About ten men in every hundred suffer from color-blindness in some way. Women are luckier: only about one in two hundred is affected on this matter. Perhaps, after all, it is safer to be driven by a woman!

There are different forms of color-blindness. In some cases a man may not be able to see deep red. He may think that red, orange and yellow are all shades of green. Sometimes a person cannot tell the difference between blue and green. In rare cases an unlucky man may see everything in shades of green — a strange world indeed.

Color-blindness in human beings is a strange thing to explain. In a single eye there are millions of very small things called "cones". These help us to see in bright light and to tell the difference between colors. There are also millions of "rods", but these are used for seeing when it is near dark. They show us shapes but no color.

Some insects have favorite colors. Mosquitoes（蚊子） prefer blue to yellow. A red light will not attract insects, but a blue lamp will. In a similar way human beings also have favorite colors. Yet we are lucky.

With the aid of the cones in our eyes we can see many beautiful colors by day, and with the aid of the rods we can see shapes at night. One day we may even learn more about the invisible colors around us.

   Storing food is common in members of the crow family. A new study tested the birds outside for this naturally occurring behavior, which may have evolved（进化）specifically because it gives crows a survival advantage. Some crow species are known to naturally use tools to recover food. So the researchers tested whether the birds could store and recover a tool so they could use it to find their food after a gap of 17 hours — something we wouldn’t expect them to do naturally. But they were able to instantly select the tool out of a number of unnecessary items.

In another experiment, the researchers taught crows to select a token（礼品券）from a number of items so that they could then exchange it for food. Again, the birds then showed that they could plan for the future using this new behaviour. This is different from all of the previous studies in future planning, which have focused on naturally occurring behaviour. For example, we know that chimpanzees select, transport and save appropriate tools for future needs.

These studies have shown that animals can plan for the future — but they leave an important question open for debate. Are animals only able to plan to use abilities that have evolved to give them a specific advantage, or can they flexibly and intelligently apply planning behaviour across various actions? Most critics would say the former, as the animals were tested in naturally occurring behaviour.

But the new research provides the first evidence that animal species can plan for the future using behaviour that doesn’t typically occur in nature. This supports the view that at least some recognitive（认知的）abilities in animals don’t evolve just in response to specific problems. Instead, it suggests that animals can apply these behaviour flexibly across problems in a similar way to humans. We need to study how flexible behaviour evolved. Then we might be able to see how crows’ ability to plan for the future fits in with their broader cognitive powers.

Amazing Benefits of Listening to Music

If you love listening to music, you’re good company. 【小题1】

★Music makes you happier.

When you listen to music, your brain produces a special matter. It biologically (生物学上) causes listeners to feel emotions like happiness, excitement, and joy. So next time you need an emotional increase, listen to your favorite tunes for 15 minutes.

★【小题2】

Listening to music you enjoy reduces levels of the stress in your body. This is an important finding since stress causes many illnesses. To stay calm and healthy during a stressful day, turn on the radio.

★Music helps you sleep better.

A study showed that students listening to classical music for 45 minutes slept better than students who did nothing. If you’re having trouble sleeping, try listening to a little Bach or Mozart before bedtime.

★Music helps you eat less.

【小题3】If you’re looking for ways to reduce your appetite (食欲), try dimming the lights and listening to soft music next time you sit down for a meal.

★Music strengthens learning and memory.

Researchers discovered that music can help you learn and recall information better. 【小题4】 Memorize these results. You now have a strategy to study more effectively for your next test.

★Music raises IQ and school performance.

Research shows that taking music lessons predicts higher school performance and IQ in young children. 【小题5】