Episode 1: “Love”

The first episode of the series Babies starts with the birth of a little girl, Willow, and shows the mild chaos and raw emotion of the moments after birth. A voiceover begins and details the puzzle of how babies are born so helpless and then grow to become “masters of the universe,” also declaring that babies have the “answer to what it means to be human.” Dr. Ruth Feldman, who directs the Centre for Developmental Social Neuroscience at IDC Herzliya, Israel, describes the importance of our bonds with our parents and her desire to understand what is going on in our brains when “we fall in love with our babies.” In Dr. Feldman’s lab, the role of the hormone oxytocin in parent-infant bonding is studied, indicating that oxytocin increases in both mothers and infants who have a lot of physical contact. This increases the desire to bond and gives mothers the feeling of a reward. The episode continues with clips of families with babies in both London, England and Connecticut, focusing on the interactions of the fathers with their babies. The oxytocin in fathers with new babies was also measured and revealed identical levels to the mothers. Dr. Feldman details that the more you do with your child, the more oxytocin is produced, proving “fatherhood is biological.”

Further research from Dr. Feldman’s lab showed that the maternal oxytocin surge activated the mother’s amygdala much more than in fathers, perhaps demonstrating why mothers are so in-tune with their babies at night. A group of gay couples was also studied to look at oxytocin in parents who did not give birth to the children. The results showed that men who are primary caregivers have the same amygdala activation as mothers even without pregnancy and childbirth, revealing “it is a choice to be a parent to that infant.”

At Harvard University, Professor Ed Tronick studied babies in social relationships using the still-face experiment. Mothers would stop reacting to their babies and the babies would smile and cry in order to get their mothers to keep reacting to them, attempting to get back into a relationship. Professor Tronick declared that babies are born with the ability to be in social relationships, the disruption of which may have a very powerful emotional effect. Professor Tronick also studies whether a good relationship between mothers and babies helps the baby to cope with stress by measuring cortisol. Infants with better relationships show lower cortisol levels and less stress during the experiment.

Next, Dr. Anne Rifkin-Graboi, head of Infancy and Early Childhood Research at NIE, NTU, Singapore, watches as her kids go down a zipline and wonders about the impact of parenting choices on infant development. Dr. Rifkin-Graboi watched mothers play with their six-month old babies and rated their responses to their children. The babies got brain scans in an MRI, and after comparison with brain scans from soon after birth, the researchers discovered that the hippocampus varied with parenting styles, and infants with less responsive parents had slightly larger hippocampi. This suggests that the babies were managing their own stress as their parents were doing less for them. Dr. Rifkin-Graboi emphasizes the importance of babies knowing the world is safe so they can explore, instead of “thinking about safety and comfort.”

The episode involves the research of three experts which all demonstrate the importance of early bonding and support for babies in healthy development. There is also a focus on the bonding between fathers and their children, not only the commonly-studied mother-infant bond. In support of material covered in Paleo Parenting, the study “Oxytocin administration, salivary testosterone, and father–infant social behavior” indicates that men with lower basal testosterone (T) have better relationships with their children and are more involved in childcare (Weisman et. al., 48). The study involved fathers ingesting oxytocin and observing their interactions with their children. Fathers with lower basal T had a greater T increase after oxytocin administration and had “greater social–behavioral reciprocity between father and infant, indicating greater investment in the parenting context” (Weisman et. al., 51). Therefore, oxytocin supports father-infant bonding as it does in mothers, and it does so even more effectively in men who may be more likely to be more involved in childcare in the first place.

Episode 2: “First Food”

The second episode, titled “First Food,” introduces the importance of food for babies. A narrator describes that food impacts the immune system of babies and another questions how the nutrients they receive shape their lives. In Phoenix, Dr. Katie Hinde, an anthropologist at Arizona State University, explains her interest in breast milk. Dr. Hinde describes that mothers “nourish, protect, and guide” their babies through their milk. Dr. Hinde remembers being dissuaded from studying breastmilk, but explains she stuck with her curiosity and studied the breast milk of monkeys. Next, Dr. Hinde details a discovery of patterns of “richer, more energetically dense” milk for sons and higher calcium-phosphorus ratios for daughters. She explains that skeletal development is faster in females as they reach adulthood faster than males. Dr. Hinde researched this phenomenon in over a million dairy cows and found, after cows have daughters, they produce significantly more milk than if they have a son, for reasons still unknown.

A British mother describes how much she enjoys breastfeeding and how she does not know how she will calm her baby after she stops breastfeeding him. A mother of twins in Connecticut explains why she stopped breastfeeding after not being able to provide enough milk for both babies. Dr. Hinde confirms that the best option after breastmilk is formula designed with the science of human breastmilk rather than cow’s milk. She then details that “an individual mom makes individualized milk for an individual baby,” and that daily experiences leave signatures in their milk. Mothers can increase their antibodies to go into milk to help their babies fight infections when they sense that the baby is ill. Dr. Hinde points out that hormones travel from the mother to the baby through milk, allowing for a “conversation.”

At the University of Minnesota Institute of Child Development, Dr. Michael Georgieff details his early research, where he discovered that many babies were deficient in metals such as iron, zinc, and copper, which are important in brain development. Babies are born with enough iron to last them around four months, but in some mothers with health conditions, not enough iron was transferred in the womb. Babies are studied using an EEG to see if their memory system allows them to determine whether their mother or a stranger is speaking. Babies with sufficient iron are more able to differentiate between the two voices than iron-deficient babies, indicating a more efficient hippocampus. Dr. Georgieff also claims that getting rid of metal deficiencies in billions of people around the world would “shift the world’s IQ positively by ten points.”Finally he says that the nutrients we consume both inside and outside the womb build our personalities and who we are as people.

In San Francisco, Dr. Susan Lynch, a professor in the Department of Medicine at UCSF, explains that it is very important for babies to ingest microbes from a young age. Human gut microbiomes are quite complex and can be used to predict whether babies will go on to live a healthy life. Dr. Lynch explains a study that showed that early exposure to dogs and cats protected babies from immune diseases. Using dust from households, Dr. Lynch analyzed the microbial DNA and determined that in houses with no pets, there was less bacterial exposure. Stool samples from one-month-old babies were analyzed for patterns of microbial gut colonization, revealing three distinct patterns, two of which were associated with lower chance of developing allergies and asthma. Therefore, a sterile environment is not healthy for a baby’s future, and environments with lots of microbes are protective against disease in childhood. To conclude, Dr. Hinde declares that food is a core part of human culture, and when babies begin to eat solid food, they are joining the family.

We have all heard the phrase “breast is best” but the evidence behind this is not so widespread. This episode, along with material from class, indicates how human breastfeeding gives benefits to babies. A scholarly article titled “ Breastfeeding protects against illness and infection in infants and children: a review of the evidence,” offers more detail to the general information laid out in class and the documentary, explaining how components of breastmilk such as protein and oligosaccharides provide protection for babies against disease (Oddy 2001). The author uses evidence of protection against illness from breastfeeding in order to assert, “it is now clear that human milk is precisely engineered for the human infant,” a theory we have discussed in class (11). Dr. Katie Hinde spoke about the ability of a mother’s body to detect illness in their baby and to produce antibodies to protect against viruses and bacteria, clearly indicating that breastmilk is specialized for each individual child and that mothers are the best source of food for their children.

Episode 3: “Crawling”

The third episode, “Crawling,” begins with a narrator explaining how babies are “slaves to gravity” and remain where they are placed for their first few months until they learn to crawl and explore on their own. A mother from London describes her feelings about going back to work while her husband stays home with their son and is able to be there for all of his milestones. Her son also does not seem to want to crawl which concerns her.

Dr. Marianne Barbu-Roth, director of the Motor Development Group at the Universite of Paris in France, explains how it was thought for many years that crawling is only a transitional stage to walking. She shows how newborn babies can actually move, when on the mother’s stomach, to the mother’s breast after only one hour as well as crawling, or swimming, in water very soon after birth. She explains the basis of her experiment which gives babies the illusion that they are moving with black dots moving in the same direction on a white background. When the babies see the dots and are held above them, they begin to “swim in the air.” This behavior demonstrates a “primitive link” between vision and the brain and the motor system so the baby will move in response to something they see, proving crawling is not just a reflex. The researchers then created a “Crawlerskate,” a modified skateboard which allowed newborn babies around two days of age to move around without having to support their massive heads, and the babies were able to ‘crawl’ all over a mattress. Dr. Barbu-Roth proclaims that she thinks we are not born as bipeds, but quadrupeds, because we move both our arms and legs while walking, so crawling is not a transitory stage.

In Atlanta, Dr. Michelle Lampl, a professor at the Emory Center for the Study of Human Health, details her experiences of measuring the length of a baby over two days, with measurements that varied by two centimeters. She uses a growth chart to demonstrate how we think that babies’ growth is continuous every day, but it is not a gradual process. Dr. Lampl measured thirty babies daily and found that babies grew between 0.5 and 1.65cm in one day, between two to twenty-eight days of no growth. These growth spurts changed their sleeping patterns, inciting tantrums as well as insatiable hunger. Therefore, growth does not happen in a curve, but in jumps separated by time. Dr. Lampl describes how she was hostilely interrogated by a leading figure in the field when she presented her data as the person found it hard to believe.

In New York City, Dr. Karen Adolph, a psychology professor at NYU, details how human mobility is not always on a flat surface, so babies are required to use perception to guide their movements. Dr. Adolph built an “adjustable slope apparatus” where babies crawl down a slope that increases in steepness by six degrees at a time, having a successful trial if they crawl down without touching their stomach. The novice crawler babies approach a 90-degree drop-off in the same way as a shallower slope, indicating that they do not yet know how to distinguish what they can do. Intermediate crawlers are better able to perceive what they can and cannot do and stop at the edge, while advanced crawlers switch between crawling on hands and knees as well as using their feet. Advanced crawlers, with roughly twenty weeks of crawling experience, are better able at finding alternative strategies to crawl safely, like going backward down the slope. She also describes how babies start to crawl, and how they start by only doing it on some days with days in between with no crawling activity. There is no steady progression from one stage to another and babies acquire their skills in different orders, including the baby from the beginning of the episode who seemed to skip crawling and went straight to standing and walking. Dr. Adolph ends the episode by saying “crawling isn’t mandatory” as babies all develop in their own way.

As we can see, crawling is not entirely critical to human development, and sometimes babies decide to start walking without including the assumed transitional step. This phenomenon is also seen in the Ache people in Paraguay, where the babies are carried until they are able to walk with no crawling (Kuther, 2020). In her autobiography and memoir on her medical practice, Clio in the Clinic: History in Medical Practice, Dr. Jacalyn Duffin describes her research and experience with babies. She uses evidence from multiple studies to show that we may have recently changed our babies’ developmental trajectory by placing them on their backs in order to prevent SIDS (Duffin, 155). In a study started in England in 1990, it was discovered “as parents uniformly began putting babies on their backs, more and more babies did not roll over or crawl on schedule, and increasing numbers never crawled” (Duffin 155). Therefore, babies are not required to crawl to walk and public health measures can affect how babies start to move.

Episode 4: “First Words”

The fourth episode, titled “First Words,” starts with clips of a family visiting a museum with their baby. The mother expresses her amazement that babies can learn a language while they do not know what language is. Dr. Kathy Hirsh-Pasek, director of the Infant Language Lab at Temple University in Philadelphia, tells a story of overhearing a three year old girl talking to her mother with very precise adult grammar. Babies hear “the melodies of speech” in their environment and somehow solve the problem of “mapping sound to language.” The British family explains how they have noticed tone is much more important than the actual sounds their son makes. Dr. Hirsh-Pasek describes her experiment which asks whether the melodies of language actually help us break language into smaller units. In their study, the researchers took samples of speech and put pauses in natural or non-natural places, then played the samples of speech out of different speakers and found that babies watched the side of the speakers with natural pauses for longer. Dr. Hirsh-Pasek also said that it is very likely that babies hear the patterns of language while they are still in the womb and they can distinguish between classes of language while very young. She also recommends the best way to develop strong language skills is to comment on what babies notice and pretend to have conversations.

In Madison, Wisconsin, Dr. Jenny Saffran, a psychology professor at UW Madison, explains how human culture is so dependent on language and knowing the meaning of words. Dr. Saffran describes that word learning is central to language acquisition and that babies may be learning language by statistics, determining which words go together frequently. Dr. Saffran made up a language with a few words that have no meaning and created a stream of the words in random order, so babies can determine which sounds, and words, go together. Words from the new language are played by themselves and are alternated with non-words, and babies control how long they listen to the sounds by looking in the direction of the speakers. The babies listen longer to the non-words as they get tired of the words that they have already learned. Dr. Saffran also tells the audience that babies who may not even be speaking can understand between 10 and 50 words by the time they are one.

A bilingual family in London has the father speak French to the children while the mother speaks English. Dr. Saffran details that babies in bilingual families can sort between the two languages by their “musical properties.” Dr. Erich Jarvis, a professor at the Lab of Neurogenetics of Language at Rockefeller University, is trying to understand why babies learn to speak later than they understand speech. Dr. Jarvis explains that among the vertebrates, there are only three birds and five mammals that are vocal learners, able to imitate a novel sound. Dr. Jarvis believes that the mechanism by which babies learn language is similar to that of how songbirds learn novels sounds. The brain regions used for speech and making sounds in both species are similar and further research revealed a connection between motor and vocal areas. The motor theory of vocal learning was developed, so muscles control our speech. Dr. Jarvis uses the analogy of spoken language as “learning how to coordinate your body.” Speech therefore comes with a delay because it is necessary to practice first. Humans have an extra copy of a gene called SRGAP2 which maintains more connections in the brain, and enables more sharing between cells and better learning. The episode ends with clips of three families reading stories to their babies before bed, while the experts speak about the gift of human language.

From the episode, it is clear that the best thing to do for an infant is to speak with it as much as possible and to try and enter into a “conversation.” This activity requires the caregivers to be close to the babies, also fostering a better relationship. In an article which describes the results of many studies about Infant-Directed Speech or Baby Talk, the authors write that “language learning is therefore powered by the shared social relationship between infants and caregivers” and “infants’ active participation in the conversation and maternal responsiveness to that participation” are “key elements in the acquisition process” (Golinkoff et. al 341). As Dr. Jarvis explained, infants learn speech through practice, and though they may sound unintelligible, they are building the foundations for future speech.

Episode 5: “Sleep”


The penultimate episode covers the “universal human challenge,” getting babies to sleep, as it is fundamental to their development. One of the narrators describes how sleep is when “the brain lives out its own existence,” and we are completely unaware. A family in London documents their experiences with their one-month-old son and his sleep patterns, detailing their own sleep deprivation. In New York City, Dr. Andre Fenton, director of the Neurobiology of Cognition Lab at NYU, studies when babies learn to sleep steadily like adults. Dr. Fenton gets his data from apps which parents use to track their baby’s sleep events. Parents record the events accurately to the minute, gathering millions of data points without needing to be measured by the researchers. Along with Dr. Pascal Wallisch, Dr. Fenton discovered there is an initial cycle of eating and sleeping starting around four months and there is a clear pattern within a year, with babies consistently sleeping through the night. 

At the University of Iowa, Dr. Mark Blumberg, a professor of psychology and brain sciences, explains the circadian rhythm, a cycle tied to the sun which comes from the hypothalamus as well as the brainstem. He shows how younger babies cycle from sleep to wakefulness very quickly and found that connections between the hypothalamus and brainstem are not initially present, but when they do connect, they start giving rise to the circadian rhythm. Dr. Blumberg shows videos of multiple species of animals that twitch in their sleep, describing that many consider the movements to be “byproducts of dreams.” In the lab, babies are observed using an EEG headpiece and allowed to sleep. When a baby is twitching, the brain is sending out a signal, trying to “map the body,” learning about the synergies of muscles and how they control joints. 

In Amherst, MA, Dr. Rebecca Spencer, a professor of Psychological and Brain Science, at the University of Massachusetts, studies how sleep makes learning and memory better. In the lab, infants are shown toys and the researchers play with them in certain ways. Then the babies are given the toys to see if they play with them in the same way as the researchers. Afterward, the babies are either kept awake or allowed to nap, and then they see whether the babies remember the actions with the toys. When the babies are not allowed to nap, they remember less of the objects and play with them in a new way compared to the babies who napped. After analyzing the nap brain data, Dr. Spencer explains that sleep spindles, a type of brain wave, are important for transferring information from the short-term memory area, the hippocampus, to the long-term memory areas in the cortex. She illustrates that babies need to sleep multiple times a day in order to more frequently move memories from short-term to long-term more frequently than adults, as they are learning so much about the world in a short period of time. Dr. Spencer concludes the episode by emphasizing the importance of sleep for our cognitive and emotional health throughout our entire life. 


The article titled “Sleeping like a baby: Examining relations between habitual infant sleep, recall memory, and generalization across cues at 10 months,” offers data which demonstrate the importance of infant sleep for the formation of memory (Lubowski and Milojevich, 2013). The main results indicated that babies were better at remembering actions after a two-hour delay and there was a positive correlation with the amount of time spent napping (374). However, the study also had results which demonstrated a negative correlation between the percent of sleep completed at night and memory performance, a fact contrary to popular opinion (374). From this study, it was better for the babies to sleep more during naps than to sleep more at night in order to have higher scores on the memory tests. Therefore, the study reaffirms common knowledge of the importance of sleep in memory and emphasizes the importance of napping for infants around the age of 10 months. 

Episode 6: “First Steps”

The final episode of the series, titled “First Steps,” covers the complex time period in which babies are first able to walk on their own. The first family shown has a set of eleven-month-old twins of which one twin is close to walking, while the other is more comfortable to continue jumping and crawling around. In Amsterdam, Dr. Nadia Dominici, associate professor at the Department of Human Movement Sciences at Vrije Universiteit, demonstrates how babies have a reflex to start walking at a young age if you hold them up and support most of their weight. Her research is trying to determine whether this reflex, or “newborn stepping,” is the foundation for future walking, or if it disappears and independent walking is a new phenomenon. Muscular activity was compared between newborn stepping and independent walking by measuring the electrical activity of muscles as well as mapping by movement sensors. The babies ‘walked’ while held on a treadmill and the toddlers walked independently in front of a camera. The toddlers keep the same movement patterns as the newborns, indicating that they keep the original building blocks for walking and that babies are born with innate walking skills. Dr. Dominici recommends for parents to try and develop the physical skills that babies need to walk by encouraging them to move even before they start walking.

Dr. Libby Cowgill, an associate professor of Biological Anthropology at the University of Missouri, studies how exercise is reflected in physical remains and “how the young human skeleton responds to the challenges of standing upright and taking its first steps.” She looked at bone cross-sections of over 600 infant remains that were between tens and thousands of years old. She saw that the cross sections of young children’s leg bones were not teardrop-shaped like adults, but more like an oval, indicating their bones respond to exercise. Along with Dr. Cara Ocobock, an assistant professor of Anthropology at the University of Notre Dame, Dr. Cowgill measured force plate data, or ground reaction force, of babies walking. Babies move side to side while walking and due to that, their bodies lay down more bone on the sides of the bone to resist the forces, resulting in the different bone shapes than adults.

In Merced, California, Dr. Eric Walle, professor of Developmental Psychology at UC Merced, studies how walking and ‘traveling’ changes a baby’s world. In his experiment, babies were allowed to play in a room with toys that had been associated with different emotions while their parents filled out a language survey. Dr. Walle discovered that walking babies had a much larger vocabulary of words they understood and could say. They recorded all of the words that the babies heard in a day as well as all the words that the babies babbled. The researchers found that walking and crawling babies heard roughly the same number of words per day and seemed to make the same number of vocalizations during the day. Dr. Walle then focused his attention on the quality of the language and found differences between how parents respond to crawling and walking infants, which helped walking infants have a higher rate of word learning. When children start walking, it matters even more what the parents say to them. The episode ends with a montage of all the babies featured in the series walking, including the twin who was slower to start than his sister.

In the final episode, Dr. Dominici researches whether babies are born with an innate ability to walk or if newborn stepping is a fluke and then forgotten on the way to independent walking. Having such an innate ability to walk from a young age would indicate that walking is a trait passed down through our genes from our ancestors who transitioned to bipedalism. To support Dr. Dominici’s theory that newborn stepping and independent walking are related, a chapter titled “The Road to Walking” by Karen Adolph and Scott Robinson tells us that babies seem to lose their newborn stepping ability as “infants’ legs increase in mass faster than they increase in strength” (Adolph and Robinson 4). The babies are therefore unable to continue stepping as their legs are too heavy. Eventually, their strength catches up with their mass and they are able to transition to independent walking, indicating that they would continue stepping if their legs did not become so heavy after the first few months.