Methods of dating artifacts
This number is usually written as a range, with plus or minus 40 years (1 standard deviation of error) and the theoretical absolute limit of this method is 80,000 years ago, although the practical limit is close to 50,000 years ago.
Because the pool of radioactive carbon in the atmosphere (a result of bombardment of nitrogen by neutrons from cosmic radiation) has not been constant through time, calibration curves based on dendrochronology (tree ring dating) and glacial ice cores, are now used to adjust radiocarbon years to calendrical years.
Relative dating methods allow one to determine if an object is earlier than, later than, or contemporary with some other object.
It does not, however, allow one to independently assign an accurate estimation of the age of an object as expressed in years.
Culture history and diffusionism may - with hindsight - seem excessively preoccupied with classification and social evolution, and to have applied unsophisticated historical interpretations instead of asking fundamental questions about human behaviour.
The earliest-known hominids in East Africa are often found in very specific stratigraphic contexts that have implications for their relative dating.
They do not, however, give "absolute" dates because they merely provide a statistical probability that a given date falls within a certain range of age expressed in years.
Chronometric methods include radiocarbon, potassium-argon, fission-track, and thermoluminescence.
These strata are often most visible in canyons or gorges which are good sites to find and identify fossils.
Understanding the geologic history of an area and the different strata is important to interpreting and understanding archaeological findings.