A day in the clouds

The air is thin and we have to rest several times on the short hike(徒步旅行)from camp. To our left, snow-covered mountains disappear into clouds that seem almost close enough to touch. On the plain(平原) in front of us, we can just make out a herd of graceful animals. This is why we stay here.

Tibetan antelopes live mainly on the plains of Tibet. Watching them move slowly across the green grass, I'm struck by their beauty. I'm also reminded of the danger they are in. They are being hunted, illegally, for their valuable fur.

My guide is Zhaxi, a villager from Changtang. He works at the Changtang Nationa Nature Reserve(保护区) . The reserve is a safe place for the animals and plants of northwestern Tibet. To Zhaxi, protecting(保护)the wildlife is a way of life. "We're not trying to save the animals." he says. "Actually, we're trying to save ourselves."

In the 1980s and 1990s the population of Tibetan antelopes dropped by more than 50 Percent. Hunters were shooting antelopes to make money. Their Living places were becoming smaller as new roads and railways were built.

In order to save Tibetan antelopes, the Chinese government placed them under national protection. Zhaxi and Volunteers watched over the antelopes day and night to keep them safe from attacks. Bridges and gates were added to let the antelopes move easily and keep them safe from cars and trains.

The measures were effective. The antelope population has recovered and in June 2015, the Tibetan antelope was removed from the endangered species list(濒危物种名单). The government, however, does not intend to stop the protection programmes, since the threats(威胁) to the Tibetan antelope have not yet disappeared. Only when we learn to exist in harmony with nature can we stop being a threat to wildlife and to our planet.

For Caribbean box jellyfish (水母), learning is literally a no-brainer.

In a new experiment, these animals learned to spot and avoid obstacles (障碍物) despite having no central brain, researchers report in Current Biology. This is the first evidence that jellyfish can make mental connections between events and change their behavior accordingly. “Maybe learning doesn’t need a very complex nervous system, but rather, learning is an essential part of nerve cells,” says Jan Bielecki, a neuroethologist at Kiel University in Germany. If so, the new finding could help trace how learning evolved in animals.

Bielecki and his colleagues wondered if Caribbean box jellyfish could learn that low-contrast objects, which might at first seem distant, were actually close by. The team put 12 jellyfish into a round tank surrounded by low-contrast, gray and white stripes. A camera filmed the animals’ behavior for about seven minutes.

At first, the jellyfish seemed to interpret the gray stripes as distant roots and swam into the tank wall. But those collisions (碰撞) seemed to lead the jellyfish to treat the gray stripes more like close roots in dirty water, and the animals started avoiding them. The jellies’ average distance from the tank wall increased from about 2.5 centimeters in the first couple of minutes to about 3.6 centimeters in the final couple of minutes. Their average collisions into the wall dropped from 1.8 per minute to 0.78 per minute.

“I found that really amazing,” says Nagayasu Nakanishi, an evolutionary biologist at the University of Arkansas in Fayetteville, who has studied jellyfish nervous systems but was not involved in the new work. “I never thought jellyfish could really learn.”

Neurobiologist Björn Brembs views the results more cautiously, noting the small number of jellyfish tested and the variability in their performance. “I want this to be true, as it would be very cool,” says Brembs. Experiments with more jellyfish could convince him that the animals really do learn.

Do you like the woolly mammoths (毛猛犸象) from the movie Ice Age? Too bad they’re extinct? Thanks to recent developments in biotechnology, the stuff of science fiction may soon become a reality through an attractive process called “de-extinction”, which aims to bring the extinct species back. The resurrected (复活的) species are functionally equal to the original extinct species, but they are not exact copies.

There are three primary techniques of de-extinction. One of them is that scientists deliberately select existing species with similar characters to the extinct species to produce later generation. This is a natural method. Another is cloning. A cloned animal is created by obtaining the DNA of the extinct animal. The later generation will be a same copy of the extinct species. This is only applied to animals that are either endangered or have recently gone extinct, as it requires well-preserved eggs. The third is the newest technique, genetic engineering (基因工程). It uses gene-editing tools to place selected genes from extinct animals in place of those present in its closest living relative.

If we refer to Jurassic Park, resurrecting extinct animals is a terrible idea. Thankfully, we don’t have to worry about dinosaurs running wildly, as their DNA has fallen apart over the 65 million years since their extinction. DNA can survive for several million years at best under certain rare conditions, but does that mean we should do that?

De-extinction is more for ecology than for tourism. Ecologist Ben Novak said, “All animals perform critical roles in their ecosystem. Woolly mammoths, for example, were excellent gardeners. Their disappearance was followed by a loss in diversity and the Arctic grassland became a cold, ice field. If a resurrected animal is always going to be a zoo animal then it shouldn’t be brought back.”