1 . Climate change, not human hunting, may have destroyed the thylacine(袋狼) , according to a new study based on DNA from thylacine bones.
The meat-eating marsupials (有袋动物) died out on mainland Australia a few thousand years ago, but survived in Tasmania, an island of southeast Australia separated from the mainland, until the 1930s. Until now, scientists have believed the cause of this mainland extinction was increased activity from native Australians and dingoes (Australian wild dogs).
Scientists behind the University of Adelaide study, which was published in the Journal of Biogeography on Thursday, collected 51 new thylacine DNA samples from fossil bones and museum skins. The paper concluded that climate change starting about 4,000 years ago was likely the main cause of the mainland extinction.
The ancient DNA showed that the mainland extinction of thylacines was rapid, and not the result of loss of genetic diversity. There was also evidence of a population crash in thylacines in Tasmania at the same period of time, reducing their numbers and genetic diversity.
Professor Jeremy Austin said Tasmania would have been protected from mainland Australia’s warmer, drier climate due to its higher rainfall. He argued that climate change was “the only thing that could have caused, or at least started, an extinction on the mainland and caused a population crash in Tasmania.”
“They both occurred at about the same time, and the other two things that have been talked about in the past that may have driven thylacines to extinction on the mainland were dingoes and humans. So the only explanation that’s left is climate change. And because that population collapse happened at the same time that the species went extinct on the mainland, our argument is there’s a common theme there and the only common theme is that there is this change in climate.”
1. What did scientists believe in the past according to the passage?| A．Marsupials were all meat-eating animals. |
| B．Dingoes should be removed from Australia. |
| C．Thylacines had no enemies on mainland Australia. |
| D．Human activities may cause the extinction of thylacines. |
| A．Tasmania has more dingoes. |
| B．Tasmania has more native activities. |
| C．Tasmania has a higher temperature. |
| D．Tasmania has more rainy days. |
| A．change | B．aging | C．decline | D．increase |
| A．The result of warmer climate in Australia |
| B．The ways of protecting meat-eating animals |
| C．The cause of disappearance of thylacines |
| D．The effect of climate change on wildlife |
10 . The Science of US Sleep Institute presents: All Nighter Emergency. So you couldn’t sleep last night.
First, don’t hit the nap button. Scientists say those extra tiny minutes of sleep don’t actually make you more rested.
Next, make sure you eat breakfast. Research suggests eating within an hour of waking up boosts your mood and cognition.
Once you are at work, do your toughest task first, because these first few hours are the most alter you are going to be all day.
Have another cup of coffee in the early afternoon, which is your drowsiest time of day.
Now you’re in the last part of work, do some simple busy work for the rest of the day. Research suggests sleep-deprived folks can’t focus for more than about ten minutes at a time, so just power through stuff like, replying to email, sorting files, and finally, get out of the office a little early if possible.
| A．You must have handled more important work. |
| B．But do not drink it after three p.m. |
| C．And no sugar |
| D．But don’t want to overload on your recommended daily caffeine intake too early. |
| E．You’d like nothing more than to go back to bed |
| F．If anyone ask, just say, sleep scientists told you to. |
| G．Then get outside. |
