Everyone wants to live forever, but the truth is that we all have only a limited time to be alive. In this lesson, we'll look at life expectancy and life span, as well as factors that can influence how long a person lives.
Susannah is 80 years old, much older than she ever thought she'd live! She's seen her kids have kids, and now even her grandkids have kids. Being able to meet her great-grandchildren is a special treat for Susannah, one that she is so happy that she was able to live long enough to see.
Susannah is in late adulthood, or the time of life after age 65. For those lucky enough to live into late adulthood, this can be an exciting time as they watch their family grow and find time after retirement for many of the passions they couldn't pursue during the busy earlier time in life.
But how likely is it that someone, like Susannah, can live into late adulthood? And is there anything she can do to increase that likelihood? Let's look at life expectancy and life span and factors that influence how long a person might live.
Expectancy vs. Span
When Susannah was born 80 years ago, no one ever thought that she'd live this long. Not because there was anything wrong with her, but because very few people at that time made it to age 80.
Life expectancy is the number of years the average person in a society lives. For example, the average life expectancy for babies born in the United States in 2014 is 79. The average length of time that a baby born in Sweden in 2014 can expect to live is 82.
In contrast, when Susannah was born in 1934, the average life expectancy was around 60 years old. That's a big difference! So, as you can see, both where and when you are born influence your life expectancy. But does that mean that all babies in America live two years shorter than all babies in Sweden?
Not at all! Life expectancy is just an estimate based on the statistics of that population. It is what the experts would expect to happen.
In contrast, life span is the length of time an individual person lives. It is the measure of the span of a person's life. So Susannah's expectancy might only be around 60, but we know that her life span is at least 80, and perhaps even longer!
Now that Susannah has great-grandchildren, she wants to stay alive even more than ever. Her goal is to live to see her great-grandchildren get married, which might be 20 or even 30 years from now!
Of course, Susannah can't really control how long she lives. She might get hit by a bus tomorrow or have a heart attack. But is there anything that Susannah can do to help increase her life span?
There are many factors that can impact a person's life span, some of which are out of Susannah's control. Some of the larger influences on how long a person lives can be remembered by the acronym 'GERD.' This stands for:
1. Genetics. There's not a lot that Susannah can do about this one. A person's genes can influence up to 25% of life span.
2. Exercise. Fitness plays a role in how long a person lives. Even at 80, Susannah is active. She likes to go for walks and even lifts weights a few days a week.
3. Reproduction. Some studies have shown that women who have fewer children at later ages live longer lives. In particular, women who have babies as teenagers tend to have a shorter life span. Susannah didn't have her first baby until she was in her 20s, so this might have an impact.
4. Diet. Like fitness, eating healthy has a large impact on life span. Susannah eats a healthy, well-balanced diet, which can help her extend her life.
Late adulthood is the time of life after age 65. How long late adulthood lasts depends on an individual's life span, or length of time they live, which is often (but not always) similar to their life expectancy, which is the average length of time a person in a society lives. Life span can be influenced by many things, including genetics, exercise, diet, and reproduction.
After reviewing this lesson, you should have the ability to:
- Identify the age at which late adulthood begins
- Differentiate between life expectancy and life span
- List factors that influence life span