22 discoveries this year changed our understanding of how animals communicate, compete, and defend themselves

One of the best ways to build a rapport with your cat, a study showed, is to narrow your eyes and blink slowly at them.

To cats, slow blinking is a form of smiling, and solicits happy, positive emotions. The researchers found that a cat will respond to a human's slow blink with a slow blink of their own, and is more likely to approach an unfamiliar person who is slow blinking at them.

A common rule of thumb for dog owners had been that one year for dogs is equivalent to seven human years.

But the new research showed that young puppies age much faster than young humans do, so that simple one-to-seven year ratio is wrong. A 1-year-old dog is more "like a 30-year-old human," one of the study authors said.

But as dogs get older, they age more slowly. So the researchers found that a 12-year-old labrador would be the equivalent of 70 in human years.

A dog's brain isn't wired to appreciate the beauty of its owner's face, the research showed.

Although humans rely heavily on faces to gather information and social cues — and have specialized brain areas that activate when we look at faces — dogs rely more on body language and vocal cues instead.

When humans hear someone speak, our brains first parse out a speaker's underlying tone, then process the meaning of what we've heard. Dogs' brains divvy up the task of speech processing in the same way, according to research published in August.

Our pets process "simpler, emotionally loaded cues" like tone first and then "more complex, learnt cues," according to a press release about the study.

Typically, canines use their sense of smell to navigate. But that's not the only tool at their disposal: Hunting dogs like terriers and dachshunds can also orient themselves using Earth's magnetic field, according to a June study.

Birds, dolphins, and some whales may also use this same sixth sense, called magnetoreception, to plot their migrations.

A February study found that during solar storms — which cause temporary disturbances in the magnetic field — gray whales are more likely to get stranded on shore.

The disturbances affect gray whales' internal compasses, preventing them from navigating accurately.

"We think whales are getting stranded more often during solar storms because they've gone blind," Jesse Granger, lead author of the study, previously told Business Insider. "The impacts of these storms on Earth could be shutting down the animals' ability to sense the magnetic field."

More than 200 gray whales got stranded or washed up dead onshore in the northeastern Pacific Ocean in 2019.

That's the longest any animal has ever been known to hold its breath. According to the researchers, the record dive is almost seven times longer than a whale of this size should be able to do without oxygen.

Cuvier's beaked whales are among the ocean's deepest and longest divers, reaching depths of up to 10,000 feet (nearly 2 miles).

Greenland sharks are found in north Atlantic and Arctic waters and can live for up to 400 years.

An August study determined via genetic analysis that there are two geographically separate populations of Greenland sharks. One group swims near Canada's Baffin Basin, above the Arctic Circle, while the other occupies waters of the north Atlantic Ocean between Nova Scotia and Svalbard, near Norway.

As shark species like great whites expand their ranges, that could mean more fin sightings — and possibly attacks.

Great whites will be "found more commonly in Maine waters in the years ahead," George Burgess, former director of the Florida Program for Shark Research, told Business Insider in June.

The predators are proliferating in Massachusetts too, which is likely a consequence of ballooning populations of grey and harbor seals off the coast of Cape Cod, Burgess said.

A September study found that megalodons, a type of prehistoric shark, reached lengths of 52 feet. That research also showed that a 52-foot megalodon had a head and tail 13 feet long and a dorsal fin equal to the height of an average woman.

One analysis suggested these extinct predators reached such gargantuan sizes by cannibalizing each other in the womb.

In April, scientists discovered a 150-foot-long siphonophore off the coast of western Australia — the longest creature ever observed.

Siphonophores are predators that feed as jellyfish do, dangling long, stinging tentacles that prey swim into.

Researchers announced in November that they'd seen the bigfin squid off the coast of Adelaide. The creatures are rarely captured on camera; they'd only been spotted a dozen times since the 1980s, and had never been seen in Australian waters before.

A bigfin squid's body is only 6 inches long, but its tentacles stretch 6 feet.

The discovery may indicate that mammals evolved biofluorescent fur more than 150 million years ago. This glowing fur could help nocturnal mammals camouflage, or it could play a role in mating rituals, according to new research.

Broad-tailed hummingbirds can pick up on colors in the ultra-violet spectrum that are imperceptible to the human eye, a June study showed. This expanded range of vision helps the animals identify food sources.

Imagine a 200-pound man being crushed by the weight of nearly two space shuttles and coming out unscathed. That's about how indestructible the diabolical ironclad beetle is.

The beetle has hardened casings on each wing that interlock and support its exoskeleton, which enables it to get run over by a car and survive, research showed. Scientists are exploring how to mimic the design of the beetle's exoskeleton to build better planes and armored vehicles.

A study published in August pinpointed a chemical scent that triggers locusts to gather together. The study authors suggested using that same pheromone to lure locusts into areas in which they can then be killed en masse in order to save crops.

In West Virginia, some cicadas have gotten infected with a fungus called massospora over the last two summers. According to an August study, the fungus manipulates the male cicadas into flicking their wings in a pattern that imitates females' mating invitations. That sham siren call lures in unsuspecting healthy males, who then get infected, too. Once the fungus takes hold, the insects' genitals rot.

Researchers nicknamed the infected bugs "flying salt shakers of death."

After months of investigation, researchers deduced that the elephants had died because watering holes in the Okavango Delta were contaminated with cyanobacteria.

The blue-green algae's toxins affect both humans and other animals — they can be inhaled or swallowed, or seep through the skin, leading to gastrointestinal problems, paralysis, and even death in dogs, fish, and cattle.

An October study revealed that octopuses explore their prey using their eight arms.

This ability to "taste" through touch enables octopuses to detect hiding prey, and it can also prompt them to retreat from an object that seems toxic. Octopuses can detect bitter-tasting chemicals emitted as a defense or warning signal by marine animals like jellyfish, sponges, mollusks, and crabs.

Lorises typically reserve their venomous bites for attacks on other lorises, according to a study published in October. Their venom packs a nasty punch: It causes extreme pain and rots flesh.

"It causes necrosis, so animals may lose an eye, a scalp or half their face," Anna Nekaris, the lead author of the study, told The New York Times.

The baby was only 10 days old and had died after falling from a tree, the study authors said. Together, a male and female ate the infant's lower body in half an hour, while the mother watched. Only the baby's head, chest, and arms were left behind.

Other primates, like bonobos, also eat one another, but this incident was the first recorded case of cannibalism among white-faced capuchins.

Humans tend to cultivate fewer, more meaningful friendships as they grow older. A prevailing psychological theory suggests this is because we recognize our impending mortality and seek to prioritize fulfilling connections in the time we have left.

Chimps, it turns out, do the same thing — but probably not because they understand their own mortality, the study authors wrote. Their changing friendship priorities might simply come about because their behavior becomes less aggressive over time.