“She was all over him like white on rice.” We might have to update the old saying, because it turns out rice wasn’t always white. Ten thousand years ago, all rice was red. Research published this week shows that white rice today takes its color from a mutation in a single gene in red rice. The mutation truncates a critical protein in the molecular pathway leading to rice’s red color.

The research suggests that early farmers selected the pale variety of rice and spread it all over the world. White rice cooks faster, and its hull is easier to pick off — two traits that would have made it a more valuable crop than its red relative.

I find this particularly relevant in the days of hysteria over genetically modified foods. There are certainly valid reasons to be worried about wanton doctoring of DNA, but it brings some perspective to the issue to realize that when it comes to our food, it’s all been genetically modified. The standard “non-modified” white rice is actually a mutation spread by early farmers.

Now for some weirder news: Could obesity be spread by a virus? Adenovirus-36 is a common bug that causes respiratory and eye infections in humans. Researchers at Louisiana State University announced this week that the virus may be causing more that sneezes and watery eyes: it could be accelerating the obesity epidemic.

The researchers used hunks of fat sucked out of patients via liposuction, and isolated adult stem cells from the tissue. These powerful stem cells are capable of turning into bone, cartilage, fat and muscle. In this experiment, exposing the cells to adenovirus-36 turned them into fat cells.

Adenovirus-36 has come under scrutiny before. Previous research showed that chickens and mice injected with the virus gained more weight than the control group. Another study found that 30 percent of obese people were infected with adenovirus-36, compared to 11 percent of skinny individuals.

But there may yet be hope. In addition to demonstrating the nefariousness of adenovirus-36, scientists may also have uncovered a way to fight it. The same research group from Louisiana announced that they’ve found the specific gene in adenovirus-36 that makes infected animals fatter. According to the researchers, the gene could be targeted in future human therapies such as vaccines and antiviral medicines. A vaccine against obesity? I’m a bit skeptical, but what the heck. Sign me up — and then pass me the potato chips.

Ornithological news: Some very smart crows are proving that “bird brain” may actually be a compliment. New Caledonian crows look a lot like their local relatives, but they live only in a smattering of islands off the coast of Australia. In 2002, the crows impressed researchers by cleverly making tools out of wire, a material they don’t encounter in the wild.

Two birds, Betty and Abel, were choosing between a straight piece of wire and a hooked piece of wire to retrieve a small bucket of their favorite meat. When Abel flew off with the hooked wire, an undeterred Betty simply tweaked the straight wire into a hook and snatched her snack.

It turns out the crows’ talents extend even further. Researchers at the University of Auckland reported this week that the birds can spontaneously use one tool on another tool to get a snack. The awed researchers called it “meta-tool use.”

The crows were presented with some meat in a hole, along with a stick too short to reach the snack. They also got a longer stick that could access the food, but it was out of reach inside a box. The clever crows used the short stick to get the long stick out of the box, and then used the long stick to snag their tasty snack.

Six out of seven birds solved the problem on their first try — evidence of true reasoning ability rather than simple trial and error. The crows actually do as well as apes in solving the problem. Not bad for a bunch of featherbrains!

Email Shelby at samartin@stanford.edu.