Human Growth and Development

Examples

Aggression is influenced by both genes and environment. Studies on twins and adopted children suggest that 40-50% of aggression is linked to genetic predisposition . One well-known gene, monoamine oxidase A (MAOA) —sometimes called the "warrior gene" —is associated with increased aggression, especially when combined with childhood maltreatment or stress. Intelligence is also shaped by both hereditary and environmental factors. Research shows that IQ is 50-80% heritable , meaning genes play a significant role. However, education, nutrition, and life experiences are just as important in shaping cognitive abilities. While genetic testing can identify variants linked to intelligence, it does not determine intellectual potential. B. Prenatal and Early Influences Prenatal and early influences are crucial in shaping a child's development. Factors during pregnancy and the early years can have a significant impact on physical, cognitive, and emotional growth.

Prenatal Development Prenatal development, also known as gestation, is the period of growth and development of a human embryo and fetus inside the uterus.

It can be broadly divided into three stages:

Germinal Stage (Weeks 1 & 2): ●​ Begins at fertilization when the sperm and egg form a zygote.

●​ The zygote travels down the fallopian tube and implants in the uterus. ●​ Rapid cell division occurs, forming a blastocyst (a hollow ball of cells). Embryonic Stage (Weeks 3 - 8): ●​ This stage is characterized by rapid development of the major organ systems. ●​ The placenta develops to nourish the embryo. ●​ The heart and head start to take shape. ●​ Cephalocaudal development: Growth occurs from head to toe. ●​ Proximodistal development: Growth occurs from the center of the body outward. ●​ Three primary germ layers (ectoderm, mesoderm, endoderm) develop and will eventually form all the body's organs and tissues. ●​ Fetal membranes, including the chorion and amnion , form around the embryo and provide protection and support. ●​ The umbilical cord forms, connecting the fetus to the placenta.

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