At 50% of maximum life span, survivorship for a Type I curve is:

• A. About the same as Type III
• B. Nearly 1,000 times greater than Type III
• C. About half as great as Type III
• D. Lower than Type II

Answer: (B)

Survivorship curves show what fraction of a cohort remains alive at different ages. A Type I curve has very high survival early in life and tends to have most deaths occur late in life, while a Type III curve has high mortality soon after birth and only a small fraction survives to old age. At the halfway point of the maximum lifespan, many individuals on a Type I curve are still alive, whereas very few on a Type III curve survive to that age. That makes the survivorship for a Type I curve vastly greater than for Type III—about a thousand times higher in the typical comparison. The other options don’t reflect that dramatic disparity at midlife: Type I isn’t lower than Type II or comparable to Type III, and it’s not half as great as Type III.