Determine which of the following passages are arguments. For those that are, identify the conclusion. For those that are not, determine the kind of non-argument.
Although it is customary to think of human population as increasing continuously without declines or fluctuations, population growth has not been a steady march. For example, great declines occurred during the time of the Black Death, during the fourteenth century. Entire towns were abandoned, production of food declined, and in England, one-third of the population died within a single decade.