4 . In the name of social distancing, this year’s graduation ceremonies have become different. However, one tradition has continued to exist — the square graduation cap, commonly known as a mortarboard hat.

European scholars (学者) have been wearing caps since the first universities were started in the 11th century, but their early caps looked more like Amelia Earhart’s pilot cap than the square caps we know today. Early scholars first used the pileus (伞状帽). By the 14th century, pileus caps were becoming taller, similar to a modern chef’s hat but shorter. This style, the “pileus rotundus”, was used mainly by university students studying law, medicine, and science.

By the middle of the 16th century, a new cap style made waves in universities: the “pileus quadratus“, a soft, square cap that required less material to make. Soon the two styles, round and square, became symbols of different statuses. One century later at the University of Oxford, under-graduates wore the older, rounded caps, while those with higher degrees were allowed to wear the pileus quadratus.

The first American colleges were started in the mid-1600s, and their class structures and degree requirements followed famous English universities. And European scholarly traditions were kept- including ideas of proper academic dress. Today, American graduates in law, medicine, and philosophy still wear rounded caps, but undergraduates always use the square cap.

Although the square hat has a centuries-old history, new cap traditions are popping up across the US. About 100 years ago, students began moving their tassels (流 苏) from the right side of their cap to the left. To this day there are no formal rules on where the tassel should be placed, but the act of moving it from one side to the other has been widely popular.

While the ways in which we observe graduation may change, the four-cornered black hat will likely remain a sort of culture for academic achievements —a symbol of celebration with roots going back to medieval Europe.

5 . One of the most common beliefs among researchers is that humans first arrived in North America 16,000 years ago. According to a recent fossil discovery, that might not be true. The new finding suggests that humans might have arrived in North America far earlier.

In 2013, a damaged mammoth (猛犸象) skull and other bones that looked “deliberately broken” were found. The damage to the bones suggested that humans were the ones who caused it to make tools. Carbon- dating analysis suggested the pieces are roughly 37 ,000 years old. This discovery could shift our understanding of humans ‘earliest existence in North America. These fossils suggest humans killed animals in the area much earlier than 16, 000 years ago.

Previous research led scientists to believe the first humans that settled in North America belonged to the Clovis culture. This was a group of people who left behind carefully made tools 16,000 years ago. However, carbon-dating analysis of the mammoth bones indicates that the site is around 36, 250 to 38, 900 years old. That means it’s the oldest known site left behind by ancient humans in North America.

“That’s not the only interesting thing about the discovery,” said Timothy Rowe, a professor at the University of Texas. “The similar findings supporting an earlier date for human arrival have been mostly ignored. This is because they have contradicted previous research.”

Now, however, he thinks there’s a good chance that researchers will find evidence of humans farther back in time.

The early humans shaped bones into sharp blades, which were used to take apart animals’ remains, according to Rowe. There are also signs that they cooked the animal bones over a fire to melt off the fat. “The real evidence that we have has to do with the breakage patterns, and how thorough they are. They must have used rocks or hammer stones to bust the skeleton apart... These people would use whatever they could,” Rowe told USA Today.

6 . A new study provides the earliest known evidence of amputation — the medical term for cutting off a part of a person’s body. Around 31,000 years ago, a young adult had his left foot and part of his left leg removed in what is modern-day Indonesia, the study suggests.

Scientists say the ancient surgery was performed when the person was a child — and that the individual went on to live for years. It suggests that humans were carrying out medical operations much earlier than scientists had thought.

Tim Maloney, the study’s lead researcher, said that researchers were exploring a cave in Borneo, a rainforest area known for ancient rock art, when they came across the person’s burial.

Although much of the skeleton(骨骼)remained, it was missing its left foot and the lower part of its left leg, Maloney explained. After examining the remains, the researchers concluded the foot bones were not missing from the burial or lost in an accident. Instead, the bones had been carefully removed. The remaining leg bone showed a clean cut that healed over, Maloney said. There were no signs of infection, which would be expected if the child had gotten its leg bitten off by a creature like a crocodile. And there were also no signs of a crushing fracture(粉碎性骨折),which would have been expected if the leg had been cut off in an accident.

The child appears to have lived for around six to nine more years after losing the limb, eventually dying from unknown causes as a young adult, researchers said.

The evidence suggests that the ancient people knew enough about medicine to perform the surgery without fatal blood loss or infection. Researchers do not know what kind of tool was used to perform the surgery, or how infection was prevented. But they believe that a sharp stone tool may have made the cut, and some of the plant life in the area could have been used for medical treatment.

“The discovery of this early surgery rewrites the history of human medical knowledge and developments,”Maloney said at a press conference.

8 . The History of Music Festivals

Outdoor music festivals have become a big gathering of summertime for many adults. While music festivals appear to be a recent development, their history dates back to hundreds of years ago. But they have always been about bringing people together to share a common cultural experience through music.     1    

The earliest known music festival occurred in the 6th century BC. After centuries’ development, by the late 1960s, Rock bands began to organize their own music festivals. Perhaps the first formal and well-known festival to Rock was the Monterey Pop Festival in 1067, which brought that band to the attention of American audiences.     2     It started in 1968 as an event with about 10,000 people.

By 1970, the festival grew to bring in more than 600,000 people, showing the popularity of music festivals to organizers. Many others also began to organize such events. The Summerfest Festival was established in 1968.     3     Interestingly, this festival made cities realize festivals could bring many benefits. This helped to spread the idea of creating not only musical festivals but also other types of festivals, such as those related to food and film.

    4     It drew so many people, making it the first large Rock music festival. Billed as “three days of love and peace”, Woodstock featured many well-known bands and artists, making Rock music festivals known to many Americans and Europeans.

Today, it’s hard to imagine summer without musical festivals. Many genres now have their own music festivals, ranging from Classical music to Heavy Metal. Countries in every habitable continent have music festivals.     5     Others are intended for younger audiences or those who prefer period-based music. Music festivals have become very popular venues that have become well established as part of summer culture.

10 . Icehouse and ice ticket

As early as Pre-Qin Dynasty, people used natural ice to keep food fresh and make cold drinks. The Zhou royal court had a specialized department called “ice administration”. They collected natural ice blocks each December to store in the icehouse. During the Qing Dynasty, “ice tickets” were used and they were available only to officials and the rich.

Ice container

The most commonly used cooling tool is called “Jian”, which is a big container filled with ice. It was made of clay in early Chinese history, and was later made of copper (铜). The “Jian” can be seen as an ancient refrigerator, which can be used to make cold drinks.

Hiding food in the well

During the Qin and Han dynasties, for common people, the most common way to cool off is by using their wells. Some families put a pot in the well as a cold closet, or put food in a basket and lowered the basket into the well with a rope.

Herbal drinks

During the Qing Dynasty, taking Chinese herbal medicine was popular in Beijing. In hot summer, some people preferred to drink ice water, some boiled perilla leaves, and liquorice as summer soup to keep off the heat. Ancient people also loved to make lotus seed soup in summer for the benefit of strengthening the body.