As samples get older, errors are magnified, and assumptions can render carbon dating all but useless.
For example, variations in greenhouse effects and solar radiation change how much carbon-14 a living organism is exposed to, which drastically changes the “starting point” from which a radiocarbon dating test is based.
So even brand-new samples contain incredibly tiny quantities of radiocarbon.
Eventually, the amount of carbon-14 remaining is so small that it’s all but undetectable.
When an organism dies, it stops taking in new carbon-14, and whatever is inside gradually decays into other elements.
Two plants that died at the same moment, but which naturally contained different levels of radiocarbon, could be dated to drastically different times.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.