Australasian Science Magazine

The skull of a young woman from Quiani-7 shows abnormal bone formation (arrowed) that may be associated with scurvy-related haemorrhage of the infraorbital artery. Credit: A. Snoddy

By Anne Marie Snoddy & Siân Halcrow

Ancient human remains have revealed evidence that the adoption of agriculture led to malnutrition in a mother, her foetus and other infants.

The foundation of modern society is rooted in agricultural dependency, a development that provided the necessary resources for population expansion. However, research by biological anthropologists who study ancient human remains has shown that the development of agriculture resulted in an increase in nutritional stress, food shortages and disease in many parts of the world.

New findings from the Atacama Desert in northern Chile has found that the adoption of agriculture is associated with an increase in premature death and vitamin deficiencies passed on from the mother to her infant. This work also provides the first direct evidence of the maternal–foetal transmission of a nutritional deficiency in ancient human remains.

The Atacama Desert is well-known for the earliest evidence in the world for purposeful mummification of the dead, pre-dating the ancient Egyptian mummies by two millennia. It’s thought that these intricately prepared and decorated funerary rituals, largely focused on infants and children, were a social response to the high rate of foetal, infant and maternal death in the region’s Chinchorro populations. Although there has been an archaeological focus on the Chinchorro and their associated mummy burials, recent research has highlighted periods of increasing infant mortality during the period when they transitioned from hunter-gatherer to agricultural practices. However, the ultimate causes for this has eluded archaeologists.

Our research, published in the International Journal of Paleopathology (https://tinyurl.com/ycdg3ou5), has revealed the impact of the agricultural transition on these people, showing rare evidence of pathology related to food deficiencies in newborns and foetuses, including a possible mother–baby pair. The research aimed to assess if there was any impact on the reduction of dietary diversity with the adoption of agricultural food practices by investigating evidence for disease on the skeletons of individuals from a transitional coastal Early Formative Period site (3200–3600 years before present). This site was important as it shows the first evidence for a clear cultural shift from Archaic Period Chinchorro mortuary practices of mummification to early evidence of the adoption of domesticates on the coast. Here the maritime-based hunter-gatherer economy became supplemented with cultivars such as beans, squash, potatoes and quinoa.

All the infants at this site showed evidence for nutritional deficiency in the form of scurvy, and so did an adult female from the mother–foetal pair. Scurvy is a condition that occurs after a long period of severe deficiency of vitamin C, a nutrient contained in many fruits and vegetables but not found in high quantities in cereal crops such as corn. Agricultural societies rely on nutirent-poor crops for the majority of their calories, and this can lead to deficiencies of many important vitamins and minerals.

Mothers and babies are particularly venerable to vitamin and mineral deficiencies: mothers have a higher daily requirement of vitamin C to support foetuses in utero, and babies require more vitamin C for their rapid growth and development. Because of this, the nutritional deficiencies in women, babies and young children can provide important information about the nutritional status of the larger population.

Vitamin C is necessary for many physiological functions within the body, such as collagen formation, hormone synthesis and iron absorption. Collagen is a major component of many connective tissues, including the organic portion of bone and the membrane that lines blood vessels. In the absence of sufficient vitamin C, bone does not form properly and blood vessels become “leaky”, resulting in chronic low-grade haemorrhaging at muscle attachment sites and in regions with major blood vessels.

Very minor trauma from normal muscular actions, such as chewing, can cause this chronic haemorrhaging to occur. Small amounts of blood pool at these sites, and this can cause abnormal bone to form. By analysing the patterning of this abnormal bone formation throughout the skeleton, researchers can identify people who suffered from a period of vitamin C deficiency during their life.

Importantly our research also contributes to an understanding of the sensitive relationship between the ill health of the mother and infant in the past, including the maternal–infant transference of vitamin C deficiency. Foetal remains often do not survive in the burial environment because they are very delicate and not fully mineralised. However, the very dry environment of the Atacama Desert has resulted in exquisite preservation of foetal and infant remains at this site, and has allowed researchers to identify markers of scurvy that might go unnoticed in other archaeological samples.

This research is important for the wider interpretation of the environmental context of the Atacama Desert in northern Chile, in which these populations lived. Most of the work on the agricultural transition has been undertaken in temperate areas, especially in North America and Europe. The Atacama Desert is one of the harshest environments in the world, with the least amount of rainfall (<2 mm per year) of any hot desert on Earth. However, this is contrasted by a rich abundance of marine mammals and fish, stimulated by the cold Humboldt Current.

The stresses on these people may have intensified with their dependence on agricultural food crops, which are poor sources of many important nutrients. The skeletal evidence showed that the vitamin C deficiency was possibly due to periodic food shortages due to El Niño events in the area.

The prevalence of scurvy at this site and others in the region is far higher than in most archaeological samples. We argue that the extreme arid environment of the Atacama Desert means that the region’s ecology is particularly unstable, with climate change having major impacts on both marine and land resources.

Ongoing work on bone and tooth chemistry, and micro-fossil analyses of dental plaque, may provide further insights into the Chinchorro people’s dietary transition during this time.