Researches have found that various monkeys have pet-like relationships with other species.

At one point in the 20th century, more than a million Americans had pet monkeys

This choice to domesticate monkeys proved to be trickier than expected, and thus isn't a very appealing option for humans. Monkeys breed more slowly than other animals, while also being susceptible to diseases and challenging to contain.

Baby monkeys chose a soft, warm doll over a wire one with food

Harry Harlow performed controversial experiments with newborn monkeys, separating them from their mothers and letting them bond with stand-in mother figures made from either wire or figures covered in cloth—both with monkey-like faces. The work investigated touch, bonding, and attachment, and found that monkeys overwhelmingly preferred the cloth dolls over the wire ones in various stressful situations.

Can animals understand fairness?

Academics have long wondered if fairness is solely a concern of humans. In the largest meta-analysis to date, UC Berkeley researchers tested whether monkeys felt jealousy after receiving unequal rewards. The patterns showed low evidence for inequity aversion and instead frustration due to their expectations not being met by humans. These findings suggest that pursuing fairness and equality is uniquely human.

Nine different studies exploring animals' relationship to music

Researchers have conducted multiple studies attempting to answer a certain question: do animals like human music? Across species, they observed different results and no clear pattern. Primates appear to prefer silence, and cockatoos appear to dance to funky beats.

Across the animal kingdom, parenting can include adults carrying their young, providing their bodies for sustenance, searching for food and shelter for their children, and separating siblings who may eat one another.

Grieving primate mothers will carry dead infant for long after death—and others will comfort her

An examination of infant corpse carrying practices among non-human primate mothers found that 40 species of primate mothers will carry around their dead infant for days, weeks, or even months. In some cases, a grieving primate's group members would provide grieving support—hugging or staying close to mothers who experienced a loss.

Animals get SAD—especially those in zoos, like pandas

Giant pandas in locations outside their evolved latitudinal range (from southeast Asia to northern regions around Beijing) exhibit more sluggish behavior, even when they were born there. Researchers have observed that similar sensitivities to "photoperiods" (or time with light) impacts many animals, including birds, insects, and our pets. (Nautilus imposes a metered paywall.)

Chimpanzees are dying from human colds

For some great apes, the threat of human-borne diseases outweighs poaching or habitat loss. This article details the danger of reverse zoonoses, which refers to diseases that spread from humans to animals.

What we can learn from animal societies' ethics

Birds, rodents, monkeys, lizards, bats, apes, and livestock can all get malaria—just like humans.

Here's how early humans lived

Explore the evidence of early human behavior—from ancient footprints to stone tools and the earliest symbols and art – along with similarities and differences in the behavior of other primate species.

Ancient humans and other early hominins were closer than you might think

Evidence that human ancestors and other early hominins coexisted continues to accumulate, raising the question of just how close these ancient people truly were. This article details how evidence is changing the theory that early hominins like...

What we can learn from how penguins express affection

Pebbling, a term used to describe small acts of love within a relationship, comes from penguins. Male gentoo penguins, a species of penguin that lives on sub-Antarctic islands, present pebbles to their potential mates later used to build nests. This small but helpful act is something we humans can learn from. Think of the “pebbles” you can share with loved ones on a daily basis.

Charles Darwin studied goose bumps by scaring zoo animals in London with a stuffed snake

Read the famous naturalist’s work from the late 1800s, detailing how he sought to draw comparisons between how animals and humans respond to fear. As part of that work, he exposed monkeys and a peccary to a stuffed snake and noted the animals’ hair-raising fear response.

Wild chimpanzees have been spotted with leprosy lesions

In research published in 2021, scientists reported discovering cases of leprosy in wild chimpanzees from Guinea-Bissau and the Ivory Coast—marking the first time the disease has been found in any nonhuman species in Africa. They confirmed that leprosy was the cause of the deformities by testing the animals' poop for the presence of the disease-causing bacteria.

Where are humans on the evolutionary tree?

This interactive tree-shaped map explores the evolutionary connections between more than two million species. According to this map, humans are on the same branch as great apes, tarsiers, and treeshrews. That branch then splits into even smaller branches, with humans appearing on the same twig-like branch as chimpanzees and bonobos.

The adorable happiness of animals, in photos

Can animals experience happiness? And even if they do, do their bodies manifest happiness in similar ways to humans? Regardless, you surely will derive some happiness after viewing these thirty photos of a variety of animals appearing to smile big, beautiful smiles.

What ancient goat teeth reveal about ancient human-animal relationships

About 4,000 years ago, several goats with terrible teeth managed to outlive their better-teethed brethren. With such intense dental damage, the goats were likely fed higher-quality feed than the more dentally gifted herd members, a dietary shift that would've contributed to the difference in life span. These goat teeth underscore the hard truth that humans may inflict harm on the animals they care about most, regardless of intention.

Watch David Attenborough's unexpected interaction with a family of gorillas on 'Life on Earth'

On the border between Rwanda and the modern-day Democratic Republic of the Congo, Attenborough used specific vocalizations and behaviors to approach a female gorilla peacefully, only to have two of her children lie down on him. Through a comical exchange, the incident helps show the creatures to be the opposite of the aggressive, violent stereotypes about them.

Similarities between human and animal sleep

Have you ever noticed the wide-ranging differences in sleep between humans and animals? Sleep as a necessity is present amongst all animal species, but the specific patterns of sleep vary widely. Just think of the differences between how an owl, a whale, and a horse might sleep. This helpful resource from the Sleep Foundation explores the relations between human and animal sleep, complete with some fascinating statistics about sleep patterns throughout the animal kingdom!

The Paranthropus genus, our mysterious extinct cousins

In the last century, skull and jaw fragments have been discovered in East Africa suggesting an ancient hominin species lived, evolved, and died alongside humanity's ancestors. With large, broad skulls and strong jaws, the Paranthropus genus—which includes several related species—is an absorbing case of the effects of niche partitioning, where species coexist by adapting differently to the environment. Paranthropus died out and human ancestors endured. Find out why here.

Animal brain studies show brain activity similar to what we'd expect during dreams, but parsing whether animals are truly dreaming depends on how one defines dreaming and how scientists could prove it.

Cats began cozying up to humans around 10,000 years ago

The feline family is a hugely diverse group of lions, panthers, and kitties that have spread all over the world. The ancestors of the cats we love today helped solve rodent problems when humans first invented agriculture. They've been worshipped, loved, and scorned by humans since.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

The secret life of urban crows

Dolphins have doulas too?

For the first time in over a decade, a dolphin gave birth at Brookfield Zoo, and she didn’t do it alone. Right beside her was another dolphin, acting as a doula. Why do dolphins support each other this way? The answer reveals something incredible about how animals care for one another.

Why humans evolved single-child pregnancies

While birthing twins has been a rare occurrence for humans, research suggests that twins were actually the norm much further back in primate evolution. It’s proposed that single-childbearing turned out to be critical for the evolution of larger babies with larger heads. Discover more about the shift that gives insight into primate evolution.

Mpox, formerly known as monkeypox, does not come from monkeys but it was first identified in laboratory monkeys in 1958.

Some animals may speak because of duplicated connections in the brain

Neuroscience suggests that connections responsible for motion made during embryonic brain development—such as those connecting hearing and movement pathways that allow reactive motion when started—are duplicated and connected to the larynx in some animals. This allows some mammals and song-learning birds to speak, provided they have the necessary physiological structures.

Humans are wired to pick up on each other's emotion, making laughter contagious

The reaction plays a key role in establishing interpersonal connections and relieving stress by releasing endorphins—feel-good hormones. A 2021 study identified at least 65 animal species that produce playful sounds, such as laughter.

Some animals seem to live well on little sleep

African bush elephants typically sleep for about 2 hours per 24-hour day, coming in well under a human's recommended seven-hour minimum. Other animals also appear to skimp on sleep, by human standards, without the consequences humans associate with being sleep deprived. This academic article details the sleeping habits of animals that appear to thrive on fewer than 40 winks and explores whether their sleep processes are just built different.

Zoo animals have developed allergies, too

Although scientists do not know if allergies manifest among wild animals—and if animals can survive with them—in a zoo setting, veterinarians have observed zoo animals with common allergy symptoms, including itchiness, crusty skin, and runny eyes. Veterinarians have identified Asian elephants with pollen allergies and at least one jaguar with an allergy to fleas.

See a wild bear observe fellow bears at the zoo

At the Sequoia Park Zoo in California, a wild bear visited the bear enclosure to see three bears in captivity. Zookeepers referred to him as a "polite visitor," adding, "He stayed on the boardwalk path, kept two feet on the ground, and didn't try to climb over the railings!"

The animals that paved the way for space travel

The history of animals in space exploration is often overlooked. Before humans first made their way to space in 1961, fruit flies, primates, and canines preceded us. Watch this video for a further appreciation of the contributions and sacrifices made by animals for scientific progress.

Watch wild elephants 'mourn' their dead

Wild elephants in Samburu National Reserve in northern Kenya visited their dead matriarch's body weeks after her death and displayed behaviors that researchers are hesitant to call "mourning" though they do believe the animals are displaying a specific reaction in response to the death. The video shows elephants using their trunks to touch and explore the carcass while standing in place for extended periods, which is uncommon for the animals.

Humans may have evolved to need less sleep.

Pigs are preferred for xenografts because of their size and low disease risk

Pigs are of particular interest for xenotransplants because the animals are close to human size, are easily raised in captivity, and have large litters. They’re already routined killed for food and they’re less genetically related to humans than nonhuman primates, which reduces disease transmission risks and some researchers’ ethical concerns.