Rhonda Pendleton, age 11, of Peoria Heights, I11., for her question:

WHAT ARE THE SHORTEST AND LONGEST LIFE SPANS?

Life span is primarily determined by heredity. Offspring will live just about as long as their parents, if all other conditions are normal.

Shortest life span record goes to many flies and some other insects that survive as adults for only a few hours because they cannot eat.

Record for the longest life span goes to the redwood trees of the Pacific Coast of the United States. These giants live for thousands of years.

The average life span of people living in the United States and Canada continues to go up year by year. The increase in the average is caused primarily because there has been a sharp decrease in deaths of infants. Also, modern medicine helps push up the average.