Over 60 further radionuclides are detectable in nature, either as daughters of these, or through natural production on Earth by cosmic radiation.
These skeletons are among the most radioactive ever found, on par with those at Hiroshima and Nagasaki.
At one site, Soviet scholars found a skeleton which had a radioactive level 50 times greater than normal.
During those processes, the radionuclide is said to undergo radioactive decay. The unstable nucleus is more stable following the emission, but will sometimes undergo further decay.
Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay.) for that collection can be calculated from their measured decay constants.
The range of the half-lives of radioactive atoms have no known limits and span a time range of over 55 orders of magnitude.
Radionuclides occur naturally and are artificially produced in nuclear reactors, cyclotrons, particle accelerators or radionuclide generators.
The DNA is exceedingly rare in the soil compared with that from plants, animals, fungi and microbes.
It is also easy to mix it up with DNA from human excavators, for instance.
The technique opens up a new way to probe prehistory.
From sediments in European and Asian caves, a team led by geneticist Viviane Slon and molecular biologist Matthias Meyer, both at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced genomes of cell structures called mitochondria from Neanderthals and another hominin group, the Denisovans. “It’s exciting to see that you can end up with a whole pile of ancient-human DNA from just dirt,” says Michael Bunce, an evolutionary biologist at Curtin University in Perth, Australia.
There are about 730 radionuclides with half-lives longer than 60 minutes (see list of nuclides).