【推荐2】For generations, people have enjoyed the simple joy of flying a kite. However, kites were not always the toys we think of today.

Kites actually started as instruments of war. The first known kites were flown in China around 3,000 years ago and were used by the Chinese military to send signals, spy on (侦察) enemies, and deliver urgent messages. Kites were also used to measure long distances. One general flew a kite above a town to measure how far his army would have to tunnel underground to go secretly under the city walls. With this information, his army were able to surprise their enemy.

The first kites were practical, not necessarily pretty. But during the Tang Dynasty, people started using lighter materials to make kites. A new focus was put on kites' appearance. By the 1300s, making kites had appeared as an art form, and kites were decorated with colorful pictures. They were flown for enjoyment and celebration of the Chinese New Year. As the years went on, kites became more complicated. Some artists added whistles so the kites could make sounds as they danced among the clouds.

Over time, the tradition of kite flying spread worldwide. It grew in popularity across Southeast Asia North Africa first. When explore Marco Polo returned to Italy, he brought back many stories about kites. These stories and the growing influence of Asian culture helped popularize kites across Europe. From there, knowledge of kites crossed the Atlantic with travelers heading to America.

Since then, kites have become more than just pieces of flying art. They have played a meaningful role in discoveries. Perhaps the best-known use of a kite was in an experiment described by Benjamin Franklin in 1752, which eventually led Franklin to invent the lightning rod (避雷针). Another important use of kites was by the Wright brothers in the early 1900s, which helped them create the world's first successful airplane.

For hundreds of years, kites have played a significant role in human exploration and artistic expression. Even now, kites are still an important part of cultural celebrations. Despite their changing appearance and uses through the ages, kites hold a valued place in human history.

【推荐1】Fun Indoor Activities for Kids to Do At Home

Indoor days can be just as fun as the get-up-and-go ones, with a little planning and preparation. These are some of the most fun indoor activities for kids.

DIY Your Own Masterpieces

Time to bring out all your markers, glue, paint, paper places, and whatever other odds and ends you have around the house and let the kids go to town. When you’re done, take the works of art and display them on shelves.

Start an Indoor Garden

You don’t even need empty planters to get the garden growing — an old egg carton will do the trick at first. To make it more of a STEM activity, give kids journals so they can take notes on what they’ve planted and keep track of their garden’s progress. Bonus: Plant basil seeds or other herbs, and you’ll have delicious ingredients for a cooking project.

Break out the Board Games

It’s the oldest idea in the book, but if you really want some screen-free family time, old-fashioned board games still do the trick. Get your competitive spirit up and get ready to play.

Indoor Obstacle Course

This activity is great for young ones working on their coordination (协调) or older ones who might need to get some energy out. Cardboard boxes can transform into tunnels to crawl through. You can tie strings around furniture and pretend that they’re laser beams that kids have to step over or crawl under. See who in the family has the fastest time getting through the obstacles.

Stock up on the materials now — though you might have what you need lying around the house already — and you’ll never fear an indoor day again.

【推荐3】A new study analyzing stone tools from southern China provides the earliest evidence of rice harvesting, dating to as early as 10，000 years ago. The researchers identified two methods of harvesting rice, which helped start rice domestication(家庭种植).

To harvest rice, some sort of tools would have been needed. “For quite a long time, one of the puzzles has been that harvesting tools have not been found in southern China from the early Neolithic period or New Stone Age (10，000－7，000 Before Present)—the time period when we know rice began to be domesticated” says lead author Jiajing Wang, an assistant professor of anthropology at Dartmouth.

“However, when archaeologists (考古学家) were working at several early Neolithic sites in the Lower Yangtze River Valley, they found a lot of small pieces of stone, which had sharp edges that could have been used for harvesting plants.”

“Maybe some of those small stone pieces were rice harvesting tools, which is what our results show.”

In the Lower Yangtze River Valley, the two earliest Neolithic culture groups were the Shangshan and Kuahuqiao.

The researchers examined 52 flaked (成薄片的) stone tools from the Shangshan and Hehuashan sites, the latter of which was occupied by Shangshan and Kuahuqiao cultures.

To determine if the stone flakes were used for harvesting rice, the team conducted use­wear and phytolith residue (植物石残渣) analyses.

For the use­wear analysis, micro­scratches (划痕) on the tools’ surfaces were examined under a microscope. The results showed that 30 flakes have use­wear patterns similar to those produced by harvesting siliceous (silica­rich) plants, likely including rice.

Through the phytolith residue analysis, the researchers analyzed the microscopic residue left on the stone flakes known as “phytoliths” (silica skeletons of plants). They found that 28 of the tools contained rice phytoliths.

“What’s interesting about rice phytoliths is that rice husk and leaves produce different kinds of phytolith, which enabled us to determine how the rice was harvested,” says Wang.

The findings from the use­wear and phytolith analyses illustrated that two types of rice harvesting methods were used—“finger­knife” and “sickle” techniques. Both methods are still used in southern China today.