Bible critics have long used use the "lack of evidence proves something" tactic. One explanation for the lack of camel bones in copper mines is that camels were too valuable to be used in the day to day operation of such mines, but were used for what they do best, which is long distance transportation. It's to be expected then that their bones rarely ended up in copper mines. The critics dismiss the presence of such bones in early layers as being those of wild camels, as if any wild camel would hang around a working copper mine.
What the research really shows is at what time camels became cheap enough to use in copper mines, but of course such a claim wouldn't win any notoriety or research grants.
