This week in science, we scanned the skies mournfully looking for the remnants of comet ISON, likely consumed in the furnace of the sun; pondered the question of personhood rights for chimps; and got a look at a new kind of 3D printer that fabricates with metal. But there’s a lot more!

The search for birth control for men took a promising step forward this week, as researchers found a new method that’s 100 percent effective – in mice. While previous efforts focused on making sperm dysfunctional, these have often been a mixed bag (sometimes with sexual side effects like low libido or infertility). The new method simply stops sperm from leaving the testicles during ejaculation. But more work needs to be done – mice were shooting blanks thanks to genetic manipulation, and scientists will have to find drugs that replicate the effect. [Discover]

“You know the type/ loud as a motorbike/ but wouldn’t bust a grape in a fruit fight.” Jay Z’s lyric about a would-be tough guys seems to apply to song sparrows as well. Ecologists found that birds who displayed the most aggressive signals toward a stuffed, fake sparrow frequently didn’t follow through with their threats. It’s actually the quiet ones that you have to look out for: Researchers saw that some sparrows tend to attack without warning:

Are the strong but silent sparrows just confident enough in their prowess that they don’t bother talking it up? The scientists aren’t quite sure yet. [Nature]

Science writer David Dobbs has an interesting critique of the “selfish gene” metaphor popularized by Richard Dawkins. Some biologists, it turns out, are questioning the gene-centric view of evolution, saying that "we need to see the gene less as an architect and more as a member of a collaborative remodeling and maintenance crew.” It’s a provocative thesis, and has already drawn critical responses from evolutionary biologists, including Dawkins himself. [Aeon / Evolution Is True / Richard Dawkins]

U.S. pregnancy rates are nearing record lows set nearly 20 years ago, according to a recent government study. Abortion rates have also been dropping since a peak in 1990. [Washington Post]

One of the many widespread effects of climate change is what’s called “ocean acidification,” a gradual rise in the pH of the sea, caused by increased carbon dioxide emissions reacting with seawater. And according to a new study, this phenomenon seems to be making fish more anxious. Hey -- if your neighborhood were getting more and more acid rain, you’d be getting a little nervous too. [Southern California Public Radio]

How necessary are bees? NPR’s Robert Krulwich looks at how Chinese apple farmers coped surprisingly well with a dip in the honeybee population: They began pollinating their trees by hand. And humans actually turned out to be more efficient pollinators, since bees won’t work in rainy and cold conditions, and the people were careful to spread pollen on all the blossoms they could reach. The result? A 30 percent to 40 percent greater harvest. [NPR]