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PYC4805: Exam Answers Question 6
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- University Of South Africa (Unisa)
PYC4805: Question 6 Exam Preparation Answers
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Question 6: Chapter 4Discuss the influence of genetic and environmental factors
as well as ethnic, gender and international differences on
longevity. In a concluding paragraph, give an example of
how the interaction between these factors could influence
longevity. (20)
4.1: How Long Will we Live?
Knowing how long we will live is important not only for us but also for government agencies,
service programs, the business world, and insurance companies.
The length of life has an enormous impact on just about every aspect of life, from decisions
about government health care programs (how much money should Congress allocate to
Medicare?) to retirement policy (debates over the age at which people may collect
maximum retirement benefits) to life insurance premiums (longer lives on average mean
cheaper rates for young adults because they are now healthier for longer periods of their
lives).
Life expectancy can be examined from the perspective of the basic developmental forces,
because how long we live depends on complex interactions among biological, psychological,
socioeconomic, and life-cycle forces.
For example, some people, like Susie, have many relatives who live to very old age, whereas
others have relatives who die young.
Tendencies toward long lives (or short ones, for that matter) tend to run in families.
Our “long-life genes” play a major role in governing how long we are likely to live.
But the world in which we live can affect how long we live, too.
Environmental factors such as disease and toxic chemicals modify our genetic heritage and
shorten our lifetime, sometimes drastically.
By the same token, environmental factors such as access to high-quality medical care can
sometimes offset genetic defects that would otherwise have caused early death, thereby
increasing our longevity.
In short, no single developmental force can account for the length of life.
*Average and Maximum Longevity
How long you live, called longevity, is jointly determined by genetic and environmental
factors.
, Researchers distinguish between two different types of longevity: average longevity and
maximum longevity.
Average longevity is commonly called average life expectancy and refers to the age at which
half of the individuals who are born in a particular year will have died. Average longevity is
affected by both genetic and environmental factors.
Average longevity can be computed for people at any age.
The most common method is to compute average longevity at birth, which is the projected
age at which half of the people born in a certain year will have died.
This computation takes into account people who die at any age, from infancy onward.
Advances in medical technology and improvements in health care mean that more people
survive to old age, thereby increasing average longevity in the general population.
Maximum longevity is the oldest age to which any individual of a species lives.
Even if we were able to eliminate all diseases, around 120 years because key body systems
such as the cardiovascular system have limits on how long they can last.
It remains to be seen whether maximum longevity will change as new technologies produce
better artificial organs and health care.
An important issue is whether extending the life span indefinitely would be a good idea.
Because maximum longevity of different animal species varies widely, scientists have tried to
understand these differences by considering important biological functions.
Increasingly, researchers are differentiating between active life expectancy and dependent
life expectancy; the difference is between living to a healthy old age (active life expectancy)
and simply living a long time (dependent life expectancy).
Said another way, it is the difference between adding years to life and adding life to years.
One’s active life expectancy ends at the point when one loses independence or must rely on
others for most activities of daily living (e.g., cooking meals, bathing).
The remaining years of one’s life constitute living in a dependent state. How many active and
dependent years one has in late life depends a great deal on the interaction of genetic and
environmental factors.
*Genetic and Environmental Factors in Average Longevity
Genetic Factors Environmental Factors
Living a long life has a clear, but Although genes are a major
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