7,000 year-old stressed toddlers: a tale of two cemeteries

A new publication by CRESIDA member Colette Berbesque, and collaborator Kara Hoover (University of Alaska, Fairbanks) compared stress in remains from two populations of hunter-gatherers living about seven thousand years ago in different regions of the US (Texas and Florida).

Lots of different types of illness and disease leave indicators on the human skeleton.  These are used to give insight into basic levels of health and disease in different populations, such as farmers versus hunter-gatherers, as well as into differences that may be based in culture.

Linear Enamel Hypoplasias in teeth of skeleton

To investigate stress in these two archaeological populations, Berbesque and Hoover analysed high-resolution photographs of the teeth of both of these populations, looking for defects in the enamel. These defects, called Linear Enamel Hypoplasias, look like dark lines across teeth and can result from diseases, malnutrition, fever, and a host of other stress factors.  Unlike other bones, which heal when damaged, teeth don’t reform or heal over time and permanent teeth form during early childhood. This makes teeth a perfect permanent record for childhood stress.

X-ray of Linear Enamel Hypoplasias in teeth

Berbesque and Hoover analysed populations from the Windover site in Florida and the Buckeye Knoll in Texas. Both populations are extremely important for investigating hunter-gatherers.  In addition to being two of the oldest populations discovered in the US, the analysed remains were found on locations that were used as cemeteries around the same time.  Additionally, the preservation of the Florida population is nothing short of spectacular.  Windover was a cemetery that became a bog – preserving not only skeletal material, but textiles, wood, brain material, and even stomach contents.

The three main results of the study are:

  • People with signs of early childhood trauma had more trauma overall.

As the timing of enamel formation during childhood is documented, Berbesque and Hoover were able to estimate the childhood age that each individual was when each Linear Enamel Hypoplasia occurred.  These measures of the timing of the defects then helped the researchers determine whether early childhood trauma had consequences for later childhood health, and it did.  Children that had trauma earlier in life had more signs of trauma overall.

  • Florida hunter-gatherers at Windover had twice as many Linear Enamel Hypoplasias as the Texan population at Buckeye Knoll.

Berbesque and Hoover found a huge and unexpected gap in health between these two different hunter-gatherer populations. While both were living in the south of the US around the same time, it is not clear why the Windover population was so much more stressed that that in Buckeye Knoll. This substantial difference needs to be investigated further.

  • Both of the c. 7000 year old populations had more Linear Enamel Hypoplasias than more recent populations.

Most studies have documented that early hunter-gatherer populations are healthier than those of early farmers. The results of Berbesque and Hoover’s study did not fit that expected pattern. The researchers believe that it is possible that higher rates of Linear Enamel Hypoplasias in these two populations is due to the documented dramatic climate change around the time that both of these cemeteries were in use, effecting food availability and quality of nutrition.

The Study is available for free here.

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