Preeclampsia May Have Shaped the Fate of Neanderthals and Given Homo sapiens an Edge
Neanderthals didn’t just vanish. Their disappearance as a species likely involved a complex web of physical, environmental, and social factors. A new study, published in the Journal of Reproductive Immunology, explores whether a hidden biological vulnerability may have played a large role in their struggle for survival.
In the study, researchers suggested that preeclampsia, a dangerous pregnancy complication still affecting humans today, may have posed an even greater threat to Neanderthals, potentially limiting their ability to reproduce and sustain stable populations. If true, one of the oldest diseases documented in written history may have once shaped the fate of our closest ancient neighbors.
“We propose that the burden of preeclampsia — previously described as the ‘curse of human reproduction’ — may have constituted an additional, underappreciated selective pressure in Neanderthals, contributing to their extinction,” said the study authors in the study.
Read More: Neanderthals Mated With Modern Human Women — And It Still Shapes Many People’s DNA Today
What Is Preeclampsia, and How Did Homo sapiens Adapt?
Preeclampsia is a serious condition marked by high blood pressure during pregnancy, often placing strain on vital organs like the heart, kidneys, and liver. In severe cases, it can progress to eclampsia, which involves seizures and can be fatal.
Today, preeclampsia affects roughly 2 to 8 percent of pregnancies, while eclampsia occurs in fewer than 1 percent. Even so, the global toll is high. The condition contributes to more than 70,000 maternal deaths and around 500,000 perinatal deaths each year.
At its core, preeclampsia is tied to how the placenta develops. If it implants too shallowly in the uterus, it may struggle to deliver enough nutrients to the fetus. In response, the pregnant body raises blood pressure — a risky compensation mechanism, especially in the later stages of pregnancy.
Humans, however, appear to have evolved a partial safeguard. In many cases, this protective mechanism prevents preeclampsia from triggering fetal growth restriction, allowing pregnancies to continue without catastrophic outcomes. Without it, rates could climb as high as 10 to 20 percent, a level that would dramatically reduce reproductive success.
Could Preeclampsia Explain Neanderthal Extinction?
Neanderthals shared key reproductive traits with modern humans, including a type of placentation that makes preeclampsia possible. But the study’s researchers suspect they may have lacked the same protective adaptations as Homo sapiens.
“Critically, humans evolved a protective mechanism decoupling maternal preeclampsia from 75 percent of fetal growth restriction cases, a severe condition where the placenta fails to provide adequate nutrition,” explained the study authors.
Without this safeguard, Neanderthals may have faced higher rates of pregnancy complications, maternal death, and infant loss. In already small and isolated populations, even slight reductions in birth rates can have long-term consequences.
Why Proving This Theory Is Difficult
Despite its appeal, this hypothesis is challenging to confirm. Preeclampsia does not leave clear marks on skeletal remains, making it nearly invisible in the fossil record.
Instead, researchers in this study relied on indirect evidence, like genetic data, modern medical knowledge, and evolutionary population modeling. While these tools are often accurate, they cannot definitively reconstruct how often Neanderthals experienced pregnancy complications.
Although hard to fully prove, this research highlights an important possibility: that reproduction itself — often overlooked in extinction debates — may have been a critical weakness for the Neanderthals.
Read More: Humans Outlived Neanderthals Likely Because of Differences in Anatomy and Social Skills
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