Isotopes of helium a thousand times lower than helium-4 (2.17 K). This difference is explained by quantum statistics, since helium-3 atoms are fermions, while helium-4 atoms are bosons, which condense to a superfluid more easily. The most common isotope, , is produced on Earth by alpha decay of heavier radioactive elements; the alpha particles that emerge are fully ionized nuclei. is an unusually stable nucleus because its nucleons are arranged into complete shells. It was also formed in enormous quantities during Big Bang nucleosynthesis. Terrestrial helium consists almost exclusively (99.99986%) of this isotope. Its boiling point of 4.2 K is the lowest of
Stone boiling sources: the Database of North American Indians, Binford’s Hunter–Gatherer Database, and the eHRAF files. Access to the requisite fuels to heat stones is likely associated with stone boiling's use. For example, the Deg Hit'an and the Aleut used this cooking technique despite being above the 58-degrees latitude generalized threshold, which Harold E. Driver and William C. Massey attribute to their access to wood. Stone boiling Stone boiling is a moist-heat cooking method. It involves placing heated rocks into a water-filled container to heat the liquid to the point where it can be used to cook. This method of food preparation