The U.S. Surgeon General's office estimates that more than 20 million people have a substance-use disorder. Meanwhile, the nation's drug overdose crisis shows no sign of slowing.

Yet, by all accounts, there aren't nearly enough physicians who specialize in treating addiction — doctors with extensive clinical training who are board certified in addiction medicine.

When Frans de Waal first started studying nonhuman primates in the Netherlands more than 40 years ago, he was told not to consider the emotions of the animals he was observing.

"Thoughts and feelings — the mental processes basically — were off limits," he says. "We were told not to talk about them, because they were considered by many scientists as 'inner states' and you only were allowed to talk about 'outer states.' "

The president of the Japanese Olympic Committee said he will step down amid allegations of corruption into the successful bid for Tokyo to host the 2020 Olympics.

Tsunekazu Takeda, 71, is a former Olympic equestrian jumper who competed at the 1972 and 1976 Olympics. He is also the chair of the International Olympic Committee's Marketing Commission.

He maintains his innocence and intends to serve out the rest of his 10^th term as president, resigning in June. He'll also step down from the IOC.

Authorities are looking into whether the suspect in last week's terror attack on two mosques in New Zealand was inspired by an emerging, European-based breed of white nationalism. The identitarian movement, formed in France in 2016, broadly believes that white people in Europe and North America are being displaced by non-European immigrants.

Kazakh President Nursultan Nazarbayev says he will resign the post he has held for nearly 30 years, abruptly announcing the end of an era that began in 1990. But Nazarbayev, 78, also said he'll keep several key official posts, in a speech that aired on national TV Tuesday.

In the former Soviet bloc, formerly comprised of 15 countries, Nazarbayev is the only long-standing leader to sustain power for three decades. The president of Uzbekistan Islam Karimov died in 2016 after his presidential reign of 26 years.

From the front, the unassuming Nashville building that's home to Dan Auerbach's Easy Eye Studio looks like a place more likely to house drab offices than creative labor. In fact, its proprietor confirms a call center once operated inside its walls before he bought the facility and had tracking and control rooms built to his specifications.

As floodwaters begin to recede, Vice President Pence announced in a tweet that he will visit Nebraska on Tuesday to take stock of the devastation.

His visit comes as 74 cities, 65 counties and four tribal areas have declared states of emergency in Nebraska, according to the Nebraska Emergency Management Agency.

As the barren California desert sprang to life, they descended. With their selfie sticks, their smartphones and their gee-whiz-look-at-all-the-flowers smiles, they seemed blissfully unconcerned that they were causing something close to a panic at the highest levels of local government.

The U.S.-backed Syrian Democratic Forces are now in control of an ISIS encampment in Baghouz after weeks of operations and attacks on the village. But isolated gun battles are continuing in the area, seen as ISIS' last remaining redoubt.

"This is not a victory announcement, but a significant progress in the fight against Daesh," said Mustafa Bali, the head of the SDF press office. In a tweet, he added, "Clashes are continuing as a group of ISIS terrorists who are confined into a tiny area still fight back."