A recently published paper finds that following a Mediterranean diet for three weeks can help reduce depression and anxiety among young adults.

In the study, participants in the test group were instructed to eat about six more servings of fruits and vegetables per week, compared with the control group. In addition, they were told to get per week three servings of fish besides three recommended servings per day of whole grains. As for milk, the recommendation was three servings per week, unsweetened. Participants were also asked to consume three tablespoons of nuts and seeds per week, as well as two tablespoons of olive oil per day.

“One of the shortcomings of nutrition science is that it often relies on asking people to recall what they ate and how they felt in the past. Given our failing memories, these data can be unreliable,” says Heather Francis, one of the researchers. “But our study included a device, called spectrophotometer, which can detect the degree of yellowness in the skin, which can precisely monitor the intake of carotenoids (类胡萝卜素), which the participants get from their food.”

“We have highly consistent and extensive evidence from around the globe linking Mediterranean diets to reduced depression risk,” says Felice Jacka, a professor at Deakin University in Australia who was not involved in the study. “I think the next step is to show how diets can reduce depression.”

However, it’s almost impossible to unravel how diet changes may help improve mental health according to the strict standard in medical research, where participants do not know that they are part of the group assigned to take the medicine or the placebo (安慰剂).

“In a diet study, there’s no way to ‘blind’ the participants so that they don’t know if they’re getting the ‘medicine’ or ‘placebo’,” says Heather Francis. “And research has shown that if people are told that they’re doing something that may make them less depressed, they will indeed report less depression. That’s known as the placebo effect.”

One of the things that make humans mammals (哺乳动物) is that we’re warm-blooded — our bodies have high metabolism (新陈代谢) that maintains our internal temperature independent of the surroundings, unlike cold-blooded animals that have to lie in the sun for heat. Among modern animals, only mammals and birds are warm-blooded and our ability to keep ourselves warm has enabled us to survive in icy weather and make long migrations. But it’s been a mystery exactly when mammals evolved their high metabolism. In a new study, scientists point to an unlikely source for determining when ancient mammal ancestors became warm-blooded.

The ears of all living creatures that have backbones contain tiny canals (管道) filled with fluid that helps us balance. The runniness (流动性) of that fluid changes based on temperature, and our inner ears have evolved different sizes so that the fluid can flow correctly. Cold-blooded animals’ ear fluid is cooler and thicker, so it needs wider spaces to travel through, while warm-blooded animals have runnier ear fluid, so our canals are different.

“Canals were generally used to predict the movement of fossil organisms. However, by carefully looking at their biomechanics (生物力学) , we figured that we could also use them to infer body temperature,” says Romain David, one of the study’s lead authors. “This is because, like honey, the fluid inside canals gets runnier when temperature increases, impacting function. Therefore, during the transition to endothermy (温血性) , physical adaptation was required to keep best performances, and we could track ear canals in mammal ancestors. ”

To track these evolutionary changes, the researchers compared the sizes of the inner ear canals of over 300 animals, including 243 living species and 64 extinct ones. They found that mammal ancestors didn’t develop the kinds of inner ear structures ideal for warm-blooded animals until 233 million years ago.

The origin of mammalian endothermy is one of the great mysteries to be solved. Many different approaches have been used to try to predict when it first evolved, but they have often given unclear or conflicting results. This method shows real promise because it has been confirmed using a very large number of modern species.

There was a time when we thought humans were special in so many ways. Now we know better. We are not the only species that feels emotions, or follows a moral code. Neither are we the only ones with personalities, cultures and the ability to design and use tools. Yet we have all agree that one thing, at least, makes us unique: we alone have the ability of language.

It turns out that we are not so special in this aspect either. Key to the revolutionary reassessment of our talent for communication is the way we think about language itself. Where once it was seen as an unusual object, today scientists find it is more productive to think of language as a group of abilities. Viewed this way, it becomes apparent that the component parts of language are not as unique as the whole.

Take gesture, arguably the starting point for language. Until recently, it was considered uniquely human - but not any more. Mike Tomasello of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and others have collected a list of gestures observed in monkeys and some other animals, which reveals that gestures plays a large role in their communication. Ape(猿) gestures can involve touch, vocalising or eye movement, and individuals wait until they have another ape’s attention before making visual or auditory gestures. If their gestures go unacknowledged, they will often repeat them.

In an experiment carried out in 2006 by Erica Cartmill and Richard Byrne from the University of St Andrews in the UK, they got a person to sit on a chair with some highly desirable food such as banana to one side of apes and some undesirable food such as vegetables to the other. The apes, who could see the person and the food from their enclosures, gestured at their human partners to encourage them to push the desirable food their way. If the person showed incomprehension and offered the vegetables, the animals would change their gestures - just as a human would in a similar situation. If the human seemed to understand while being somewhat confused, giving only half the preferred food, the apes would repeat and exaggerate their gestures - again in exactly the same way a human would. Such findings highlight the fact that the gestures of the animals are not merely inborn but are learned, flexible and under voluntary control - all characteristics that are considered preconditions for human-like communication.