To discover the secrets of longevity, health specialists are studying people that reach ages well over 100. Researchers say that about 30 percent of aging is genetic. And for those who get to extreme old ages, family history may play an even more important role. For instance, Ruben Landau’s mother lived to 100. He is nearly 102，and still practices law.
Dr. Thomas Peris also studies these superhuman centenarians, and he has found that many centenarians lack a certain gene, E-4，that’s associated with an increased risk of heart disease and Alzheimer’s. One study found the gene is in 29 percent of young men, but only 15 percent of centenarians. Peris is also trying to determine if those who reach 100 have some type of protective gene. Researchers are also finding that children of centenarians have a 60 percent reduced rate of heart disease, diabetes, stroke, and high blood pressure. One day all this genetic research will lead to drugs that can slow the aging process.
Other experts believe that good diet is very important. The Okinawans are famous for their longevity. They include lots of vegetables, tofu, miso，and little fish and meat in their diet. The elders in Okinawa have been through two world wars and credited this diet to the hardship of the wars - when people were extremely poor. This poor people’s diet will be the key for their longevity today. Besides good habits and diet, experts who studied the Okinawans also contribute their longevity to ‘ikigai’，which translates to “that which makes one’s life worth living.”
【題組】46. What is the passage mainly about?
(A) The secrets of very long life.
(B) The diets of the elders in Okinawa.
(C) A place where people enjoys long life.
(D) Use of genetic technology to change the genes.