Is the end near? Scientists at Duke University say the world is on the brink of its sixth great extinction, since certain species of plants and animals are now dying out at least 1,000 times faster than they did before humans came into existence.

The study, published Thursday in the journal Science, measured the the rate at which species are disappearing from Earth. In 1995, the researchers found that the pre-human rate of extinctions was roughly 1. Now, that rate is about 100 to 1,000.

Stuart Pimm, the study's lead author, said habitat loss is mostly to blame for the increasing death rates. As humans continue to alter and destroy more land, animals and plants are increasingly being displaced from their natural habitats. Climate change is also a factor, he added.

"Whether we avoid it or not will depend on our actions," Pimm warned. Jordan Valinsky

Sunday's cyberattack on Iran's underground Natanz uranium enrichment facility, widely believed to be the work of Israel, has added another layer of uncertainty over the already delicate indirect talks between Iran and the U.S. on reviving the 2015 nuclear deal. Iranian Foreign Minister Mohammad Javad Zarif on Monday threatened retaliation against Israel and "any power with knowledge" of the sabotage, but he said Iran will take part in scheduled Wednesday negotiations in Vienna, conducted through European and other parties to the nuclear accord.

Israel, whose government strongly opposed the 2015 deal and has criticized President Biden's efforts to resurrect it, has neither publicly denied or claimed responsibility for the cyberattack, which temporarily set back Iran's ability to enrich uranium at the facility. But Israeli media has heavily suggested the country is behind the sabotage, and U.S. and Israeli officials confirmed to The New York Times that Israel at least played a role.

The Biden administration has neither condemned nor celebrated the Natanz attack. White House Press Secretary Jen Psaki said Monday "the U.S. was not involved in any manner" and has "nothing to add on speculation about the causes or the impacts," adding, "Our focus is on the diplomatic path forward."

It isn't clear if the U.S. was warned about the sabotage beforehand or whether Israel timed the attack to coincide with a visit to Israel by U.S. Defense Secretary Lloyd Austin. Austin did not mention Iran at a news conference Monday with Israeli Prime Minister Benjamin Netanyahu.

The talks to restart the agreement, which former President Donald Trump pulled out from in 2018, are at an early stage, and the U.S. and Iran don't agree about which U.S. sanctions would be lifted and under what conditions; Iran wants them lifted before it returns to compliance with the nuclear deal while the U.S. sees Iran's compliance as a precondition. At this point, both sides are committed to the negotiations.

Israel wants "to take revenge because of our progress in the way to lift sanctions," Zarif said. "We will not fall into their trap. ... We will not allow this act of sabotage to affect the nuclear talks." Peter Weber

The Biden administration has reached a deal with Mexico, Honduras, and Guatemala to increase security at their borders in order to curb increased migration at the U.S. southern border.

White House Press Secretary Jen Psaki on Monday said Mexico will keep 10,000 troops stationed at its southern border and Honduras has deployed 7,000 police officers and members of the military to its border. Guatemala has sent 1,500 police officers and troops to its southern border and will also set up 12 checkpoints inside the country, along a route taken by migrants.

Psaki said the "objective is to make it more difficult to make the journey" to the U.S. "and make crossing the borders more difficult." Last month, Border Patrol agents encountered almost 170,000 migrants at the U.S. southern border, the highest number since March 2001, The Guardian reports.

Migrants are fleeing poverty, violence, corrupt governments, and extreme weather. Security forces in Mexico, Honduras, and Guatemala have all been accused of abusing migrants and targeting them for extortion and robbery, The Guardian says. Catherine Garcia

A student in a bathroom at Austin-East Magnet High School in Knoxville, Tennessee, opened fire on officers Monday afternoon when police responded to a report of a possible shooter on campus, authorities said.

Tennessee Bureau of Investigation Director David Rausch said during a Monday night news conference that officers ordered the student to leave the bathroom, but he refused and reportedly opened fire. Police returned fire, killing the student.

An officer was shot in the upper leg and was rushed into surgery, authorities said; he is expected to recover. There were no other injuries reported. "It's a sad day for Knoxville, and it's tough for Austin-East," Rausch said. It is not clear why the student brought a gun to school or fired it at officers.

There has been an increase in gun violence affecting Austin-East students, with three being shot and killed less than three weeks apart earlier this year, The Associated Press reports. State Rep. Sam McKenzie (D) represents the district where Austin-East is located and also attended the school, and released a statement saying he is "at a loss to describe my sadness as yet another horrific act of gun violence has happened in my community." He called on neighbors to "make sure we take every step and make every effort to prevent these tragedies from continuing to occur." Catherine Garcia

For the second night in a row, hundreds of people are protesting the officer-involved shooting of Daunte Wright, a 20-year-old Black man who was shot and killed Sunday afternoon during a traffic stop in Brooklyn Center, Minnesota.

Brooklyn Center is a suburb of Minneapolis, and about 10 miles away from the courthouse where the Derek Chauvin trial is being conducted. On Monday morning, Brooklyn Center Police Chief Tim Gannon said it appears the officer who shot Wright intended to fire a Taser, but accidentally grabbed her gun. Demonstrators have been stationed outside of the Brooklyn Center Police Department headquarters all day, and a fence and concrete barriers have been put up; there are also members of the Minnesota State Patrol and Minnesota National Guard on site.

As night fell, protesters began chanting and banging drums, ignoring a 7 p.m. curfew put in effect by Gov. Tim Walz (D). NBC News reports there have been projectiles and tear gas fired into the air, and there are people looting a Dollar Store across the street from the police department.

Earlier in the evening, at least 300 people attended a vigil for Wright, the Star Tribune reports, and his mother, Katie Wright, addressed the crowd. "I just need everyone to know that he was my life," she said. "He was my son. And I can never get that back. Because of a mistake? Because of an accident?" Catherine Garcia

Use-of-force expert Seth Stoughton testified on Monday that no "reasonable" officer would have done what former Minneapolis Police Officer Derek Chauvin did during the arrest of George Floyd last May.

Chauvin, a 45-year-old white man and 19-year police veteran, is facing murder and manslaughter charges in the death of Floyd, a 46-year-old unarmed Black man who died while being arrested on suspicion of using a counterfeit $20 bill. Video recorded by a witness shows Floyd facedown, with Chauvin's knee on his neck for more than nine minutes.

Stoughton, a professor at the University of South Carolina School of Law, said that "no reasonable officer would have believed that that was an appropriate, acceptable, or reasonable use of force." There were several times during the arrest where Chauvin should have been aware that Floyd was in distress, Stoughton said, and it was unreasonable for the officers at the scene to think Floyd could escape or cause them harm once he was handcuffed and on the ground.

Dr. Jonathan Rich, a cardiology expert from Northwestern Memorial Hospital in Chicago, testified that Floyd died due to low oxygen levels, saying it was "truly the prone restraint and positional restraints that led to his asphyxiation." The defense has theorized that Floyd's death could have been the result of his high blood pressure and narrowing arteries, plus methamphetamine and fentanyl found in his system.

The prosecution also called to the stand Floyd's younger brother, Philonise Floyd, who provided "spark of life" testimony, sharing stories about their bond as a way to show the jury Floyd was a person, not just a victim. He talked about how they played football together, and called his brother "a leader in our household." George Floyd was also charismatic, Philonise said, and people would attend their church because he went there. "He just was like a person everybody loved around the community," Philonise added. "He just knew how to make people feel better." Catherine Garcia

President Biden plans on nominating Christine Wormuth, a top Defense Department policy official during the Obama administration, as Army secretary, the White House announced Monday.

If confirmed by the Senate, Wormuth will be the first woman to lead the Army. She started working at the Pentagon in 1996, and in 2014, became policy chief, shaping the military's campaign against the Islamic State, Politico reports. Wormuth has also served on the National Security Council, directing defense policy and strategy, and was director at Rand, the international security and defense policy center.

The White House also announced three other nominations on Monday: Susanna Blume as head of the Pentagon's Cost Assessment and Program Evaluation office; former Rep. Gil Cisneros (D-Calif.) as undersecretary of defense for personnel and readiness; and Christy Abizaid as director of the National Counterterrorism Center at the Office of the Director of National Intelligence. Catherine Garcia