An AD&D® game world is usually one of
action and tumult. Humanoid armies meet
human and demi-human forces regularly in
mortal combat. Countries are invaded and
their inhabitants are killed or driven off.
Magical or natural disasters lay waste to
large areas at least once every millennium.
Monsters hunt travelers in the wilderness,
and are in turn hunted by other monsters or
by adventurers.
 

True, there are safe places in the world,
but they are usually preserved by force of
arms and magic, or because they are isolated
and perhaps occupy an undesirable
position (such as in the middle of a swamp).
Many of these backwaters are poor lands,
where starvation is enemy enough. Immortality
is only for the gods, and not even for
all of them.

This is as it should be for an exciting
campaign. Adventurers are naturally found
with trouble and change. There is, however,
the question of replacement. Where do the
hordes of humanoids come from, those that
spring up to kill and be killed time and time
again? How do the humans and demihumans
make up their inevitable losses?
What of the other inhabitants of the world,
from brownies and beholders to wyverns
and worgs? Presumably their populations
grow in the same way that populations do in
the real world, unless they are somehow
spontaneously generated by the natural and
supernatural forces that surround them.
This has some interesting corollaries.

The DMG contains
(on p. 13) a table indicating that the
humanlike races in an AD&D game world
grow and develop more or less in proportion
to how long they live: a century-old elf is
equivalent to a human teenager, while a
half-orc is full grown well before twenty
years of age and past the prime of life at
thirty. Combining this information with that
on lifespans from the Monster Manual, the
"age categories" data in the DMG can be
expanded to include some of the humanoids;
see the table below.

Age Categories
 

Species	Young Adult	Mature	Middle Aged	Old	Venerable
Bugbear	15-20	21-35	36-55	56-75	76-100
Gnoll	7-10	11-20	21-25	26-35	36-45
Goblin	10-12	13-25	26-35	36-50	51-65
Hobgoblin	12-15	16-30	31-45	46-60	61-80
Kobold	20-30	31-65	66-100	101-135	136-180
Ogre	14-20	21-40	41-60	61-90	91-120
Orc	8-10	11-20	21-30	31-40	41-55

The proportion of its life that each humanoid
spends in the age categories given is
based on the proportions given for a halforc.
This should be about right for most of
these humanoids, except in the case of
kobolds; for reasons to be explained later,
they probably reach the young adult stage
much sooner than this table indicates. Leaving
kobolds aside for the moment, look at
the figures for gnolls and orcs. A gnoll is
ready to reproduce by the age of 7, and an
orc at the age of 8. The others are not far
behind, with the exception of the two larger
creatures, bugbears and ogres. This early
maturity has important implications for the
balance of power and numbers in an AD&D
game world.

The growth potential of a population
depends primarily on its generation time ?
the average period between the birth of a
female and the birth of her female offspring.
(Males are not considered in this calculation,
since they do not represent the ratelimiting
factor in population growth.) This
means that populations in which females
reproduce earlier will grow more quickly.
The counter-intuitive effect of this is that a
population of long-lived but slowly maturing
creatures will grow more slowly than a
population of short-lived but more quickly
maturing ones.

For instance, if a female high elf were to
have a child every year of her reproductive
life (from about 100 to 550 years of age),
she would have hundreds of daughters. This
is, of course, a ridiculously high number;
aside from the physical strain of those centuries
of pregnancies and births, imagine
the difficulty of caring for dozens of elven
children at the same time ? none of them
even out of diapers before the age of 10! It
might be expected that with such a huge
increase in population per generation, elves
would soon outstrip the other humans and
demi-humans in number. Actually, such
busy and healthy elves as these would still
not increase so quickly as a normal human
population can. While the elves steadily
increase their numbers, year by year and
century by century, the humans have children,
who will soon have children, who will
soon have even more children . . . and
the multiplication effect wins out. The
mathematical expression of this tendency,
well known to ecologists, is:

where r is the rate of a population?s increase
over time, F is the number of new females
per female in a generation, and G is the
generation time. (The log, function, or
natural logarithm, sometimes written as ln,
is found on many calculators these days, or
failing that, in the back of a mathematics
textbook.) The aforementioned productionline
elves, according to this equation, would
increase in number by about 2% per year,
doubling their population every 42 years or
so. To achieve this rate, humans needn?t
put out nearly so much effort. With early
marriage, and families of quite modest size
(three surviving children), they easily outstrip
the elves. Orcs could do this even
more easily.

Of course, a very large change in the
number of surviving offspring will have
some effect. If the value of F is exactly 1
(simple replacement), the population will
remain stable and not grow at all ? the
phenomenon known as zero population
growth. If F falls below 1, the population
will actually decrease, in which case the
longer-lived species are favored by a slower
decline.

Fertility and mortality will affect a population
?s F value, but one or both must
change drastically to counteract the effect of
generation time. For instance, it is apparent
from the ratio of adult males to females in
most humanoid tribes that only half as
many females reach maturity as do males.
Given the nature of the creatures in question,
this may be due to the practice of
selective infanticide by male humanoids
who are impatient for warrior sons ? a
practice not unknown in human societies of
the real world. The killing of half of the
female infants born, while perhaps favorable
to the individual males involved, cuts
the tribe?s growth rate per generation in
half, striking directly at the potential childbearers.
Its effect on the overall growth rate
of a given humanoid population is to bring
it down to near-human levels. Similarly,
even though dwarves and gnomes have half
as many adult females as males (presumably
a natural trait rather than an imposed one),
dwarven and gnomish communities still
have a good deal more growth potential
than elvish ones.

The effects of generation time can be seen
every day in the real world. Organisms with
relatively short generation times, like insects,
rodents, or dandelions, can survive
determined attempts at their extermination,
since only a few individuals need to survive
to fuel a population explosion when favorable
conditions return. On the other hand,
those with long generation times, such as
whales, albatrosses, or giant sequoia trees,
may take long years to recover from a major
setback in their numbers. Such effects cannot
be avoided or ignored in a selfconsistent
fantasy world, either. Alchemy
may replace chemistry, the world may be
flat instead of round, and the elements may
be mythic ones rather than scientific, but
numbers remain the same. Just as insects
can appear in hordes on incredibly short
notice, so can orcs, and just as oak trees
might take centuries to rebuild their population,
so do elves.

It must be admitted that a population?s
growth potential is not the sole predictor of
abundance and success. Oaks may take
hundreds of times as long to mature as
dandelions do, but they can still dominate
forests. There are many other factors to
consider here, particularly those related to
the competitive ability of a species compared
to others trying for the ecological
niche. Growth rate is highly significant,
however, under unstable conditions in
which a population must recover from
periodic disasters. Droughts, forest fires,
earthquakes, floods, wars, and other catastrophes
favor a species which has a short
generation time, since it will tend to fill the
gaps left by less prolific competitors. In this
way, grasses and weeds can dominate an
area that is periodically swept by fire, even
if they would otherwise be shaded out by
taller plants.

All of this has particular relevance for the
inhabitants of an AD&D game world in
which many intelligent species may be in
competition for the same real estate. In the
turbulent times in which most adventurers
live, a short generation time can be a great
advantage. This is especially true of the
humanlike species, who may become involved
in long-term wars of near genocidal
scope, such as those between gnomes and
kobolds, between dwarves and hill giants,
and between dwarves and orcs.

On the whole, the conclusions that can be
drawn from the above information mesh
surprisingly well with the campaign background
of most AD&D game worlds, with
information given or implied in the various
official books, and in particular with events
and conditions in the archetypical AD&D
game campaign, the WORLD OF GREYHAWK
 Fantasy Game Setting. In fact, a
number of otherwise inexplicable events are
accounted for by these assumptions, and
new gaming possibilities are opened up.

It is not surprising that in uncertain and
chaotic times the humans and humanoids
have spread, while demi-humans have at
best merely held their ground. Demihumans
are most commonly found in relative
backwaters like forests and hills, where
conditions are politically stable because of
the difficulty of invading such territory.
Naturally, this is most notable in the slowly
maturing elves and gnomes. Dwarves and
halflings are more likely to be found in the
mainstream of society, though even there
they are most common in peaceful areas.
Within their enclaves, demi-humans may
be quite common since they have significant
competitive advantages over the average
human or humanoids.

The conflict between humanoids and
demi-humans is traceable to more than just
alignment differences. Perhaps coincidentally,
it is a conflict between two very different
life strategies. Like insects and rodents,
humanoids depend primarily on their short
generation times for survival. They are
natural colonists. If lands are emptied by
war or pestilence, they will fill them up
quickly and be firmly entrenched by the
time otherwise superior competitors arrive.
Demi-humans, on the other hand, are
superior in almost every field of species
competition except reproduction; they are
generally more intelligent, are more willing
to help one another, have more special
skills, and produce more powerful and
unique individuals than the humanoid races
do. Demi-humans thrive under conditions
of peaceful competition. Unfortunately,
such "high-quality material" cannot be
replaced quickly. Over time, humanoids are
favored by conditions of cataclysm and
violent confrontation, which by their very
natures humanoids tend to bring about.

When it comes to war, the demi-humans
seem to do well. A few elven wizards with
fireball spells can destroy a tribe of orcs; an
ambush by halfling archers in the woods
can lay low a whole company of hobgoblins;
goblin heads may roll by the dozens under
dwarven attack. All of this is in vain, because
in a decade or two the humanoids will
be back. The contest between demi-humans
and humanoids is like that between a fighter
and a troll; the troll?s wounds heal in minutes,
while its opponent must wait days or
weeks. The only successful course of action
for the fighter, other than to retreat, is to
strike harder and more often than the troll,
and most importantly to ensure that no
small piece of the troll remains undestroyed
to regenerate the monster. Despite the
casualties they inflict, demi-humans cannot
maintain a long war. They must win
quickly or not at all, and they must win
completely. Their warriors will learn
through bitter personal experience that each
humanoid survivor signifies dozens more to
be dealt with in the years ahead. The image
of a few brave individuals holding back
thousands of the enemy, inflicting great
damage but still doomed to lose, is a frequently
appearing one in fantasy literature.
It must appear with depressing frequency in
the history of demi-humans as well.

Humans, intermediate between humanoids
and demi-humans in both alignment
and in their reproductive abilities, as well as
in their talents, are not unnaturally found
on both sides of the conflict between humanoids
and demi-humans. Overall, they
seem to have the best of both worlds, since
they reproduce almost as quickly as humanoids
and can produce at least as many exceptional
individuals as do the
demi-humans. This may explain their success
in both war and peace, while the demihumans
must diminish in number if they
cannot achieve both victory and stability.

The short generation time of most humanoids
explains how they can survive
seemingly crippling mortality rates and still
be in no danger of extinction. Losses from
disease, malnutrition, infanticide, or warfare
are unimportant; life is cheap. So long
as a few tribes or individuals survive in
some dark corner of the world, there will be
new hordes every few decades. From this
viewpoint, the larger and more individually
dangerous humanoids such as bugbears and
ogres are less of a threat than their weaker
brethren, because they have a slower rate of
reproduction and replenishment among
their populations.

Humanoid societies that are guided by
superior leaders are generally more prominent
than those not possessing the same
characteristic. This prominence may be due
to more than good military generalship; it
may have more to do with the fact that an
intelligent commander can see, with no
calculations, that more warriors will ultimately
be raised if female children are
spared. If he is so foresighted and can enforce
penalties against infanticide, the reproductive
power of a humanoid tribe is
greatly increased. This is itself a more terrible
weapon than any strategy or spell that
could be employed on the battlefield. With
sufficient food, a humanoid army can be
raised almost overnight (in relative terms)
and unleashed upon opponents before they
are aware of their predicament. It is interesting
to note that hobgoblins do not have
the characteristic shortage of females found
among other humanoids. This may be due
to the greater intelligence of their leaders.

An enigma concerning dragons is neatly
explained by generation time effects:
namely, why dragons have not overrun a
world that is, from their point of view, one
large hunting ground. Hundreds of humans
and other short-lived creatures might die
before the elimination of a single dragon,
but each dragon lost is a serious blow to the
next generation of their kind. By the time a
replacement is full grown, the dragons'
opponents will have long ago recovered
their losses. It is not at all surprising that
dragons tend to live in out-of-the-way
places and guard their offspring as zealously
as they do their gold.

Though the undead do not reproduce in
the normal way, some are able to propagate
themselves by attacking living creatures. In
this they have the equivalent of a very short
generation time ? potentially as short as a
few days or even minutes. This opens up
some interesting possibilities. A vampire
with its minions might be able to take over
a whole village before news of the deed
spread to the outside world. If the vampire
were a particularly ambitious one, rescuers
might arrive to find the place deserted, its
inhabitants having left to find more ?food.?
Whole nations of undead might arise in this
way. This ability explains in part how vampires,
spectres, and the like can survive
despite their vulnerability to such things as
clerics, holy water, and sunlight. Fortunately,
the undead are sharply limited in
their potential for expansion; once the
supply of victims runs out (or runs away), a
group of undead creatures can grow no
further.

Lycanthropes can reproduce themselves
by infection, the disease taking hold in a
relatively short time. Again, they have the
equivalent of a very short generation time
in this power. If lycanthropy is hereditary as
well, so that the supply of uninfected humans
is not limiting, it is difficult to see
why the werebeasts have not spread further
than the Monster Manuals indicate.
Though less dangerous individually than
the undead, lycanthropes are much better at
concealing their presence from human
populaces. Their relative scarcity may be
due in part to their tendency to withdraw
from human society. Some lycanthropes
such as wererats, though, live near normal
human populations. Perhaps they refrain
from drawing attention to themselves out of
fear of human adventurers, or perhaps they
prefer to eat their victims rather than infect
them. Perhaps they have qualms about
inflicting lycanthropy on unwilling victims
? even an evil lycanthrope can see that the
more lycanthropes there are, the fewer
humans there are to eat. An interesting
alternative hypothesis is that lycanthropy is
a fairly recent addition to one?s fantasy
world, and is spreading quickly!

By taking generation time into account, a
DM can develop additional background
information for a campaign. Most large or
otherwise dangerous creatures probably
have long maturation times, and possibly
long lives to match (though low fertility and
high mortality might play their parts).
Similarly, small and weak creatures, with no
other significant defenses, probably mature
quickly. Thus, giants of all sorts are probably
long-lived and slow to mature in proportion
to their size, while xvarts probably
grow as quickly as goblins. The few creatures
specifically described as quick to mature
but relatively powerful must have very
low fertility or high mortality rates, or both.
A good example of these last would be
quicklings (see Monster Manual II); with a
generation time like theirs, the increase per
generation must be very low in order for
them to stay rare. Perhaps this is due to
high-speed crashes. . . .

In a few cases, the conclusions arrived at
via the generation-time argument seem to
contradict official game information or
deductions that one may make from the rule
books. Despite the figures given for kobolds
in the ?age categories? table, it seems that
they probably reach maturity as quickly as
other humanoid species do, instead of following
the pattern of the demi-human races
as their lifespan of 135 years seems to imply
that they do. Certainly, they need the
advantage of a short generation time, since
they have few other survival advantages.
They might reasonably be expected to reach
young adulthood before the age of 10 (7
years or earlier might be even better), and
then go on to long reproductive lifespans as
well. Their ability to lay eggs may enable
them to have more young more often as
well.

Contrary to the birth tables published in
DRAGON® Magazine #70, and contrary to
indications in the Monster Manual, it is
unlikely that demi-humans will have fewer
children per family or community than
humans do. There are two reasons for this.
The first is that demi-humans will probably
try to make up for their small but significant
losses against humanoids and evil
humans. Though they cannot equal the
growth rates of shorter-lived races, having
few children per generation only makes
matters worse. In terms of game balance, it
does no harm to grant demi-humans greater
fertility, since there is certainly no danger
that they will overrun their rivals. In fact, it
might help to explain how demi-humans
have managed to hold on for so long.

The second reason why demi-humans
might have large families is that they have
longer fertile lifespans in proportion to the
time it takes one of their children to grow
up. A human female might have a reproductive
life as long as 30 years, or about
twice as long as it takes for one of her children
to reach early maturity. A high elven
female, on the other hand, might be able to
bear children throughout a span of 400
years or more, which is at least 4 times as
long as it takes an elven child to reach
young adulthood. Thus, demi-humans can
have more children than humans do and
still spend a smaller fraction of their lives
raising them. Doubtless they will spend
some of this extra effort in providing better
care for the children they have, but even so
they are likely to have at least as. many
children as humans do.

It is likely that the behavior of AD&D
game characters will be influenced by generation
time effects. Paladins, for instance,
might not be reluctant to destroy the apparently
harmless females and young in a
humanoid lair. In fact, such action might
well be regarded as a holy duty, to prevent
the further spread of evil in the world.
Rangers might also demonstrate strong
feelings (and similarly strong actions) on the
subject; to a lesser extent, so might demihumans
of most alignments. Good characters
in general are provided with a more
satisfactory motive than greed or immediate
necessity in their forays against evil monsters.
The more prolific ones, such as humanoids,
must be cut back. The less prolific
monsters might be eliminated entirely, or at
least so reduced in number that they will
not trouble the world for centuries to come.

Ambitious characters of evil alignment
will often associate with or make use of
humanoids. Since humanoids are easy to
replace and are not particularly bright, they
make ideal ?cannon fodder.? (There are no
cannons in fantasy, but the principle is the
same ? ?wizard fodder? might be a better
term.) It is plain to any evil character that
the power of humanoids is ascendant, and it
is foolish not to use such power. A bold and
intelligent individual, slave to no morality
or scruples, can ride the humanoid tide to
victory, guiding and controlling it and reaping
the rewards of conquest. Personal like
or dislike for humanoids has nothing to do
with the matter, since the important thing is
to be on the winning side and in control. If
relationships with humanoids include hate
and fear, so much the better. Such emotions
add spice to an otherwise rather bland and
businesslike arrangement. This point of
view may be shared by evil humans and
demi-humans alike. The drow, who would
be willing to expend cheap humanoid lives
in place of their own, are a case in point.

Of course, evil characters will be contemptuous
of the bulk of demi-humans,
since such races are "obviously" unfit to
survive in a hard world, as is shown by
their retreat before more ?vital? forces. Out
of foolish squeamishness, the demi-humans
have tried to stem the humanoid tide rather
than control it. Evil half-orcs in particular
may be inclined to this point of view. They
Would be particularly eager to give tottering
demi-human groups the final push into
oblivion, thereby deriving much profit and
pleasure from the action as well as greater
safety for themselves and their humanoid
followers.

From a druid's viewpoint, there is nothing
wrong with humanoids as such except
that, like weeds in a garden, they must be
periodically rooted out and cut back, lest
they threaten the Balance of Neutrality with
their numbers. The more dangerous creatures
such as evil dragons must be kept rare
because of their destructive tendencies.
Such corrective action is not needed with
demi-humans, since they are less destructive
of field and forest and are unlikely to
threaten the Balance with uncontrolled
expansion.

Other neutral characters may share the
druid?s point of view; though they may be
more strongly influenced by considerations
of personal gain. Certainly they will deal
with humanoids if this is expedient, but in
general the more foresighted persons will
act to preserve their neighbors and associates
of good alignment in preference to evil
ones. This is not altruism; it is simply more
pleasant and profitable to deal with wellmeaning
and uncommon peoples than with
numerous and aggressive ones. In general,
halflings, elves, or humans of good alignment
are easier to live with than ogres or
goblins. Unless they think the demi-humans
and their allies have no chance, neutral
characters will probably support them in
interracial conflicts.

The effects of generation time can be as
far-reaching in an imaginary world as they
are in the real one. If a DM chooses to take
them into consideration, they can go a long
way toward providing a more detailed and
plausible campaign background.

September 1984

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I would like to congratulate Stephen Inniss on
his excellent article ?Survival is a group effort? in
issue #89. I find the growth and decline of populations
in the AD&D world an interesting topic
and was ecstatic to find an article on this subject.

There is, however, one item which has confused
me about the life spans of different races
which was not answered in the article. This
problem is associated with the levels of fighting
characters who are of various races. The conflict
is with the length of time that a demi-human
character can spend adventuring, as compared to
that of the shorter-lived human or humanoid
characters, this factor then influencing the level of
the character.

Here is an example: Two characters start
adventuring as first-level thieves at the same
time. One is human, the other an elf. Therefore,
both have the advantage of having no limit to the
level of experience that they can reach. The
human starts at age 19, and the elf at age 105
(each starting at the youngest age he can, as
detailed on page 12 of the DMG). After constant
adventuring for 17 years, each character is now
level 12. The human is now age 36, soon ready to
retire from journeying, while the elf, at age 122,
can continue adventuring for centuries more. At
this rate, the elven thief can attain a phenomenal
level of experience in his lifetime.

It is easy to see how the varying life spans can
cause certain problems with the level of character
in a game. How is this problem remedied, so
that there is a balance among the races, and so
the longer-lived beings don?t become too powerful
in their world, or in someone?s campaign?

Eric Herman
Marlboro, N.J.

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