The Link Between Neanderthal Genes and Headaches
From the noise of traffic to excessive smartphone use, there are numerous modern-day factors that can cause headaches. However, recent scientific research suggests that for some individuals, these headaches might have a much older origin—tracing back to the genetic legacy of Neanderthals.
According to new studies, certain people may be more prone to specific types of headaches due to the presence of Neanderthal genes. These headaches are linked to a condition known as Chiari malformations, which occur when part of the brain extends too far into the spinal cord. This condition affects approximately one in 100 people, with the mildest cases causing headaches and neck pain, while more severe forms can lead to serious health issues.
Scientists had previously speculated that such malformations could result from interbreeding between Homo sapiens and other ancient human species. Given that these early hominins had different skull structures, genes responsible for healthy development in their species might have led to malformations in modern humans.
In a paper published in the journal Evolution, Medicine, and Public Health, researchers specifically identified Neanderthal genes as a potential source of this condition. They proposed that the mildest form of Chiari malformation, known as CM-I, could have originated from interbreeding between Homo sapiens and other hominins.
To explore how these traits might have been passed down, scientists examined the skulls of various human species. They compared 3D models of 103 modern individuals with and without Chiari malformations against eight fossilized skulls from ancient hominins, including Homo erectus, Homo Heidelbergensis, and Homo neanderthalensis (Neanderthals).
The study found that individuals with CM-I had differences in brain shape, particularly in areas where the brain connects to the spine. However, among the ancient hominin skulls, only those of Neanderthals showed similar characteristics. In contrast, the skulls of Homo erectus and Homo Heidelbergensis were closer to those of healthy humans.
Dr. Kimberly Plomp, the lead researcher, noted that both Homo erectus and Homo Heidelbergensis are believed to be ancestors of both modern humans and Neanderthals. She stated that finding these species closer in shape to healthy human crania strengthens the argument that the similarities between Neanderthals and humans with Chiari malformations are not just part of a shared lineage.
While the study did not conduct genetic analysis, Dr. Plomp suggested that some human skull shapes may be influenced by Neanderthal genes, and these shapes could contribute to Chiari malformations. However, it does not mean that all Neanderthals suffered from chronic headaches. Their large brains might have helped mitigate the issue, but interbreeding with Homo sapiens could have caused similar problems in some Neanderthals.
Dr. Plomp explained, “Our study suggests that malformations can occur because the shape of our brain doesn’t fit properly when our skull has some Neanderthal features. Potentially, if there was a Neanderthal with some modern human cranial shape traits, their brain would not fit properly either.”
Scientists believe that Homo sapiens and Neanderthals had two major periods of overlap and interbreeding. The first occurred around 250,000 years ago in what is now the modern-day Levant and lasted nearly 200,000 years. Previously, scientists thought these interbreeding events were brief and isolated, but new evidence indicates they happened more frequently than previously believed.
Today, up to 45% of the complete Neanderthal genome survives in the modern human population, though the distribution of Neanderthal genes varies by geography. This variation could help test the researchers’ theory, as rates of Chiari malformations should be lower in regions with less Neanderthal DNA.
For instance, people in East Asia may inherit up to four percent of their genes from Neanderthals, while many people in Africa, where Neanderthals never lived, have no Neanderthal genes at all. If the theory holds, the prevalence of Chiari malformations should be higher in East Asia than in Africa.
Ultimately, the researchers hope these findings could lead to better methods for treating or even preventing Chiari malformations. The study concludes that the methods used could deepen understanding of the condition’s causes and improve diagnosis and treatment options.
