10 Amazing Facts About the Infant Brain

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While there’s little argument that babies are generally cute, it’s far more difficult to determine how intelligent they are, since we can’t measure their know-how by standards of adult brain development. Yet infants’ brains develop so rapidly they are pure, consolidated potential in their first three years. Consider that a 4-week-old fetus forms new neurons at a rate of 250,000 every minute, and by the time a child is three, their brain will reach 80 percent of adult volume and process close to 1000 trillion connections between neurons. Here are 10 mind-blowing facts about the amazing infant brain.

1. ALL BABIES ARE BORN "EARLY."

Thanks to the size of the average human birth canal, and the heavy metabolic burden a baby places on its mother in gestation, a baby’s head can only be so big and still emerge from its mother, which means babies are born with underdeveloped brains that are hypersensitive to stimulus. One popular theory explaining this is that their first three months of life outside the womb equal a “fourth trimester” which may be why newborns like to be wrapped tightly and respond well to loud white noise, details which mimic the conditions of life in utero. Further theory suggests that humans are designed to be social and cultural animals, and that being born earlier may allow an infant’s brain to soak up the many impressions and senses of being raised within a group of people. 

2. BABIES ARE BORN WITH ALL THE NEURONS THEY WILL EVER HAVE. 

Assuming normal development, a healthy baby will emerge from the womb with 100 billion neurons, nearly twice as many neurons as adults, in a brain that’s half the size. This massive number of neurons is necessary for the tremendous amount of learning a baby has to do in its first year of life. While brain volume will double by the age of 3, not all of those neurons will stick around; synaptic pruning takes place as a baby ages, in which the brain gets rid of weaker synaptic connections in favor of stronger ones.  

3. BIRTH TO AGE 3 SEES THE FASTEST RATE OF BRAIN DEVELOPMENT IN THE ENTIRE HUMAN LIFE SPAN.

Though you may think your darling is growing like a weed as chubby toddlerhood gives way to lanky kid, in the first three years of your child’s life, their brain is growing faster than any other body part. At birth, a baby's brain is about one-third the size of an adult's brain. In 90 days, it more than doubles its volume, to 55 percent of its final size. The cerebellum in particular, a brain structure at the back of the brain involved in controlling movement, grows the fastest of all brain structures; in just three months it will be 110 percent bigger than it was at birth.

4. MOST OF THE ENERGY A BABY EXPENDS IS CONCENTRATED IN THE BRAIN.

As a result of all that rapid brain development, 60 percent of a baby’s metabolic energy (primarily the consumption of glucose) is spent on growing those soon-to-be massive brains. In contrast, the brain of an adult uses only about 25 percent of the body’s metabolic energy. 

5. BABIES' BRAINS PREPARE FOR SPEECH LONG BEFORE THEY UTTER A WORD. 

A study of 7-month-old babies at the University of Washington showed activation of motor parts of babies’ brains associated with the physical aspects of speech—Broca’s area and the cerebellum—before they actually began to speak. This suggests that the brain sets up a transitional groundwork in a process known as “analysis by synthesis” in which the brain predicts the motor movements that will be required to make the sounds of speech and prepares to do so.

6. BILINGUAL BABIES' BRAINS HAVE STRONGER EXECUTIVE FUNCTION.

Not only are babies capable at birth of learning any language, those babies who are spoken to regularly in two or more languages have better executive function later in life, specifically the ability to control attention to conflicting perceptual or representational features of a problem. In other words, bilingual children have better attention or focus, which bodes well for school and work performance. 

7. PHYSICAL TOUCH STRENGTHENS BABIES' SYNAPSES.

Babies who receive regular touch have stronger neuronal connections, and greater overall well-being. It’s well known now that babies who are deprived of touch suffer a number of negative health effects, from low weight to emotional disorders such as anxiety and depression. A study of 92 7- to 9 year-olds, who had previously been studied in preschool, showed that those who had received more nurture by their mothers (or caregivers) had a thicker hippocampus than those who were not as well nurtured. A stronger hippocampus is associated with improved memory, better focus, ability to retain learning, and more.

8. BABY BRAINS ARE HARDWIRED TO PREFER THEIR MOTHER'S SCENT.

Much of the infant-mother bond in the early days is determined by smell and touch, more specifically the bonding hormone oxytocin, which can induce a feeling of euphoria and love in humans. Studies have shown that babies are imprinted with, and attracted to, the scent of their own amniotic fluid, which helps them to find their mother’s nipple. Over several days, healthy babies grow to prefer the scent of their mother’s breast. One study even showed that formula-fed babies still prefer the odor of their mother’s breast to that of their formula up to two weeks after birth.

9. A BABY'S UNWILLINGNESS TO LEAVE A PARENT SIGNALS THE DEVELOPMENT OF LONG-TERM MEMORY.

Mothers who find they must pry a suddenly crying baby off of them when they prepare to leave might be relieved to know it may be the earliest signs of long-term memory development. Jerome Kagan, a Harvard University professor of psychology, suggests that around 9 months, an infant’s unwillingness to leave their parent is a sign that the child has a clear memory of his or her mother “being there” and can now form an emotional association to the event. 

10. HYPOTHERMIA CAN PROTECT NEWBORN BRAINS. 

A new study at Children’s Hospital Los Angeles of newborns treated for hypoxic-ischemic encephalopathy (HIE)—a condition that occurs when the brain is deprived of an adequate oxygen supply—found that inducing hypothermia through a targeted cooling of the brain had a neuroprotective effect.

Without treatment, these babies often develop cerebral palsy or other severe complications that affect as many as 1 million babies worldwide. The study found that hypothermia works by reducing energy metabolism, but also reduced the synthesis of glutamate and other excitatory neurotransmitters.   

25 Amazing Facts About the Human Body

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The human body is an amazing piece of machinery—with a few weird quirks.

  1. It’s possible to brush your teeth too aggressively. Doing so can wear down enamel and make teeth sensitive to hot and cold foods.

  2. Goose bumps evolved to make our ancestors’ hair stand up, making them appear more threatening to predators.

Woman's legs with goosebumps
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  1. Wisdom teeth serve no purpose. They’re left over from hundreds of thousands of years ago. As early humans’ brains grew bigger, it reduced space in the mouth, crowding out this third set of molars.

  2. Scientists aren't exactly sure why we yawn, but it may help regulate body temperature.

  3. Your fingernails don’t actually grow after you’re dead.

  4. If they were laid end to end, all of the blood vessels in the human body would encircle the Earth four times.

  5. Humans are the only animals with chins.

    An older woman's chin
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    1. As you breathe, most of the air is going in and out of one nostril. Every few hours, the workload shifts to the other nostril.

    2. Blood makes up about 8 percent of your total body weight.

    3. The human nose can detect about 1 trillion smells.

    4. You have two kidneys, but only one is necessary to live.

    5. Belly buttons grow special hairs to catch lint.

      A woman putting her hands in a heart shape around her belly button
      iStock.com/PeopleImages
      1. The satisfying sound of cracking your knuckles comes from gas bubbles bursting in your joints.

      2. Skin is the body’s largest organ and can comprise 15 percent of a person’s total weight.

      3. Thumbs have their own pulse.

      4. Your tongue is made up of eight interwoven muscles, similar in structure to an elephant’s trunk or an octopus’s tentacle.

      5. On a genetic level, all human beings are more than 99 percent identical.

        Identical twin baby boys in striped shirts
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        1. The foot is one of the most ticklish parts of the body.

        2. Extraocular muscles in the eye are the body’s fastest muscles. They allow both of your eyes to flick in the same direction in a single 50-millisecond movement.

        3. A surgical procedure called a selective amygdalohippocampectomy removes half of the brain’s amygdala—and with it, the patient’s sense of fear.

        4. The pineal gland, which secretes the hormone melatonin, got its name from its shape, which resembles a pine nut.

        5. Hair grows fast—about 6 inches per year. The only thing in the body that grows faster is bone marrow.

          An African-American woman drying her hair with a towel and laughing
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          1. No one really knows what fingerprints are for, but they might help wick water away from our hands, prevent blisters, or improve touch.

          2. The heart beats more than 3 billion times in the average human lifespan.

          3. Blushing is caused by a rush of adrenaline.

12 Intriguing Facts About the Intestines

When we talk about the belly, gut, or bowels, what we're really talking about are the intestines—long, hollow, coiled tubes that comprise a major part of the digestive tract, running from the stomach to the anus. The intestines begin with the small intestine, divided into three parts whimsically named the duodenum, jejunum, and ileum, which absorb most of the nutrients from what we eat and drink. Food then moves into the large intestine, or colon, which absorbs water from the digested food and expels it into the rectum. That's when sensitive nerves in your rectum create the sensation of needing to poop.

These organs can be the source of intestinal pain, such as in irritable bowel syndrome, but they can also support microbes that are beneficial to your overall health. Here are some more facts about your intestines.

1. The intestines were named by medieval anatomists.

Medieval anatomists had a pretty good understanding of the physiology of the gut, and are the ones who gave the intestinal sections their names, which are still used today in modern anatomy. When they weren't moralizing about the organs, they got metaphorical about them. In 1535, the Spanish doctor Andrés Laguna noted that because the intestines "carry the chyle and all the excrement through the entire region of the stomach as if through the Ocean Sea," they could be likened to "those tall ships which as soon as they have crossed the ocean come to Rouen with their cargoes on their way to Paris but transfer their cargoes at Rouen into small boats for the last stage of the journey up the Seine."

2. Leonardo da Vinci believed the intestines helped you breathe.

Leonardo mistakenly believed the digestive system aided respiratory function. In 1490, he wrote in his unpublished notebooks, "The compressed intestines with the condensed air which is generated in them, thrust the diaphragm upwards; the diaphragm compresses the lungs and expresses the air." While that isn't anatomically accurate, it is true that the opening of the lungs is helped by the relaxation of stomach muscles, which does draw down the diaphragm.

3. Your intestines could cover two tennis courts ...

Your intestines take up a whole lot of square footage inside you. "The surface area of the intestines, if laid out flat, would cover two tennis courts," Colby Zaph, a professor of immunology in the department of biochemistry and molecular biology at Melbourne's Monash University, tells Mental Floss. The small intestine alone is about 20 feet long, and the large intestine about 5 feet long.

4. ... and they're pretty athletic.

The process of moving food through your intestines requires a wave-like pattern of muscular action, known as peristalsis, which you can see in action during surgery in this YouTube video.

5. Your intestines can fold like a telescope—but that's not something you want to happen.

Intussusception is the name of a condition where a part of your intestine folds in on itself, usually between the lower part of the small intestine and the beginning of the large intestine. It often presents as severe intestinal pain and requires immediate medical attention. It's very rare, and in children may be related to a viral infection. In adults, it's more commonly a symptom of an abnormal growth or polyp.

6. Intestines are very discriminating.

"The intestines have to discriminate between good things—food, water, vitamins, good bacteria—and bad things, such as infectious organisms like viruses, parasites and bad bacteria," Zaph says. Researchers don't entirely know how the intestines do this. Zaph says that while your intestines are designed to keep dangerous bacteria contained, infectious microbes can sometimes penetrate your immune system through your intestines.

7. The small intestine is covered in "fingers" ...

The lining of the small intestine is blanketed in tiny finger-like protrusions known as villi. These villi are then covered in even tinier protrusions called microvilli, which help capture food particles to absorb nutrients, and move food on to the large intestine.

8. ... And you can't live without it.

Your small intestine "is the sole point of food and water absorption," Zaph says. Without it, "you'd have to be fed through the blood."

9. The intestines house your microbiome. 

The microbiome is made up of all kinds of microorganisms, including bacteria, viruses, fungi, and protozoans, "and probably used to include worm parasites too," says Zaph. So in a way, he adds, "we are constantly infected with something, but it [can be] helpful, not harmful."

10. Intestines are sensitive to change.

Zaph says that many factors change the composition of the microbiome, including antibiotics, foods we eat, stress, and infections. But in general, most people's microbiomes return to a stable state after these events. "The microbiome composition is different between people and affected by diseases. But we still don't know whether the different microbiomes cause disease, or are a result in the development of disease," he says.

11. Transferring bacteria from one gut to another can transfer disease—or maybe cure it.

"Studies in mice show that transplanting microbes from obese mice can transfer obesity to thin mice," Zaph says. But transplanting microbes from healthy people into sick people can be a powerful treatment for some intestinal infections, like that of the bacteria Clostridium difficile, he adds. Research is pouring out on how the microbiome affects various diseases, including multiple sclerosis, Parkinson's, and even autism.

12. The microbes in your intestines might influence how you respond to medical treatments.

Some people don't respond to cancer drugs as effectively as others, Zaph says. "One reason is that different microbiomes can metabolize the drugs differently." This has huge ramifications for chemotherapy and new cancer treatments called checkpoint inhibitors. As scientists learn more about how different bacteria metabolize drugs, they could possibly improve how effective existing cancer treatments are.

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