Kiwi puts twist on ancient history of agriculture

South America's Atacama Desert is one of the harshest environments in the world.

The shift from hunter-gatherer to crop farmer came with poorer health for mothers and babies, according to surprising findings uncovered by Kiwi scientists.

New evidence from the University of Otago and the Universidad de Tarapaca in Chile indicates the adoption of agriculture was linked to poor maternal and infant health in the ancient Atacama Desert.

The findings, supported by the Marsden Fund and published in the International Journal of Paleopathology, offers the first direct evidence for maternal-foetal transfer of a nutritional deficiency in an archaeological sample.

"Women and children are particularly vulnerable to the negative effects of agricultural intensification and resource scarcity."

Study lead author and PhD candidate Anne Marie Snoddy, of Otago's Department of Anatomy, said agriculture did provide some evolutionary advantages, including increased resources for population growth.

"However, crop foods are quite poor in many nutrients needed by growing babies and their mothers," she said. "Women and children are particularly vulnerable to the negative effects of agricultural intensification and resource scarcity.

"Our new paper sheds light on to the impact of the agricultural transition on these past people, showing rare evidence for newborns and foetuses, including a possible mother-baby pair, with signs of pathology related to food deficiencies.

This kind of direct evidence of maternal-foetal transfer of a nutritional deficiency is not something we have ever seen in the archaeological record."

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 disease evidence on the skeletons of individuals from a transitional Early Formative Period site, between 3600 and 3200 years ago. All the infants at this site showed potential evidence for nutritional insufficiency in the form of scurvy, or vitamin C deficiency.

"Scurvy leaves its signature on bones," Snoddy said.

"Prolonged vitamin C deficiency causes poor bone formation and leaky blood vessels. Small amounts of blood collect at muscle attachment sites and this can cause abnormal bone to form.

"By analysing the patterning of this abnormal bone formation throughout the skeleton, we can identify people who suffered from a period of vitamin C deficiency during their life, and this can give us information about the general quality of their diet.

"Scurvy is associated with low dietary diversity and generally poor nutrition."

Study senior author and Otago researcher Dr Sian Halcrow said there has been a focus archaeologically on the exploration of the pre-agricultural Chinchorro people and associated elaborate mummy burials.

However, recent research highlights periods of increasing infant mortality during the transitional period from hunter-gatherer to agricultural practices.

"This work is important for the wider interpretation of the environmental context of the Atacama Desert, in northern Chile, in which these populations lived," Halcrow said. "This desert is one of the harshest environments in the world, with the least amount of rainfall of any hot desert.

"The stresses on these people may have gotten worse with the adoption of agricultural food crops, which are poor sources of many important nutrients."

Snoddy said the researchers interpreted that the vitamin C deficiency was possibly due to periodic food shortages from El Nino events in the area. "In this paper, we argue that the extreme arid environment of the Atacama means that it is particularly ecologically unstable, with climate change causing major impact on both marine and land resources."

Halcrow said that, importantly, the group's latest findings also contributed to an understanding of the sensitive relationship between the ill health of the mother and infant in the past.