According to the World Health Organization, the most social acceptable prejudice in the world is ageism. Cornell University gerontologist Karl Pillemer said you don't have to look hard to find it.
"I can give you an easy example," he said. "If you look at the presidential race, no one is comfortable using racist or sexist humor among the candidates, but they are very comfortable using ageist humor around the older candidates, and it is invariably asked if candidates are too old to serve."
One of the most fascinating -- and sobering -- findings to emerge from research is how damaging our own ageist attitudes are.
"People who internalize ageist attitudes and are very afraid and negative about their own aging really do worse in the last third of life," Pillemer said. "You're actually more likely to die earlier if you have extremely negative views about aging."
Pillemer calls ageism an "absurd prejudice" because all of us -- if we're lucky -- will get old enough to be the target of it.
"There's no official age where it begins," he noted. "It often begins as people start to show obvious signs of being in the later years. It's also relative, so there's ageism in some industries against people who are 40 or 45 and older."
But there is good news.
There are relatively easy and inexpensive ways to change people's negative attitudes about age. That was what Pillemer and his team of researchers at Cornell found when they analyzed over 60 studies of programs that encourage intergenerational contact and educate people about the facts of aging.
"The facts about aging are much more positive than most people believe," he stressed.
Pillemer said experts thought these approaches work, but no other study actually established it until now. He said he thinks programs like these should be in place around the country -- and it should happen soon because we're in one of the most age-segregated societies that ever existed, meaning young people have little contact with older people except for intermittent experiences within their own families.
"If you look at research on social networks, most people are much more likely to have a close friend of a different race than they are to have a close personal friend who is 10 years older or 10 years younger than they are," he said. "And if you don't believe me, I ask you to tell me a time that you can think of that a 27-year-old that you know had a Super Bowl party with pizza and beer and invited over his 74-year-old personal friend.
"It's so unusual that people have these cross-age personal experiences now that we really do need to be doing more than just relying on it to happen naturally."
To be fair, ageism is a two-way street. Older people have ageist attitudes toward younger people, too.
"Older people may stereotype millennials or high school students as irresponsible or narcissistic, so it does work both ways," Pillemer said.
But because our society is aging, it's in everyone's best interest, he said, to get rid of stereotypes about aging and replace them with more realistic views about what it means to get older.
"We have this massive longevity bonus which can lead to all sorts of good things," he said, "including older people as incredible resources for volunteer work, for work, for productive social change, but none of this is going to happen if we exclude them from important roles and relationships."
Pillemer's study was published in the June 20 issue of the American Journal of Public Health.