Additionally, this term is used in the field of
demography when the
subject of discussion is the
tremendous upsurge in
population of the
twentieth century in
the third world following an
unnaturally fast
mortality transition. The concept is that in a
high mortality society, the introduction of basic
health care and
hygiene measures, especially for the very young, drives mortality down within one or two
generations if introduction is quick and effective enough. That's not as good as it sounds, though, as humans in high mortality societies have a very high
fertility rate in order to compensate for high mortality and thereby continue the
species, and the fertility rate often lags behind the mortality rate when the mortality rate drops. It can take as long as thirty years for social
customs to begin to adapt to new biological circumstances, and in this time the population will
skyrocket or
metaphorically "
explode," hence the
population
bomb.
This term is not used often in serious articles on population and demography, but you'll be hard pressed to find a class on recent demography and demographic change that does not use that term in lecture and discussion regularly.