April 07, 2020

Span vs. expectancy

In the column on longevity (BDN, Jan. 23), Clair Wood confuses life span with life expectancy. The former is fixed; rarely do humans live beyond 110 or 112 years. Thus it is not accurate to say, as Wood does, that human life span “has been altered in recent times.” What has been altered in our century is life expectancy. It has nearly doubled.

One reason, as Wood notes, is that childhood deaths have greatly decreased. It is also true that life expectancy benefits from the postponement of cancer, heart attack and stroke. On the other hand, gerontologists usually don’t consider factors that reduce life expectancy. The breast cancer epidemic is an example. And many children in Los Angeles develop asthma or bronchitis by age 5 because of air pollution there. It is doubtful these children will live to be 80. Margaret Cruikshank School of Social Work University of Maine Orono

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