(October 2011) The question of how many people have ever lived on Earth is a perennial one among information calls to PRB. First published in 1995 and updated in 2002, this latest 2011 article includes data through mid-2011 and a short video explaining the estimate.
Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.
Uncalibrated radiocarbon measurements are usually reported in years BP where 0 (zero) BP is defined as AD 1950.
Historians of the time had followed a variety of previous dating schemes, including the dominant Roman one of "A. C." ("Ab Urbe Condita" or "After the Founding of the City") or a shorthand method that simply named the reigning consuls of that year. Support for the BC/AD system over BCE/CE due to it being based on the birth of Jesus is strange, considering that AD and BC are inaccurate themselves.
In Exiguus' time, the dominant system was Anno Diocletiani - years since the beginning of the reign of the Emperor Diocletian. The birthdate of Jesus was definitely not in 1 AD,, and definitely not around December 25th.
It is also worth noting that the half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, which is known as the Cambridge half-life.
Although it is less accurate, the Libby half-life was retained to avoid inconsistencies or errors when comparing carbon-14 test results that were produced before and after the Cambridge half-life was derived.It is no surprise, then, that they began to use the same method of dating for both their religious timekeeping and secular events. There have been several suggestions to pick an earlier starting point, which would enable a single system to address all of history.Joseph Scaliger proposed Julian Era dates, from 4713 BCE.Calibration is not only done before an analysis but also on analytical results as in the case of radiocarbon dating—an analytical method that identifies the age of a material that once formed part of the biosphere by determining its carbon-14 content and tracing its age by its radioactive decay.Carbon-14 is a naturally occurring isotope of the element carbon.But Exiguus did not like that, since Diocletian launched one of the greatest persecutions of Christians in history. Therefore, since the BCE/CE is technically an arbitrary date, which is set due to the historical precedent of BC/AD in the Gregorian calendar, and doesn't shift, it will always remain accurate.