Genomics Yields Insights About Ancient Humans

Scientists are using genomics to reconstruct the evolutionary history of humans. It sheds new light on our past, and also yields insights into related species like the Neanderthals as well as other ancient hominids. The recent Advances in Genome Biology and Technology conference included two reports that offered new insight into human history.
A potentially revolutionary, new way to track human evolution comes from a team at the Max Planck Institute for Evolutionary Anthropology. One of the biggest challenges for researchers has been the limited fossil record: well-preserved ancient remains are scarce, and any DNA in the remnants is highly degraded. Scientist Matthias Meyer, who participated in the earliest efforts to sequence DNA from remains of a Neanderthal, has helped develop a novel method that addresses this problem by extracting DNA not from bones or teeth but from the sediment at archaeological excavations.
His team has successfully detected ancient human DNA from sites where no human remains were recovered. This could be a major advance for tracking the history of the recently discovered Denisovans, a branch of the ancient human family for which fossil evidence has only been recovered in a single cave in Siberia.
Getting that information helps answer other research questions. Because of his team’s previous analysis of the Neanderthal genome, for instance, Meyer and others have been able to confirm that ancestors of modern-day humans interbred with their Neanderthal cousins. Today, people of European, Asian, and Native American descent typically owe about 2 percent of their genomes to those long-ago Neanderthal ancestors. While less is known about the Denisovan line, scientists have been intrigued to discover evidence of their DNA in modern humans only near Papua New Guinea.
Meanwhile, scientist Ed Green from the University of California, Santa Cruz reported at the conference that what he calls “one of the biggest mysteries in human evolution” is separately being explored with genomic tools more than 1,000 miles to the west of Papua New Guinea, on the Indonesian island of Flores. The ancient hominid genome discovered there in 2003, better known as “the hobbit,” is characterized by its tiny stature and small cranium.
Experts on human evolution have no idea where this ancient human might fit into the family tree. One theory was that the fossil is an ancestor of a modern-day pygmy population that lives near the cave where it was discovered. So Green and his research team headed to Flores to collect their DNA and look for signs of unusual ancestry. An analysis of 33 individuals found no evidence that the modern population is related to the fossil, suggesting that there may have been two completely separate dwarfism-inducing episodes on the island.
The Max Planck Institute’s Meyer noted that without permafrost-level protection, DNA is no longer viable for study after about 130,000 years. Now scientists hope to develop new technical protocols that will make it possible to study DNA that’s even older.