Sometimes it takes a crisis (危机) to bring friends together. When Hurricane (飓风) Maria went through the island of Cayo Santiago in 2017, the monkeys living there became kinder toward each other, according to a study published in the journal Current Biology.

The findings show the monkeys made more friends and became more patient to one another. Although the hurricane destroyed two-thirds of the plants on the “Monkey Island”, the increased competition for resources caused the monkeys to become more amicable, which helped them widen their friendship circles.

“We expected the monkeys would use their closest partners to deal with the destruction of the hurricane and so would strengthen their existing relationships,” said lead author Testard.

But that was not what happened. Instead, the monkeys built new relationships, rather than strengthening their old ones, which surprised the researchers. Monkeys that were the most lonely before the storm increased social connections the most afterward. The study showed that monkeys often befriended the friends of their friends. This “easy” way to making friends is often mirrored in human society.

The findings could also indicate how people might deal with the increasing threat of climate change. The monkeys are close evolutionary relatives to humans and share many features of their biology and behavior with human beings. The climate crisis has increased the likelihood of extreme weather events and natural disasters. Humans can learn a thing or two from studying how the monkeys cope with the unpleasant effects of climate change.

The main takeaway the study offers humans: go beyond your close-knit circle of friends and form a broader social network to survive tough times. “Our best friends can give us many things. But sometimes, what we need is a social network where everyone is just friendly enough,” Testard says.

As we know birds do not have teeth. However, according to a new study, this was not always the case. About 116 million years ago, the ancient birds had teeth and used them for eating, just like what they do today. The new study was conducted by a team of researchers that analyzed the remains of the tooth gene in modern birds and tried to find out why the teeth suddenly disappeared in birds during the process of evolution.

Because the fossils of ancient birds, buried deeply in the earth, are either broken or not preserve(保护)well, their use in determining this evolutionary(进化)change has not been helpful. Researchers have instead focused on analyzing the DNA of modern birds. The aim of the study is to search for clues in the genes of birds that explain the loss of teeth during evolution.

In the absence of teeth, birds heavily rely on their beaks(鸟嘴)to process food. They also have an excellent ability to digest the food properly. However, at some point in history, birds used to rely on their teeth for chewing(咀嚼)food just like us.

The earliest known clue in this regard was found in Germany in 1862. The fossil of an ancient bird found there, suggested that birds had teeth in the past. Today, scientists have confirmed(确认)that birds evolved form dinosaurs that were known for their sharp and pointed teeth.

Until now, there has been no definite explanation of the significant evolutionary change in birds. In the ongoing study, researchers analyzed the genes of modern birds that are responsible for tooth production. They searched for any kind of genetic mutation(基因突变)that may have made the gene to become inactive. The gene mutation first occurred about 116 million years ago.

Half of US dog owners and 62 percent of American cat owners share the sheets with their pets, a practice that sleep experts warn can lead to sleep deprivation (剥夺). Besides，Mayo Clinic found that more than half of the patients seeking consultations at its sleep clinic were pet owners whose sleep was disturbed by their cats or dogs in 2014.

However, a 2018 study found that is not the case. Researchers from Mayo Clinic in Scottsdale, Arizona, surveyed 150 of the patients who visited the facility’s center for sleep medicine. Every participant received a piece of paper and answered questions on it about their sleeping habits, their pets’ behavior, sleeping locations and how their pets affected their nightly sleep.

The researchers found that 56 percent of the study participants shared their bed or bedroom with their cat or dog. However, while 20 percent reported disturbed sleep because of their pets, 41 percent said that their pets presence in bed actually helped them sleep better.

Those who reported sleeping more soundly when their pets were present said that having them in the bedroom or on the bed offered them relaxation and provided a sense of companionship and security. Single sleepers were especially likely to report that sharing a bed with a cat or dog helped them get some shut-eye.

“Participants described feeling secure, content and relaxed when their pet slept nearby,” the study authors wrote. “The value of these experiences, although poorly understood, cannot be dismissed because sleep is dependent on a state of physical and mental relaxation.”

A similar small study published by the researchers from the University of Alberta found that having pets in bed can help people with chronic (慢性的) pain sleep better, while also easing feelings of loneliness and anxiety.

“They liked the physical contact with their dogs — cuddling before bed, and how it distracted them from feeling anxious about being alone at night,” researcher Cary Brown said. “They felt more relaxed and safer, so they weren’t anxious as they were trying to sleep.”