# carbon dating fallacy **URL:** \ **Category:** Factual Questions\ **Created:** [May 31, 2012, 1:17pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646 "2012-05-31T13:17:53Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![rtfgirl](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@rtfgirl](https://boards.straightdope.com/u/rtfgirl)\ **Post date:** [May 31, 2012, 1:17pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/1 "2012-05-31T13:17:53Z")
there has been numerous times when carbon dating has been proven flawed… when was the most recent? ---
**Author:** ![Sicks\_Ate](https://avatars.discourse-cdn.com/v4/letter/s/258eb7/32.png) [@Sicks\_Ate](https://boards.straightdope.com/u/Sicks_Ate)\ **Post date:** [May 31, 2012, 1:19pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/2 "2012-05-31T13:19:49Z")
Ohhhh, I get to say it first! Cite? ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [May 31, 2012, 1:20pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/3 "2012-05-31T13:20:48Z")
> [@rtfgirl](#): > > there has been numerous times when carbon dating has been proven flawed… when was the most recent? Perhaps you could name an occasion you would like to discuss? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [May 31, 2012, 1:27pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/4 "2012-05-31T13:27:23Z")
When was the most recent? Probably in someone’s imagination. But the OP needs to flesh things out a bit. I’m certain there are times when particular readings were wrong and had to be corrected because of contamination or something. However, the concept is sound and has never scientifically been shown to be flawed. ---
**Author:** ![Bootis](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@Bootis](https://boards.straightdope.com/u/Bootis)\ **Post date:** [May 31, 2012, 1:33pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/5 "2012-05-31T13:33:11Z")
> [@rtfgirl](#): > > there has been numerous times when carbon dating has been proven flawed… when was the most recent? All the time, probably yesterday or even today- carbon dating is only accurate to within a few years! That’s a flaw right? That it’s not accurate to the the minute? Another flaw is it doesn’t work well on things that contain no carbon. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [May 31, 2012, 1:37pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/6 "2012-05-31T13:37:35Z")
> [@rtfgirl](#): > > there has been numerous times when carbon dating has been proven flawed… when was the most recent? How about when that bar of Confederate gold was confirmed? 😃 ---
**Author:** ![rtfgirl](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@rtfgirl](https://boards.straightdope.com/u/rtfgirl)\ **Post date:** [May 31, 2012, 1:38pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/7 "2012-05-31T13:38:13Z")
> [@leahcim](#): > > Perhaps you could name an occasion you would like to discuss? haha i asked u!!! but a little hint… it’s less than 50 years ago! ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 31, 2012, 1:39pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/8 "2012-05-31T13:39:43Z")
[Carbon dating flaws](http://news.slashdot.org/story/08/09/10/2257242/research-finds-carbon-dating-flawed). OK, it’s not Carbon-14, but the OP didn’t specifically say that. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 31, 2012, 1:46pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/9 "2012-05-31T13:46:13Z")
This comes up all the time as a creationist debating point, and the argument, such as it is, is generally based on a fundamental misunderstanding of how carbon dating works and when it’s appropriate to use it. To summarize, carbon dating works reliably only upon certain types of samples - organic material that was once alive - and upon material of a certain age. Because radioactive decay is an exponential process, using it to date very young or very old (relative to the half life of the isotope) is bound to give wildly inaccurate results. Critics of carbon dating point to these limitations, usually by pointing to the wildly inaccurate results obtained by dating very inappropriate samples, and claim that therefore carbon dating is wrong and should never be used. The fact is, of course, that the scientists who actually use it are well aware of these limitations and make sure to work within them. This fact is universally ignored by the critics. ---
**Author:** ![BowlOfDucks](https://avatars.discourse-cdn.com/v4/letter/b/2bfe46/32.png) [@BowlOfDucks](https://boards.straightdope.com/u/BowlOfDucks)\ **Post date:** [May 31, 2012, 1:46pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/10 "2012-05-31T13:46:19Z")
Usually when they carbon date sea life or something that eats sea life, since carbon dating doesn’t work on sea life or anything that eats a lot of it. So from time to time you hear someone discrediting carbon dating, mentioning that they found a living shellfish that was carbon dated to be 50,000 years old or something like that. Well duh, it’s sea life. Carbon dating does not work on sea life. Scientists know it doesn’t work on sea life, so they don’t use it to date sea life! Or some idiot says they carbon dated a fossil dinosaur bone to be 5,000 years old or something like that. Again, DUH, it’s a fossil, there’s no carbon in it! The bone has long ago rotted away and has been replaced by rock. If you’ve found carbon to date in a fossil, it’s a modern contaminant, there’s no bone there, it’s rock! ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 31, 2012, 1:47pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/11 "2012-05-31T13:47:45Z")
Given that carbon dating is not a great deal more than 50 years old as a scientific tool, and it was a considerably blunter and less accurate version back then than now, it seems difficult to understand how an issue so long ago can be meaningful. It is well understood that as we attempt to date things a very log time ago he accuracy declines, largely because we have to make assumptions about the rate of production of the isotopes that depend on things we know vary but can’t directly know what those rates were. But within the bounds of those assumptions it works very well. There are the usual cranks who try to work up some tortured logic to attempt to prove creationism, or some variant of a 6000 year old Earth. Either by assuming what they wish to prove, or by blandly ignoring how it actually works. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [May 31, 2012, 1:52pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/12 "2012-05-31T13:52:10Z")
> [@rtfgirl](#): > > haha i asked u!!! but a little hint… it’s less than 50 years ago! In case you haven’t read the rules here, this forum is for asking questions that have factual answers. It’s not a forum for posing riddles. Might I suggest you come out and say whatever it is you have to say? ---
**Author:** ![supery00n](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@supery00n](https://boards.straightdope.com/u/supery00n)\ **Post date:** [May 31, 2012, 1:53pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/13 "2012-05-31T13:53:41Z")
Here’s a couple of paragraphs on the need for calibration of radiocarbon dating (Wikipedia article on Radiocarbon dating): > [@](#): > > Dates may be expressed as either uncalibrated or calibrated years (the latter abbreviated as cal or cal.). A raw BP date cannot be used directly as a calendar date, because the level of atmospheric 14C has not been strictly constant during the span of time that can be radiocarbon dated. The level is affected by variations in the cosmic ray intensity which is in turn affected by variations in the Earth’s magnetosphere.[18] In addition, there are substantial reservoirs of carbon in organic matter, the ocean, ocean sediments (see methane hydrate), and sedimentary rocks. Changes in the Earth’s climate can affect the carbon flows between these reservoirs and the atmosphere, leading to changes in the atmosphere’s 14C fraction. As the graph to the right shows, there is an overstatement of the age of the sample of nearly 1000 years in an uncalibrated dating of 7000 BP. > > Aside from these changes due to natural processes, the level has also been affected by human activities. From the beginning of the industrial revolution in the 18th century to the 1950s, the fractional level of 14C decreased because of the admixture of large quantities of CO2 into the atmosphere, due to the excavated oil reserves and combustion production of fossil fuel. This decline is known as the Suess effect, and also affects the 13C isotope. However, atmospheric 14C was almost doubled during the 1950s and 1960s due to atmospheric atomic bomb tests.[19] In short, if the ratio of carbon 12 to carbon 14 is taken to correspond perfectly to a calendar year, then that will lead to errors that are unacceptable. But calibration reduces these errors to a point where for objects less than about 50,000 years, carbon dating can be extremely effective. The controversies that have been found in radioactive dating are more prevalent in the radioactive isotopes that are nonbiological, which generally tend to have extremely long half lives so that even a small error could lead to a million or even billion year error in worst case scenarios. One example is the discovery that solar flares correlate with the decay rate of a particular radioactive isotope; this finding has been confirmed independently by multiple laboratories. What is more, it was found that the change in the decay rate actually _preceded_ the detection of the solar flare itself, with the difference in arrival time corresponding almost precisely with a particle that was traveling at the speed of light. The “smoking gun,” so to speak, was the finding that research stations on the night-side of the Earth recorded the change in the decay rate; this has resulted in a tentative hypothesis that the decay rate of at least one radioactive isotope is a function of the neutrino flux through that region where the radioactive isotope is located, as neutrinos are the only known particle that can penetrate the solid body of the earth to be detected at an undiminished flux. The impact of this finding is theoretically revolutionary, and as far as I know, there are no theoretical explanations as to why the decay constant should be dependent on external environmental variables (such as neutrino flux, possibly). Pertaining to the accuracy of our dating, I think the impact will be less than revolutionary, but almost certainly nontrivial. Here’s a link: [http://news.stanford.edu/news/2010/august/sun-082310.html](http://news.stanford.edu/news/2010/august/sun-082310.html) ---
**Author:** ![Sicks\_Ate](https://avatars.discourse-cdn.com/v4/letter/s/258eb7/32.png) [@Sicks\_Ate](https://boards.straightdope.com/u/Sicks_Ate)\ **Post date:** [May 31, 2012, 1:53pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/14 "2012-05-31T13:53:57Z")
Why does this strike me as a creationist homework assignment? Or homeschool homework assignment… ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [May 31, 2012, 1:57pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/15 "2012-05-31T13:57:15Z")
10 years BP +/- 30 is my guess. 🙂 ---
**Author:** ![Foggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foggy/32/1082_2.png) [@Foggy](https://boards.straightdope.com/u/Foggy)\ **Post date:** [May 31, 2012, 1:58pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/16 "2012-05-31T13:58:35Z")
If it weren’t for carbon dating, I wouldn’t date at all. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [May 31, 2012, 2:03pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/17 "2012-05-31T14:03:15Z")
> [@Sicks\_Ate](#): > > Why does this strike me as a creationist homework assignment? Or homeschool homework assignment… $5 says it’s a “Shroud of Turin is real!!!1!” delusion. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [May 31, 2012, 2:08pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/18 "2012-05-31T14:08:21Z")
> [@rtfgirl](#): > > haha i asked u!!! but a little hint… it’s less than 50 years ago! Would you like the Moderators to move your guessing game to The Game Room forum? ---
**Author:** ![supery00n](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@supery00n](https://boards.straightdope.com/u/supery00n)\ **Post date:** [May 31, 2012, 2:12pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/19 "2012-05-31T14:12:39Z")
I think it’s important to distinguish between radioactive dating errors that occur due to -differences in the initial ratio of parent-to-daughter isotopes (due to environmental conditions) in the initial sample (the varying atmospheric concentration of C-14 that make calibration necessary falls under this case), with the actual decay \*\*\*rate \*\*\* remaining constant -the actual decay rate itself varying (also due to environmental conditions); the possible causal relationship between solar events (neutrino fluxes?) and observed decay rates of radioactive isotopes The second category of error is far more pernicious in my opinion, as it is much harder to calibrate for. A similarity between the two is that both are due to environmental conditions. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [May 31, 2012, 2:15pm UTC](https://boards.straightdope.com/t/carbon-dating-fallacy/623646/20 "2012-05-31T14:15:55Z")
It’s hard to prove a negative. Carbon dating is a clue which suggests the age of something. Its accuracy depends on the sample. Carbon in the upper atmosphere is subject to cosmic ray bombardment that creates isotopes, specifically carbon 14 with a half-life of about 5700 years - that is, half of a sample decays in that time. The amount of carbon 14 in the atmosphere is a pretty standard ratio, as it is being replenished as fast as it decas. Living animals/plants use this carbon while alive, stop absorbing it when dead. Measure the amount of carbon 14 in a bone, shell, or chunk of wood, and compare to the standard ratio, and it tells you when this organism stopped absorbing carbon compounds. What can go wrong? One theory says the ratio of carbon14 was lower during the ice age, this throwing a lot of measurements off by a significant fraction. Of course, the sample might have been infused by contamination - newer or older material; bacteria in a wood sample. (there’s a campsite in S. America allegedly showing humans were there 30,000 years ago; or did older organic material mix in with it during the time it was buried? A sample may have used material that was not from the normal atmosphere; beyond about 30,000 years ago, it’s hard to get a reliable reading. Some people still argue the Shroud of Turin dating (about 1300AD) is inaccurate, and claim contamination from pollen, bacteria, soot from a fire where it was stored, invisible reweaving that incorporated newer material onto the shroud, from which the sample was taken - some or all of these mistakes conspired to produce a date precisely when a forgery was likely to have been done. [Next page](https://boards.straightdope.com/t/carbon-dating-fallacy/623646.md?page=2)