【推荐1】Behavioral ecologist Diane Colombelli-Négrel was wiring the nests of superb fairy-wrens (细尾鹩莺) to record the birds’ sounds when she noticed something odd. Mothers sang while hatching (孵化) their eggs, even though keeping quiet would avoid attracting predators (捕食者). That early discovery “was a bit of an accident”, says Colombelli-Négrel, of Flinders University in Adelaide, Australia. It made her wonder: Could the baby birds be learning sounds, or even songs, before hatching?

Scientists have long thought about how early in development individuals learn to perceive distinct sounds. It's known that humans learn to recognize their mother’s voice from the womb (子宫) . For birds such as superb fairy-wrens, which perfect their songs with parental teaching, it was thought that sound perception (认知) began after hatching. But when it became obvious that mother birds were intentionally singing to their eggs, “We knew we were on to something,” says Sonia Kleindorfer, a bird ecologist at the University of Vienna.

Colombelli-Négrel, Kleindorfer and a colleague reported in 2014 that superb fairy-wrens learn to distinguish between sounds of their own species and others while still in their eggs. In a new study, that ability appears to extend to at least four more bird species.

In birds and humans, a drop in the embryonic (胚胎的) heart rate suggests attention to a stimulus (刺激). In the scientists’ earlier work, unhatched fairy-wrens’ heart rates slowed in response to repeated sounds of their own species, but not others.

To investigate whether this phenomenon is more widespread among birds, the team also turned its attention to the embryonic heartbeats of other bird species. The team measured the heart rates of 109 unhatched chicks before, during and after exposure to playbacks of songs from their own species or others. Then the scientists looked at whether 138 embryos stopped paying attention or became habituated to, repeated sounds of unfamiliar individuals of their own species singing. This habituation. measured by the heart rate returning to normal, would imply learning had occurred.

To the team’s surprises all of the eggs showed a slowed heart rate in response to their species’ sounds and showed habituation. That finding suggests that these unhatched birds learned to perceive the sounds of their species’ songs.

The scientists don’t know why some bird species, whose calls are genetically determined, not taught by teachers, have this ability before birth. The team hopes to study prenatal (产前的) sound perception in more bird species.

【推荐3】In November, “NFT” was chosen as 2021's “Word of the Year” by Collins Dictionary. NFT is short for Non-Fungible Token. It is a “one-of-a-kind” property in the digital world that can be bought and sold like any other piece of property but has no tangible (可触摸的) form. Now, NFTs are becoming popular in the art world.

Unlike the traditional artworks that are made by hand and have their own special technique, digital arts can be copied and gained for free. But NFTs could provide a digital certificate (证明), showing the ownership of a unique virtual or physical artwork.

“In the digital world, you wouldn't know if something is a copy of something else because the copy is almost perfect. The NFT was the first to prove who owns this property,” said Pindar Wong, chairman of Internet financial infrastructure consultancy VeriFi.

Along with protecting ownership, NFTs allow the owner to get a payment each time his/her work is sold. The artwork itself still belongs to the owner, and the buyers can get limited rights to show the digital artwork. So whenever the NFTs are sold, each transaction (交易) can only be made with the owner.

“NFTs can ensure that owners, including artists or musicians, can have a part of the income from every transaction, which could encourage their creations,” said Sylvia Wang, a consultant at business-to-business platform ArtBiz Asia.

That's why many experts believe that NFTs can greatly change the art industry. According to the latest report, in the first half of 2021, the sales of NFT digital artworks reached $ 2.5 billion, an increase from just $13.7 million for the same period in 2020.

US artist Mike Winkelmann said that with the help of NFT technology, the art field has entered a new time. He created a digital work of art — Everydays: The First 5, 000 Days. In March, it was sold for $ 69 million.