What makes an animal cute? In a published in "Trends in Cognitive Sciences," researchers found that cuteness plays an important role in the infant-caregiver relationship. The world's have features that tug on their parents' heartstrings (and increase their brain activity). Animals with traits similar to human babies — such as big heads, big eyes, soft skin (or fur) and a pleasant smell — can trigger some of the same emotions we feel in the presence of a human infant. Advertisement The ( ) is a small mammal with all the traits humans find adorable: a big forehead, round eyes, small mouth, a boop-able nose and thick red fur. (Its reddish coloring is distinctive but doesn't necessarily make it cuter — humans are drawn to anything soft-looking, including fluffy fur.) With an average length of 22 to 25 inches (56 to 63 centimeters), these adorable animals are about the size of a domestic cat. Unlike cats, red pandas will stand on their hind legs when threatened, giving them a bear-like appearance. Advertisement The red panda lives in the same high-altitude bamboo forests as the giant panda ( ), but the two species are not closely related. Giant pandas — cute animals in their own right — are members of the bear family (Ursidae); red pandas are not. Sadly, red pandas are . "Grazing pressure and the unsustainable harvest of forest resources have placed tremendous pressure on red pandas," Saroj Shrestha, former program coordinator for the in Nepal, told HowStuffWorks. Advertisement Its exterior may be prickly, but its round eyes and the way it curls up into a little ball makes the hedgehog a certifiably cute animal — so cute that some people keep . The African pygmy hedgehog ( ), also known as the four-toed hedgehog, is the species most commonly kept as a pet. Native to central and eastern Africa, ole "four toes" is the smallest species of hedgehog, measuring just 7 to 9 inches (18 to 23 centimeters) long. Advertisement Four-toed hedgehogs can be domesticated, but this small animal is illegal in some states and might not be the best option if you're looking for a cuddly creature to bring home. "Many are not the biggest fans of being cuddled and prefer to explore their surroundings on their own," Atlanta-based veterinarian
Sydney Brehm told HowStuffWorks. Advertisement Don't think squirrels are cute? Wait until you see the Siberian flying squirrel ( ). This little ball of gray-and-white fur has huge eyes, a tiny nose and mouth and chipmunk-like cheeks. (FYI: A .) Siberian squirrels don't just live in
Russia — you can find them in Finland, Estonia, Latvia, Mongolia,
Japan and Korea. They are adapted to cold climates and prefer spruce forests. Advertisement A subspecies known as the Ezo flying squirrel has become somewhat of a tourist attraction in Hokkaido, Japan, where they are a protected species. Cats are so cute that humans have kept them as pets for thousands of years. When it comes to wild cats, many start out as adorable kittens, then grow into intimidatingly large adults. Some wild cats, however, stay small for life, keeping their cuteness factor. Some of the smallest wild cats are: Advertisement Rusty-spotted Cat is than a domestic cat, with a body just 13 to 19 inches (35 to 48 centimeters) long, a height of 8 inches (20 centimeters) and a weight of 2.2 to 3.5 pounds (1 to 1.6 kilograms). It may be cute, but the rusty-spotted cat is a formidable hunter. The species feeds primarily on small rodents, but this tiny creature has been known to attack gazelles. Sand Cat is adorable not just because of its tiny stature (18 to 22.5 inches or 45 to 57 centimeters long and 3 to 7.5 pounds or 1 to 3.5 kilograms in weight), but its wide face and huge eyes, which give the that "baby face" look. And let's not forget its velvety fur! Sand cats live in some of the world's driest climates: the Sahara Desert, Arabian Peninsula and parts of Central Asia. Kodkod , also known as the guiña, is the in all of Central and South America. It lives in
Argentina and Chile and looks like a tiny leopard. These little animals are just 14.5 to 22 inches (37 to 56 centimeters) long and weigh 3.3 to 6.6 pounds (1.5 to 3 kilograms). Black-footed Cat of Southern Africa is the continent's , standing 8 inches (20 centimeters) tall, 14 to 20 inches (36 to 52 centimeters) long and weighing 2.2 to 5.5 pounds (1 to 2.5 kilograms). According to local legend, black-footed cats can take down a giraffe. Advertisement Baby primates look more like baby humans than any other animal, so it makes sense that we'd find them adorable. The pygmy (genus ), also known as the pocket monkey, dwarf monkey or finger monkey, is an especially cute specimen. There are two species of pygmy marmosets ( and ) in South America, both roughly 6 inches (14 centimeters) in length — about the size of a human hand — and just 1.3 pounds (600 grams), making the pygmy marmoset the world's smallest monkey. Advertisement Sea otters ( ) might just be the world's cutest marine mammals. They're in the same family as weasels but live their entire lives in the Pacific Ocean. Their thick fur, fluffy paws and round, mischievous faces make sea otters some of the most adorable animals in the ocean. These cuddly animals hold each other's paws when they sleep, and babies often hitch a ride on their mothers. They're also incredibly playful. Advertisement Foxes are some of the cutest wild animals around. They're in the dog family, so they resemble man's best friend, but foxes are smaller and less intimidating than wolves or coyotes. The fennec fox ( ) is one particularly adorable species. This small fox uses its huge ears (about or 15 centimeters long) to shed heat in the hot climates of North Africa and the Arabian Peninsula, where fennec foxes live. Advertisement Despite its enormous ears, the fennec fox is actually the smallest species of fox, clocking in at a body length of just 14 to 16 inches (36 to 41 centimeters) and weight of 3.3 pounds (1.5 kilograms), about the size of a small Chihuahua. If you think big ears are cute, check out the bat-eared fox of Eastern and Southern Africa, whose ears are almost as large as a fennec's. Advertisement These adorable creatures are so cute, we humans decided that their common name should have the word "baby" in it. The bush baby (family Galagidae) is a small, fluffy primate found in the rainforests, savannas and shrublands of Sub-Saharan Africa. The smallest bush baby species — there are over 20 — weighs just 2.5 ounces (70 grams), and the largest is 4 pounds (1.8 kilograms). These little creatures have humongous eyes, which help them see at night and make them incredibly cute to humans. Advertisement