Discovered: FedEx and UPS won't ship research animals anymore; marijuana may slow aggressive cancer; smoking doesn't come cheap in New York; why rats binge on M&Ms. 

Low-income New York City smokers are getting gouged. Science's number one point about smoking is: don't. We all know it's incredibly unhealthy and leads to all sorts of nasty cancer. But still, you have to feel for addicted smokers living in New York City, where cigarettes cost $14 a pack, give or take. New data collected by RTI shows that low-income New York City nicotine fiends spend a quarter of their income on cigarettes alone. That's about twice the national average, due in large part to New York state and city cigarette taxes, which are the highest in the country. Much of that money goes to noble causes such as cancer research, but some wonder if cigarette taxes place too high of a burden on low-income residents. "Although high cigarette taxes are an effective method for reducing cigarette smoking, they can impose a significant financial burden on low-income smokers," says lead author Matthew Farrelly. [Chicago Tribune]

Marijuana might mellow out aggressive cancer. Here's another reason for pot-smokers to defend their drug of choice: a marijuana-derived compound might be able to stop metastasis of aggressive forms of cancer. That would be a huge finding, allowing people with advanced cancer to stave off death. Pierre Desprez, one of the scientists from California Pacific Medical Center in San Francisco behind the findings, says "It took us about 20 years of research to figure this out, but we are very excited." They discovered that Cannabidiol could effectively 'turn off' the ID-1 gene, thought to be culprit in spreading cancer. The researchers hope to take clinical trials from animals to humans soon. [Huffington Post]

Why some rats go overboard when eating chocolate. If you've ever gorged yourself silly on M&Ms and felt guilty about it later, take comfort in knowing that it's not you doing it, it's your brain. Rodents with similar brains do the same thing. Researchers from the University of Michigan let lab mice have at an unlimited supply of M&Ms, and found that rats who had the neostriatum region of their brain over-stimulated  binged on twice the number of candy pieces than their peers. The research suggests that the neostriatum is closely linked with overeating, especially when it receives an influx of the chemical enkephalin. "This means that the brain has more extensive systems to make individuals want to over-consume rewards than previously thought,” said the study’s lead author, Alexandra DiFeliceantonio. "It may be one reason why over-consumption is a problem today." [Smithsonian]

UPS and FedEx will stop shipping lab animals. Scientists will have to find another way to get their research subjects delivered, because PETA has convinced UPS and FedEx to stop shipping lab animals. Neither company plays a huge part in the shipping of lab animals, but the move is seen as a victory for PETA, who've been battling the use of animals in scientific research for years. Still, researchers like Columbia University neurobiologist Darcy Kelley, who studies vocal communication in Xenopus frogs, says that they are "deeply concerned" about how they'll get animals in the future. UPS was an important next-day deliverer of the frog, and she believes their decision to stop will "set my research back years." The companies aren't going all bleeding heart in their statements as to why they've decided to cease shipping animals. UPS rep Norman Black says the choice was simply, "based both on our sustainability principles and on our marketing decisions. We do not consider animal shipments to be a target market for us, either economically or operationally." [Scientific American