Dr. Daniel Krupp, Queen’s University – Life Expectancy and Life Decisions

Jun 18, 2012

In today’s Academic Minute, Dr. Daniel Krupp of Queen’s University reveals how our unconscious beliefs about life expectancy can influence major life decisions.

Daniel Krupp is a postdoctoral research fellow in the Department of Mathematics and Statistics at Queen’s University in Kingston, Ontario, where his research examines the functional and mechanistic design of social behavior. His primary research program is concerned with cooperation and conflict, and a secondary program is focused on reproductive decision-making.  He holds a Ph.D. from McMaster University.

About Dr. Krupp

Dr. Daniel Krupp – Life Expectancy and Life Decisions

In many places, people are taking more time in school, having children and marrying later, and terminating their marriages and pregnancies at increasing rates. Yet, these “plans” can still vary considerably from person to person and place to place.

A powerful explanation for the variation in these family planning decisions stems from a branch of Biology known as “life history theory.” The idea is quite simple: when the shadow of the future is long, it can pay to invest in your education and other aspects of your development to build up resources that can be spent on your children’s future success. But when time is fleeting, resources spent saving for the future come at the expense of the children and the marriage you could have today.

The logic of this is transparent to people as they age and feel their “biological clocks” ticking away, and the same principle may apply over the course of our lives: cues of life expectancy may cause people to adjust their family planning decisions. In a recent study in Canada, I found that an increase in life expectancy (over and above any effect of wealth) is associated with an increase in the age at first marriage and reproduction, as well as divorce rates, abortion rates, educational achievement, and the number of years spent in school. These findings support others examining similar relationships across nations and even within cities.

I don’t imagine that people are actually privy to their life expectancy, but they may have evolved ways to make a good guess about it. Information about one’s own physical health (“Do I have lots of energy? Am I sick all the time?”) and the health of one’s family (“Are my grandparents still kicking?”) might be good cues, and there are plenty of others. It’s likely that we’re aware of some of these cues but not all of them, and that they affect our decisions subconsciously. Interestingly, though, they might all be bound together, such that changes in policy that affect one decision may affect others. This isn’t inherently a bad thing, but it is something we may need to appreciate before tinkering with people’s lives in this way.