There are many colors in nature. But do you think that a color has ________? I think you’ll say “no”. But I’m ________ you are wrong. If you don’t believe it, you may do a small experiment.

First, put two objects with the same weight into two boxes. Then ________ the boxes with a thin piece of paper. Third, pack one box with a red piece of paper, and the other one with a white piece of paper. OK. Now hold the boxes with your hands one by one. Without doubt, you will think the red one is a little ________. Why do you think so? A scientist found that different colors have different weights in man’s mind. Red is a special color and seems to weigh more than other colors. Colors also have smell. Can you smell the color? Of course not. But scientists said it did have smell. That is ________ every color stands for a kind of light with a certain wavelength (波长). It reaches our brain through sense organs (器官).

It is early days for the idea that toys shaped humanity, but Felix Riede, at Aarhus University in Denmark, and his colleagues recently published a paper outlining some interesting case studies. ______, examining the records of communities living in Greenland from around 4500 years ago, they found that the early colonisers ______ toys and also showed little innovation in their material culture, but the Thule, who migrated into Greenland around 800 years ago, had many tiny objects that appear to have been designed specifically for child’s ______, including toy weapons and dolls. Their appearance seemed to coincide with an explosion of new adult technologies, such as advanced designs for boats and elaborate clothes. The records aren’t ______ enough to determine which emerged first, the toys or the advanced technology, but Riede thinks the two may have grown together, with the richer material culture inspiring new play objects, which ______ equipped the young minds for further innovation.

The team also points to sites in Western Cape, South Africa, dating back 60,000 to 80,000 years ago. Analyses of rocks show that children were imitating the adults’ stone striking, producing ______ useless copies of real tools. This “play-copying” again seems to coincide with new technologies, including the first arrowheads, suggesting that the childhood games might have ______ greater cultural innovation.

It is the invention of the wheel, however, that offers the most persuasive ______ for Riede’s idea. The oldest evidence of wheeled vehicles suggests that the technology ______ around 5500 years ago, across western Eurasia – in the northern Caucasus, Mesopotamia and central and northern Europe. But some two centuries beforehand, we ______ small models of animals with holes drilled through their feet for an axle (车轴), and ceramic (陶瓷) discs that served as wheels. But given their ______ and the fact that small animals are playthings in many modern cultures, Riede believes that they were toys. “You could easily call them quite cute,” he says.

If so, like any kid with a train set today, children playing with those toys would have been exploring the ______ of spinning motion. They might have used their toys to carry various objects, and practised different ways of driving them – from the front or the back, or letting them roll down a slope. They might even have ______ wheels of different sizes, or made from different materials to see different results. As the children grew up, those same ______ would have helped them make the cognitive leap necessary to imagine a wagon, but a society that lacked those toys would have ______ to think of a workable design.