In the Caucasus Mountains of Russia, nearly fifty out of every one hundred thousand people live to celebrate their hundredth birthday, and many don't stop at 100! By comparison, in America only three in one hundred thousand people reach 100. But these Russian old people aren't alone. The Pakistanis, who live in the Himalaya Mountains and the Ecuadorans of the Andes Mountains , seem to share the secret of long life, too. These people remain healthy in body and spirit in spite of the passage of time. While many persons in industrial societies become weak and ill in their 60s and 70s, some Caucasians, aged 110 to 140, work in the fields beside their great grandchildren. Even the idea of aging is foreign to them. When asked, "at what age does youth end?" most of these old people had no answer. Several replied, "well perhaps at the age of 80," and the very youngest estimate was at the age of 60. What accounts for this ability to survive to such an old age, and to survive so well? First of all, hard physical work is a way of life for all these long - lived people. They begin their long days of physical labor as children and never seem to stop. All these people get healthful rewards from the environment in which they work. They all come from mountainous regions. This reduced - oxygen environment makes the heart and blood vessel system stronger. Another factor that may contribute to the good health of these people is their isolation. To a great extent, they are separated from the pressures and worries of industrial society. Inherited factors also play some role.  It is clear that isolation from urban pressures and pollution, clean mountain air, daily hard work, moderate diets, good genes, and a youthful approach to life all contribute to the health and long life of all these people. The following factors except   _   contribute to the health and long life of all these people.
clean mountain air daily hard work good genes stress and pressure