Longetivity & Genetics
The duration of human life (longevity) is influenced by genetics, the environment, and lifestyle. Environmental improvements beginning in the 1900s extended the average life span dramatically with significant improvements in the availability of food and clean water. It better housing and living conditions, reduced exposure to infectious diseases, and access to medical care.
Most significant were public health advances that reduced premature death by decreasing the risk of infant mortality. Increasing the chances of surviving childhood and avoiding infection and communicable disease. Now people in the United States live about 80 years on average, but some individuals survive for much longer.
They have found that long-lived individuals have little in common with one another in education, income, or profession. The similarities they do share, however, reflect their lifestyles—many are nonsmokers, are not obese, and cope well with stress.
It is Also, most are women. Because of their healthy habits, these older adults are less likely to develop age-related chronic diseases. Examples are high blood pressure, heart disease, and cancer.
The siblings and children (collectively called first-degree relatives) of long-lived individuals are more likely to remain healthy longer. And they live to an older age than their peers. People with centenarian parents are less likely at age 70 to have age-related diseases that are common among older adults. The brothers and sisters of centenarians typically have long lives, and if they develop age-related diseases. These diseases appear later than they do in the general population. Longer life spans tend to run in families, which similar genetics and lifestyle. Anyway, both play an important role in determining longevity.
The science behind longevity
The supercentenarians, however, also have many other newly identified gene variants that possibly promote longevity. Scientists speculate that for the first seven or eight decades. Its lifestyle is a stronger determinant of health and life span than genetics. Eating well, not drinking too much alcohol, avoiding tobacco, and staying physically active enable some individuals to attain a healthy old age. Genetics then appears to play a progressively important role in keeping individuals healthy, as they age into their eighties and beyond. Many nonagenarians and centenarians can live independently and avoid age-related diseases until the very last years of their lives.
Some of the gene variants that contribute to a long life are involved with the basic maintenance and function of the body’s cells. These cellular functions include DNA repair, maintenance of the ends of chromosomes (regions called telomeres). Also protection of cells from damage caused by unstable oxygen-containing molecules (free radicals).
In addition to studying the very old in the United States, scientists are also studying a handful of communities in other parts of the world. People often live into their nineties and older—Okinawa (Japan), Ikaria (Greece), and Sardinia (Italy). Most are lower-income, have little industrialization, and tend to follow a traditional (non-Western) lifestyle. Unlike other populations of the very old, the centenarians on Sardinia include a significant proportion of men.