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South Asian toolmaking withstood the biggest volcanic blast in 2 million years
Stone tools found in central India suggest that ancient South
Asians stayed the course after a massive explosion of Indonesia’s Toba volcano
around 74,000 years ago, researchers say. While the volcanic eruption was
Earth’s largest in the last 2 million years, scientists have disagreed about
how much it affected human populations as well as the global climate.
Studying the tools, excavated at the Dhaba site in India’s
Middle Son River Valley, the researchers found that the style of toolmaking stayed
largely unchanged from
roughly 80,000 to 48,000 years ago. That means toolmakers were striking
sharp-edged flakes from prepared chunks of rock both before and after Toba
erupted, report archaeologist Chris Clarkson of the University of Queensland in
Brisbane, Australia, and his colleagues.
The finding, published February 25 in Nature Communications, adds to skepticism about claims that Toba’s ashy outburst triggered a planetary chill that nearly wiped out humankind (SN: 5/13/13).
Instead, the researchers say, people must have maintained their way of life in the area, despite the likelihood that ash from the volcanic blast temporarily blocked out the sun. Ash layers from the Toba eruption have been unearthed about 700 meters east of Dhaba.
In dating the tools, the researchers estimated when sediment
layers containing the objects had last been exposed to sunlight. The oldest
stone tools at Dhaba resemble artifacts
that originated in Africa as early as 400,000 years ago (SN: 1/31/18) as well as stone
tools found in Australia (SN: 7/19/17)
that date to about 65,000 years ago.
To explain those similarities, the investigators suggest that some Homo sapiens left Africa by 100,000 years ago and moved eastward through South Asia and on to Australia, bringing with them an ancient toolmaking tradition. No fossils of H. sapiens or any other hominid have been found at Dhaba.
We may be on the brink of a coronavirus pandemic. Here’s what that means
The coronavirus outbreak that began late last
year in China has now spread to 29 countries, touching every continent except
South America and Antarctica. While the vast majority of cases are still in
China, the virus is gaining a foothold in other countries, raising fears the
world is on the brink of a pandemic. South Korea has seen nearly 1,000 people
sickened just in the last week, while Italian health officials say 229 people
nationwide have recently been diagnosed with the disease, now
called COVID-19 (SN: 1/29/20).
But who decides what counts as a pandemic, and
what does that mean? Here’s what we know so far.
What is a pandemic?
According to the World Health Organization, a
pandemic is the worldwide spread of a new disease. It’s most often used in reference to influenza, and
generally connotes that an epidemic has spread to two or more continents with
sustained, person-to-person transmission.
The severity of illness doesn’t fall under the
WHO’s strict definition of a pandemic — just the disease’s spread — though the
WHO may take the overall burden of the disease into account before declaring a
pandemic. As the top global health agency, the WHO is relied upon to be the
first to make the pandemic declaration.
Is COVID-19 a pandemic?
Despite the global reach of the disease, the WHO
has so far declined to declare COVID-19 a pandemic.
“For the moment, we are not witnessing the uncontained global spread of this virus, and we are not witnessing large-scale severe death or disease,” WHO Director-General Tedros Adhanom Ghebreyesus said in a news conference February 24.
“Does this virus have pandemic potential?
Absolutely,” Ghebreyesus said. “Are we there yet? From our assessment, not
yet.”
When was the last pandemic?
The last time that the WHO declared a pandemic
was in 2009, for a
then-novel H1N1 strain of influenza, which some researchers
estimate infected 1 billion people in the first six months, and killed hundreds
of thousands in its first year (SN:
3/26/10). By comparison, over 2,700 people have died from COVID-19 since it
emerged in December.
The Spanish Flu of 1918 is the worst pandemic in
recent memory; it claimed the lives of at least 50 million people worldwide
from 1918 to 1919.
How is a pandemic different from an outbreak or epidemic?
All pandemics begin with an outbreak
of a new disease in a specific geographic location. If that outbreak becomes
larger, but is still confined to a specific region, it becomes an epidemic. At that
point, the WHO may declare a public health emergency of international concern
to raise awareness that a serious disease is spreading and may affect nearby
countries, but ultimately may still be contained. Once a disease spreads
globally, with multiple epidemics across different continents, it’s a pandemic.
Exactly when an outbreak crosses the threshold
to become a pandemic isn’t entirely clear, according to Amesh Adalja, an
infectious disease physician also at Johns Hopkins Center for Health Security
in Baltimore. “There’s not some strict criteria that you check off,” he says. “In
some ways, it’s a term of art.”
But when multiple countries across the globe are
reporting outbreaks sustained by person-to-person transmission that can no
longer be directly tied to the initial source, it’s a pandemic, Adalja says. “I
think we’re in the early stages of a pandemic, from an infectious disease
physician’s standpoint, and it’s just a matter of time before [the WHO]
officially declares it.”
In January, the WHO declared
the new coronavirus outbreak a public health emergency of international concern, or PHEIC, signaling to the global community that COVID-19 was a
serious threat (SN: 1/30/20). That declaration allowed WHO to make
stronger, though nonbinding, recommendations to member countries in an effort
to contain the virus and prevent it from becoming a pandemic.
Declaring a pandemic grants the WHO no
additional powers. But it does signal that this virus is no longer containable
within a specific region or regions, and that countries may want to shift their
focus toward coping with COVID-19 and away from containment measures, such as overly
restrictive quarantines.
What happens if WHO declares COVID-19 a pandemic?
The coronavirus that causes COVID-19 has reached
this point, unlike SARS or MERS, because it spreads much more like the common
flu than those more severe, but less transmissible viruses, says Michael
Osterholm, an epidemiologist at the University of Minnesota in Minneapolis.
“Trying to stop influenza transmission is like trying to stop the wind,” he
says. “Containment [of COVID-19] was never going to work.”
Osterholm says that, whether or not the WHO
declares COVID-19 a pandemic in the coming days, we should all change our mind-set,
to shift away from containment toward dealing with a virus that can’t be kept
out by travel restrictions. While such measures may temporarily slow the spread
of the virus, they’re ineffective in the long term, he says, and can lead to
disruptions in the supply chain of medical supplies, much of which is produced
in China.
Instead, Osterholm says countries should focus
on minimizing the impact of COVID-19. That may be a challenge, since most
countries aren’t
prepared for a pandemic, according to a study
published in late 2019 by the Johns Hopkins Center for Global Health Security. After
investigating 195 countries, researchers found that most had insufficient
systems in place for detecting novel diseases, rapidly moving to contain their
spread or caring for the sick. Even the nine most prepared countries, including
Canada and the United States, had significant gaps in preparedness.
Osterholm says the first step is to protect
health care workers and bolster health care systems for the possible extra
burden of treating critical COVID-19 cases, on top of routine cases of flu,
heart attacks and cancer diagnoses.
The vast majority of COVID-19 cases will be
mild, with some people experiencing no symptoms at all. But experts say
identifying individuals who are most at risk for serious complications will
help health systems triage resources.
“We’re all gonna get through this,” Osterholm
says. “But how we get through this is determined only in part by what the virus
does. It’s also a matter of how well we all work together to minimize the
impact.”