continuing elevation represents increased development.
b. Discontinuous development. This is akin to an individual climbing stairs. Developmental progression is evident with each higher step, but the steps are discrete intervals.
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Length, in centimeters, is listed for specific ages. Data for ages and lengths are approximations.
0.95 to 1.05: 61 centimeters
1.05 to 1.15: 62 centimeters
1.2 to 1.3: 63.5 centimeters
1.3 to 1.45: 65 centimeters
1.5 to 1.6: 65.5 centimeters
1.6 to 1.65: 67 centimeters
1.65 to 1.75: 67.5 centimeters
1.75 to 1.8: 68 centimeters
1.8 to 1.85: 69 centimeters
1.85 to 2.0: 70 centimeters
2.0 to 2.5: 71 centimeters
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Illustration 1: A baby is being fed from a bottle and making sucking movements.
Illustration 2: While the baby is feeding from the bottle, a person touches the center of the baby’s forehead.
Illustration 3: When the baby is touched in the center of his forehead, he makes sucking movements, even though he is not being given a bottle.
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In the center of the map are three terms: person, behavior, and environment. Each term is connected to the other with a double-headed arrow.
Pointing to the person concept are two labels. One reads emotional, social, and cognitive abilities. The other reads knowledge, beliefs, and attitudes.
Pointing to the behavior concept is a label that reads verbal, motor, and social actions.
Pointing to the environment concept are two labels. One reads physical and social surroundings. The other reads family and friends.
Back to Figure
In the center of the map are three terms: person, behavior, and environment. Each term is connected to the other with a double-headed arrow.
Pointing to the person concept are two labels. One reads emotional, social, and cognitive abilities. The other reads knowledge, beliefs, and attitudes.
Pointing to the behavior concept is a label that reads verbal, motor, and social actions.
Pointing to the environment concept are two labels. One reads physical and social surroundings. The other reads family and friends.
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At the top of the image is the word Genetics. Extending from the left of this term is a large arrow that points to a list of developmental stages: conception, birth, childhood, adolescence, and adulthood.
Extending from the right of the term Genetics are two smaller arrows. One points to the label Epigenetic factors. The other points to the label Environment. Extending from both of these labels are two larger arrows that point to the list of development stages.
A note along the arrow pointing to Environment reads Genetic susceptibility to environmental effects.
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1. No poverty
2. Zero hunger
3. Good health and well-being
4. Quality education
5. Gender equality
6. Clean water and sanitation
7. Affordable and clean energy
8. Decent working and economic growth
9. Industry, innovation, and infrastructure
10. Reduced inequalities
11. Sustainable cities and communities
12. Responsible consumption and production
13. Climate action
14. Life below water
15. Life on land
16. Peace, justice, and strong institutions
17. Partnerships for the goals
2 Biological and Environmental Foundations
Tara L. Kuther
Hannah Gal/Science Source
“Roger and Ricky couldn’t be more different,” marveled their mother. “People are surprised to find out they are brothers.” Roger is tall and athletic, with blond hair and striking blue eyes. He spends most afternoons playing ball with his friends and often invites them home to play in the yard. Ricky, 2 years older than Roger, is much smaller, thin, and wiry. He wears thick glasses over his brown eyes that are nearly as dark as his hair. Unlike his brother, Ricky prefers solitary games and spends most afternoons at home playing video games, building model cars, and reading comic books. How can Roger and Ricky have the same parents and live in the same home yet differ markedly in appearance, personality, and preferences? In this chapter, we discuss the process of genetic inheritance and principles that can help us to understand how members of a family can share a great many similarities—and many differences.
Learning Objectives
2.1 Discuss the genetic foundations of development.
2.2 Identify examples of genetic disorders and chromosomal abnormalities.
2.3 Discuss the choices available to prospective parents in having healthy children.
2.4 Describe the interaction of heredity and environment, including behavioral genetics and the epigenetic framework.
Genetic Foundations of Development
Roger looks quite different from his older brother but shares so many characteristics with his father that most people comment on the strong physical resemblance. In other ways, however, Roger is more like his highly sociable mother. His older brother Ricky also shares similarities with each of his parents. Ricky resembles his mother and her brothers
