Figure 1: Twisted Sister, a typical Hair Band of the eighties (ebcak, 2008).
Rock cores are long thin pieces of rock removed from beneath the Earth's surface using a hollow drill. These segments are cut through the many layers of rock laid down by past events (Plummer, 2004). When removed and laid out for examination, the newest layers are at the top, with a visible progression of events continuing down the core to the oldest layer at the base (Plummer, 2004). Likewise, hair strands are produced from the top down, in protein units with the oldest segment at the end of the hair (see Figure 2) (Beatty, 2002).
Various landmarks throughout a rock core, such as fossils, deposits, and change in rock types can be used to deduce the geological history of that point in time (Plummer, 2004). Surprisingly enough, biochemical and isotopic signatures can be read along the hair strand, giving a history of an individual's health. Chemical indicators can be used to note hormonal changes, stress levels and diet (Hill Wood-Salomon, 2011). Hair samples have even been tested from preserved specimens, finally solving mysteries such as what percentage of a population was affected by events such as water contamination (Matsumoto and Yoshinaga, 2009), or the geographic route traveled by a murder victim (Courtland, 2008). Events such as change in location can be determined by a sudden switch in isotopic concentration (drinking from a different water source, for example) in the keratin units of the hair strand (Ehleringer et al., 2008).
Figure 2: A side-by-side comparison of rock cores and hair strands (ISGS, 2010; Hair Compounds, 2010).
Rock deposits can be altered through further events such as folding and fractures, changing the accuracy of events read along a core sample (Plummer, 2004). Similarly in hair, as the age of the event in question increases, the likelihood of taking an accurate measurement of chemical ratios decreases. Hair is structurally altered and often damaged by environmental factors such as sun and wind. Hair and scalp conditions produce abnormal strands, containing different initial chemical ratios, which would give quite different results than a healthy hair (Beatty, 2002). Physical abuse occurs on a daily basis for many, through brushing, heat styling, and chemical alteration such as colouring and perming. Furthermore, data is lost when the hair is cut, removing the oldest records at the base of the hair strand (Beatty, 2002). This process is also observed in rock samples, where glacial erosion has removed one or more layers of rock, leaving a gap in the timeline of relative dating (Plummer, 2004).
Hair analysis techniques are still in discovery and developmental stages. Nevertheless, the potential applications are incredible. Many conditions which are currently tested for by drawing blood may be examined by taking a reading from a strand of hair (Hill Wood-Salomon, 2011). Depending on the length, the recorded sequence can reveal events years into the past, providing an impressive ready-made medical record (Cerling et al., 2009). Who knows what the future may hold? As they say...hair today, gone tomorrow.
Beatty, D., 2002. Milady’s Standard Cosmetology.
Cerling, T.E. et al., 2009. History of Animals using Isotope Records (HAIR): A 6-year dietary history of one family of African elephants. Proceedings of the National Academy of Sciences of the United States of America, 106(20), pp.8093-8100.
Courtland, R., 2008. Your history is printed in your hair : Nature News. [online] Available at: <http://www.nature.com/news/2008/080225/full/news.2008.617.html> [Accessed 26 November 2011].
ebcak, 2008. 80′s Glam Metal Rock Bands | Cool Stuff - ebcak. [online] Available at: <http://www.ebcak.com/archives/559> [Accessed 26 November 2011].
Ehleringer, J.R. et al., 2008. Hydrogen and oxygen isotope ratios in human hair are related to geography. Proceedings of the National Academy of Sciences, 105(8), pp.2788 -2793.
Hair Compounds, 2010. Measuring Stress Through Hair | Hair & Compounds Blog. [online] Available at: <http://www.haircompounds.com/hairextensions/measuring-stress-through-hair/> [Accessed 2 December 2011].
Hill Wood-Salomon, J., 2011. Science for hairstylists: the potential uses of hair samples in medicine. [personal communication] [Discussed 7 October 2011].
ISGS, 2010. ISGS - Geological Samples Library Collections. [online] Available at: <http://www.isgs.uiuc.edu/sections/indust-min/samplib/collections.shtml> [Accessed 26 November 2011].
Matsumoto, M. and Yoshinaga, J., 2009. Isotope ratios of lead in Japanese women’s hair of the twentieth century. Environmental Science and Pollution Research, 17pp.643-649.
Plummer, C., 2004. Physical geology & the environment. 1st ed. Toronto: McGraw-Hill Ryerson.