Page:Popular Science Monthly Volume 81.djvu/624

618 some five higher than England, which has given to France a stationary, and last year a decreasing, population.

It is a question of fundamental importance whether the relation between the birth rate and the death rate will be maintained under existing conditions so as to give an increased or, at all events, a stationary, population. Will both continue to decrease, will they remain approximately as at present, or will the balance of the nineteenth century be lost as has apparently happened in France? The death rate has been halved by the practical abolition of war, pestilence and famine in their grosser forms, and by alleviation of their milder aspects—improved conditions for the struggling classes, the limitation and mitigation of disease, and better conditions of living. There is abundant room for further improvement, and it is stated by reputable authorities that the death rate can be halved again. But this is impossible; indeed, it seems that in certain nations the death rate has now reached its minimum. Australia and New Zealand now report a death rate of ten. This means that in a stationary population the average age at death is 100 years. For every infant that aies, a man must live to be 200 years old, or ten men live to be 110. This is almost beyond the limit of possibility. In 1910 the death rate in England and Wales was 13.5. This means in a stationary population an average age at death of 74 years, and as more than one seventh of all infants die, the average age of those surviving infancy would be about 85. The expectation of life of those 40 years old, which has not increased in the course of the last sixty years in spite of the lower death rate, is 28 years, so they die at the average age of 68 years.

The paradox is explained by the age constitution of the population. Owing to the high birth rate in England prior to 1876 and its subsequent decrease, an unusually large percentage of the population is from 5 to 40 years old, at which age the death rate is on the average only five per thousand. The population of England has about doubled by natural increase since 1850. Consequently old people more than sixty years old represent a population only half as great as children, and if a stationary population should hereafter be maintained, the percentage of old people would double. Indeed, as the death rate of children and of those under forty has decreased and will still further decrease, the percentage of old people will increase perhaps threefold. At present there are in France about as many people over sixty-five as there are children under five, while in England there are less than half as many, and in Russia with its high birth rate and death rate there are less than a third as many. The death rate of those over sixty-five is about 100; it has not decreased in the past sixty years, and is not likely to decrease considerably in the future. These old people now form about one thirtieth of the English population and contribute about three and a third units to its death rate; when they increase threefold, they will contribute ten units, and, if other conditions remain the same, the death rate will rise from 13.5 to 20. There will surely be a further decrease in the death rate of those under forty, but this will increase the number of those over forty, and will tend to increase their death rate. Probably a death rate of 15—an average age for those surviving infancy of from 75 to 80—is as low as will ever be permanently maintained by any nation. One may well wonder whether the birth rate will cease to decrease before or when it reaches the minimum death rate.

is no Nobel prize in astronomy, otherwise America would have had greater claims for the award than has been the case in medicine, physics and chemistry. It is a curious fact