Baby’s amazing brain

From round-headed Charlie Brown to square-headed SpongeBob, heads (inside and out) have captivated and entertained. Scientists, eager to know what made Albert Einstein so smart, went so far as to preserve his brain. And while they never found the answer to his genius, their investigation transformed our understanding of how the brain works

What made Einstein a genius? Genes? Hormones? Life experience? Genes help explain why parents can’t make their kids smarter, but does that mean intelligence is a “what you see is what you get” proposition? Einstein’s brain showed abnormally high numbers of astrocytes, specialized cells that communicate via chemical signals, which could be one explanation for his genius. But who’s to say experience didn’t contribute to the high number of astrocytes in the first place? We once thought brains were fully developed at birth; then it was by the age of 5. Now we know that brain development continues throughout adolescence under the influence of hormones, and perhaps beyond, but at a much slower pace. By better understanding how brain development works, parents can not only help their children achieve their genetic potential, but perhaps support the next Einstein in the process.

Understanding how babies’ brains grow 

Shaped like a mushroom, the average infant brain weighs less than a pound. Along with the spinal cord and nerves, it makes up the nervous system, with the brain functioning as the control center and directing most of the body’s functions. 

Brain development begins when a fetus (unborn baby) is about 4 weeks old. This is also the critical time when neural tube defects, such as spina bifida, can occur. 

Pregnant mothers are often unaware of early fetal movements, but by the end of the first trimester, the fetus has already begun to stretch, grasp, yawn, hiccup, suck, and swallow, all signs of a functioning nervous system. Because the brain develops slowly, nature makes sure that the brain stem, the part of the brain responsible for vital functions such as breathing, sucking, and swallowing is fully operational by the end of the second trimester, giving babies born prematurely a better chance of survival. With more complex functions developing over time, babies truly enter the world with a brain that is best described as a work in progress. 

From birth to 5 years, the brain grows at a phenomenal rate. During the first three years, an infant brain reaches 80 percent of its adult size; by age 5, a child’s brain is 90 percent of its adult size. This rapid growth requires a steady supply of nutrients, with the most sensitive period being mid-pregnancy to 2 years of age. Studies show that if pregnant mothers and young children are poorly nourished during this critical time period, the lack of brain growth can be irreversible

Since growth is a measure of health and human milk promotes normal growth, the World Health Organization, in 1997, coordinated the development of new growth charts based on a diverse population of nearly 8,500 breastfed children from six countries. Researchers followed participants from birth to 5 years of age. All were exclusively breastfed for six months, after which complementary foods were added to the diet. Breastfeeding continued for as long as mom and child desired. 

With the release of the WHO Child Growth Standards in 2006, researchers showed for the first time how children should grow rather than how they do grow. Four years passed before the Centers for Disease Control and Prevention (CDC) recommended that the growth standards be applied to all U.S. children ages 0–2 years

Just like parents, kids come in a wide variety of healthy shapes—big, small, short, tall. Most parents tend to focus on weight and length as indicators of growth, but head circumference (the distance around the largest part of the head) is equally important, especially during the first three years. If your baby’s head is bigger or smaller than other children his size, or his head stops growing or grows too fast, it may indicate a problem. An unusually large head may be a sign of hydrocephalus, a buildup of fluid inside the brain. A head that is smaller than expected may be a sign that the brain is not growing properly or has stopped growing altogether.

Nature versus nurture 

Debates over whether genes or environment plays the more important role in brain development invariably ends in a tie. Experts now agree that both (along with hormones) play important, albeit very different, roles. Genes predict a child’s potential, but day-to-day experiences determine the extent to which that potential is realized. 

Development occurs at different rates. Einstein, for example, didn’t start talking until he was nearly 3 years old, and even at age 9, he struggled with language. Genes alone can’t confer verbal skills. Language development, like many other skills, requires repeated exposure. Activities such as reading a book, riding a bicycle, or giving a hug, turn on electrical circuits in the brain. The more often a circuit is turned on, the stronger it gets. Those that are rarely used are eventually eliminated through a process called pruning. Think of the human brain as a tree with branches. By pruning out the branches that are weak or broken, you strengthen the remaining branches and therefore the entire tree. Pruning is a lifelong process, but it is most common in early childhood. 

Though much of the development of the brain occurs by age 5, magnetic resonance imaging (MRI) studies show that brains continue to develop into the teenage years. Scientists once believed that overproduction and pruning of gray matter, (the part of the brain responsible for thinking) occurred only once, in infancy. They now know that structural changes occur in adolescence as well and that sex hormones likely play a key role. 

Although the brain constantly changes (increasingly less over time), animal studies show that there are critical time periods for brain development, and if particular circuits aren’t sufficiently stimulated during these windows of opportunity, animals (and perhaps humans) fail to develop specific behaviors. In a classic 1950s study, Harlow found that baby monkeys deprived of social interaction during the first six months became emotionally disturbed. Scientists believe that human infants may also have windows of opportunity when it comes to development. The critical period for learning a language starts to close around 5 years of age, and ends completely around puberty. Visual acuity (the ability to see fine detail) and binocularity (the coordinated movement of both eyes) develop only if one has normal visual experience as a child. Whether the same is true of mathematical and musical skills is unclear. Who knows what the outcome might have been had Einstein not been given a compass at age five? Captivated by the movement of the needle, he was intent on figuring out why it always pointed in a certain direction.

Can parents aid brain development? 

Parents can’t make babies smarter, but they can build on their child’s strengths and compensate for their weaknesses by engaging in activities that promote the development of a wide range of skills. (Read more about this on baby gooroo here.) Whether it’s a baby learning to roll over, crawl, or walk, a child learning to tie his shoes (something Einstein never learned to do) or play a musical instrument, or a teenager learning to drive a car or organize his time, most activities require time and attention. Studies consistently show that elite-level athletes share one common trait—a minimum of 10,000 practice hours! 

In addition to stimulation, brains (even Einstein’s) need nutrients. To ensure that babies get the nutrients they need, health care providers carefully monitor weight, length, and head circumference. These measurements inform health care providers and parents alike that a baby is growing well or that there is cause for concern. 

Breast milk, nature’s brain food, provides the perfect blend of nutrients, and is the only food a baby needs for about the first six months. After six months, iron-rich solid foods (such as iron-fortified cereals and meats) that fuel brain growth are added to the breast milk diet. Even with the addition of solid foods, breast milk continues to be an excellent source of nutrients for babies, toddlers, and young children. 

As your child transitions from curious, crawling infant to walking, talking toddler, provide safe opportunities for exploration. Stimulate the senses through a wide range of activities such as baby massage, sign language, exploring, reading, singing, dancing, and more. 

It’s unlikely that Einstein’s parents knew their infant son was a genius. No parent knows what their child is going to be when they grow up. But Einstein’s parents provided the stimulation—the compass—that allowed his genius to be realized.

Last updated November 20, 2020

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