The ghost in your genes
Inside the Max Planck Institute for Evolutionary Anthropology, a team led by geneticist Svante Pääbo accomplished a task once considered impossible. They sequenced the entire 3-billion-base-pair genome of a Neanderthal, our closest extinct relative. The project, initiated in 2006, faced immense technical hurdles. Ancient DNA is not pristine; it shatters into tiny fragments over tens of thousands of years and becomes heavily contaminated with microbial DNA. Worse, any handling by modern humans risks overwhelming the sample with our own DNA.
To solve this, Pääbo's group developed new methods, including working in ultra-sterile clean rooms and tagging DNA fragments with unique identifiers to filter out contaminants. The primary genetic material came from less than half a gram of bone from three female Neanderthals found in Vindija Cave, Croatia. By 2010, the team published its first draft sequence. The results showed that gene flow from Neanderthals to modern humans occurred. People with ancestry outside of Africa carry between 1 and 4 percent Neanderthal DNA, a direct genetic echo of contact between 47,000 and 65,000 years ago. For this work, Svante Pääbo was awarded the Nobel Prize in Physiology or Medicine in 2022.