Climate scientists rubbed elbows with Quakers, food activists, and labor unions on Sunday, when more than 100,000 people (400,000, the organizers say; one group of observers calculated it was more like 125,000) thronged to the Upper West Side for the People’s Climate March, a massive demonstration designed to coincide with a United Nations meeting happening on the other side of Manhattan. One notable feature of this march was that it was organized into themed sections: Indigenous groups and other communities on the front lines of climate change led, while labor and student groups, renewable tech, and so forth, got their own designated section. The climate science contingent, which lined up just a block or two away from the American Museum of Natural History, formed behind a line of massive yellow flags that proclaimed in black block lettering: “The Debate Is Over,” echoed among the signs in the science bloc (some sporting charts): Sneak preview… Scientists are bringing the data to the #PeoplesClimate March! #ScienceStands pic.twitter.com/wSd1XWxin8 — Science Stands! (@sciencestands) September 21, 2014 Framing climate change as a settled consensus, not a debate, was certainly the sentiment among scientists at the march. It’s hard to argue with the fact that 97 …

It increasingly looks like the swirling cosmic pattern seen by scientists using the BICEP2 telescope is not a signal of gravitational waves—and, consequently, evidence for the rapid inflation of our universe right after the Big Bang—but rather an artifact of magnetized dust spread throughout our galaxy that originates from dying stars. In March, the BICEP2 team pointed to a swirling pattern they detected in the cosmic microwave background radiation, which reverberates from the Big Bang to this day. If confirmed, the BICEP2 results would have been an exciting piece of evidence for cosmic inflation, vindicated one of Einstein’s predictions, and given scientists a key to unlocking the secrets of quantum gravity. But only if the discovery was confirmed, as many physicists were careful to point out. There always remained the possibility that the signal was not from gravitational waves, but something else. Now, another research team has released a new analysis of data collected by the Planck space telescope showing a full sky map of the interstellar dust around us. And the region examined by BICEP2, omitted by previous dust maps, turns out to be really dusty—enough that the polarization of said dust by the magnetic fields of the Milky Way can start …

Seven days; lots of science in the news. Here’s our roundup of this week’s most notable and quotable items: Chimpanzees seem to have a natural inclination for murder. The tiny, dense galaxy M60-UCD1 was found to have a humongous black hole that accounts for 15 percent of its mass. T. Rex died for your fall leafpeeping excursion: Scientists now believe the meteorite that wiped out the dinosaurs also remade Earth’s landscape, favoring deciduous flowering plants over the once-dominant evergreens. An ancient Egyptian woman was buried 3,300 years ago wearing a complex hairstyle involving 70 separate hair extensions. In mice, artificial sweeteners seem to encourage glucose intolerance, which leads to higher-than-normal blood sugar levels and is a known precursor to diabetes. Scientists discovered the modernEuropean gene pool is a mixture of three distinct types of ancestors that combined within the last 7,000 years: blue-eyed, darker-skinned hunters and fairer, brown-eyed farmers from the Near East, plus a third population from Siberia. A new analysis of King Richard III’s skeleton (discovered underneath a parking lot in 2012) shows he died after suffering 11 stab wounds, nine of them to his head. Syphilis cases are spiking in Australia. Genetically engineered tobacco plants contain enzymes from blue-green algae that allow them to perform photosynthesis faster than normal plants. Earth’s population could hit …

For molecular biologist Liz Heinecke, one of the perks of having a physicist father was getting to try out some of the cool physics apparatus at Kansas State University, like a big rotating table that provided hands-on demonstrations of centripetal force. Not every family has a physics lab handy for inspiration, though, so Heinecke made it her mission to highlight how parents can teach science with everyday household ingredients. We talked to her about her plan for putting science in action on the home front.

Colin Pitchfork might not be as recognizable a name as Ted Bundy or Jeffrey Dahmer, but he does occupy a certain significance in the annals of crime: He is the first person to be convicted based on DNA fingerprinting, apprehended for the rape and murder of two young girls in 1986 after being betrayed by the bodily fluids he had left at the scene. DNA fingerprinting not only led to Pitchfork’s arrest, but also exonerated a young teenage boy who had initially confessed to the murders. Since 1989, 317 people have been exonerated by DNA evidence after being convicted of crimes, according to the Innocence Project; of those reopened cases, 154 have led to the identification of the true perpetrator (or at least a more likely suspect). Current Practice: Telltale Little Pieces As laboratory techniques advance, investigators are finding new ways to use DNA evidence. The initial technique used for DNA fingerprinting, developed by British geneticist Alec Jeffreys in the late 1970s (and initially primarily used for paternity testing), was called restriction fragment length polymorphisms (RFLP) analysis. In this technique, an investigator uses an enzyme to break the DNA sample at certain specific points in the genetic code. The lengths …