Note 1 — HOW WE LEARN about Prehistoric Men

It is important that the limitations of the radioactive carbon “dating” system be held in mind. As the statistics involved in the system are used, there are two chances in three that the “date” of the sample falls within the range given as plus or minus an added number of years. For example, the “date” for the Jarmo village (see chart), given as 6750 ± 200 B.C., really means that there are only two chances in three that the real date of the charcoal sampled fell between 6950 and 6550 B.C. We have also begun to suspect that there are ways in which the samples themselves may have become “contaminated,” either on the early or on the late side. We now tend to be suspicious of single radioactive carbon determinations, or of determinations from one site alone. But as a fabric of consistent determinations for several or more sites of one archeological period, we gain confidence in the “dates.”