No Going Back
She couldn’t believe what she saw on the screen, there had to be some kind of mistake. But no matter what she tried, the results were the same.
Slon was shown the answers she had always been looking for by a strange small girl. The discovery would be life changing.
Viviane Slon works as a paleogeneticist, but she could never have expected what she would find one ordinary day while in Leipzig, Germany.
She loved to find out where people originated from. This passion drove her to study to become a scientist. And she had become a great one.
More Than It Seemed
A piece of bone was found in a cave in Siberia in 2012. The ancient fragment was thrown into a pile along with other fossils and was forgotten about.
They assumed it was just another fossil like the rest, but that wasn’t quite right. The fossil would turn out to be quite remarkable.
Denisova was discovered when a fossil was found in the Altai mountains and was determined to be a new species of hominin – which means an early human.
There are a few hominins that have been discovered so far. And many date back to as far as four million years!
All The Unknowns
Our oldest human ancestor is the Ausralopithecines who walked on two leaves and could climb very well. These relatives of humans came from Africa millions of years ago.
To put things into perspective, Homo Sapiens only emerged around 250,000 years ago. But Slon needed to figure out more about this period.
The small piece of bone was in slon’s lab at Max Planck Institute for Evolutionary Anthropology. Then, she told a colleague to examine the pile for old fossils to add to their new system. Little did they know what it would mean.
There had to have been a mistake. There had to have been a mistake, she couldn’t believe what she was seeing on the screen once the sample was processed.
Experience And Expertise
Slon had studied for many years and had seen her fair share of fossils. But even with all the early humans she had studied she had never seen something quite like this.
Homo heidelbergensis was a specimen that she loved more than most others. The hominin emerged 700,000 years ago.
The Homo Heidelbergensis came from Africa and Eurasia and were much more like modern people in their appearance. They were particularly interesting to Slon as they laid the foundation for how their descendants would evolve.
But they acted pretty differently from their predecessors, too. Just like another species, Slon was fascinated by…
The Neanderthals are widely known in today’s society as they only emerged 40,000 years ago. Their DNA still remains in most people of European and Asian descent and that’s because they mated with Homo Sapiens.
Slon was fascinated by what the world looked like at that time and how all the species interacted with each other to result in the world and people we have today. But she could have never imagined she’d find a real-life clue.
Asking For Help
Slon’s colleague studied the bone fragment as instructed and immediately asked for her help. The sequence in the DNA wasn’t like the Denisova sample she was expecting. She stared at the sample, puzzled over what went wrong.
That’s when Slon came to lend her expertise and help her colleague understand what was occurring in the DNA. Or more aptly, to discover what secret the DNA was hiding.
Analyzing The Data
When Slon analyzed the DNA present in the bone’s mitochondria, she had no idea what was waiting for her. The bone fragment was just one inch in size but she could already tell something for certain.
The DNA indicated that it belonged to a teenage girl who was about 15-years-old. At first, the bone looked like it belonged to Denisova but something didn’t quite add up.
Slon grabbed more equipment and began to analyze the nuclear DNA. “This was already very exciting,” Slon told National Geographic. “It only got more exciting when we started looking at the nuclear DNA.”
“That’s when we realized there was something a bit funky about this bone,” Slon continued.
Slon’s knowledge of genetics told her that material is passed down by both the mom and dad. It wasn’t enough to know who this bone belonged to but where she came from and who her parents were.
Slon excitedly got to work but nothing could have prepared her for the shock of making a monumental scientific discovery.
When she studied the results at first, she thought she had made a mistake. She redid the analysis again and again before coming to the realization that she had stumbled upon something extraordinary.
While studying the bone fragment, she realized that the ancient girl’s genetic makeup was incredibly diverse.
Her heterozygosity was incredibly high. For relatives, heterozygosity would present in DNA as relatively meager. For unrelated but same species, it would present higher but still relatively small. But in this ancient girl, the presence of heterozygosity at an alarmingly high rate could only mean one thing.
Slon’s eyes grew wide as she looked at the test analysis for the final time. She had discovered one of the holy grails in human evolution.
Belonging To Two Species
Slon discovered that this bone fragment belonged to a first-generation child of interbreeding between two different species. Who were her parents?
The analysis showed that this girl was the love child of a dad who was a Denisovan and a mom who was a Neanderthal. But how was it even possible?
“We knew from previous studies that Neanderthals and Denisovans must have occasionally had children together,” Slon told London newspaper the Evening Standard. “But I never thought we would be so lucky as to find an actual offspring of the two groups.”
Geneticist David Reich who worked at Harvard University agreed…
First Generation Hybrid
“It’s amazing to be able to find something like this,” Reich said to National Geographic. “It seemed unlikely that we would be able to catch it happening in the act – an individual that’s really the product of a first-generation hybrid.”
However, how is interbreeding possible without resulting in deformities in the offspring?
Although a mule which is bred by a donkey and a horse can be born relatively healthy, it will always be infertile, preventing it from producing young of its own.
But there are other species that defy the deformities science of interbreeding and one such case is seen in big cats. Have you ever heard of a liger?
Evolution of Interspecies
A liger is a hybrid breed of a lion and a tiger. They aren’t bred in the wild as the locations of the two species’ habitats are too far apart but they have been bred in zoos.
These beasts grow to be much larger than their lion and tiger parents and can indeed produce offspring of their own. Not to mention, of course, the interbreeding between Homo sapiens and Neanderthals…