A new study suggests that there may be a limit to how long people can live. American researchers found that the longest a human being can live is about 115 years.

The researchers are with the Albert Einstein College of Medicine in New York City. Their findings were published in the journal Nature.

The study was based on mortality and population records from the Human Mortality Database. The database has a collection of records from more than 40 countries dating back to 1900.

The researchers found that the average life expectancy has risen greatly since the 19th century. This has resulted partly from developments in modern medicine, including the use of vaccines, antibiotic drugs and improved treatments for cancer and heart disease. In addition, there have been many improvements in public health and nutrition.

In 1900, someone born in the United States could expect to live 47 years. Today, Americans can expect to live an average age of 80.

According to the U.S. Central Intelligence Agency, the Mediterranean nation of Monaco has the highest average life expectancy in the world -- 89.5 years. Next are Singapore and Japan -- each at 85 years.

The oldest documented person to ever live was Jeanne Calment of France. Calment was 122 years old when she died in 1997. An Italian woman, Emma Morano, is currently recognized as the world's oldest living person. She is 116 years old.

Researchers in the new study said their findings suggest that the greatest average human lifespan was reached during the 1990s. They noted that some individuals born in the U.S., France, Japan and Britain lived to be at least 110 years old between 1968 and 2006. But the number of people living past 110 years is very small, and considered not reachable by most of the population.

The study found that survival rates have improved since 1900, with some older adults living to age 100 and above. But then many of those individuals died a short time later, regardless of when they were born.

The head of the study, Jan Vijg, is head of the genetics department at Albert Einstein College of Medicine. He said the findings show a decrease in the ability to reduce death rates among older adults. He said this suggests a possible limit to human lifespan.

Brandon Milholland was a lead scientist on the study. As he noted, “It is possible that someone might live slightly longer, but the odds of anybody in the world surviving to 125 in any given year is less than one in 10,000.”

Jan Vijg noted that continued medical developments to improve the quality of life -- especially in the developed world -- could push average life expectancy beyond 80. But he said researchers still do not expect the average human lifespan to ever break 100.