FOX News medical contributor Dr. Marc Siegel joins 'FOX News @ Night' to discuss the potential causes of a decline in U.S.

life expectancy and the homelessness crisis in San Francisco. Human life expectancy has potentially been pushed to the max, new research suggests. The recent increase in people's longevity appears to be slowing down despite new developments in medicine , according to a study published in the journal Nature Aging.

During the 20th century, human life expectancy at birth rose by about 30 years in high-income nations, the study noted, driven by advancements in public health . ULTRA-PROCESSED FOODS MAKE UP 60% OF AMERICA'S DIET, WHO'S AT BIGGEST RISK Researchers from the University of Illinois Chicago (UIC) analyzed the national vital statistics of the longest-living populations in Australia, France, Italy, Japan, South Korea, Spain, Sweden and Switzerland, as well as Hong Kong and the United States, from 1990 to 2019. The expectation that human life expectancy will surpass 100 years old is most likely untrue, the study revealed.

(iStock) Since 1990, the average life span has only risen 6-1⁄2 years in the countries in the study, which casts doubt on expectations that human life expectancy would exceed 100 years in people born today. The researchers concluded that overall life expectancy improvements have slowed down, and that radical human life extension is "implausible in this century" unless the biological aging process can be "markedly slowed." 'Diminishi.