Two recent studies suggest that the gene flow (as the young people call it these days) between Neanderthals and our species happened during a short period sometime between 50,000 and 43,500 years ago. The studies, which share several co-authors, suggest that our torrid history with Neanderthals may have been shorter than we thought.
Max Planck Institute of Evolutionary Anthropology scientist Leonardo Iasi and his colleagues examined the genomes of 59 people who lived in Europe between 45,000 and 2,200 years ago, plus those of 275 modern people whose ancestors hailed from all over the world. The researchers cataloged the segments of Neanderthal DNA in each person’s genome, then compared them to see where those segments appeared and how that changed over time and distance. This revealed how Neanderthal ancestry got passed around as people spread around the world and provided an estimate of when it all started.
“We tried to compare where in the genomes these [Neanderthal segments] occur and if the positions are shared among individuals or if there are many unique segments that you find [in people from different places],” said University of California Berkeley geneticist Priya Moorjani in a recent press conference. “We find the majority of the segments are shared, and that would be consistent with the fact that there was a single gene flow event.”
© Sumer et al. 2024
In 2013, researchers reported an eye-opening case of a healthy pregnant woman with a puzzling prenatal test result. A routine genetic screen using cell-free DNA—a highly accurate blood test—suggested her fetus had an extra copy of chromosome 13 (Patau syndrome) and only one copy of chromosome 18. These results are devastating; both conditions can cause severe abnormalities. Those with Patau syndrome often only survive a few days or weeks after birth. But, when doctors looked at scans and did additional pregnancy testing, all they found was a healthy fetus developing normally. The woman carried on with her uncomplicated pregnancy and gave birth to a healthy baby.
The alarming genetic results may have been written off as a freak testing flub. But soon after giving birth, the otherwise healthy 37-year-old mother of two reported severe pelvic pain. Imaging revealed what looked like multiple bone tumors, and she was subsequently diagnosed with metastatic small cell carcinoma of vaginal origin. Tragically, she has since died.
Testing of one of her tumors found that the cancerous cells had an increased number of chromosome 13 relative to chromosome 18. Her prenatal test had picked up her deadly cancer.
© Getty | NataliaDeriabina
