U. S. cherries, watermelons and some other summertime favorites may depend on wild bees more than previously thought.

Many farms in the United States use managed honeybees to pollinate (授粉) crops and increase the total amount of crops, sometimes trucking beehives (蜂箱) from farm to farm. Now an analysis of seven crops across North America shows that wild bees can play a role in crop pollination too, even on conventional farms with managed honeybees. Wild volunteers add at least $1.5 billion in total to the harvest for six of the crops, a new study estimates.

“To me, the big surprise was that we found so many wild bees even in intense production areas where much of the produce in the USA is grown, says Rachael Winfree, a pollination ecologist at Rutgers University in New Brunswick, N. J.

That means threats to wild bees could deplete profits even when farms raise honeybees, the researchers reported on July 29 in Proceedings of the Royal Society. Both honeybees, which aren’t native to the United States, and wild pollinators such as bumblebees face dangers including pesticides (杀虫剂).

To see what, if anything, wild native bee species contribute, researchers checked bee visits to flowers at 131 commercial farm fields across the United States and part of Canada. On the other hand, the researchers also calculated to what extent the number of bee visits limited production. These intensive farms with plenty of fertilizer, water and other resources often showed signs of reaching a pollinator limit, meaning fields didn’t have enough honeybees to get the maximum production, and volunteer wild bees were adding to the total. Then the team estimated what percentage of the production native bees were adding — versus just doing what honeybees would have done anyway.

“Wild bees don’t seem to help California’s orchards (果园)，but based on orchards in Michigan and Pennsylvania, some $ 1. 06 billion of apples depends on native pollinators,” the researchers say. Watermelons, particularly in Florida, get an estimated $146 million benefit, and sweet cherries $ 145 million.

Italians are some of the fastest speakers on the planet, chatting at up to nine syllables (音节) per second. Many Germans, on the other hand, are slow ones, delivering five to six syllables during the same period. Yet in any given minute, Italians and Germans express about the same cover of information.

Scientists started with written texts from 17 languages. They calculated (计算) the information density (密度) of each language in bits. They found that Japanese, which has only 643 syllables, had an information density of about 5 bits per syllable, while English, with its 6949 syllables, had a density of just over 7 bits per syllable. Vietnamese, with its hard system of six tones, topped the charts at 8 bits per syllable.

Next, the researchers spent 3 years recording 10 speakers—five men and five women—from 14 of their 17 languages. Each read aloud 15 identical texts that had been translated into their mother tongue. After noting how long the speakers took to get through their readings, the researchers calculated an average (平均) speech rate per language, measured in syllables/second.

Some languages were clearly faster than others: no surprise there. But when the researchers took their final step to find out how much information moved per second, they were shocked by the agreement of their results. No matter how fast or slow, how simple or hard, each language moved toward an average rate of 39. 15 bits per second.

Language science has explained things so long like grammatical difficulty, so this information passing-on rate has been ignored. But the “why” is another question entirely. Some scientists doubt that the answer has everything to do with the weakness from our biology. Research in neuroscience (神经科学) supports that idea, with one recent paper suggesting an upper number to hearing processing of 9 syllables per second in U.S. English. It really seems that the bottleneck is in putting the ideas together.

When we hear the word “pyramid”(金字塔) there is little doubt that Egypt(埃及) and the desert come to mind. Did you know, however, that continents and oceans away — in what is today Central America and Mexico — people also built pyramids? While they look somewhat different from the ones we see in Egypt, they also were built with great skill.

The pyramids of Central America were built by the Mayan(玛雅) and Aztec(阿芝台克) peoples, as well as other smaller groups. Both Mayan and Aztec cultures built pyramids for their gods. They thought that building higher pyramids would allow them to get close to heaven. These cultures believed that the gods were found in nature. One of the most important gods was the sun. Many of the pyramids were for their sun god. At the top of the pyramids they built temples to make the gods happier. However, pyramids were not used only for their gods.

Before Europeans came to the area in the 1500s, many of the cultures of the Americas, such as the Mayan and Aztec, had much knowledge about mathematics and astrology. They thought that the night sky could be used as a mirror to explain many aspects of life, which is the reason why they studied it carefully. The temples on top of the pyramids were also used as places for watching the skies. The Mayans had a solid understanding of the movement of stars and planets. This helped them understand the seasons. They were the first to create a 365-day calendar.