A groundbreaking study conducted by scientists at Clemson University and Loyola University New Orleans has discovered a significant link between rare gene variants inherited from Neanderthals and the development of autism. These findings shed new light on the genetic factors underlying autism susceptibility.

The researchers analyzed genomic data from three ethnic groups in the United States, namely black non-Hispanic, white Hispanic, and white non-Hispanic. They found that rare Neanderthal variants, which occur in less than 1 percent of the population, were markedly more common in individuals with autism compared to non-autistic individuals at a population-wide level.

However, the exact association between these genes and autism remains unclear. Autism is believed to be caused by a combination of genetic and environmental factors. The study's results indicate that Neanderthal-derived DNA plays a significant role in the susceptibility to this developmental disorder.

It's important to note that this research does not suggest that autistic individuals are "more Neanderthal" than their non-autistic counterparts. The human genome consists of over 3 billion nucleotide pairs, with the majority being identical among individuals. Nonetheless, specific sites in the genome exhibit variation, and Neanderthal DNA contributes to this variation.

Dr. Emily Casanova, assistant professor of neuroscience at Loyola University New Orleans and study author, explained, "In our study, we've found that autistic people, on average, have more rare Neanderthal variants, not that they have more Neanderthal DNA in general." These rare variants appear to play a significant role in the diversity of the human genome.

The interbreeding between Homo sapiens and Neanderthals, estimated to have occurred around 50,000 years ago when their ranges overlapped in Eurasia, has resulted in most modern humans carrying genes from our "sister species." On average, Neanderthal genes make up approximately 1 to 4 percent of the human genome, although this proportion varies among different populations. Those of European or Asian descent tend to have a higher proportion, while those of African descent have fewer or even zero percent Neanderthal genes.

This latest study adds to the growing evidence of how Neanderthal DNA influences various traits and health conditions in modern humans. Previous studies have linked Neanderthal genes to lower pain thresholds, increased vulnerability to diseases like COVID-19, depression, drug metabolism, and even physical traits such as larger noses.

The findings of this study, published in the journal Molecular Psychiatry, emphasize the intricate interplay between ancient DNA and neurodevelopmental disorders like autism. Further research is needed to uncover the specific mechanisms through which these gene variants contribute to the risk of autism.

Understanding the genetic basis of autism not only advances our knowledge of human evolution but also paves the way for improved diagnostic tools and potential targeted therapies in the future.