This is the VOA Special English Science Report.
In the year Nineteen-Hundred, a baby born in the United States could expect to live to be about forty-nine years old. Today, the life expectancy for a baby in the United States is seventy-seven years. The main reasons for this change are better food, improved medical care and cleaner water and waste removal systems.
Some scientists say this may explain why people live to be seventy or eighty. But only an extremely small number of Americans live to be one-hundred years old. Many of these people have brothers or sisters older than ninety. Some scientists believe these people have genes that help protect them from diseases or permit them to age more slowly than other people.
A group of researchers from Boston, Massachusetts wanted to find out more about such family groups. They studied one-hundred-thirty-seven groups of very old brothers and sisters. One person in each group was at least ninety-eight years old. The brother or sister was at least ninety-one. There were three-hundred-eight people in the study. The oldest was one-hundred-nine years old.
The researchers say they made progress is finding the gene that may permit some people to live extremely long lives. The scientists took blood samples and tested the genes of all the sisters and brothers in the study. They compared genetic structures to find genes that might be linked to aging. They found an area in one chromosome that appears to contain a gene or genes that may be linked to extreme old age. This one part of the chromosome has between one-hundred and five-hundred genes. The scientists say it is not clear which one or how many of the genes may affect long life.
The researchers believe the gene or genes may somehow provide resistance to disease. This may explain why many people older than one-hundred remain healthy and active.
The researchers reported the results of their study in “The Proceedings of the National Academy of Sciences.”Scientists say more work needs to be done to find the gene or genes involved in living to be very old. They say such work could result in drugs that could help people without those genes to live longer.
This VOA Special English Science Report was written by Nancy Steinbach.