Human Development
Human development is a genetic process involving the role of genetic, environmental and social functioning. In this chapter, you will learn how genetics and external factors affect, how they will affect social development and strengthen the weak abilities of the newborn. We will approach these beautiful human development groups. Human evolution is a dynamic process shaped by genetic, environmental, and social interactions. In this chapter, you will examine how genetics and external factors affect growth, the natural abilities of newborns, and the role of social development in fostering relationships and attachment Let us explore humans these interesting aspects of development do not go into detail.
By the end of this chapter, you should know about:
- How do heredity and environment affect development?
- What Can Newborn Babies Do?
- Social Development — Baby, I’m Stuck on You
Let’s take a closer look at them.
Test Your Knowledge
At the end of this section, take a fast and free pop quiz to see how much you know about Human Development.
How do heredity and environment affect development?
Developmental psychology studies change in behavior and abilities throughout life, from conception to death. Both heredity (nature) and environment (nurture) influence us across our lifespan. For instance, certain traits, like sexual maturity, are largely determined by heredity, while others, like learning to swim, are influenced by the environment. The interaction between heredity and environment shapes who we are.
Heredity (Nature)
Heredity refers to the genetic transmission of traits from parents to children. At conception, each person receives genetic material from both parents, which governs many physical and psychological traits.
DNA and Chromosomes: Human DNA, found in the nucleus of every cell, is the genetic code. It is organized into 46 chromosomes (23 from each parent). Each chromosome contains genes that control various traits like eye color, height, and susceptibility to diseases.
Dominant and Recessive Genes: Genes can be dominant (showing their effect when present) or recessive (requiring two copies to show their effect). For example, brown-eye genes are dominant, while blue-eye genes are recessive.
Polygenic Traits: Most characteristics, like height, are controlled by multiple genes (polygenic). More than 200 genes influence height alone.
Maturation: Heredity also dictates stages of development, including physical growth, intelligence, personality traits, and sexual orientation. Some milestones, like toilet training, depend on the child’s level of maturation—there’s an optimal window for learning certain skills.
Environment (Nurture)
The environment refers to external factors that influence development, such as experiences, culture, and learning. Environmental factors shape our development and the brain’s plasticity, particularly in the early years.
Brain Development: At birth, the brain has fewer connections (synapses) than an adult’s. Early experiences form and refine these connections through “blooming and pruning” (eliminating unused connections).
Cultural Influence: Modern culture accelerates human DNA evolution, but despite this, humans today are still quite similar to ancient humans. The environment, such as education and career opportunities, significantly impacts a child’s potential.
Human Development: Prenatal Influences
The intrauterine environment (inside the womb) can affect development even before birth. Factors such as the mother’s health, stress, and nutrition can influence the fetus. Harmful substances like drugs, alcohol, and radiation can cause congenital problems.
Teratogens: These are substances that can disrupt normal fetal development, such as drugs (e.g., cocaine or alcohol), smoking, and exposure to toxins.
Fetal Alcohol Syndrome (FAS): Heavy drinking during pregnancy can result in birth defects like low birth weight, facial malformations, and cognitive impairments.
Other Risks: Smoking reduces oxygen to the fetus, leading to underweight or premature babies, with long-term developmental consequences.
Human Development: Sensitive Periods
Certain times in early life are particularly sensitive to environmental influences. Experiences during these periods can have lasting impacts on development.
Critical Periods for Attachment and Learning: For example, forming a bond with a caregiver early in life is crucial for emotional development. Similarly, children who don’t hear normal speech within their first year may develop language impairments.
Reversibility of Damage: Some early-life damage, such as the effects of abuse, can have lifelong consequences. However, interventions, like extra care, can sometimes reverse the effects of early negative experiences.
Human Development: Deprivation and Enrichment
Deprivation
Deprivation refers to a lack of normal stimulation, comfort, nutrition, or love in the environment. Children who experience severe deprivation often suffer from severe emotional and developmental damage. While such extreme cases are rare, milder forms of deprivation—especially in families coping with poverty—are more common and can have long-term negative effects on a child’s development.
Effects of Poverty
Poverty can affect children in two major ways: Lack of resources: Poor families often can’t provide nutritious meals, healthcare, or educational materials, leading to frequent illness, delayed mental development, and poor school performance. Emotional stress: Poverty can cause marital problems and stress, leading to less positive parenting and poorer parent-child relationships. This emotional turmoil increases the risk of mental illness and delinquent behavior.
Adults who grew up in poverty often remain trapped in a cycle of continued poverty, as millions of Americans face this situation every day.
Enrichment
Enrichment refers to creating an environment that is stimulating, loving, and supportive. Researchers have demonstrated that enriched environments can positively influence development.
Animal Studies (Rats)
Studies on rats raised in “enriched” environments (e.g., colorful walls, platforms, and cubbyholes) showed improvements in their ability to learn mazes and a larger, thicker cortex, indicating better brain development. Although this study involved rats, it suggests that human infants also benefit from enriched environments.
Human Application
Psychologists recommend providing children with environments full of sensory stimulation—colors, sounds, textures, and opportunities for exploration. This can include taking babies outside, hanging mobiles over their cribs, playing music for them, and offering varied toys. These stimulating experiences are important for cognitive and emotional development.
Parents can also encourage curiosity by responding to their child’s interests and allowing safe exploration in the home.
Reaction Range
The concept of reaction range illustrates how environmental factors limit or enhance the effects of heredity. For example, if a child has genetic potential for normal intelligence, an enriched environment can help that child reach or exceed that potential, while a deprived environment might lead to underdevelopment of cognitive abilities. Although genetic traits set limits, the environment plays a crucial role in shaping developmental outcomes.
The Whole Person
Development is a dynamic interaction between genetics, environment, and behavior. A child’s temperament, which is inherited, plays a central role in shaping how they interact with their environment and how parents respond to them.
Temperament Types
Newborns exhibit different temperaments:
Easy babies (40%): Relaxed, agreeable, and responsive.
Difficult babies (10%): Moody, intense, and easily angered.
Slow-to-warm-up babies (15%): Shy or reserved.
Others (35%): Do not fit into these categories.
Reciprocal Influence
Babies are active participants in their development. For example, an easy baby’s frequent smiles can encourage positive interactions from parents, which in turn reinforces the child’s happy disposition. Conversely, a difficult child might lead to more negative parenting, which further exacerbates their challenges. The interaction between a child’s temperament and parental behavior is reciprocal and dynamic, influencing emotional and social development.
What Can Newborn Babies Do?
At birth, newborns like Samantha are helpless, relying entirely on adults for survival. They cannot feed themselves, lift their heads, or turn over. However, despite their limitations, they are not unfeeling or unaware of their surroundings. Newborns possess a surprising array of physical and mental abilities, many of which are closely linked to the maturation of their brain, nervous system, and body.
Sensory and Reflexive Abilities
Sensory Capacities:
Newborns have functioning senses—they can see, hear, smell, taste, and feel pain. While their sensory abilities are less acute than an adult’s, they are highly responsive. For example, babies can follow moving objects with their eyes and turn toward sounds.
Adaptive Reflexes:
Newborns exhibit several reflexes that are crucial for survival:
Grasping Reflex: When an object is placed in their palm, babies will grasp it with surprising strength. This reflex helps prevent them from falling.
Rooting Reflex: Babies turn their heads when their cheek is touched, a behavior that helps them find a nipple for feeding.
Sucking Reflex: Once a nipple touches their mouth, newborns instinctively begin rhythmic sucking to obtain nourishment.
Moro Reflex: A sudden change in position or a loud noise causes babies to make a “hugging” motion, which may help them cling to their mothers.
These reflexes are genetically programmed and serve to aid survival, especially in terms of feeding and securing safety.
Human Development: Motor Development
Maturation of Motor Skills:
The development of motor skills, like crawling and walking, follows a predictable order. Babies typically sit before they crawl, crawl before they stand, and stand before they walk. This pattern is consistent worldwide, with individual variations in the rate of development. For instance, some children might roll or shuffle instead of crawling.
Cephalocaudal and Proximodistal Patterns:
Motor control generally develops from head to toe (cephalocaudal) and from the center of the body outward (proximodistal). Even if a baby like Samantha doesn’t follow the typical motor milestones exactly, the general sequence of development remains consistent.
Learning and Practice:
Babies learn motor skills through trial and error. As Samantha begins to crawl or take her first steps, her movements may be wobbly and uncoordinated, but with practice, she will refine her skills to move more smoothly and efficiently.
Perceptual and Cognitive Development
Infants as Mimics:
Infants are born with an impressive ability to mimic facial expressions. Psychologist Andrew Meltzoff demonstrated that even at 20 days old, babies can imitate gestures such as sticking out their tongue, opening their mouth, or pursing their lips. This ability helps babies learn quickly from their caregivers.
Learning and Memory:
Even in the early months, babies show signs of cognitive abilities. They actively explore their environment by looking, touching, and tasting. Studies suggest that babies as young as 3 to 8 weeks old can understand that a person’s voice should match their body’s movements. For instance, if they hear their mother’s voice coming from a loudspeaker rather than from her body, they become agitated, suggesting they expect a connection between sound and sight.
Vision and Perception:
Newborns can see, but their vision is much less developed than an adult’s. By 3 days old, babies prefer complex patterns, such as checkerboards, over simpler shapes. By 6 months, they can distinguish between different categories of objects and recognize faces. By age 1, their vision will have improved to adult levels.
Human Face Recognition:
Newborns have a special affinity for human faces, especially their mother’s. By just hours after birth, babies can distinguish their mother’s face from a stranger’s. This preference for faces helps form early social connections. As babies grow, they become increasingly skilled at recognizing and responding to human faces.
Human Development: Emotional Development
Early Emotions:
Infants begin with basic emotions like general excitement, which gradually develops into more complex emotions such as anger, fear, and joy. By around 10 weeks, babies start to express a range of emotions, with “interest” being the most common, followed by joy, anger, and sadness.
Social Smiling:
One of the most important emotional developments in the first year is social smiling. Around 8 to 12 months, babies begin to smile more frequently at people, signaling interest and engagement. This social smile is a critical form of communication for babies and is an important social signal that encourages caregivers to interact with them.
Cry Communication:
Crying is a primary way babies express discomfort or need. This early communication form helps ensure that babies get the attention they need from their caregivers, whether for food, comfort, or attention.
Social Development — Baby, I’m Stuck on You
The significance of a child’s emotional bond with adults is foundational to their early social development and overall well-being. Babies are social creatures, and emotional attachment to caregivers, usually parents, plays a critical role in their development of self-awareness, security, and social interactions.
Human Development: Attachment and Its Importance
At the core of social development is the attachment bond, a close emotional connection that babies form with their primary caregivers. Research by Harry Harlow, through his famous studies with rhesus monkeys, demonstrated that attachment begins with contact comfort—the soothing, reassuring feeling babies get from cuddling soft, warm objects, such as a mother. These findings emphasize that attachment goes beyond just providing food; it is rooted in the emotional and physical comfort provided by caregivers.
Attachment is typically most critical during the first year of life, a sensitive period when forming secure bonds is essential for healthy emotional development. During this time, babies begin to show signs of attachment, such as preferring their mothers over strangers around 2 to 3 months of age and exhibiting separation anxiety at 8 to 12 months. While mild separation anxiety is normal, intense or prolonged anxiety may indicate developmental issues that need attention.
Human Development: Quality of Attachment
The quality of attachment plays a significant role in later emotional and social outcomes. According to Mary Ainsworth’s research, the way babies react when their mothers return after a separation can reveal the type of attachment they have. Securely attached infants are comforted by their mothers’ return, whereas insecurely attached infants may avoid or angrily resist contact. Secure attachment tends to promote positive outcomes, such as curiosity, problem-solving ability, and strong social skills in preschool.
Poor attachment, such as that experienced by children in overcrowded orphanages, can have lasting negative effects, resulting in anxiety, emotional detachment, and difficulty forming healthy relationships later in life. This highlights the crucial role early caregiving plays in emotional well-being.
Human Development: Promoting Secure Attachment
The foundation of secure attachment is responsive, sensitive caregiving. When caregivers respond appropriately to a baby’s needs and cues, the baby feels secure and learns to trust and bond. In contrast, neglectful or inconsistent caregiving can hinder attachment. This dynamic is true across cultures, underscoring the universal importance of sensitive caregiving.
Fathers also play an important role in attachment, with those who are supportive, affectionate, and involved helping to promote secure attachment in their children.
Human Development: Attachment and Day Care
A common concern among parents is whether commercial daycare interferes with attachment. The quality of daycare is key. High-quality daycare, characterized by trained caregivers, a low child-to-caregiver ratio, and a nurturing environment, does not harm attachment and can even improve a child’s social, cognitive, and language skills. However, poor-quality daycare can have negative effects on attachment and behavior.
Affectional Needs
Babies have strong affectional needs, which are as important as their basic physical needs. Providing consistent love and affection during the first year of life is essential for their emotional development. Contrary to fears of “spoiling” a baby, giving attention and affection is necessary and can build a foundation for future emotional health and capacity for forming loving relationships.