Second, radiocarbon dating becomes more difficult, and less accurate, as the sample gets older.
Radiocarbon dating can’t tell the difference between wood that was cut and immediately used for the spear, and wood that was cut years before being re-used for that purpose.
Nor can it tell if a much older spearhead was attached to a brand-new shaft.
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.
For example, a steel spearhead cannot be carbon dated, so archaeologists might perform testing on the wooden shaft it was attached to.
This provides good information, but it only indicates how long ago that piece of wood was cut from a living tree.
Carbon dating is reliable within certain parameters but certainly not infallible.
Several factors affect radiocarbon test results, not all of which are easy to control objectively.For this reason, it’s preferable to date objects using multiple methods, rather than relying on one single test.