Condition that affects up to 10% of modern pregnancies may have wiped out Neanderthals

Pre-eclampsia is one of the leading causes of prenatal mortality. Now, a new (and controversial) study explains how the dangerous condition may have gotten the better of Neanderthals.

An international group of neonatologists and specialists in obstetrics and gynecology recently advanced the hypothesis that preeclampsia may have contributed to the demographic decline and eventual disappearance of Neanderthals.

Pre-eclampsia is a complication of pregnancy associated with high blood pressure and presence of proteins in urine. It appears, in most cases, from 20 weeks of gestation onwards and can also appear shortly after birth — rarely, in the following four weeks, a situation called postpartum pre-eclampsia. And it can be serious, with an impact on organs such as the liver, kidneys and brain.

The association with Neanderthal extinction is presented in an article on January 30th in Journal of Reproductive Immunologybut researchers in paleoanthropology and genetics consider that, for now, it is mainly a theoretical exercise without direct evidence.

In the study, the authors argue that pre-eclampsia and eclampsia have rarely been considered in hypotheses about Neanderthal reproductive biology. Although the exact origin of these conditions continues to be clarified, medical literature points to a link to the way the placenta implants in the uterus and the way the transfer of nutrients between mother and fetus is regulated.

Pre-eclampsia can put the life of the pregnant woman and the fetus at risk. According to , it is estimated that it affects between 6% and 10% of pregnancies and the condition is noted as one of the main causes of prenatal mortality.

The study authors also report that, currently, the condition can affect up to around 8% of pregnancies and can also appear after birth. One of the hypotheses discussed in the article is that an abnormally superficial placental implantation can trigger a “fight” of the placenta for nutrients, leading to an increase in blood pressure, especially in the third trimestera stage in which the fetal brain grows rapidly.

The team suggests that the metabolic demands of babies from large-brained human species would have favored, throughout evolution, deeper placental implantations to ensure efficient nutrient transfer. When this balance fails, it could increase the risk of fetal growth restriction, pre-eclampsia and eclampsia, with impacts on maternal and neonatal survival and, ultimately, fertility and population growth.

The authors go even further: they propose that Neanderthals could not have developed a “maternal safety mechanism” which, according to previous work by some of the same researchers, could exist in Homo sapiens and mitigate the risk of pre-eclampsia. But this protection, once again, remains speculative and has not yet been conclusively identified, highlights the , which also points out that several experts dispute the strength of the conclusion of this new study.