One of the most firmly established idea of manliness(男子汉) is that a real man doesn’t cry. Although he might cry a bit at a funeral, he is expected to quickly regain control. Crying openly is for girls. One study found that women cry significantly more than men do—five times as often, on average, and almost twice as long per period.

Historically, however, men usually cried, and no one saw it as shameful. For example, in the Middle Ages, knights(骑士) cried only because they missed their girlfriends. In The Knight of the Cart, no less a hero than Lancelot cries at a brief separation from Guinevere. There’s no mention of the men in these stories trying to hold back or hide their tears. They cry in a crowded hall with their heads held high. Nor do other people make fun of this public crying; it’s universally regarded as an expression of feeling to show love.

So where did all the male tears go? The most obvious possibility is that this is the result of changes as we moved from an agricultural(农业的) society to one that was urban(城市的)and industrial(工业的). In the Middle Ages, most people spent their lives among those they had known since birth. If men cried, they did so with people who would sympathize(同情). But from the 18^th to 20^th centuries, the population became increasingly urbanize, and people were living in the midst of thousands of strangers. Furthermore, changes in the economy required men to work together in factories and offices where expressions of feelings and even personal conversations were discouraged as time wasting.

Yet human beings weren’t designed to hide their feelings, and there’s reason to believe that restraining tears can be harmful to your well-being. Research from the 1980s has suggested a relationship between stress-related illnesses and not enough crying. Crying is also, somewhat related with happiness and wealth. Countries where people cry the most tend to be richer and more confident.

It is reported that the sense of smell plays a dominant role in the social interactions of all land animals except humans. Then the question arises: Is this because humans don’t use their noses in social settings the way all other land animals do? Or is this behavior covert (隐蔽的), rather than overt, in humans?

In fact, this is exactly what Inbal Ravreby, a graduate student in Prof. Noam Sobel’s laboratory in Weizmann’s Brain Sciences Department, tried to answer. And as several lines of evidence suggest that humans are constantly, although mostly subconsciously, sniffing themselves and others, Ravreby supposed that the latter is the case.

To test her hypothesis, Ravreby conducted the study with pairs of click friends: same-sex nonromantic friends whose friendships had originally formed very rapidly. Because such friendships emerge prior to an in-depth acquaintance, they may be particularly influenced by physiological characteristics such as body smell. She then collected body smell samples from these click friends and conducted two sets of experiments to compare the samples with those collected from random pairs of individuals. In one set of experiments, she performed the comparison with a device known as an electronic nose, or eNose, which assessed the chemical signatures of the smells. In the other, she asked volunteers to smell the two groups of body smell samples in order to assess similarities measured by human perception. In both types of experiments, click friends were found to smell significantly more like each other than the individuals in the random pairs.

Next, to rule out the possibility that body smell similarity was a consequence of click friendships, rather than a contributing cause, Ravreby performed an additional set of experiments, in which she used the eNose to “smell” a number of volunteers who were complete strangers to one another, and then asked them to engage in nonverbal (非言语的) social interactions in pairs. After each such structured interaction, the participants rated the other individual in terms of how much they liked that person. Subsequent analysis revealed that the individuals who had more positive interactions indeed smelled more like each other, as determined by the eNose.

“These results imply that, as the saying goes, there is chemistry in social chemistry,” Ravreby concludes. However, Sobel offers words of caution, “This is not to say that we act like dogs or goats — humans likely rely on other, far more dominant signals in their social decision-making. Nevertheless, our study’s results do suggest that our nose plays a bigger role than previously thought in our choice of friends.”

Have you ever wondered if you see the same colours as other people? Most people know what blue is when they see it. They call it "blue” because they were taught the word and connected it with what they saw. But how do you know what you see as blue isn’t someone else s red?

The ability to perceive (感知) different colours is up to receptors (接受器) in our eyes. Light waves hit these receptors and they react depending on which colour the light is, sending signals to the brain. The brain then reads these signals to determine which colour light the eyes are receiving.

Some people’s receptors are more developed than others. The inability of the receptor to feel the light waves correctly means that some people cannot tell the differences between similar colours.

Those with more developed receptors can see more colours. We sometimes hear people having an argument about whether something is dark blue or black. It might be because one person has stronger receptors to feel the light than another.

In the past, most scientists would argue that everyone saw colours in the same way. However, research was conducted on monkeys, in which their receptors were changed. This enabled them to see more colours than usual. Normally monkeys can only see blue and green, but the change allowed them to see red. Their brains automatically (自动地) got used to new colours. This suggests that our brains may adapt depending on our stimulus (刺激) and find new colors of the things we see. Colours could be a very personal experience, unique to everyone.

So, the next time you talk about your favourite colour, just remember if yours is blue and your friend says red, you two might actually be thinking about the same colour. What if everyone in the world has the same favourite colour, but just calls it different names?