On Birth Rate, Longevity, and the Misleading Arithmetic of Population

The reproductive statistics of the Principal Races are frequently quoted and almost as frequently misunderstood. This is partly because politicians enjoy percentages, partly because newspapers enjoy alarming them, and partly because the ordinary annual birth rate is a remarkably poor measure by which to compare peoples whose natural lifespans differ by nearly an order of magnitude.

Consider the most recent continental census. Among Humans, approximately twenty-six births are recorded annually for every thousand living persons. The Dwarven figure is eleven, the Aesir slightly under eight, and the Elven, depending upon the territory examined, varies between two and three. Presented without context, these figures have repeatedly inspired articles announcing that Elves are “vanishing,” that Dwarven fertility is “in decline,” or that Humans are reproducing at an unsustainable rate. All three conclusions are ordinarily false.

A Human generation is short. An Elf generation is not. A people whose members live approximately a millennium need not produce children at anything resembling a Human rate merely to maintain a stable population. Indeed, if Elves reproduced with Human frequency while retaining Elven mortality, every respectable population projection would cease to be a demographic forecast and become a warning to neighbouring countries. The important quantity is not simply how many children are born in a year, but how many are born over the reproductive life of an individual, how many survive to maturity, and how rapidly members of the preceding generations die.

Humans, whose reproductive period occupies a relatively narrow portion of life, tend to produce children in clusters separated by only a few years. A Human household may therefore contain three or four siblings of similar age, followed within several decades by grandchildren. This rhythm is so familiar to Human demographers that they have repeatedly mistaken it for the natural pattern of reproduction itself, when it is merely the Human pattern.

Among Dwarves, births are less frequent and commonly spaced farther apart. A Dwarven couple may have one child, wait fifteen or twenty years, and then have another without considering the interval remarkable. Their longer lives permit family formation to proceed at a pace Humans often misinterpret as infertility. A Dwarf of seventy who has produced only one child may still have a substantial reproductive future ahead of him or her, and a Human statistician examining the same household at a single moment may record a “low completed fertility” which is not, in fact, completed.

This error once appeared in a government report claiming that urban Dwarves were failing to replace themselves. The report was issued after twelve years of observation. Twelve years is an adequate period in which to study Human demographic change; for Dwarves, it is sometimes the gap between children.

Aesir present a related but distinct pattern. Their great body size, long gestation, and the considerable energetic burden of pregnancy make frequent births physiologically expensive. Recorded Aesir birth rates are therefore low by Human standards, yet family size over the course of three and a half centuries may be quite substantial. Birth intervals of a decade or more are common, and among traditional herding populations they may be longer still during periods of migration difficulty or poor mammoth yields. The result is a society in which siblings separated by thirty years may regard themselves as belonging to the same immediate generation, a thing Human visitors find peculiar until reminded that some Human men have children thirty years apart and merely arrange matters less elegantly.

Elves are more extreme. Elven fertility is low, but not because Elves are generally incapable of conception. Rather, conception itself appears naturally less frequent, with pregnancies widely spaced, and cultural practice often stretches reproductive decisions across centuries. An Elf may marry at two hundred, have a first child at three hundred, a second at four hundred and fifty, and a third at six hundred without producing anything resembling an unusual family history. This makes annual statistics nearly absurd if interpreted through Human assumptions.

During one fifty-year period, the district of Selvarin recorded a substantial decline in Elven births. Newspapers in three Human capitals reported an “Elven fertility crisis.” The following half-century recorded almost twice as many births. Nothing medically significant had changed; a large number of Elven households had simply reached the point at which they had decided to have children. One cannot detect a population trend in Elves by watching them for less time than it takes some of them to redecorate a dining room.

The relationship between lifespan and fertility becomes even clearer when age structure is considered. In a Human city, the proportion of the population consisting of children is relatively high because childhood occupies a substantial fraction of the total lifespan and each generation replaces the previous one quickly. In an Elven settlement, children may constitute only a small fraction of the population even when births are perfectly sufficient to sustain long-term numbers. This has led travellers to describe Elven communities as “childless” or “dying.” They are neither. They simply contain an extraordinary number of adults who have not yet had the decency to die.

A stable Elven population may therefore appear old when judged by Human census categories while remaining biologically vigorous. The category “over sixty,” which Human administrators frequently use as shorthand for advanced age, is particularly useless when applied to a population in which sixty-year-olds may still be regarded as inexperienced youths.

Dwarven and Aesir census bureaus solved this problem centuries ago by using race-specific age bands. Several Human governments resisted doing so on the grounds that standardised categories simplified administration. They did. They also simplified accuracy.

Gremlins, as usual, ruin every elegant comparison. Their annual reproductive statistics appear modest if one records only the number of clutches produced. They become alarming if one records offspring. A single Gremlin reproductive event may produce dozens of eggs. The majority of Gremlins reproduce relatively few times during their approximately fifty-year lifespan, but each successful clutch creates, in biological terms, an entire Human classroom at once.

This is necessary because Gremlin mortality is heavily concentrated early in life. Hatchling dispersal is dangerous, juvenile survival historically poor, and parental care essentially absent. Before the development of modern sanitation, food distribution, and urban shelter, many hatchlings never reached adulthood.

Thus the Gremlin reproductive strategy is almost the inverse of the Elven one. Elves produce very few offspring and invest extraordinary amounts of time in lives expected to continue for centuries. Gremlins produce many offspring at once and rely upon rapid independence, dispersal, and numbers to compensate for early mortality. Both strategies can sustain stable populations, and nature has no obligation to choose the same arithmetic twice.

Modern cities have complicated the Gremlin equation considerably. Hatchling survival has risen sharply wherever food is abundant, winters are survivable, predators scarce, and municipal authorities object to newborn citizens dying in drains. This has occasionally produced localised Gremlin population surges without any corresponding increase in mating frequency. The Gremlins are not breeding more; more of them are surviving.

This distinction becomes politically important whenever a newspaper prints the phrase “Gremlin population explosion,” which it does with tiresome regularity. I have yet to see a headline reading “Improved Juvenile Survival Among Urban Minority Population.” Accuracy seldom survives typography.

There is, however, a broader pattern beneath these differences. The longer-lived races generally reproduce more slowly. Humans reproduce faster than Dwarves; Dwarves faster than Aesir; Aesir faster than Elves. Gremlins appear to violate the pattern only because their reproductive strategy compensates for an unusually short life and historically severe early mortality.

This does not imply some mystical law by which nature assigns each race a predetermined number of descendants. It is simply demographic balance. A population in which individuals remain alive for centuries accumulates adults rapidly unless births are correspondingly infrequent, while a population whose members rarely survive beyond fifty must replace itself much faster. The mathematics is almost disappointingly ordinary. Its social consequences are not.

Human societies turn over quickly. Within a century, most adults alive at its beginning are gone, and political memory passes largely into documents. Dwarven institutions may contain officials who personally remember reforms enacted a century earlier, and Aesir clans may retain living participants from disputes that Humans regard as historical. In an Elven community there may be individuals who watched entire Human states rise and disappear while producing only two children themselves.

Birth rate and lifespan therefore shape more than population. They shape memory and inheritance, the speed at which customs change, the duration of political grudges, the meaning of ancestry, the size of households, and the degree to which a society is governed by people who personally remember why its rules were created. Demography is often treated as bookkeeping, which is unfair to bookkeeping. It is, in fact, one of the quieter forms of destiny.