A Truly Unique Case Of The Only Known Individual With Parents From Two Different Species

This revelation has caught the attention of the scientific community, highlighting a fascinating aspect of human evolution.

The story of human evolution is rich and complex, with the Neanderthals being our most well-known relatives. 

However, there's another group that lived during the Lower and Middle Paleolithic ages called the Denisovans, about whom much less is known due to the scarcity of their remains. 

Only small pieces of bones and teeth from Denisovans have been found, primarily in the Denisova Cave located in the Altai Mountains of Siberia. 

Despite these limited finds, scientists have managed to piece together significant information.

Aiming to uncover more details about Denisovans and their interactions with both Neanderthals and Homo sapiens, a project named "Finder - Fossil Fingerprinting and Identification of New Denisovan Remains from Pleistocene Asia" was initiated.

The team had to study tiny bone fragments for answers. Credit: Thomas Higham/University of Oxford

Katerina Douka of the Max Planck Institute in Jena, Germany, and a visitor at Oxford University, articulated the project's objectives in 2018, stating:

"We aim to find out where they lived, when they came into contact with modern humans – and why they went extinct."

The exploration of bone fragments from the Denisova Cave, discovered in 2010, revealed the challenge of identifying them due to damage from animals. 

To circumvent the slow traditional methods of identification, Douka and Tom Higham, deputy director of Oxford University’s Radiocarbon Accelerator Unit and an adviser to Finder, employed a novel approach called Zooarchaeology by mass spectrometry. 

This technique utilizes the unique collagen signatures of different mammal groups.

John Bavaro's interpretation of Denny. Credit: John Bavaro

One particular bone, initially unidentified, was sent to Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig for further analysis. 

It was determined that the bone came from an individual who was at least 13 years old at the time of death.

The Leipzig team's further analysis revealed an astonishing fact: exactly half of the DNA sample contained Neanderthal DNA, and the other half Denisovan DNA. 

This led to the confirmation that the 90,000-year-old remains belonged to a girl, a hybrid of a Neanderthal mother and a Denisovan father, affectionately nicknamed Denny.

"If you had asked me beforehand, I would have said we will never find this, it is like finding a needle in a haystack," remarked Pääbo.

JOE MCNALLY, NAT GEO IMAGE

To provide a visual representation of Denny, artist John Bavaro depicted her on his website, drawing from a genome analysis of the specimen’s mitochondrial DNA. 

He explained: "By taking a genome analysis from the specimen’s mitochondrial DNA on a single bone fragment recovered from the Denisova Cave in the Altai Mountains of Russia, palaeogeneticists Viviane Slon and Svante Pääbo of the Max Planck Institute for Evolutionary found that she had 40 percent Denisovan genes from her dad and 40 percent Neanderthal genes from her mom."

The research, published in the journal Nature in August 2018, illuminated the interactions between Neanderthals, Denisovans, and other hominin groups during the Late Pleistocene. 

"Neanderthals and Denisovans are extinct groups of hominins that separated from each other more than 390,000 years ago."

The study presented the genome "Denisova 11", from the bone fragment found in Denisova Cave, as proof that it belonged to "an individual who had a Neanderthal mother and a Denisovan father."

"The father, whose genome bears traces of Neanderthal ancestry, came from a population related to a later Denisovan found in the cave," they wrote.

"The mother came from a population more closely related to Neanderthals who lived later in Europe than to an earlier Neanderthal found in Denisova Cave, suggesting that migrations of Neanderthals between eastern and western Eurasia occurred sometime after 120,000 years ago. The finding of a first-generation Neanderthal–Denisovan offspring among the small number of archaic specimens sequenced to date suggests that mixing between Late Pleistocene hominin groups was common when they met."

"The finding of a first-generation Neanderthal–Denisovan offspring among the small number of archaic specimens sequenced to date suggests that mixing between Late Pleistocene hominin groups was common when they met."