Our genetic history can now be traced, thanks in part to DNA extracted from fossils.

Credit: Francois Mori/AP

The Human Story Behind Our Genes

December 14, 2017

Earlier this year, an international team of scientists came across Homo sapien fossils in Morocco. At 300,000 years old, the bones became the oldest known human fossils on Earth.  

The discovery solidified something scientists have known for a while: modern human life began in Africa. But geneticist Adam Rutherford says our understanding of the genetics of these fossils is progressing more quickly, thanks to rapid advances in technology.

“I’ve been doing science now, as an adult, for 25 years or so, and I’ve never come across a field which has been in such perpetual revolution in the last five years as the human story,” said Rutherford. “It all has to do with the fact that we are now capable of extracting DNA from people who have been dead for thousands of years.”

Rutherford is the author of the book, “A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes.” He says recent genetic discoveries have helped scientists paint a clearer picture of how our ancestors made their way around the globe. In the process, we’ve had to change the idea of what our species’ family tree looks like.

For example, Homo sapiens in East and North Africa began migrating out of the continent around 100,000 years ago. They eventually met up with and became, ahem, very friendly with European Neanderthals.   

“Genetics has a lot of euphemisms in it, and we called them, ‘gene flow events’,” Rutherford said. “We know that because I carry Neanderthal DNA in me. And we only know that it’s Neanderthal DNA because we’ve sequenced the Neanderthal genome. We now know that every European carries Neanderthal DNA in them.”  

These origin stories are a big reason why, genetically speaking, Rutherford says race isn’t relevant.

“It doesn’t really exist,” Rutherford said. “The trouble is that genetics does not reflect, in any way, the human variations we see in front of us.”

Rutherford says that physical characteristics are deceptive because we use them as identifiers. But in reality, they’re not representative of what we see in our genomes.

“You take two black guys from Boston and from New York, and they’re probably genetically less related to each other than either one is to me, or you, or the prime minister of China,” Rutherford said.  

But that explanation doesn’t satisfy people who are trying to use race as a justification for politically-driven motives.   

“I get a lot of correspondence from Neo-Nazis who are saying, ‘I am Aryan and I can prove that I’m Norse or European,’ and you can’t do that,” Rutherford said. “There isn’t a way of doing that. But they’re using genetics to say, ‘This is who I am. This is my political and cultural identity,’ which is not something genetics can do.”

Even with all the breakthroughs in modern genetics, Rutherford says there’s quite a bit of work to be done in order to fully understand the human story.

“We pretty much understand the broad aspects of how human biology works, but it’s all in the details and, my Lord, genetics is all about the details,” Rutherford said.

And those details make up the questions that drive research. Questions from, "Why does a human have fewer genes than a banana?” to “How do we relieve and better understand complex disease?” Rutherford says we’re just at the stage where we’re chipping away at the details in order to find the answers.  


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