WASHINGTON: Humans are the only animal that lives in virtually every possible environment, from rainforests to deserts to tundra.
This adaptability is a skill that long predates the modern age. According to a new study published Wednesday in Nature, ancient Homo sapiens developed the flexibility to survive by finding food and other resources in a wide variety of difficult habitats before they dispersed from Africa about 50,000 years ago.
“Our superpower is that we are ecosystem generalists,” said Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute of Geoanthropology in Jena, Germany.
Our species first evolved in Africa around 300,000 years ago. While prior fossil finds show some groups made early forays outside the continent, lasting human settlements in other parts of the world didn’t happen until a series of migrations around 50,000 years ago.
“What was different about the circumstance of the migrations that succeeded — why were humans ready this time?” said study co-author Emily Hallett, an archaeologist at Loyola University Chicago.
Earlier theories held that Stone Age humans might have made a single important technological advance or developed a new way of sharing information, but researchers haven’t found evidence to back that up.
This study took a different approach by looking at the trait of flexibility itself.
The scientists assembled a database of archaeological sites showing human presence across Africa from 120,000 to 14,000 years ago. For each site, researchers modeled what the local climate would have been like during the time periods that ancient humans lived there.
“There was a really sharp change in the range of habitats that humans were using starting around 70,000 years ago,” Hallett said. “We saw a really clear signal that humans were living in more challenging and more extreme environments.”
While humans had long survived in savanna and forests, they shifted into everything from from dense rainforests to arid deserts in the period leading up to 50,000 years ago, developing what Hallett called an “ecological flexibility that let them succeed.”
While this leap in abilities is impressive, it’s important not to assume that only Homo sapiens did it, said University of Bordeaux archaeologist William Banks, who was not involved in the research.
Other groups of early human ancestors also left Africa and established long-term settlements elsewhere, including those that evolved into Europe’s Neanderthals, he said.
The new research helps explain why humans were ready to expand across the world way back when, he said, but it doesn’t answer the lasting question of why only our species remains today.

After nearly two years of stark divisions over the war in Gaza and support for Israel, Democrats are now finding themselves at odds over US policy toward Iran as progressives demand unified opposition to President Donald Trump’s consideration of a strike against Tehran’s nuclear program while party leaders tread more cautiously.
US leaders of all stripes have found common ground for two decades on the position that Iran cannot be allowed to obtain a nuclear weapon. The longtime US foe has supported groups that have killed Americans across the Mideast and threatens to destroy Israel. But Trump’s public flirtation with joining Israel’s offensive against Iran may become the Democratic Party’s latest schism, just as it is sharply dividing Trump’s isolationist “Make America Great Again” base from more hawkish conservatives.
While progressives have staked out clear opposition to Trump’s potential actions, the party leadership is playing the safer ground of demanding a role for Congress before Trump could use force against Iran. Many prominent Democrats with 2028 presidential aspirations are staying silent, so far, on the Israel-Iran war.
“They are sort of hedging their bets,” said Joel Rubin, a former deputy assistant secretary of state who served under Democratic President Barack Obama and is now a strategist on foreign policy. “The beasts of the Democratic Party’s constituencies right now are so hostile to Israel’s war in Gaza that it’s really difficult to come out looking like one would corroborate an unauthorized war that supports Israel without blowback.”
Progressive Democrats use Trump’s ideas and words
Rep. Ro Khanna, D-Calif., has called Trump’s consideration of an attack “a defining moment for our party” and has introduced legislation with Rep. Thomas Massie, R-Kentucky, that calls on the Republican president to “terminate” the use of US armed forces against Iran unless “explicitly authorized” by a declaration of war from Congress.
Khanna used Trump’s own campaign arguments of putting American interests first when the congressman spoke to Theo Von, a comedian who has been supportive of the president and is popular in the “manosphere.”
“That’s going to cost this country a lot of money that should be being spent here at home,” said Khanna, who is said to be among the many Democrats eyeing the party’s 2028 primary.
Vermont Sen. Bernie Sanders, an independent who twice sought the Democratic presidential nomination, pointed to Trump’s stated goal during his inaugural speech of being known as “a peacemaker and a unifier.”
“Very fine words. Trump should remember them today. Supporting Netanyahu’s war against Iran would be a catastrophic mistake,” Sanders said about Israeli Prime Minister Benjamin Netanyahu.
Sanders has reintroduced legislation prohibiting the use of federal money for force against Iran, insisted that US military intervention would be unwise and illegal and accused Israel of striking unprovoked. Senate Democratic leader Chuck Schumer of New York signed on to a similar bill from Sanders in 2020, but he is so far holding off this time.
Some believe the party should stake out a clear anti-war stance as Trump weighs whether to launch a military offensive that is seemingly counter to the anti-interventionism he promised during his 2024 campaign.
“The leaders of the Democratic Party need to step up and loudly oppose war with Iran and demand a vote in Congress,” said Tommy Vietor, a former Obama aide, on X.
Mainstream Democrats are cautious, while critical
The staunch support from the Democratic administration of President Joe Biden and Vice President Kamala Harris for Israel’s war against Hamas loomed over the party’s White House ticket in 2024, even with the criticism of Israel’s handling of the humanitarian crisis in Gaza. Trump exploited the divisions to make inroads with Arab American voters and Orthodox Jews on his way back to the White House.
Today, the Israel-Iran war is the latest test for a party struggling to repair its coalition before next year’s midterm elections and the quick-to-follow kickoff to the 2028 presidential race. Bridging the divide between an activist base that is skeptical of foreign interventions and already critical of US support for Israel and more traditional Democrats and independents who make up a sizable, if not always vocal, voting bloc.
In a statement after Israel’s first strikes, Schumer said Israel has a right to defend itself and “the United States’ commitment to Israel’s security and defense must be ironclad as they prepare for Iran’s response.”
Sen. Jacky Rosen, D-Nevada, was also cautious in responding to the Israeli action and said “the US must continue to stand with Israel, as it has for decades, at this dangerous moment.”
“It really seems like the Trump and Iran war track is kind of going along like a Formula 1 racetrack, and then the Democrats are in some sort of tricycle or something trying to keep up,” said Ryan Costello, a policy director for the Washington-based National Iranian American Council, which advocates for diplomatic engagement between US and Iran.
Other Democrats have condemned Israel’s strikes and accused Netanyahu of sabotaging nuclear talks with Iran. They are reminding the public that Trump withdrew in 2018 from a nuclear agreement that limited Tehran’s enrichment of uranium in exchange for the lifting of economic sanctions negotiated during the Obama administration.
“Trump created the problem,” said Sen. Chris Murphy, D-Connecticut, on X. “The single reason Iran was so close to obtaining a nuclear weapon is that Trump destroyed the diplomatic agreement that put major, verifiable constraints on their nuclear program.”
The progressives’ pushback
A Pearson Institute/Associated Press-NORC Center for Public Affairs Research poll from September 2024 found that about half of Democrats said the US was being “too supportive” of Israel and about 4 in 10 said their level support was “about right.” Democrats were more likely than independents and Republicans to say the Israeli government had “a lot” of responsibility for the continuation of the war between Israel and Hamas.
About 6 in 10 Democrats and half of Republicans felt Iran was an adversary with whom the US was in conflict.
Democratic Rep. Yassamin Ansari, an Iranian American from Arizona, said Iranians are unwitting victims in the conflict because there aren’t shelters or infrastructure to protect civilians from targeted missiles as there are in Israel.
“The Iranian people are not the regime, and they should not be punished for its actions,” Ansari posted on X, while criticizing Trump for fomenting fear among the Iranian population. “The Iranian people deserve freedom from the barbaric regime, and Israelis deserve security.”