Explain the concepts of asynchronous growth and the secular trend.

What will be an ideal response?

Answers will vary. Adolescents may be awkward and gawky due to asynchronous growth; different parts of the body grow at different rates. The hands and feet mature before the arms and legs do. As a consequence, adolescent girls and boys may complain of big hands or feet. Legs reach their peak growth before the shoulders and chest. Boys stop growing out of their pants about a year before they stop growing out of their jackets.During the 20th century, children in the Western world grew dramatically more rapidly and wound up taller than children from earlier times. This historical trend toward increasing adult height was also accompanied by an earlier onset of puberty, and is known as the secular trend. At the age of 15, boys were more than six inches taller and girls were more than three inches taller, on average, than their counterparts from the previous century. The occurrence of a secular trend in height and weight has been documented in nearly all European countries and the United States. However, children from middle- and upper-class families in developed nations, including the United States, no longer grow taller, whereas their poorer counterparts continue to gain in height from generation to generation. Improved nutrition would appear to play a key role.