Survival of the fittest  is a phrase that originated from an evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success.
The normal respiratory rate is 30 to 60 breaths per minute from birth to one year, 24 to 50 breaths per minute from one to three years and 22 to 34 breaths from three to six years old. As the child moves into school-age, the normal respiratory rate slows. From age six to twelve, the normal rate is 18 to 30 breaths per minute, while 12 to 16 breaths is the normal rate from age 12 to 18.
The average pulse of an infant at birth is 140 beats per minute. A normal pulse rate for children under one year old ranges from 90 to 170 beats per minute. This decreases slightly throughout the child's first year, but pulse rates up to 170 beats per minute are considered normal. child's pulse will be higher after exercising and lower while she is resting. Pulse rate is not the same thing as blood pressure. A child's pulse rate is how many times her heart beats per minute.