most articles trace back to this source[0] from 1967, but if newer information exists, they've done a really bad job at spreading it. [0]: https://bionumbers.hms.harvard.edu/bionumber.aspx?&id=101940 https://bionumbers.hms.harvard.edu/bionumber.aspx?&id=101940
- 3JPLW 7y agoApparently it is possible to do radiocarbon dating on tooth enamel. Enamel contains 0.4% carbon and is indeed frozen at time of development. Unfortunately, we're limited to post-nuclear testing because without the atmospheric diffusion C14 has very low precision due to the half-life of 5730 years. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2957015/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2957015/ https://www.nature.com/articles/437333a https://www.nature.com/articles/437333a
- iguy 7y agoThanks! That's interesting, to use the post-nuclear curve as a modern clock, instead of using C14's half life for an ancient clock. For a given tooth they seem to assume all enamel was from one date, during childhood.
- sbuttgereit 7y agoAs I recall, there's also an issue with radio-carbon dating anything after atmospheric atomic weapons testing commenced.
- Someone 7y agoThat problem started earlier, when we started burning significant quantities of coal. https://en.wikipedia.org/wiki/Radiocarbon_dating https://en.wikipedia.org/wiki/Radiocarbon_dating: ”Research has been ongoing since the 1960s to determine what the proportion of 14C in the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age […] Because the time it takes to convert biological materials to fossil fuels is substantially longer than the time it takes for its 14C to decay below detectable levels, fossil fuels contain almost no 14C, and as a result there was a noticeable drop in the proportion of 14C in the atmosphere beginning in the late 19th century. Conversely, nuclear testing increased the amount of 14C in the atmosphere, which attained a maximum in about 1965 of almost twice what it had been before the testing began.”