Ancient Offspring Of Two Different Human Species Found
A piece of bone from a cave in Russia has yielded what may be the biggest archaeological find of the year, media reported on August 30.
The bone belonged to an ancient human who had a Neanderthal mother and a Denisovan father. Nicknamed "Denny," the specimen is the first scientists have found that is a first-generation offspring from such interbreeding.
Scientists said the find may provide evidence that hominins interbred more often than previously thought. It also suggests that extinct groups like Neanderthals may not have died out, but rather were absorbed by the human species.
In prehistory, members of our species interbred with at least two other ancient humans: the Neanderthals and the mysterious Denisovans, who are known only from fragments of bone and teeth discovered in the Denisova Cave in Russia.
These interbreeding events were thought to be rare. But a few years ago, archaeologists found a 90,000-year-old bone fragment in the Denisova Cave.
Samantha Brown, then at the University of Oxford, discovered that it came from a hominin by examining the proteins preserved inside it. Based on the structure of the bone, her team postulated that Denny died at about age 13.
A photo of the bone fragment found at the Denisova Cave
After examining Denny’s DNA, scientists discovered that the individual in question was female, and that she had astonishing parentage. Her DNA was almost half Neanderthal and half Denisovan.
Denny’s mitochondrial DNA, which is inherited only from mothers, is Neanderthal. Therefore, her mother was Neanderthal and her father Denisovan.
The significance of the find is that it shows "interbreeding among different human lineages was more common than previously thought," Katerina Harvati-Papatheodorou of the University of Tübingen, Germany, told New Scientist magazine.
A 40,000 year-old Homo sapiens with a Neanderthal ancestor recently found in Romania also bolsters this notion.
Climate change doomed Neanderthals, study says
The amount of information we have about the human family tree is steadily growing, but there are still plenty of unanswered questions. One of the biggest mysteries is why our particular branch of human history was able to endure, while others like the Neanderthals were snuffed out. A new study by a group of researchers from multiple institutions in the US and Europe suggests that plunging temperatures may have been too much for Neanderthals to handle.
The work, which was published in Proceedings of the Natural Academy of Sciences, used observations of stalagmites that are tens of thousands of years old. The rocky formations can act as a sort of timeline of change, offering information on how climate patterns shifted over thousands and thousands of years.
In the paper, the scientists explain that a change appears to have taken place somewhere around 44,000 years ago. During this time, they believe the climate began to grow colder over a period of thousands of years and remained chilly for an extended period of time.
Temperatures eventually returned to where they were, but the archaeological record seems to indicate that many Neanderthals couldn’t push through the extended cold snap. These cold cycles repeated themselves, and each time they did things got worse for the Neanderthals.
“For many years we have wondered what could have caused their demise,” Dr. Vasile Ersek of Northumbria University explains in a statement. “Were they pushed ‘over the edge’ by the arrival of modern humans, or were other factors involved? Our study suggests that climate change may have had an important role in the Neanderthal extinction.”
The study is one of the first to draw a clear link between natural climate change and the effect it may have had on the Neanderthal population. The researchers note that the number of tools made by Neanderthals during the suspected cold periods seems to have been very low, hinting at the possibility that the ancient people were having a very hard time coping with the changing world. With a greatly diminished population, the race was ultimately doomed to extinction, especially when our own human ancestors began expanding into new areas.
