It's common knowledge that the woman in Leonardo da Vinci's most famous painting seems to look back at viewers, following them with her eyes no matter where they are in the room. But this common knowledge turns out wrong.

A new study finds that the woman in the painting is actually looking out at an angle of 15.4° off to the viewer's right-well outside the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, “She's not looking at you.”

This is ironic, because the entire phenomenon of a person's gaze in a photograph or painting seeming to follow the viewer is called the “Mona Lisa effect”, which is absolutely real. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as at the angle of the person's gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars when Horstmann took a long look at the “Mona Lisa” and realized she wasn't looking at him.

To make sure it wasn't just him, the researchers gathered 24 people to view images of the “Mona Lisa” on a computer screen. They set a ruler between the viewer and the screen and asked the participants to note which number on the ruler intersected Mona Lisa's gaze. To calculate the angle of Mona Lisa's gaze as she looked at the viewer, they moved the ruler farther from or closer to the screen during the study. Consistently, the researchers found, participants judged that the women in the “Mona Lisa” portrait was not looking straight at them, but slightly off to their right.

So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn't sure. It's possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term “Mona Lisa effect” just thought it was a cool name.

Red pandas are native to the high forests of Asia. They are only a little bigger than a house cat and considered to be endangered. Scientists reported last month that not all red pandas belong to the same species. There are two different species of this animal，not just one，a study found. The scientists reported finding major differences in three genetic markers between Chinese red pandas and Himalayan red pandas. Scientists identified the markers after studying DNA from 65 of the creatures. DNA carries genetic information for the development，growth and reproduction of living things. Documenting the existence of two separate species could help guide efforts for protecting red pandas，scientists added.

Chinese red pandas live in northern Myanmar，as well as southeastern Tibet，Sichuan and Yunnan provinces in China. Himalayan red pandas are native to Nepal，India，Bhutan and southern Tibet in China，the researchers said.

Conservation biologists Yibo Hu and Fuwen Wei 1ed the study.   “To conserve the genetic uniqueness of the two species，we should avoid their interbreeding(杂交繁殖)in captivity，”Hu said. “Interbreeding between species may harm the genetic adaptations already established for their local habitat environment. ”

Scientists had earlier suggested there were two species of red panda. But the new study was the first to provide the genetic information necessary to permit such a judgment. International experts estimate a total population of around 10，000 red pandas in the wild. The two species differ in coloration and skull shape. The Himalayan red panda is the rarer of the two.

Major dangers to red pandas include deforestation and habitat loss. While they have similar names，red pandas and giant pandas are not closely related. Giant pandas are one of the world’s eight bear species. Red pandas are sometimes called living fossils because they have no close living relatives. They are the only remaining member of their mammalian family.

I started considering the power of dogs during one of my daily walks around my neighborhood. Almost invariably, I’ll run into at least one person walking his dog. It’s a joyous moment to approach the dog and pet it. I always walk away from these exchanges feeling just a bit more relaxed and happy. And that got me wondering: Could these short interactions with other people’s dogs actually be good for me?

“Absolutely. I think it is safe to say that animals are beneficial to our mental and physical health,” says Nancy Gee, a professor of psychology at Virginia Commonwealth University. Gee says there’s some evidence that the act of actually touching a dog might be an important part of the calming effect. For instance, one study done in Canada found college students reported less stress and reduced feelings of homesickness after brief interactions with dogs, and that the effect was much bigger in those who actually got to pet the animals.

Now, the therapy (治疗) dogs used in research are screened for things like friendliness, good behavior and responsiveness to their handler’s cues (提示). And of course, not everyone is a dog person. “Pets are not a panacea (灵丹妙药),” Gee says. “They’re not necessarily going to be great for every single person. But for people who really connect with the animals, they can make a big difference.”

Research on the health benefits of human interactions with animals, especially with dogs, has exploded in recent years, thanks to the support of the National Institutes of Health and the Waltham PetCare Science Institute. Though the field is still young, Gee says the quality of the evidence is improving all the time, including more randomized controlled trials looking at short interactions. “We’re seeing really nice effects,” she says. “We actually saw those effects one month later. And there’s some evidence that they may exist six months later.”