Arnulfo Palma, age 13, of Tucson, Ariz., for his question:
HOW CAN THE LENGTH OF LIFE BE EXTENDED?
Theologians, philosophers and scientists have long pondered the great mystery of life. What is it? There’s no simple definition. We know how organisms grow, what conditions they need to live, how they reproduce and how they act. We can classify living things as plants or animals but we cannot say exactly what life itself actually is.
We know that the potential length of life of all living things is determined primarily by heredity. For example, some types of insects survive as adults for only a few hours because they cannot eat. And we also know that the redwood trees in Western America live for thousands of years.
The length of man’s life is steadily increasing. Maintaining proper health patterns—getting the right amount of sleep, proper food and ample exercise—can add additional years to a person’s lifespan.
In basic terms, few people can expect to live to be more than 100 years old at the present time. But i t may be possible at some not too distant future date to push the average length of life over this mark.
A North American baby born in 1900 could expect his life to last 47.3 years. In the late 1960s a newborn baby boy’s life expectancy was 66.6 years and a newborn girl’s was 74.0 years.
The decrease in deaths of babies has been the major cause of the increase in average life expectancy. About 1,980 babies out of 100,000 in the United States died before reaching the age of one during the early 1970s. In 1915, 9,990 children out of every 100,000 would die before reaching the age of one.
So that’s the way human life has been and can continue to be extended: find and eliminate the reasons why humans die at early ages.
Scientists have been unable to determine exactly why the length of mammals’ lives varies so. Why does a lion live to be 20 or 25 years old while the tiger only lives to age 11? We don’t know.
Both the robin and the blue jay are about the same size, yet the robin will live for 12 years while his feathered blue jay friend will only live to be 4 years old. And why does the alligator reach 56 years while the crocodile rarely gets older than 13?
Longevity in mammals, scientists have determined, is set by the limits of heredity.
And yet, back on the human life scale, it is undoubtedly the addition of better environment and health patterns that makes the average life expectancy for a Canadian to be 72.2 years while a resident of Afghanistan can only look forward to being on earth for 40.5 years.
Life can exist only under certain limited conditions. All living things, for example, must have certain chemical elements and compounds for nutrition and cellular respiration. And temperatures must be right: life processes in general cease near 32 degrees F. and at about 175 degrees F. On hand must be oxygen, hydrogen, carbon and nitrogen.
In order to live, organisms must also have an ability to adapt to various environmental changes which take place each day, each season and over a lifetime.