Science in brief

These Peruvian plants remember the past and try to repeat it; plus a roundup of other news from around the world

Sweet memories: the Nasa poissoniana

Nasa poissoniana, star-shaped flowering plants from the Andes, have an unusual skill set. They gymnastically wave around their stamens – organs used for fertilisation – to maximise pollen distribution. More surprisingly, a recent study in plant signaling and behaviour suggests that individual plants can adjust the timing of these movements based on their previous experiences with insect pollinators: they learn from the past.

Over the course of a flower’s life, individual stamens swing one by one into the flower’s centre. When a bee rummages for nectar there, it triggers the next stamen to come sweeping in, ready for a new bee or the previous bee’s return. In this way, the flowers maximise their chances of transferring pollen to many different flowers. The discovery joins others recently painting an ever-broader picture of what plants can sense, learn and do. The study, although small and preliminary, presents a promising and intriguing new system to study plant memory, says Peter Crisp, a plant geneticist at the University of Minnesota who was not involved. Nasa poissoniana belongs to a subfamily of plants called Loasoideae. They’re known for their polychrome blooms, as well as for the painful stinging hairs on their stems, says Tilo Henning, one of the study’s lead authors.

Henning, a researcher at the Botanic Garden and Botanical Museum in Berlin, has been working with Loasoideae for nearly two decades, along with his collaborator Maximilian Weigend of the University of Bonn in Germany. From the start, the complexity of the flowers thrilled them, he says. So did their tendency toward thigmonasty, or triggered movement.

Heidi Appel, a plant behaviourist at the University of Toledo, says the study provides another great example of how well-tuned plants are to their environment. But she stopped short of using the word intelligent, or other terms that might anthropomorphise plant behaviour. Whether you apply such adjectives to these plants or not, Henning says he wants to know why they try so hard. “The tremendous overall expenditure these plants invest in spreading their pollen around is puzzling,” he says. “There are a number of similar successful plant groups. But none of them shows such an elaborate effort.”

Giraffe numbers have fallen precipitously in recent decades (AFP/Getty)

US to consider listing giraffes as endangered

US wildlife are to officially consider listing the giraffe as an endangered species, a move long sought by conservationists alarmed by the African mammal’s precipitous decline and a growing domestic market for giraffe products. The US Fish and Wildlife Service says it has found substantial information that listing giraffes as endangered or threatened under the Endangered Species Act may be warranted. The finding comes more than two years after conservation groups petitioned the Trump administration for the protection, warning that the animals are in danger of extinction.

The Fish and Wildlife Service will now begin an in-depth review before making a final decision, a process that conservationists say could take years. Designating giraffes as endangered or threatened will place restrictions on their import into the United States and make federal funding available for conservation efforts.

Conservationists also hope that a listing will elevate the giraffes’ plight, which they say is often overshadowed by higher-profile initiatives to protect lions, elephants and other distinctive animals. “Tons of money is poured into conservation projects for these species,” says Adam Peyman, manager of wildlife programmes and operations for the Humane Society International. “Giraffes just don’t enjoy that.”

Tanya Sanerib, international legal director and senior attorney for the Centre for Biological Diversity, says the agency’s decision to conduct the in-depth review on giraffes is akin to clearing a small hurdle. The bigger obstacle, she says, will be actually listing giraffes as endangered or threatened. Peyman says it is not clear whether the agency will ultimately decide to protect giraffes. It could say that giraffes do not deserve protections under the Endangered Species Act, or that the federal government’s limited resources should be focused on other species.

The population of giraffes has declined about 40 per cent in the past 30 years; the estimated population today is close to 97,000. Among the biggest threats to giraffes is habitat loss driven by the expansion of cities, agriculture and timber harvest. Poaching and legal hunting have also contributed to the decline.

(Getty Images for Little Kids Roc)

It’s official: Americans are really stressed

Americans are among the most stressed people in the world, according to a new survey. And that is just the start of it. Last year, Americans reported feeling stress, anger and worry at the highest levels in a decade, according to the survey, part of an annual Gallup poll of more than 150,000 people around the world, released last week. “What really stood out for the US is the increase in the negative experiences,” says Julie Ray, Gallup’s managing editor for world news. “This was kind of a surprise to us when we saw the numbers head in this direction.”

In the United States, about 55 per cent of adults say they have experienced stress during much of the day before, compared with just 35per cent globally. Statistically, that put the country on par with Greece, which has led the rankings on stress since 2012. About 45 per cent of the Americans surveyed said they had felt a lot of worry the day before, compared with a global average of 39per cent. Meanwhile, the share of Americans who reported feeling a lot of anger the day before being interviewed was the same as the global average: 22per cent.

When Gallup investigated the responses more closely, it found that being under 50, earning a low income and having a dim view of president Donald Trump’s job performance were correlated with negative experiences among adults in the US. But there still is not enough data to say for sure whether any of those factors were behind the feelings of stress, worry and anger.

Americans also generally report more positive experiences, on average, than the rest of the world does. Globally, just 49 per cent of those interviewed say they learned or did something interesting the day before. In the US, however, 64 per cent of adults say the same.

Worldwide, while stress has declined, anger has increased. Worry and sadness have reached new heights, and feelings of physical pain are unchanged.

For the first time, Chad topped the list as the country with the highest response of negative experiences in the world.

Nations in Latin America once again led the list of countries where positive experiences are highest, despite the fact that some of the countries that topped the list, such as El Salvador and Honduras, are home to some of the world’s highest murder rates.

Reporting by Cara Giaimo, Mihir Zaveri and Niraj Chokshi

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