Question

As compared to the whole body, the head of an adult human being is
A.One-fifth
B.One-sixth
C.One-seventh
D.One-eighth

Answer 1

The structure and the size of the human body drastically change during growth. The most common example would be the ratio of the length of the head to the body of a child and an adult human being. During infancy, the head is one-fourth the total body length and as we grow this ratio becomes one-seventh.

Complete step by step answer:
The skull structure of an infant or child differs drastically from that of the adult in several ways. Infants and children are not miniature adults, and their body size proportions, muscle bone, and ligament strengths widely differ.
At birth, the head of an infant is usually one-fourth of the total body length, whereas in the adults it is one-seventh. This is because the trunk is longer with the upper limbs being longer than the lower limbs in the case of adults, and in infants the proportions of limbs are similar and the length of the trunk is equal to the length of the head.

It is only during puberty the limbs, torso, and other extremities grow rapidly than the head. The growth rates of the trunk and limbs are almost equal during the first half of puberty, but the trunk continues to grow even after the limbs have elongated and the growth of limbs has declined in the adolescent period. The center-point of the body is above the umbilicus in infants, and 2 years the center-point of the body is slightly below the umbilicus; at about 16 years, this center-point is near the pubic region where it remains till adulthood.
In infants and children, the skulls are very pliable, due to the segmental development and arrangement of the skull bones, plus the flexibility of individual bones. The skull develops as a loosely joined system of bones formed in the soft tissue matrix surrounding the brain. Also, major brain development happens during infancy and therefore the head is larger than most features in infants. But as we grow, the head maintains slower growth, but other body parts grow faster.

Therefore, the ratio of head to body length in adult humans is one-seventh and the correct option is C.

Note:
This analysis is of importance as it primarily divides our growth into infanthood, childhood, adolescence, and adulthood. Such studies can also be used to identify growth abnormalities in children where if a child exceeds or does not meet the ratio criteria it can be easily identified that there are issues regarding growth hormone secretion and immediate actions to resolve such issues can be done during infancy itself.