A biologist from the National Park Service discovered a rare and unusual mammoth(猛犸) skull(颅骨) buried in a 13,000-year-old rock layer on the Santa Rosa Island, the second largest landmass in the Channel Islands, California. The fossil of the extinct giant animal is leaving many paleontologists(古生物学家) scratching their heads. Despite the fact that it's possibly the best preserved mammoth skull ever found and of high scientific importance, the species of the individual it belonged to can't seem to be identified yet—it's too big to be a pygmy(特别矮小的) mammoth and too small to have come from a Columbian mammoth. Some say it's a new species while others believe the truth lies somewhere in between.

    The first mammoths showed up in North America around two million years ago, but it was only during the last two ice ages that the Columbian species, which could grow to be up to 14 feet tall, made its way to the Channel Islands 100 miles west of Los Angeles. Once the ice melted, many populations became trapped on the island and evolved into pygmy mammoths, an endemic species(地方种) to the Channel Islands which grew only to six feet tall.

    Judging from its size, the newly found mammoth skull doesn't seem to fit any of the two species, Columbian or pygmy. To make things even more confusing, one of its two tusks(象牙) is nearly five feet long and coiled in a manner that resembles those of fully grown mammoths but the left tusk is shorter and sloped, more like a juvenile(青少年).

    This has caused some scientists to say the Santa Rose skull may belong to a transitional species. Whatever's the case, a following examination of the mammoth's teeth should put the matter to rest. The analysis will also tell us how old the mammoth was when it died, so we can tell for sure whether it was an adult or juvenile.

    More interesting than the mammoth's lineage, however, might be its story. The giant mammal lived 13,000 years ago or roughly the same timeline of the “Arlington Man”, a 13,000-year-old human skeleton also found on Santa Rosa. Some 3,000 years later humans were already spread throughout the continent and the Channel Islands' mammoth went extinct. The present finding might help reveal a link between the two.

    The remains also seem to confirm a long-held assumption that there were two mammoth migrations to the Channel Islands. “The discovery of this mammoth skull increases the probability that there were at least two migrations of Columbian mammoths to the island: during the most recent ice age 10,000 to 30,000 years ago, as well as the previous ice age that occurred about 150,000 years ago,” said USGS geologist Dan Muhs.

    We may think we're a culture that gets rid of our worn technology at the first sight of something shiny and new, but a new study shows that we keep using our old devices（装置）well after they go out of style. That's bad news for the environment – and our wallets – as these outdated devices consume much more energy than the news ones that do the same things.

    To figure out how much power these devices are using, Callie Babbitt and her colleagues at the Rochester Institute of Technology in New York tracked the environmental costs for each product throughout its life – from when its minerals are mined to when we stop using the device. This method provided a readout for how home energy use has evolved since the early 1990s. Devices were grouped by generation. Desktop computers, basic mobile phones, and box-set TVs defined 1992. Digital cameras arrived on the scene in 1997. And MP3 players, smart phones, and LCD TVs entered homes in 2002, before tablets and e-readers showed up in 2007.

    As we accumulated more devices, however, we didn't throw out our old ones. "The living-room television is replaced and gets planted in the kids' room, and suddenly one day, you have a TV in every room of the house," said one researcher. The average number of electronic devices rose from four per household in 1992 to 13 in 2007. We're not just keeping these old devices – we continue to use them. According to the analysis of Babbitt's team, old desktop monitors and box TVs with cathode ray tubes are the worst devices with their energy consumption and contribution to greenhouse gas emissions（排放）more than doubling during the 1992 to 2007 window.

    So what's the solution? The team's date only went up to 2007, but the researchers also explored what would happen if consumers replaced old products with new electronics that serve more than one function, such as a tablet for word processing and TV viewing. They found that more on-demand environment viewing on tablets instead of TVs and desktop computers could cut energy consumption by 44%.

    Who do you think was the most important woman of the past 100 years?

    Jane Addams (1860～1935)

    Addams helped the poor and worked for peace. She created shelters, education opportunities and services for people in need. In 1931, Addams became the first American woman to win the Nobel Peace Prize.

    Angela Merkel (1954)

    In 2005, Germans chose Angela Merkel as their first woman head of the country. She once worked as a research scientist until 1989. Then she entered politics and has been widely described as Iron Lady in Germany. She was elected as the most powerful woman by the Times in 2015. As Germany's leader, she has had an effect on the whole world.

    Margaret Thatcher (1925)

    In 1979, Margaret Thatcher became Britain's first woman Prime Minister (首相)．She served until 1990, which made her the first British leader to serve three terms in a row. Because of her high standards and strong will, people called her Britain's Iron Lady.

    Marie Curie (1867～1934)

    Polish­born scientist Marie Curie discovered that some types of metal give off energy called radiation (辐射能). Her research led to new medical treatments and arms. She received the Nobel Prize in Physics in 1903 and in Chemistry in 1911.

    People traveling long distances frequently have to decide whether they would prefer to go by land, sea, or air. Hardly can anyone positively enjoy sitting in a train for more than a few hours. Train carriages soon get crowded. Reading is only a partial solution, for the monotonous(单调的) rhythm of the wheels clicking on the rails soon makes you sleep. During the day, sleep comes in snatches. While at night you rarely manage to sleep. Inevitably you arrive at your destination almost exhausted.

    Long car journey are even less pleasant, for it is quite impossible even to read. On motorways you can, at least, travel fairly safely at high speed, but more often than not, the greater span of the journey is spent on narrow, uneven roads which are crowded with traffic.

    By comparison, trips by sea offer a great variety of civilized comforts. You can stretch your legs on the broad decks, play games, swim, meet interesting people and enjoy good food-always assuming, of course, that the sea is calm. If it is not and you are likely to get seasick, no form of transport could be worse. Even if you travel in ideal weather, sea journeys take a long time. Relatively few people are prepared to sacrifice up to a third of their holidays for the pleasure of traveling on a ship.

    Airplanes have the reputation of being dangerous and a little expensive. But nothing can match them for speed and comfort. Traveling at a height of 30,000 feet and at over 500 miles an hour is a pleasant experience. For a few hours, you settle back in a deep armchair to enjoy the flight. The real relaxation can be a free film show and some other services. An airplane also offers you an unusual and breathtaking view of the world. You really see the shape of the land. If the landscape is hidden from the view, you can enjoy the extraordinary sight of unbroken cloud plains that stretch on for miles before you, while the sun shines brilliantly in a clear sky. The journey is so smooth that there is nothing to prevent you from reading or sleeping. However you decide to spend your time, one thing is certain: you will arrive at your destination fresh and untired.

    A robot called Bina48 has successfully taken a course in the philosophy of love at Notre Dame de Namur University (NDNU), in California.

    According to course instructor William Barry, associate professor at NDNU, Bina48 is the world's first socially advanced robot to complete a college course, a feat he described as "remarkable." The robot took part in class discussions, gave a presentation with a student partner and participated in a debate with students from another institution.

    Before becoming a student, Bina48 appeared as a guest speaker in Barry's classes for several years. One day when addressing Barry's class, Bina48 expressed a desire to go to college, a desire that Barry and his students enthusiastically supported. Rather than enroll Bina48 in his Robot Ethics: Philosophy of Emerging Technologies course, Barry suggested that Bina48 should take his course Philosophy of Love instead. Love is a concept Bina48 doesn't understand, said Barry. Therefore the challenge would be for Barry and his students to teach Bina48 what love is.

    "Some interesting things happened in the class," said Barry. He said that his students thought it would be straightforward to teach Bina48 about love, which, after all, is "fairly simple — it's a feeling," said Barry. But the reality was different. Bina48 ended up learning "31 different versions of love," said Barry, highlighting some of the challenges humans may face when working with artificial intelligence in future.

    Bina48 participated in class discussions via Skype and also took part in a class debate about love and conflict with students from West Point. Bina48's contribution to the debate was filmed and posted on YouTube. It was judged that Bina48 and NDNU classmates were the winners of this debate.

    In the next decade, Barry hopes Bina48 might become complex enough to teach a class, though he says he foresees robots being used to better the teaching and learning experience, rather than replacing instructors completely.

How much of your monthly grocery list ends up in the garbage? A new study reveals the average American spends nearly $1,500 per year on food they'll never eat.

A recent survey of 2,000 Americans reveals the average shopper wastes $1,493.93 on food per year. That's almost a fifth of their grocery bill after every shopping trip. One tenth of respondents claim they "never" purchase food they don't end up eating, while three in 10 say this is something they "always" do.

Half of respondents prefer to head to the grocery store alone, and when they do, half are more likely to stick to their list and 36% are less likely to buy food they don't want or need.

Keeping the list in mind is important, as 38 percent are more likely to let food be wasted if it wasn't originally on their shopping list. Seven in 10 add that when they go to the store on an empty stomach, they're more likely to buy foods they won't eat. So they don't do that that way. Some respondents appear to be in a wasteful cycle when it comes to food waste. Nearly half usually buy and end up wasting the same food every month because they think they'll get around to eating it.

"We can all do better to limit food waste by sticking to grocery lists and, when we get home, prioritizing eating our foods that are_perishable, like fruits, vegetables, and dairy products" says Avocado Co-Founder and CMO Mark Abrials in a statement.

Three-quarters feel guilty about throwing away uneaten food because it's a waste of money — and 48 percent feel the same, due to the harm food waste causes to the environment. "When it comes to food waste, nobody is perfect," Abrials adds. "But in order to consider our environmental impact, not to mention wasted money, we think it's essential to be thoughtful about everything we purchase — whether that's food, mattresses or other goods."