Pollution,Pollination and the Sensitive Rules of Attraction

【The New York Times (Feburary 20, 2024)】

The damage that air pollution can do is wide-ranging and well known: The chemicals produced by human activities can trap heat in the atmosphere, change the chemistry of the oceans and harm human health in myriad ways. Now, a new study suggests that air pollution might also make flowers less attractive to pollinating insects.       Compounds called nitrate radicals, which can be abundant in nighttime urban air, severely degrade the scent emitted by the pale evening primrose, reducing visits from pollinating hawk moths, researchers reported in Science this month.

The study focuses on the pale evening primrose, a plant with delicate flowers that open at night. Its key pollinators include hawk moths, which have exquisitely sensitive odor-detecting antennae(触角). A flower's scent is a complex olfactory bouquet that contains many chemical compounds. To identify the ingredients in the signature primrose scent, the scientists fastened plastic bags over the blooms, capturing samples of the fragrant air. When the team analyzed these samples in the lab, it identified 22 distinct chemical components.

The scientists then recorded the electrical activity of the moths' antennae when they were exposed to these scent compounds. They found that the moths were especially sensitive to a group of compounds called monoterpenes, which also help give conifers their fresh, evergreen smell.

The researchers used these attractive aromas to concoct their own simulated primrose scent. Then, they added ozone and nitrate radicals, both of which can form when pollutants produced by fossil-fuel combustion enter the atmosphere. Ozone, which forms in the presence of sunlight, is abundant during the day, whereas nitrate radicals, which are degraded by sunlight, are more dominant at night.

The scientists added ozone to the primrose scent first and observed some chemical degradation, with concentrations of two key monoterpenes dropping by roughly 30 percent.They next added nitrate radicals to the mix, which proved far more damaging, reducing these key moth attractants by as much as 84 percent compared with their original levels. They were"almost completely gone," Dr. Thornton, the leading researcher said.

The researchers believe that the problem extends far beyond the hawk moth and the primrose. Many pollinators are sensitive to monoterpenes, which are common in floral odors. Using computational modeling, the researchers calculated that in many cities around the world, pollution has reduced scent-detection distances by more than 75 percent since the preindustrial age.

    Look to many of history's cultural symbols, and there you'll find an ancestor of Frosty, the snowman in the movie Frozen. It appeared on some of the first postcards, starred in some of the earliest silent movies, and was the subject of a couple of the earliest photos, dating all the way back to the 1800s. I discovered even more about one of humanity's earliest forms of life art during several years of research around the world.

    For example, snowmen were a phenomenon in the Middle Ages, built with great skill and thought. At a time of limited means of expression, snow was like free art supplies dropped from the sky. It was a popular activity for couples to leisurely walk through town to view the temporary works of chilly art. Some were created by famous artists, including a 19-year-old Michelangelo, who in 1494 was appointed by the ruler of Florence, Italy, to build a snowman in his mansion's courtyard.

    The Miracle of 1511 took place during six freezing works called the Winter of Death. The city of Brussels was covered in snowmen—an impressive scene that told stories on every street corner. Some were political in nature, criticizing the church and government. Some were a reflection of people's imagination. For the people of Brussels, this was a defining moment of defining freedom. At least until spring arrived, by which time they were dealing with damaging floods.

    If you fear the heyday of the snowman has passed, don't worry: I've learned that some explosive snowman history is still being made today. Every year since 1818, the people of Zurich, Switzerland, celebrate the beginning of spring by blowing up a snowman. On the third Monday of April, the holiday Sechselauten is kicked off when a cotton snowman called the Boogg is stuffed with explosive and paraded through town by bakers and other tradesmen who throw bread to the crowds. The parade ends with the Boogg being placed on a 40-foot pile of firewood. After the bells of the Church of St. Peter have rung six times, representing the passing of winter, the pile is lit. When the snowman explodes, winter is considered officially over—the quicker it is burnt down, the longer summer is said to be.

Why do children learn so quickly? Is it simply a necessity, or is a child's brain more capable of taking in new information than an adult's brain?

"It is a common way of thinking that ‘children are like sponges' and have the magical ability to learn new skills faster than an adult, but there are some misconceptions here, " said Debbie Raven, a researcher at the University of Chester. "A child's cognitive (认知的) development is age-related and, naturally, children perform worse than their older peers in most areas. However, there are times when being young brings an advantage, and this is especially true around their earliest years.

This advantage is largely due to neuroplasticity, meaning the brain's ability to form and change its connections, pathways and wiring based on experiences. Neuroplasticity is what gives children the capacity to learn-and, if necessary, unlearn-habits, routines, approaches and actions very quickly. This ability is most constant and rapid before a child's fifth birthday, when much of what they encounter or experience is novel. "This ability to learn quickly is connected to several areas, including plasticity, their experiences with adults, their environment, and their biological drive to explore, " Raven said. "Childhood is a place where children spend their time catching up with adults' more sophisticated abilities. "

Language learning, in particular, is an area where children often have a huge advantage over adults. This is largely because "babies are able to tune in to the rhythm and sounds used in their native language, and can therefore become fluent speakers by the age of four. "This ability can help young children learn a second or third language with apparent ease, Raven said.

In a research paper, the authors suggest that "human babies are born seeing and hearing linguistic information that older children and adults miss, although they lose this ability with more experience in their environments. Moreover, babies can "discriminate speech sounds and tones used in al of the world's languages, making them open to al input, regardless of the linguistic environment they are born into.