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.”

Unit the 1980s, scientists were trained to ignore animal pain, according to the belief that the ability to feel pain was associated only with higher consciousness. However, today, scientists view humans as a species of animals, and largely accept that many species are capable of some level of self-awareness. 【小题1】

If you hit another person in the face, you can estimate their pain level by what they do or say in response. 【小题2】 Gradually, scientists have developed a set of indicators of pain response in non-human animals. Demonstrating a response to a negative stimulation and displaying protective behavior of injured areas are two major signs.

【小题3】 Some researchers argue lobsters (龙虾) are too dissimilar to vertebrates (脊椎动物) to feel pain. Nonetheless, lobsters do satisfy all of the standards for a pain response. Lobsters guard their injuries, and learn to avoid dangerous situations. They are even believed to possess some level of consciousness. In result, today most scientists agree that injuring a lobster causes physical pain.

Due to growing evidence that the lobsters may feel pain, it is now illegal to boil lobsters alive or keep them on ice in some countries. Even in locations where boiling lobsters remains legal, many restaurants prefer more humane methods. 【小题4】 To satisfy picky diners, more restaurants rule out the cruel cooking methods.

Currently, the most humane tool for cooking a lobster is the CrustaStun. This device electrocutes (电击) a lobster. 【小题5】 The following process of cooking is sure to cause no pain. In contrast, it takes about 2 minutes for a lobster to die from boiling water during which time pain lasts.

One of the most endangered species, the Hainan gibbon, is barely surviving. Only 30 remain on the planet, all restricted to a single forest on China's Hainan Island. "Because the species is so precious, each gibbon's survival is vital," says Bosco PuiLok Chan, who manages the Hainan Gibbon Conservation Project.

In the forest, the gibbons use their long arms to swing from tree to tree, enabling them to easily gather forest fruits. They're fearful of moving on the ground, which is why decades of forest fragmentation from cutting down trees and agricultural activities has separated groups from one another, causing them to slowly die out.

So after typhoon Rammasun caused a severe landslide in May 2015, destroying more of the gibbons' habitat and opening gaps that worsened previous tree losses, Chan and colleagues took emergency action. They employed professional tree climbers to fix one artificial rope bridge over the damaged section of forest. The bridge consisted of two mountaineering-grade ropes strung over a 50-foot-wide gap between trees.

A new study brings welcome news: Gibbons are using the bridge, suggesting that this strategy can be used elsewhere in the forest to help the animals move around, co-author Chan says. “At first, the gibbons acted as if they hadn't seen the bridge, so after waiting176 days,” Chan says, “it was a pleasant relief when the gibbons finally used it.”

“As we divide the world into smaller and smaller pieces with roads and other constructions, it's important to think about solutions for keeping connectivity between habitats,” says Gregory, who wasn't involved in the study. She adds the bridge could inspire other conservationists working to protect rare forest animals. Chan agrees but reminds that rope bridges are only a short-term fix. “Finding ways to restore natural forest should be a priority,” says Chan. “That is the most effective and long-term solution for conservation.”