He was a loner, with a clean-shaven face and wavy blond hair. His IQ was said to be 66. By all accounts, he was a terrible shot. But with the weapons he carried—the AR-15 and a second, self-loading military-style rifle—aim was almost immaterial. The SP1 could fire several rounds per second with little recoil. Pointing the gun at a crowd of tourists, it was hard not to hit somebody.

If all this sounds too horrifically familiar—an estranged loner, an AR-15, dozens dead in a matter of minutes—there is a remarkable twist to the story. In the wake of the Port Arthur massacre, Australian lawmakers did something about it.

Within just weeks of that tragedy, elected officials in each of Australia’s six states and two mainland territories—pressed forward by police chiefs across the continent and by the then-newly elected prime minister—banned semi-automatic and other military-style weapons across the country. The federal government of Australia prohibited their import, and lawmakers introduced a generous nationwide gun buyback program, funded with a Medicare tax, to encourage Australians to freely give up their assault-style weapons. Amazingly, many of them did. (Simon Chapman, an emeritus professor in public health at the University of Sydney, and an influential proponent of the original firearms legislation, has a very good summary here. You can also read his free ebook here.)

A land of roughneck pioneers and outback settlers, Australia had never embraced much government regulation and certainly not about their guns. This was a land of almost cartoonish toughness and self-reliance, home of Crocodile Dundee and Australian rules football. Here even the kangaroos box. But Port Arthur had followed too many prior deadly shooting sprees and Australians were clearly sick to death of them.

So what happened after the assault-weapon ban? Well therein lies the other half of the story twist noted above: Nothing.

Nothing, that is, in a good way.

Australian independence didn’t end. Tyranny didn’t come. Australians still hunted and explored and big-wave surfed to their hearts’ content. Their economy didn’t crash; Invaders never arrived. Violence, in many forms, went down across the country, not up. Somehow, lawmakers on either side of the gun debate managed to get along and legislate.

As for mass killings, there were no more. Not one in the past 22 years.

In 2002, a mentally impaired student at Monash University in Melbourne shot two people dead and injured five others. He came to his rampage with six handguns, not an assault rifle. Had he been carrying an AR-15, the toll would have been far worse. But even so, Australian lawmakers added a new National Handgun Agreement, a separate buyback act, and a reformulated gun trafficking policy to their legislative arsenal.

There has been no similar shooting spree since.

But it wasn’t just the murderous rampages that faded away. Gun violence in general declined over the following two decades to a nearly unimaginable degree. In 2014, the latest year for which final statistics are available, Australia’s murder rate fell to less than 1 killing per 100,000 people—a murder rate one-fifth the size of America’s.

Just 32 of those homicides—in a nation of 24 million people—were committed with guns. By comparison, more than 500 people were shot dead last year in the city of Chicago alone. (Chicago has about 2.7 million residents.)

Perhaps most remarkable is what happened with gun suicides in Australia in the wake of the post-Port Arthur firearm legislation. They dropped by some 80 percent, according to one analysis.

What stopped many of those would-be suicides—quite straightforwardly, it seems—was the lack of access to a gun, a generally immediate and effective method of killing. (Nine out of 10 suicide attempts with a firearm result in death, a far higher share than attempts by other methods.) Public health experts call such an effect “means restriction.” Some Australians found other ways to take their own lives—but for many, that acute moment of sadness and resolve passed in the absence of a gun.

Suicide “is commonly an impulsive act by a vulnerable individual,” explain E. Michael Lewiecki and Sara A. Miller in the American Journal of Public Health. “The impulsivity of suicide provides opportunities to reduce the risk of suicide by restricting access to lethal means.”

Which brings us back to the here and now. In 2015, an unthinkable 22,103 Americans shot themselves to death with a gun (see Table I-21)—accounting for just over half of the suicides in the country that year.

It isn’t hard to imagine what would happen without all those guns at the ready. In a world of raging hypotheticals, we actually have some good, hard answers for this. All we have to do is look down under. There are millions of American families begging us to do it.

Correction: This post has been updated to reflect the correct number of rounds fired by the AR-15.

DIGITAL HEALTH

Deep learning's learning curve. Nature is out with an intriguing—and important—piece about the chasm between the promise of AI-fueled machine learning and its use in practice. "Although deep-learning algorithms can evaluate data without human preconceptions and filters... that doesn’t mean they are unbiased. Training data can be skewed — as happens, for example, when genomic data only from northern Europeans are used," writes the journal. "Deep-learning algorithms trained on such data will acquire embedded biases and reflect them in their predictions, which could in turn lead to unequal patient care. If humans help to validate these predictions, that provides a potential check on the problem. But such concerns are troubling if a computer alone is left to make key decisions." (Nature)

INDICATIONS

Aimmune scores a peanut allergy drug trial success. Aimmune Therapeutics announced Tuesday that its experimental peanut allergy medication met the main goals of a late-stage clinical trial, initially sending shares of the company surging. According to the firm, 67% of study participants aged four to 17 who took the treatment could safely tolerate at least 600 mg of peanut protein; just 4% of those receiving placebo were able to do the same. (Reuters)

THE BIG PICTURE

Trump administration proposes longer short-term health plans. The Department of Health and Human Services (HHS) is taking another whack to the Affordable Care Act with new proposed rules that would loosen restrictions on short-term health plans. These plans, which don't have to follow many of Obamacare's key consumer protections, were limited to three-month maximums under the Obama administration; the new rules would extend that period to one year. Some public health experts said that, if enacted, the regulations would likely drive healthier enrollees out of the Affordable Care Act marketplaces, thus raising premiums in the individual insurance exchanges. (Kaiser Health News) 

Serena Williams on what her harrowing childbirth experience taught her. Legendary athlete Serena Williams is offering up some words of wisdom after her life-threatening childbirth experience. Williams took to CNN to remind readers that many black women across the globe share similar stories, but without the advantage of world-class medical care. "What if we lived in a world where every mother and newborn could receive affordable health care and thrive in life? That world is possible. And we must dare to dream it for every black woman, for every woman in Malawi, and for every mother out there," writes Williams. "Across the globe, organizations like UNICEF are committed to delivering simple solutions on behalf of every mother and newborn. These solutions include recruiting and training more doctors and midwives, guaranteeing clean and functional health facilities, making the top 10 lifesaving drugs and equipment available, and most importantly, empowering adolescent girls to demand quality care." (CNN)

REQUIRED READING

Tesla Hackers Hijacked Amazon Cloud Account to Mine Cryptocurrency, by Robert Hackett

When Will Uber's Flying Taxis Take Flight? by Don Reisinger

Meet Chronicle, Alphabet's Latest Moonshot, by Jonathan Vanian

What It Takes to Be One of the 100 Best Companies to Work For, by Michael Bush and Sarah Lewis-Kulin