Contamination and repeatability are also factors that have to be considered with carbon dating.
A tiny amount of carbon contamination will greatly skew test results, so sample preparation is critical.
Carbon dating is reliable within certain parameters but certainly not infallible.
When testing an object using radiocarbon dating, several factors have to be considered: First, carbon dating only works on matter that was once alive, and it only determines the approximate date of death for that sample.
When an organism dies, it stops taking in new carbon-14, and whatever is inside gradually decays into other elements.
The explanation given for these outliers is usually “contamination.” Inconsistent results are another reason why multiple samples, multiples tests, and various parallel methods are used to date objects.
If the spear head is dated using animal bones nearby, the accuracy of the results is entirely dependent on the assumed link between the spear head and the animal.
This is perhaps the greatest point of potential error, as assumptions about dating can lead to circular reasoning, or choosing confirming results, rather than accepting a “wrong” date.
Tiny variations within a particular sample become significant enough to skew results to the point of absurdity.
Carbon dating therefore relies on enrichment and enhancement techniques to make smaller quantities easier to detect, but such enhancement can also skew the test results. As a result, carbon dating is only plausible for objects less than about 40,000 years old.
Due to all these factors, it’s common for carbon dating results of a particular sample, or even a group of samples, to be rejected for the sole reason that they don’t align with the “expected” results.