838Babies are aggravatingly cute, but to the uninitiated, they’re basically aliens. And even the most experienced parent or childcare provider can still be baffled by one of those amazing, screaming bundles of joy.

YOU CAN’T GIVE THEM JUST ANY NAME

Many countries prohibit using profanity, numbers, or symbols in children’s names, but some take it even further. Norway won’t allow you to use a traditional last name as a first name. A French court recently ruled that a couple couldn’t name their child after a brand of delicious chocolate-hazelnut spread. Portugal bans parents from naming their child Nirvana. The U.S., however, is more lenient, and will let you name your kid Espn if you really want to.

THEY’VE EVOLVED TO BE ADORABLE 

Babies are completely dependent on adults for their survival for the first few years of their lives, so they’ve evolved to maximize the amount of attention they get from their parents and other adult humans. Scientists have pinpointed specific infant characteristics that we find irresistibly cute (known as baby schema), like a large head, round face, large eyes, and protruding cheeks.

WE NATURALLY WANT TO SQUEEZE THEM 

Yale University research has found that people tend to feel aggressive when confronted with photos of adorable babies and animals. A 2016 study found that having an intensely positive reaction to pictures of babies was linked to wanting to express aggression in ways like cheek-pinching. The researchers aren’t quite sure why this is the case, but hypothesize that it may be a way to regulate extreme positive emotions.

THEY’RE DRAWN TO SURPRISE

A 2016 study found that babies focus more on objects that surprise them. The researchers found that babies learned more about objects that defied their expectations of the world, such as a ball that seemed to be able to pass magically through a wall.

THEY HAVE A UNIQUE REFLEX THAT DISAPPEARS WITH AGE

The Moro reflex, where a baby will suddenly fling out her arms and legs and cry, is an involuntary response to feeling unsupported, but it can also happen as a baby is falling asleep, which is one reasons why swaddling is so useful for babies—it keeps them from waking themselves up with the Moro reflex. The reflex is unique to infants, and by 5 months old, healthy babies grow out of it.

THEY ALREADY KNOW TO HOLD THEIR BREATH UNDERWATER

Babies instinctively hold their breath and open their eyes underwater in what’s called the dive reflex. This reflexive response to water decreases over time.

THEY REALLY DO LIKE LULLABIES

A 2016 study found that babies remained calm for longer while listening to songs, even in unfamiliar languages, compared to regular speech.

THEY’RE WIRED TO IMITATE 

Brain activity studies have shown that when babies watch others reach for objects, the motor control regions of their brains activate, too. This helps them understand other people’s actions and think about doing something similar themselves.

THEY CAN LEARN IN THE WOMB

Scientists have found that babies can recognize sounds they heard from inside their mother’s womb, such as the theme song to their mom’s favorite soap opera. In 2013, a group of researchers found that infants who had been exposed to a made-up word during the last few months of their mother’s pregnancy recognized the word and variations of its pronunciation later on.

THEY CAN’T REALLY SEE

Until they’re around 3 months old, babies can only focus their eyes about 8 to 10 inches away from their faces, though they can see light & movement. They don’t gain depth perception until around 5 months old.

THEIR TASTE PREFERENCES CAN DEVELOP BEFORE THEY’RE BORN

While in the womb, babies swallow the amniotic fluid that surrounds them, tasting some of the flavors of the food and drink their mother has had in the process. In one study, babies born to women instructed to drink carrot juice during pregnancy or breast feeding liked carrot-flavored cereal more than babies whose mothers were told to avoid carrots altogether.

THEIR HEADS SMELL AMAZING

The smell of a newborn baby has been scientifically proven to be amazing. A study of 30 women sniffing newborns’ pajamas found that the scent increased activity in the brain’s rewards system.

THEIR BRAINS HAVE ALMOST AS MANY NEURONS AS AN ADULT’S

A child’s brain changes dramatically over the first years of its life. But the number of neurons stays roughly the same from birth—somewhere between 86 and 100 billion. However, the brain will develop thousands more synapses (connections between neurons) in the first two years after birth.

THEY CAN SEE THINGS ADULTS DON’T

Because babies’ eyes aren’t completely developed, 3- and 4-month-old kids don’t have perceptual constancy, or the ability to recognize the same object in different lights, sizes, and colors. But a 2016 study found that babies at that age can see slight differences in images caused by changes in illumination—while adults cannot.

THEY GROW UP SO FAST

It’s a cliché, but it’s also true. In the first six months, the average baby grows up to an inch per month, and doubles in weight. By a baby’s first birthday, she’ll have tripled in weight since birth.

THEY EAT LESS THAN YOU MIGHT THINK

In the first three months of life, the USDA estimates that babies need between 438 and 572 calories over the course of a day, depending on their size. That’s only a little more than a single Big Mac.

THEY HAVE UNIQUE HAIR

While some babies come into this world relatively hairless, others are born with a lot of whitish body hair, especially preemies. This soft, downy fuzz is called lanugo. It develops in the fifth month of pregnancy and if it isn’t gone by the time a baby is born, it usually disappears within a few weeks.

THEY STILL NEED PASSPORTS

Even the youngest newborns need proper documentation to travel abroad. The U.S. State Department recommends taking a picture of your baby laying on a white sheet or sitting in a car seat covered in a white sheet to ensure her passport photo has a properly plain background. Canada doesn’t allow parental hands in the photo, but does note that the “Passport Program recognizes the difficulty in obtaining a neutral expression of a newborn and will allow for some minor variations in this regard.”

IT WAS ONCE CONSIDERED TOTALLY ACCEPTABLE—HEALTHY, EVEN—TO DANGLE THEM OUT THE WINDOW

In the 19th century, people living in dirty urban areas wanted to give their babies access to the restorative properties of fresh air. Without access to backyards and country homes, they came up with a workaround: the baby cage. In the 1920s, inventors came up with compartments that could be propped on window sills in high-rise buildings, effectively dangling enclosed wire cribs outside like air conditioning units. Wonder why that went out of style?

THEY’RE IPAD PROS

A 2016 study of 270 families in Philadelphia found that 36 percent of kids had used some kind of touchscreen before they turned 1 year old. While the effect of technology use on kids’ development is still hotly debated, one thing is certain: kids love touchscreens. This is partially due to contingency, the notion that certain events are dependent on others. So when a baby pokes at an iPad and makes a video play, she’s exploring contingency, and how her actions can shape the world around her.