Life's events are encoded in your skeletal structure: dietary history revealed

In the realm of archaeology, a powerful tool has emerged that allows researchers to delve deeper into the lives of our ancestors – stable isotope analysis. This technique, which has been refined over the years, offers a unique window into the diet, movements, and environments of people long gone.

At its core, stable isotope analysis examines the isotopes of different elements, specifically atoms with extra or missing neutrons. For instance, plants absorb stable carbon-12 and carbon-13 isotopes, which have a consistent ratio to one another in Earth's atmosphere. During photosynthesis, the amount of water, sun, and other factors changes the plants' carbon isotope ratio. This ratio is passed on to plants through the soil and water they absorb.

By analyzing the amount of carbon in animal hair, teeth, and bones, researchers can determine the ratio of carbon isotopes contained in the plants they consumed. This, in turn, provides insights into their diet and the types of plants available in their environment.

One of the most intriguing applications of stable isotope analysis is in revealing the age at which a child started eating solid foods. Nitrogen isotopes, for instance, can offer such insights.

The technique was first applied to human bone by Harold W. Krueger in the early 1970s in the United States. His pioneering work is widely recognized as the foundation for the application of this method to historical and archaeological human remains.

However, it's important to note that this method has its limitations. For example, isotope analysis can't work on materials that have been burned, as the heat alters the isotopic ratios. Additionally, the older the specimen, the less that can be inferred from it, since bone collagen breaks down after about 50,000 years.

Another fascinating aspect of stable isotope analysis is its ability to reveal movement over an individual's lifespan or show that an individual wasn't born at the site at which they were recovered. This is achieved by comparing the strontium signatures in teeth and bone cells, as strontium isotopes, absorbed into teeth during their creation, provide a snapshot of where an individual lived during their childhood. Bone cells turn over constantly, gathering strontium signatures that reflect where individuals lived later.

Furthermore, stable isotope analysis has been instrumental in shedding light on the origins and behaviors of people whose burial sites have become archaeological digs. For example, in the 1970s, it was used on an ancient human skeleton in South Africa to reveal a different diet from others discovered during the excavation, suggesting previously unsuspected interactions between hunter-gatherers and farmers in the region.

Today, stable isotope analysis is used to study various archaeological materials, including bones, food residues on pots, and the source of different metals. With over 250 known stable isotopes, and 80 of the periodic table's first 82 elements having them, the potential for this technique is vast and continually growing.

However, contamination must be carefully avoided in isotope analysis. Both organic and inorganic compounds contain these isotopes, and their ratios relative to one another act like a signature. Therefore, rigorous procedures are in place to ensure the accuracy of these analyses.

In conclusion, stable isotope analysis has become an invaluable tool in the field of archaeology, offering a unique perspective on the lives and diets of our ancestors. As our understanding of this technique continues to grow, so too will our ability to uncover the mysteries of the past.