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SUNDAY SCIENCE: OLDEST HUMAN GENOMES REVEAL HOW A SMALL GROUP BURST
OUT OF AFRICA  
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Carl Zimmer
January 12, 2025
New York Times
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_ DNA from European fossils dating back 45,000 years offers new clues
to how our species spread across the world. _

An artist’s interpretation of the LRJ people, who lived across
northern Europe about 45,000 years ago. DNA reveals they were closely
related to all living non-Africans., Tom Björklund

 

Some 45,000 years ago, a tiny group of people — fewer than 1,000,
all told — wandered the icy northern fringes of Europe. Across
thousands of miles of tundra, they hunted woolly rhinoceros and other
big game. Their skin was most likely dark. To keep warm in the
bone-chilling temperatures, they probably wore the hides and furs of
the animals they killed.

These hardy people of the Ice Age, known as the LRJ culture, left
behind distinctive stone tools and their own remains in caves
scattered across Europe. On Thursday, researchers revealed
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seven LRJ individuals from fossilized bones found in Germany and the
Czech Republic — the oldest genetic specimens of modern humans yet
found.

It turns out the LRJ people were part of the early human expansion
from Africa to other parts of the world. But theirs was a surprisingly
recent migration.

The common ancestors of the LRJ people and today’s non-Africans
lived about 47,000 years ago. In contrast, studies of remains in
Australia suggest that modern humans reached that continent 65,000
years ago [[link removed]].
And in China
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researchers have found what look like the bones of modern humans
dating back 100,000 years.

The huge gap between those ages could change our understanding about
how humans spread across the world. If the ancestors of today’s
non-Africans didn’t sweep across other continents until 47,000 years
ago, then those older sites must have been occupied by earlier waves
of humans who died off without passing down their DNA to the people
now living in places like China and Australia.

“They cannot be part of the genetic diversity that’s present
outside Africa,” said Johannes Krause, a geneticist at the Max
Planck Institute for Evolutionary Anthropology in Leipzig, Germany,
and an author of the new study.

The newly discovered genomes come from fossils that have baffled
scientists for decades. In 1950, archaeologists digging in a cave in
what is now the Czech Republic found the skull of an ancient woman.
They could not determine its age, however. They found stone tools at
the site, known as Zlatý kůň, but the tools were not distinctive
enough to link the woman to any particular cultural group.

A few years ago, Max Planck researchers managed to extract some DNA
from the skull. A preliminary analysis
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belonged to an ancient branch of humans.

The Zlatý kůň skull, found in 1950 in what is now the Czech
Republic. Credit...Marek Jantač

Meanwhile, another set of ancient bones arrived from a cave in Germany
called Ranis, about 140 miles west of Zlatý kůň.

The Ranis remains were discovered more than a century ago.
Archaeologists had concluded that they had all belonged to a single
ancient culture, which they called the
Lincombian-Ranisian-Jerzmanowician, or LRJ for short. But they did not
know much more. It wasn’t clear if the LRJ people were modern humans
or Neanderthals, for example.

In 2016, a team of archaeologists went back into Ranis for a fresh
look. Marcel Weiss, an archaeologist at the University of
Erlangen-Nuremberg in Germany, and his colleagues uncovered a new
batch of fossils and tools and used 21st-century methods to analyze
them. The fossils yielded a wealth of DNA — enough to reconstruct
the genomes of six individuals.

They were all closely related to each other, including a mother and
her daughter. The scientists also discovered that two of them were
closely related to the Zlatý kůň woman.

“It’s the same group, the same extended family,” Dr. Krause
said. “It could be that they knew each other.”

The researchers estimated that all seven sets of fossils were at least
45,000 years old. Their genomes are now bringing the LRJ people out of
history’s shadow.

Their genetic similarity indicates that they belonged to a tiny
population that only numbered a few hundred at any given time. And the
close kinship between the six Ranis and single Zlatý kůň
individuals suggests that the LRJ people wandered in small bands over
vast distances, spending little time in any one place.

“If I were to go to New York and just take one person from the Bronx
and then go over to Long Island and take another person from there, it
would be unlikely that these two have a common ancestor within the
last three generations,” said Kay Prüfer, a paleogeneticist at Max
Planck and a co-author of the new study. “But, of course, we are
talking about the deep past, when things were different.”

Dr. Prüfer and his colleagues found that the LRJ people lacked some
key mutations found in living Europeans. They did not have the genes
that produce pale skin, for example, which suggests that they had dark
pigmentation, as their ancestors who emerged from Africa did.

The cave in the Czech Republic where the Zlatý kůň skull was found
in 1950. Credit...Martin Frouz

The scientists also used the genomes to figure out where the LRJ
people fit on the human family tree. Previous studies had established
that human ancestors evolved for millions of years in Africa. About
600,000 years ago, the ancestors of Neanderthals split off on their
own. They spread through the Middle East and established themselves
across Europe and western Asia. Neanderthals endured for hundreds of
thousands of years, disappearing from the fossil record about 40,000
years ago.

Modern humans remained longer in Africa before expanding to other
continents. When they met Neanderthals, possibly in the Middle East,
they interbred. Today, all humans
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the world carry at least a trace of Neanderthal DNA.

While the broad outlines of this history are well established,
scientists are still struggling to pin down the specifics. Estimates
of when modern humans and Neanderthals first interbred have ranged
from 54,000 years ago to 41,000 years ago, for example.

Dr. Krause and his colleagues discovered that, unlike living humans,
the LRJ people had long stretches of Neanderthal DNA in their genomes.
This suggests that relatively little time had passed since modern
humans interbred with Neanderthals. Dr. Krause and his colleagues
estimate that the interbreeding took place 1,000 to 2,500 years
beforehand, or about 46,000 years ago.

In another study
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Thursday, a second team of scientists reached a similar conclusion by
surveying Neanderthal DNA in fossils and in living people.

“It was really fantastic to see a similar date,” said Priya
Moorjani, a paleogeneticist at the University of California, Berkeley,
and an author of the second study.

Independent scientists said that the new timing suggested that modern
humans moved from the Middle East to the northern margins of Europe at
a remarkable speed. “The time frame gets really tight,” said
Pontus Skoglund, a paleogeneticist at the Francis Crick Institute in
London.

Dr. Skoglund also said it would be strange for non-African ancestors
to have arisen about 47,000 years ago while modern humans in Asia and
Australia dated back 100,000 years. The sites in question could have
been incorrectly dated, he said, or people could have reached Asia and
Australia that long ago, only to die out.

He Yu, a paleogeneticist at Peking University in Beijing who was not
involved in either study, said that the mystery wouldn’t be solved
until scientists find DNA in some of the ancient Asian fossils.

“We still need early modern human genomes from Asia to really talk
about Asia stories,” Dr. Yu said.

_CARL ZIMMER: I write the Origins column
[[link removed]] for THE NEW YORK TIMES and
cover news about science._

_I report on life — from microbes at the bottom of the sea to
high-flying migratory birds to aliens that may dwell on other planets.
For my column, I focus on how life today got its start, including our
own species. Along with covering basic science, I write stories about
how biological discoveries evolve into medical applications, such as
editing genes and tending to our microbiome._

_I wrote my first story for The Times in 2004. In 2013 I became a
columnist. I began my career in journalism at Discover Magazine, where
I rose to senior editor. I went on to write articles for magazines
including The Atlantic, Scientific American, Wired and Time._

_I also write books about science. My next book is “Air-Borne: The
Hidden History of the Life We Breathe,” to be published in February
2025. I am an adjunct professor at Yale’s Department of Molecular
Biophysics and Biochemistry, where I teach seminars on writing and
biology lecture courses. I have also coauthored a textbook on
evolutionary biology, now in its fourth edition._

_My books and articles have earned a number of awards, including the
National Academies Communication Award and the Stephen Jay Gould
Prize, given out by the Society for the Study of Evolution. I have won
fellowships from the Johns Simon Guggenheim Foundation and the Alfred
P. Sloan Foundation. During the Covid-19 pandemic, I contributed to
the coverage that won The Times the Pulitzer Prize for Public Service
in 2021. I am, to my knowledge, the only writer after whom both a
species of tapeworm and an asteroid have been named._

_I live with my wife in Connecticut, alongside salt marshes rife with
snapping turtles._

_Subscribe to the NEW YORK TIMES
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Ask Ethan: Can a lumpy Universe explain dark energy?
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Ethan Siegel
Starts With A Bang/Big Think
January 3, 2025

* Science
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* Africa
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* paleoanthropology
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