Affecting 1 in 100 people: Are ancient genes responsible for our headaches?
Previous research suggested that such structural abnormalities may have arisen as a result of modern humans, Homo sapiens, mating with other human species in prehistoric times, because these species had different skull structures and the genes appropriate for them could cause abnormal development in modern humans.
Researchers think that CM-I, the mildest type of Chiari malformation, may result from genetic crossovers between Homo sapiens and other human species.
To examine this possibility, 3D models of modern human skulls were compared between 103 individuals with and without Chiari malformation. These structures were then compared with those of eight ancient human fossils, including Homo erectus, Homo heidelbergensis, and Homo neanderthalensis (Neanderthals).
The study found that modern humans with CM-I malformation exhibited distinct differences in the regions where their brains connect to the spinal cord. However, this structural similarity was only seen in Neanderthal skulls. Other human ancestors were more similar to modern humans without the disorder.
"Homo erectus and Homo heidelbergensis are thought to be ancestors of both Neanderthals and modern humans. Therefore, the greater similarity to healthy human skulls makes the shared shape features between Neanderthals and humans with Chiari malformations all the more striking," said Dr. Kimberly Plomp.
Although the study didn't involve direct genetic analysis, Dr. Plomp noted that some people's skull shapes likely stem from Neanderthal genes, which predispose them to Chiari malformation. This doesn't mean that all Neanderthals suffered from chronic headaches.
Scientists believe that Homo sapiens and Neanderthals lived together and interbred frequently during two major periods in the present-day Levant around 250,000 years ago. Up to 45 percent of Neanderthal genes remain in modern humans today, but their distribution varies widely geographically.
ntv
