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In last Tuesday’s lecture, radiocarbon dating was covered briefly. It is an essential technology that is heavily involved in archaeology and should be explored in greater depth. Radiocarbon dating uses the naturally occurring isotope Carbon-14 to approximate the age of organic materials. These “materials” can be almost anything. Often, archaeologists use graves and plant remains to date sites. Since its conception by Willard Libby in 1949, it has been invaluable to the discipline. In fact, many important archaeological artifacts have been dated using this method including some of the Dead Sea Scrolls and the Shroud of Turin. Though radiocarbon dating is startlingly accurate for the most part, it has a few sizable flaws.

The technology uses a series of mathematical calculations—the most recognizable of which is known as half-life—to estimate the age the organism stopped ingesting the isotope. Unfortunately, the amount of Carbon-14 in the atmosphere has not been steady throughout history. In fact, it has fluctuated a great deal over the years. This variation is caused by both natural processes and human activity. Cosmic rays and changes in Earth’s climate can cause irregularities in the amount of Carbon-14 in the atmosphere. Humans began making an impact during the Industrial Revolution. The isotope decreased by a small fraction due to the combustion of fossil fuels, among other factors. However, the quantity of Carbon-14 was nearly doubled in the ’50s and ’60s because of the atomic bomb testings in those decades.

The answer to the problem of fluctuating amounts of this important isotope is calibration. While an uncalibrated reading may be off by a factor of 10%-20%, calibration severely reduces that value. Standard calibration curves are now used for more accurate readings. These curves indicate the changes in Carbon-14 throughout the years and modifies the end result of the tests to reflect that. Though the calibrated date is more precise, many scholars still use the uncalibrated date in order to keep chronologies consistent in academic communities.

Though it’s biggest, the calibration problem is not the only flaw of radiocarbon dating. As the lecture detailed, it is only accurate from about 62,000 years ago to 1,200 A.D. There is a sizable amount of time before and after that period that cannot be investigated using this method. Also, archaeologists cannot use their hands to touch the samples or smoke near them. They risk seriously altering the result of the test. The “Old Wood Problem” is the last flaw of radiocarbon dating that will be elaborated upon here. If an archaeologist wanted to date a dead tree to see when humans used it to build tools, their readings would be significantly thrown off. This is because radiocarbon dating gives the date when the tree ceased its intake of Carbon-14—not when it was being used for weapons and other instruments! Since trees can have a lifespan of hundreds of years, its date of death might not even be relatively close to the date the archaeologists are looking for. Thorough research and cautiousness can eliminate accidental contamination and avoidable mistakes.

This magnificent technology is the most important innovation in archaeological history. Archaeologists have the most accurate readings they are likely to ever receive! Despite its overuse and misrepresentation in the media, it is nonetheless extremely valuable. This process has seriously assisted archaeologists in their research, excavations, and scholarly studies. Though it is not without its flaws, including several not mentioned here, it is truly an incredible creation that will be used for many years to come.

This entry was posted in Student Blog Post 1 by Andrea Cohn. Bookmark the permalink. http://anthropology.msu.edu/anp264-ss13/2013/02/07/radiocarbon-dating-a-closer-look-at-its-main-flaws/