With advances in medicine, the average human lifespan probably will be extended to 85 years in the next century, but that is probably as far as it will go, a Stanford medical research believes. But while life will not be a lot longer, it will get better, he predicts. Old people will be spared the lingering illnesses they now so often suffer; instead they will simply wear out all at once like the wonderful one-horse shay. The result, according to Dr. James F. Pries, will be "that the number of very old people will not increase [but] the average period of diminished physical vigor will decrease [and] chronic disease will occupy a small proportion of typical lifespan . . ." Pries argues that the length of human life is fixed. Even without disease, people will die as their organs wear out. He bases his predictions on, among other things, the trend of lengthening lifespan in this century. Even through the average life in the United States has grown to 73 years, there has been no increase in the number of people living past 100. Each year during the 1970s, he finds, the average life expectancy from birth has increased one-third of a year, while the expectancy from age 65 has increased one month. "These curves intersect in the year 2018 at a mean age of death of 85.6 years," he said.