(Intro)

Stefan: Humans are weird, especially the little ones: babies.  Babies are like superhumans.  They have more bones than the average human and are attuned to smells that the rest of us would never notice.  They're so fascinating that we've done a lot of videos about them, so we've collected a bunch of our favorites here for you to enjoy.  In ths first one, 2013 Hank will tell you five amazing facts about babies and dispel one big baby lie, but it's from 2013, so don't blame him for lying about not having a kid in the opening.  It was true at the time.

Hank: I don't have any children of my own, but I do have an awesome nephew and a brand new niece and many of my friends are doing a lot of baby-making these days, and the more I'm around these miniature little humans, the more I'm fascinated by all of the weird things about them.

Did you realize, for example, that babies are born without fully developed tear ducts, this is why they cry all the time but they never cry. Babies are also born with a natural instinct to crawl when placed low on a mother's abdomen immediately after birth, babies will shuffle up to the breast and start feeding. That instinct vanishes soon after birth, and it will be another 7-10 months before the baby will actually crawl again, which is weird. Scientists think babies do the breast crawl because they can smell the colostrum, the highly concentrated yellow-ish milk produced during the first few days after birth. It's low in fat and high in protein and antibodies. Apparently, they can also smell other attractive odors secreted by glands around the nipple.

Amazing fact #3, a baby can not only recognize mom's voice from the moment he or she is born, but also while they are still inside of the person who's doing the talking. Fetuses respond to all kinds of outside stimuli, slam a door and a third trimester baby will often move inside the womb, but they can also differentiate between voices from inside the uterus. Studies have been conducted in which a pregnant mother and other random people read aloud to a baby in utero, they found that the baby's heart rate increases at the mom's voice, and slows down when it hears people who are unfamiliar. Scientists call it an attention mechanism, the heartbeat slows down as the baby attempts to figure out who is making that strange noise.

When the baby then recognizes mom's voice and instinctually knows how to crawl finally emerges, it will show up with about 270 bones in its body, which is 64 more than adult humans. And because babies are born with bones that will fuse together over time, mostly in the skull and spine, babies begin life with a cranium made up of eight separate bones that eventually grow into one. Infants need a soft, pliable head because otherwise, they wouldn't be able to exit through the birth canal, which is kind of important. The soft spot at the crown of the head of most infants, which is technically known as the fontanelle, is an unprotected spot in the scalp where the bones fuse together, can basically poke a baby directly on its brain.

Finally, you've heard that babies can swim, but that's a dirty lie. What's true, and pretty amazing, is a reflex called the bradycardic response, which causes infants to hold their breath and open their eyes when submerged in water. This reflex stems from the nine very watery months the baby spent inside of a person. So whether you have some of your own or not, maybe now you can appreciate babies on a whole new level, in addition to being adorable and stinky and often very noisy, they are also, in many ways, true marvels of nature.

Stefan: Babies!  Pretty amazing beings, but one of the coolest things about them is how they smell, and I'm not talking about dirty diapers.  I'm talking about the freshies, the newborns that have that heavenly smell.  What is that?  Well, here's Michael to explain why babies smell so good.

Michael:If you’ve been around a newborn baby, you might have noticed that they smell just... good. For a while, lots of people thought this mild, pleasant scent was just baby powder or sweet-smelling wipes. Others claimed it was just a myth, a hallucination by sleep-deprived new parents. But, just like new house smell and new car smell, new baby smell is real! But, what exactly causes this special scent, and why do scientists think it might be an evolutionary benefit for mothers and their babies? Our body odors are made of lots of different secreted chemicals, but it’s hard to figure out how each one contributes to our natural smells.

And newborn baby smell is extra hard to study, because the scent is usually gone after about 6 weeks. Researchers think one factor could be leftover amniotic fluid, which is the protective substance that surrounds the embryo as it grows. Plus, there might be traces of vernix caseosa, a white-ish layer of waxy oils and cells that coats babies’ skin when they’re born.

But even though we don’t know exactly what causes this scent, scientists want to understand why it exists. A 2013 study published in the journal Frontiers in Psychology found evidence that suggests this scent may affect certain brain regions of all women, but especially new mothers. To test this, they rounded up a group of 30 women that were about the same age: 15 who had given birth within the previous six weeks, and 15 who had never given birth.

The researchers isolated baby smell from baby pajamas, specifically, from 18 newborns that weren’t related to any of the participants. Then, they had the women smell the newborn odors while undergoing brain scans. All of the women showed activity in the reward-related areas of the brain.

There was slightly more brain activity in new moms. Basically, the researchers think that the smell might act as a sort of incentive: to get the new moms to feel pleasure when they take care of babies. This could promote more maternal care, and offset some of the exhaustion and hard work of parenting.

But, what about new dads? Are they affected by this baby smell too? Well, we still have a lot to learn about the smell of newborn babies. And there haven’t been any studies involving men yet, although researchers think the effects of baby smell might be similar.

Stefan: Ooh, Michael was practically a baby then, and he's actually hosted a fair amount of our baby-themed episodes, including this one about why newborns babies get jaundice.

Michael: Many newborn babies can have yellowish skin and eyes when they're only two to four days old. It's a medical condition called jaundice, and it can have lots of different causes, but usually their skin reaches its normal tone in just a week or two, after their organs are more developed. So what exactly causes jaundice, and why is it so common in newborn babies?

The word "jaundice" actually comes from the French word "jaune", meaning yellow. It's also sometimes known as "Ictarus", which comes from an ancient Greek word that referred to the medical condition and... Yellow bird? The stories say that they thought jaundice could be cured by staring at a yellow bird and magically transferring the color to it, which isn't a thing that works, in case you were wondering.

Jaundice actually occurs when your blood contains an excess of the molecule bilirubin. Bilirubin is a yellowish waste compound that's produced when old red blood cells are broken down. It's what gives bruises a yellowish hue and helps make your poop brown. Normally, bilirubin is filtered from your bloodstream by your liver, and then excreted through your intestines, but a newborn's liver is still developing, and can't remove bilirubin as quickly from their bloodstream, which turns their skin yellowish.

This mild buildup is actually pretty common in babies, it's referred to as "normal jaundice", but there are a few other forms.

Jaundice of prematurity is seen in premature babies because their bodies are even less equipped to get rid of extra bilirubin.

Babies can develop breast-feeding jaundice if they're not getting enough breast milk from their mothers. In that case, they don't have as many bowel movements, and they don't excrete as much bilirubin.

Breast milk jaundice is less common and is caused by substances in the mother's breast milk that can interfere with the liver's bilirubin processing.

Then there's Blood Group Incompatibility, which can happen in some cases when the mother and the baby have different blood types. This means the mother's body could make antibodies which attack her baby's red blood cells, resulting in an excess buildup of bilirubin in the baby's bloodstream.

Most of these forms of infant jaundice typically disappear without any extra treatment in a couple of weeks as the newborn's body matures. But if a baby develops more severe jaundice, or has other sickly symptoms, they should be taken to a hospital where doctors can lower the level of bilirubin in their blood. These treatments range from something called phototherapy, where special blue-spectrum light helps break down bilirubin in the baby's body, to a blood transfusion that gives them more healthy red blood cells.

One thing they don't have babies do, though, is stare at a yellow bird.

Stefan: I have no idea if I ever got jaundice as a baby.  In fact, I don't remember anything about being a baby.  Why is that?  Well, don't worry, there's a SciShow about just that.  

Michael: Remember that one time when you were a baby? No, of course you don't. Because if you are a teenager or older, chances are you can't remember anything that happened before you were three. The process of forgetting these really early memories is called "Childhood Amnesia." It happens to pretty much everyone and it has to do with the way our brains develop as we grow up.

Childhood amnesia starts to set in between the ripe old ages of 8 and 9. Before then, most children can remember things that happened when they were really young like visiting a family member or winning a teddy bear from one of those impossible carnival games, but the passage of time by itself isn't enough to explain childhood amnesia. After all, when you're 30, you can remember certain things that happened 20 years ago when you were 10. But when you're 20, you can't remember being an infant at all.

Plus, we don't forget everything from when we were little. Some things like language or motor skills that we pick up stick with us. But we do tend to forget episodic memories memories of specific events and details. So scientists think that childhood amnesia must have something to do with the way our brains change between infancy and adulthood. It turns out that some parts of our brains don't finish developing until long after we're born.

One of those parts is the Hippocampus, which helps us form and store episodic memories. Even as adults our brains are always producing new cells called neurons in the Hippocampus. But when you're a young growing child, your brain produces a lot of new neurons a lot faster. So to see how brain cell growth affected memory, a research team from Toronto took adult mice and experimentally made their hippocampuses produce more new neurons and it turned out that the mice became more forgetful. They seem to lose memories just like humans do with childhood amnesia. But when researchers slow down the growth of new brain cells in young mice, those mice seem to forget less of their mousy childhoods.

So the question is: why would making new brain cells be bad for your memory? Well it's not, in the long term, which is why we can keep making new episodic memories as adults. But it seems like trying to fit all those new neurons into your hippocampus when you're young could cause a problem. The new neurons shuffle around with the old ones to form new memory connections and this could make it harder for the brain to find where earlier memories were kept. It might even erase them completely.

Still, not all of our memories are kept in the hippocampus so this doesn't explain everything about childhood amnesia. There are other parts of the brain involved in memory including the amygdala and the prefrontal cortex, so scientists are studying these to see if they also make different amounts of new neurons when we're children compared to when we're adults. We don't fully understand childhood amnesia yet but we do know it happens to everyone. So you can't remember your first birthday party, don't worry neither can anyone else.

Stefan: So maybe we can't remember being babies, but we sure do a lot of growing and learning while we're just tiny little humans, and some parents try to capitalize on that by playing classical music to babies to make them smarter, but does that work?  Here's Hank with the answer.

Hank: Parents want what’s best for their kids. They want them to grow up to be smart, kind, productive people — and they’ll do almost anything to give their little bundle of joy a competitive advantage. Which has led to the strange explosion of the myth that playing classical music for babies might make them more intelligent.

You can buy all kinds of “classical music for babies” programs that supposedly, quote, “promote brain development.” But there’s no real evidence that they will actually make your baby smarter. The idea began with a paper published in Nature in 1993, called Music and Spatial Task Performance. Researchers told 36 college students to listen to either a Mozart sonata, a relaxation tape designed to lower blood pressure, or just plain old silence. Then, they were asked some questions designed to test spatial reasoning — for example, what kind of snowflake a cut-up piece of paper would look like when they opened it up.

The study found that the students’ average spatial IQ scores were 8 to 9 points higher after listening to music, but the effect only lasted about 15 minutes. But even though the study was tiny, they only included college students, and found a very specific effect that didn’t last very long, the idea was out there: music could affect the way people think.

From there, it snowballed: articles about the study started to generalize the results, saying that music made people smarter in general. Books like The Mozart Effect, and then The Mozart Effect For Children, helped spread the misconception. More researchers started to study the connection between music and intelligence. Some studies confirmed the outcome of the original study, but other researchers couldn’t reproduce the findings. Meta-analyses that compared results across all the studies found only a very small effect, if any at all.

It’s possible that music causes a slight boost in spatial reasoning because music and solving those kinds of puzzles both activate similar parts of your brain. So maybe the music is preparing those parts of your brain in some way, like an athlete warming up before a workout. But even if music helps you solve spatial puzzles, that doesn’t mean it makes you smarter overall.

The Mozart Effect does seem to help epileptic patients, though. In a few small studies, listening to Mozart’s music made seizures decrease. But as with many things in science, more research is needed. So, playing a bit of Bach or Mozart for your baby isn't going to do any harm.

But it won’t just, like, magically make them smarter. Things like good old fashioned talking and reading to your child are much more important for their development.

Stefan: There are just so many questions to ask about babies, including why do babies always seem to stare at me in grocery stores.  Well, we actually made a SciShow Psych episode about just that, which you can watch over at YouTube.com/SciShowPsych.  Thanks for learning about tiny weird humans with me.  

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