Hello! I'm Hank Green. Welcome to SciShow Breaking News.

There are a lot of things we could talk about today: new meteorites that have been studied, fossils that have been founds, new insights in medicine. These things are important and wonderful and I enjoy sharing them with you, but today I'm talking about gun violence.

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The terrible situation in Connecticut last week has us each looking for answers, and some of those answers we're trying to find on the inside. But with something so horrifyingly senseless, I can say that there are at least some things that science can add to this conversation.

A fair amount of research, as you might expect, has gone into gun violence as a public health issue, and many medical and social scientists say that there needs to be a lot more. The research that's been done into what causes such violence and how it can be prevented holds some valuable lessons, but in some cases, the findings aren't as conclusive as we might like.

For instance, when it comes to how effective certain gun laws are, studies often yield few clear findings.

A major study about the effectiveness of the 1994 Brady Law, which requires background checks for the purchase of firearms in the United States, found almost no significant difference in the rate of gun deaths where the law was imposed. The one major change was a 6% drop in suicides with firearms among senior citizens.

By the same token, research can be just as inconclusive about laws that make it easier to own, use, and walk around with guns. Studies in places like Florida, which have so-called "right to carry" laws, have found that lax gun laws haven't led to spikes in gun violence. But they've also done nothing to deter crime, which is what the law's proponents expected.

Nonetheless, when you look at overall trends in the study of guns, a picture comes into focus.

In October, the American Academy of Pediatrics published a major survey of gun violence research in the U.S. Among its findings was the fact that even though 75% of American handgun owners say they own gun for self-defense, households with firearms are at three times more risk of experiencing a homicide than homes without guns and five times more risk of a gun-related suicide. It even found that people who had a gun were four times more likely to be shot in an assault than those who were unarmed.

These numbers help explain why, according to the study, the U.S. has the highest gun fatality rate of any high-income country, particularly among young people. For the 15-24 age range, the range that included Connecticut gunman Adam Lanza, it's 35 times higher than in other countries.

Now, there are lots of factors that affect gun violence as a public health issue, especially access to mental healthcare, but the AAP study concludes that the most reliable predictor of gun violence is simply the availability of guns themselves in a home or in a community.

Science, of course, doesn't have an opinion about guns one way or another. It just has facts, and the facts, to me, are pretty clear. But there's a lot more work to do on this issue, and science is here to help. Even though we may not yet truly understand what has happened in places like Newton and Aurora -- maybe we will never understand them -- we can at least redouble our efforts to making people healthier, safer, and happier.

Thank you for watching this episode of SciShow News. We always endeavor to bring a scientific perspective to whatever's going on in the news, even when it's something as tragic as this. We'll see you next time.

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