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The BIRTH of humans

29 Jun 2017

Serbian scientist unveils the early history of human fertility in the first research project on prehistoric motherhood

By Florin Zubascu

Figurine of a woman with a baby in arms by ERC BIRTH project, BioSense Institute on Sketchfab

When it comes to studying prehistory and the evolution of humans, scientists analyse pottery, ornaments and other artefacts, but they have seldom taken it upon themselves to study more accurately the natural, cultural, and technological changes that boosted population growth and enabled prehistoric women to have more babies.

“We study pottery and ornaments but the evolution of fertility is at the margins of science,” says Sofija Stefanovic, a Serbian ERC grantee who set out to find out how food and eating habits and cultural change affected the fertility of women in the Neolithic. “[Until recently] we did not know anything about fertility in prehistory,” she says.

Her ERC-funded project, BIRTH, is the first scientific project on fertility and motherhood in prehistory. The research team led by Stefanovic at the BioSense Institute of the University of Novi Sad is analysing archaeological data from 10,000 to 5,000 BC in the territory that is now Serbia, Macedonia and Croatia, to find out more about the biology of fertility, culture and fertility, micronutrition and paleodemography.

Stefanovic built her research project on the writings of the French philosopher and 1927 winner of the Nobel Prize for Literature, Henri Bergson, who argued that often scientists pretend to know when in fact they do not. That prompted her to reflect on how we teach human evolution, how it happened and how human populations grew very quickly, leading her to the recognition that there is little evidence to describe more precisely the historic phenomena behind those stories.  “A lot of things in contemporary science are taken for granted,” Stefanovic believes. 

Stefanovic and colleagues have analysed changes in nutrition habits and how these impacted fertility rates in prehistoric women. Fascinatingly, they have found baby teeth marks on spoons made of animal bones dating from 8,000 BC. This she says, “Is evidence that in the Neolithic they started making porridge for babies.”

The introduction of new foodstuff for babies meant that mothers were able to breastfeed for shorter periods of time and, in theory, could have more babies. Isotopic analyses of the skeletons of children indicate that during the Neolithic breastfeeding periods got shorter.

Slicing through Neolithic teeth, which just like the rings on a tree provide insights into the health and lifestyle of pregnant prehistoric women, they noticed that during pregnancy the lines inside teeth change in thickness. Under microscope, they reveal details of the impact nutrition had on fertility.

Examining teeth also makes it possible to determine levels of zinc, iron and calcium during pregnancies in the Neolithic. The development of agriculture and food processing tools had by that time led to better diets. Women gained access to foodstuff with increased levels of these metallic micronutrients, which have positive effects on foetal and neonatal development. 

Bolstering the evidence of a rise in fertility, Stefanovic has found archaeological evidence that in the Neolithic the female pelvic bones became wider, which made births easier and meaning the birth weight of babies increased.

The improvements in nutrition and the changes in agriculture and cooking technology allowed for larger number of babies per woman. Once they had the ability to process grains and cook their food and preserve it, prehistoric humans were able to reproduce at a faster rate, which, in turn, enabled faster population growth.

These changes in human fertility are documented in the Neolithic through figurines representing mothers and babies, and other artefacts related to pregnancy, which were found by Stefanovic and her colleagues.