How the Last 12,000 Years Have Shaped What Humans Are Today
By OHIO STATE UNIVERSITY
Humans have been evolving for millions of years.
However,
the past 12,000 years have been the most dynamic and impactful for human
living. According to Clark Spencer Larsen, a professor of anthropology at The Ohio State University, our modern world all started
with the advent of agriculture
“The
shift from foraging to farming changed everything,” Larsen said.
Along
with food crops, humans also planted the seeds for many of the most vexing
problems of modern society.
“Although
the changes brought about by agriculture brought plenty of good for us, it also
led to increasing conflict and violence, rising levels of infectious diseases,
reduced physical activity, a more limited diet, and more competition for
resources,” he said.
Larsen is the organizer and editor of a Special Feature recently published in the journal Proceedings of the National Academy of Sciences. He is also the author of the introduction to the section, titled “The past 12,000 years of behavior, adaptation, population, and evolution shaped who we are today.”
The
Special Feature includes eight articles based mostly on bioarchaeology – the
study of human remains and what they can tell scientists about changes in diet,
behavior, and lifestyle over the last 10 millennia or so. Larsen is the
co-author on two of these eight articles.
One
message that connects all the articles is that the major societal issues of
today have ancient roots, he said.
“We
didn’t get to where we are now by happenstance. The problems we have today with
warfare, inequality, disease, and poor diets, all resulted from the changes
that occurred when agriculture started,” Larsen said.
The
shift from foraging to farming led humans, who had led a mostly transitory
life, to create settlements and live a much more sedentary existence.
“That
has had profound implications for virtually every aspect of our lives back
then, now, and going forward,” he said.
Growing
food allowed the world population to grow from about 10 million in the later
Pleistocene Epoch to more than 8 billion people today.
But
it came at a cost. The varied diet of foragers was replaced with a much more
limited diet of domesticated plants and animals, which often had reduced
nutritional quality. Now, much of the world’s population relies on three foods
– rice, wheat, and corn – especially in areas that have limited access to
animal sources of protein, Larsen said.
Another
important change in the diet of humans was the addition of dairy. In one
article in the Special Feature, researchers examined dental calculus found in remains
to show the earliest evidence of milk consumption dates to about 5,000 years
ago in northern Europe.
“This
is evidence of humans adapting genetically to be able to consume cheese and
milk, and it happened very recently in human evolution,” he said. “It shows how
humans are adapting biologically to our new lifestyle.”
As
people began creating agricultural communities, social changes were occurring
as well. Larsen co-authored one article that analyzed strontium and oxygen
isotopes from tooth enamel of early farming communities from more than 7,000
years ago to help determine where residents were from. Results showed that
Çatalhöyük, in modern Turkey, was the only one of several communities studied
where nonlocals apparently lived.
“This
was laying the foundation for kinship and community organization in later
societies of western Asia,” he said.
These
early communities also faced the problem of many people living in relatively
cramped areas, leading to conflict.
In
one article, researchers studying human remains in early farming communities
across western and central Europe found that about 10% died from traumatic
injuries.
“Their
analysis reveals that violence in Neolithic Europe was endemic and scaling
upward, resulting in patterns of warfare leading to increasing numbers of
deaths,” Larsen writes in the introduction.
Research
reported in this PNAS issue also reveals how these first human communities
created the ideal conditions for another problem that is top-of-mind in the
world today: infectious disease. Raising farm animals led to the common
zoonotic diseases that can be transmitted from animals to people, Larsen said.
While
the climate change crisis of today is unique in human history, past societies
have had to deal with more short-term climate disasters, particularly long
droughts.
In
a perspective article co-authored by Larsen, the researchers noted that
economic inequality, racism, and other types of discrimination have been key
factors in how societies have fared under these climate emergencies, and these
factors will play a role in our current crisis.
Those
communities with more inequality were most likely to experience violence in the
wake of climate disasters, Larsen said.
What
may be most surprising about all the changes documented in the Special Feature
is how quickly they all occurred, he said.
“When
you look at the 6 or so million years of human evolution, this transition from
foraging to farming and all the impact it has had on us – it all happened in
just a blink of an eye,” Larsen said.
“In
the scale of a human lifespan, it may seem like a long time, but it really is
not.”
The
research presented in the Special Feature also shows the amazing ability of
humans to adjust to their surroundings.
“We
are remarkably resilient creatures, as the last 12,000 years have shown,” he
said.
“That
gives me hope for the future. We will continue to adapt, to find ways to face
challenges, and to find ways to succeed. That is what we do as humans.”
Reference:
“The past 12,000 years of behavior, adaptation, population, and evolution
shaped who we are today” by Clark Spencer Larsen, 17 January 2023, Proceedings of the National Academy of Sciences.
DOI:
10.1073/pnas.2209613120
