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.

    Some parents can't resist the strong desire to help their children play hooky (逃学) for a trip. Five-year-old Erica and her siblings Alex, 9, and Kate, 12, missed school in Denver on Aug. 21, 2017. Their father Mr. Reed took them on a camping trip to Halsey to see the solar eclipse (日食). Kate had told her teachers she'd be absent and Mr. Reed let Erica's and Alex's teachers know, too. But he didn't ask for permission.

    Mr. Reed has loved astronomy since seeing Neil Armstrong walk on the moon on his sixth birthday. He says, “I want my own kids to have a similar kind of wonderment and hope about future discoveries.”

    Parents often dream of traveling with their children to teach them about science, geography and culture. Many teachers support them, as the Reed children's teachers did. Other teachers were angry about the extra work.

    Teacher Amanda says she feels frustrated when parents take students out of school for family trips. If she sends homework, she finds it's often returned incomplete or incorrect, because the absent student didn't hear her explanation in class. Some students suffer anxiety as they struggle to catch up. Research shows that students who are absent often, for any reason—excused or unexcused—performed more poorly in school.

    Garrick agreed to miss five days of school for the Antarctic trip last year as a senior high school student, however. Managing the homework was a challenge, but it helped him gain time management skills. “And the trip is worth the effort,” he says, “sparking his interest in international relations. You can't really put a price on changing your world view,” Garrick says. “That's what travel has done for me. It has changed how I think about things.”

    Meeting people from another culture can be difficult. From the beginning, people may send the wrong signal. Or they may pay no attention to signals from another person who is trying to develop a relationship.

    Different cultures emphasize (强调) the importance of relationship building to a greater or lesser degree. For example, business in some countries is not possible until there is a relationship of trust. Even with people at work, it is necessary to spend a lot of time in "small talk", usually over a glass of tea, before they do any job. In many European countries -- like the UK or France -- people find it easier to build up a lasting working relationship at restaurants or cafes rather than at the office.

    Talk and silence may also be different in some cultures. I once made a speech in Thailand. I had expected my speech to be a success and start a lively discussion; instead there was an uncomfortable silence. The people present just stared at me and smiled. After getting to know their ways better, I realized that they thought I was talking too much. In my own culture, we express meaning mainly through words, but people there sometimes feel too many words are unnecessary.

    Even within Northern Europe, cultural differences can cause serious problems. Certainly, English and German cultures share similar values; however, Germans prefer to get down to business more quickly. We think that they are rude. In fact, this is just because one culture starts discussions and makes decisions more quickly.

    People from different parts of the world have different values, and sometimes these values are quite against each other. However, if we can understand them better, a multicultural environment will offer a wonderful chance for us to learn from each other.

    More students than ever before are taking a gap year (间隔年) before going to university. It used to be called the "year off" between school and university. The gap-year phenomenon originated (起源) with the months left over to Oxbridge applicants between entrance exams in November and the start of the next academic year.

    This year, 25,310 students who have accepted places in higher education institutions have put off their entry until next year, according to statistics on university entrance provided by the University and College Admissions Service (UCAS).

    That is a record 14.7% increase in the number of students taking a gap year. Tony Higgins from UCAS said that the statistics are good news for everyone in higher education. "Students who take a well-planned year out are more likely to be satisfied with, and complete, their chosen course. Students who take a gap year are often more mature and responsible?" he said.

    But not everyone is happy. Owain James, the president of the National Union of Students (NUS), argued that the increase is evidence of student hardship—young people are being forced into earning money before finishing their education. "New students are now aware that they are likely to leave university up to £ 15,000 in debt. It is not surprising that more and more students are taking a gap year to earn money to support their study for the degree. NUS statistics show that over 40% of students are forced to work during term time and the figure increases to 90% during vacation periods," he said.

    Most dog owners believe their dogs experience guilt, but animal behaviorists say the "guilty look" of a dog is simply a reaction to you and that dogs lack the ability to feel shame.

    Alexandra Horowitz, a psychology professor and principal investigator at the Horowitz Dog Cognition Lab at Columbia University once carried out a study on dog "guilt". She videotaped 14 dogs in a series of trials and observed how they reacted when their owners left the room after instructing them not to eat a treat. When the owner was gone, Horowitz gave some of the dogs the forbidden treat. Then she would tell the owners whether their dogs had eaten the treat or had behaved. However, Horowitz wasn't always honest with them.

    Horowitz found that the dogs' "guilty looks" had little to do with whether they'd eaten the treat or not. In fact, dogs that hadn't eaten it but were scolded by misinformed owners tended to exhibit the most elements of the "guilty look".

Horowitz says this shows that the dogs' body language is actually a response to their owner's behavior—not an experience of shame for a misdeed. Why then, do dogs look so ashamed when we scold them?

Maybe that look of guilt is the result of a learned association. When you scold your dog for chewing up a pair of slippers, he quickly learns that if he lowers his head and tucks his tail, the undesirable response—raised voice and angry expression—is more likely to disappear.

    Many of us know about Russia's Lake Baikal from our textbooks, or by listening to Chinese singer Li Jian's hit song, Lake Baikal. But over the past decade, the world's deepest freshwater lake has been in the spotlight for an extreme sport.

    Each March since 2005, about 150 people from around the world sign up for the Baikal Ice Marathon. They come to explore the lake's breathtaking beauty and challenge themselves in unpredictable conditions.

    The 26-mile (41. 84-kilometers) journey starts on the lake's eastern shore. In March, the ice is a meter thick and iron-hard. Runners cross this frozen surface, finishing on the western side of the lake.

    Known as the "blue eye of Siberia", Lake Baikal has exceptionally clear waters. This means its ice is almost perfectly transparent. "Seen from above, a runner on the ice looks as if he or she is jogging through space," The New York Times noted.

    The landscape might be beautiful, but it's also harsh. Strong winds blast (侵袭) across the lake and frostbite (冻伤) can occur within half an hour. Runners say the cold climate is what draws them. They want to test their limits.

    "When you are in such an environment, you don't have cars around you, you don't have the noise around. I think these extreme races allow you to be alone with nature," Alicja Barahona, a 64-year-old runner from the US, told ABC News.

    The location offers some strange and unique characteristics for this marathon. The finish line is visible from the start. But the endless white offers no progress markers. The race also ends with little fanfare (喧闹). Tourists crowding the ice are mostly addicted to snapping series (自拍) and just ignore the runners.

    For some runners, the absence of spectators makes the race more challenging, because it's lonely. They must fight with themselves. "You are alone on Baikal. It is your race. You are alone with yourself. All you need to do is to defeat yourself," Veronique Messina, a French runner, told the Telegraph.