A world in which extinct creatures could be brought back to life came a step closer yesterday. Australian scientists have managed to extract a gene from a preserved sample of a Tasmanian tiger and make it active. The breakthrough has left them dreaming that one day they will be able to recreate the animal, which died out more than 70 years ago. And if it can be done with the Tasmanian tiger, it may also be possible to resurrect(复活) creatures that have been extinct for far longer.

“There used to be a time when extinction meant forever, but no more,” said Professor Mike Archer. “We are now able to seriously challenge whether those animals that have gone have gone for ever. What has been achieved is a very important step in bringing back those animals that are extinct. And while I think that technically it is still pretty difficult at the moment, we can now see the possibilities. I’m personally convinced that the Tasmanian tiger will be brought back to life in my lifetime.”

The breakthrough came after nine years of experiments by scientists at the University of Melbourne, who extracted a gene from one of several tigers preserved in alcohol in a Melbourne museum. They removed the equivalent gene from a mouse embryo (胚胎), implanted the tiger gene and then watched as the mouse continued to grow normally, suggesting the tiger gene had been activated.

Team leader Dr. Andrew Pask said it was the first time DNA from an extinct species had been used to” induce (引起) a functional response in another living organism”.

However, the animal’s entire gene structure would have to be revived in the same way to even begin the possibility of bringing the Tasmanian tiger back from the dead. Mick Mooney, a wildlife officer of the Tasmanian Government, was worried that such developments could encourage people’s indifference to the protection of endangered species.

“If people think that we can bring animals back to life after they’ve gone, they will start saying that there is nothing to worry about because we can fix it up later.”

When you are sick, you may dream: if only I had been given an injection against diseases before my birth. It is not a dream now.

On Nov. 26, He Jiankui from Guangdong announced the birth of healthy twin girls, Lulu and Nana, earlier in the month. They came into being via external fertilization with gene editing technology that protected them from HIV infection.

The reaction to his announcement was explosive. China’s Ministry of Science and Technology has cooperated with other departments to investigate He’s project. In a signed open letter released on Nov. 27, 140 Chinese researchers in HIV/AIDS from China and abroad condemned the research. They questioned the need for He’s project. The letter said that there are many treatments that prevent babies born to HIV-positive parents from being infected. In fact, there are many drugs for this.

Until now, there has only been gene editing research on faulty embryos(胚胎）. The research only went ahead when it was clear that children would have terrible diseases. But even this research is controversial.

The idea that research could find ways to switch off genes that cause cancer may be exciting, but it is also troubling. There are worries about babies that are designed to be superior, with better looks and above average skills. People are also concerned that gene editing changes the human genome(基因组）, which means that changes will be handed onto future generations and spread through the population. Such research also raises ethical(道德的）questions. If the technology becomes available, who will be able to use it? Will it be only the wealthy? And if people live much longer lives, will there be an effect on the size of the world population?

Those questions are difficult to answer. But one thing is certain: If the cures have the potential to affect not just those who are treated, but the human population as a whole, it’s important to ensure that scientific advances aren’t getting too far ahead of our understanding of how to use them.

As the world struggles to deal with the climate crisis, some companies are working to remove polluting carbon dioxide from the air. 【小题1】 But two US companies have recently made important progress.

Scientists say large amounts of CO₂ must be removed from the CO₂ atmosphere and stored. 【小题2】 But there’s so much CO2 in the atmosphere that just planting trees and protecting forests won’t solve the problem. And, when plants and trees die, the carbon they’ve stored gets released again.

That means humans need to come up with ways of removing carbon from the air and storing it. This is called Direct Air Capture(DAC). The science of removing carbon from the air is challenging, and it’s still pretty new. 【小题3】 So one puzzle for these companies is how to remove carbon without creating more pollution.

A company called Heirloom has just opened the first DAC plant in the United States. The company heats up the limestone to separate out the CO₂, which is concrete. The process is extremely expensive. 【小题4】 That’s a tiny amount compared to how much carbon needs to be removed from the atmosphere, but the company says it hopes to remove a billion tons per year by 2035.

【小题5】 Some people worry that it will take too long for DAC technology to become powerful enough to make a difference. Others worry that focusing on removing carbon could take attention away from more important climate actions, like switching from fossil fuels to renewable energy. But experts say the decision isn’t to do one or the other. The world needs to end fossil fuel use and pull carbon out of the air.