People who feel they'll live long lives are likely to make different life decisions, such as investing more in education and marrying later, than those who expect shorter stints on Earth, a new study suggests.
This phenomenon can happen at a subconscious level, so you may not even be aware that you're tying life expectancy with life decisions, the researchers said.
"It's not that you are sitting there thinking about how long you have to live," said study researcher Daniel Krupp of Queen's University in Ontario, Canada. "It doesn't have to be the sort of thing to be a logical, cold, rational decision. It can also be an emotional one. You feel like you want to have a baby soon; you feel like you want to get married now."
Previous research has shown this effect in some cities where life expectancy varies by neighborhood. The neighborhoods with the lowest life expectancy also show the youngest age of reproduction.
"When you are living in the slums of Detroit or Chicago or Rio, life is short and people are pretty good at knowing that. When you ask them, people are surprisingly realistic about some of these things," Krupp told LiveScience. "You have information coming in that says 'I'm safe' or 'I'm not safe,' and you make an adjustment."
Krupp used data from Statistics Canada, a national agency that keeps tabs on the population, which includes information on life expectancy, fertility, marriage, divorce, abortion and educational background. Available data for individual provinces spanned from 2000 to 2006, and 1996 data came from the 139 "health regions" set up by the country's public health care system.
The researchers found positive links between general life expectancy (and therefore, people's subconscious ideas of how long they will live) and a number of traits that affect family structure. These traits include timing of reproduction and marriage, the propensity to terminate a pregnancy or a marriage, and the amount of time they are willing to invest in education.
The results held even after the researchers accounted for factors like wealth that could influence family and other life decisions, Krupp said.
Krupp explained that while nobody really knows how long he or she will live, plenty of clues can be found and wrapped into our subconscious idea of life expectancy. For instance, if people have the notion that they will live longer — perhaps because they have a family history of long life, or because they've eaten right and avoided unhealthy behaviors — they will have their first children later in life, be more likely to have an abortion or divorce, and will have spent more years in school.
On the other hand, a person who doesn't feel he or she has long to live might stay in a marriage instead of divorcing, or may start having children earlier.
"There are a million cues out there that you can expect your life to be a long one or a short one," Krupp said. "As you get older, as you creep a little bit closer to death, you might make different decisions."
The study was published online today by the journal Archives of Sexual Behavior.