Based on the survivorship curves shown below, a possible reason for the change in the shape of the curve from 1900 to 1980 is Improvements in healthcare services and medical research
What is healthcare services?
Generally, Health care is comprised of a variety of different professions, including but not limited to medicine, dentistry, pharmacy, midwifery, nursing, optometry, occupational therapy, physical therapy, sports training, and other related fields.
The provision of basic, intermediate, and tertiary care, in addition to work done in public health, are all included in this category of labor.
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