W.W. Farris
The demography of the Jo ̄mon period
In 1978, archaeologist Koyama Shūzō derived population figures for the age of affluent foragers
known as the Jōmon Era. His method for this daring undertaking was as follows: First, he enumer-
ated the total number of archaeological sites throughout Japan as of 1965. This was relatively
simple, as a government agency known as the “Committee for the Preservation of Cultural Treas-
ures” (Bunka zai hogo iinkai) kept updated figures. Second, Koyama established a baseline population
for Japan during the 700s (5,400,000) based on the work of mathematician Sawada Goichi (see
below). Third, he inferred a size for villages in the relatively well- documented Kanto region, and
using an archaeological periodization that included five divisions for the Jōmon period, one for the
Yayoi, and one for the eighth century. He stipulated that the population for the early Jōmon, for
example, was one- twentieth that of the eighth- century figure, while middle and late Jōmon were
one seventh the size of eighth- century villages, and so on. Fourth, he determined the average size
of an eighth- century village by dividing the number of excavated villages into Sawada’s figure for
Kanto population (943,000 divided by 5,549 equals 170). Fifth, he derived the population for the
mid- Jōmon Kanto by multiplying 170 by one- seventh by the number of Jōmon villages (3,977), or
96,000. Sixth, he applied the same method for all five sub- periods of the Jōmon Age to fourteen
regions of Japan ranging from the northern tip of Honshu to the southern edge of Kyushu.
Clearly, both Koyama’s methods and results may be easily criticized. The data he used are
now about fifty years out- of-date. What would a similar calculation look like using current data
on Jōmon villages? It is also unclear how Koyama derived the fractions he employed to infer
Jōmon population from the eighth- century data. Finally, the number he used for eighth- century
Japan may have been too small. For these reasons and undoubtedly many others, students may be
skeptical of Koyama’s calculations.
Still, certain aspects of Koyama’s work ring true. First, his figures show Jōmon population at
20,100 around 8100 bp, 105,500 about 5,200 years ago, 261,300 at 4,300 bp, 160,300 at 3,300
years ago, and 75,800 at the end of the Jōmon period. This rise and fall of population is consistent
with what we know of the gradual spread of a foraging regime, its reaching a height of popular-
ity, and the decline that took place as Jōmon persons found foraging to be more difficult in a
harsher climate.^6 Second, his regional calculations suggested that Jōmon forager occupations suc-
ceeded best in northern and eastern Japan, and poorly in western Japan. For example, the south-
ern Kanto was home to about 71,000 people around 4,300 bp while the Kinai and vicinity had
only about 2,700 persons. These figures correspond well to what archaeologists know about
regional variations during the Jōmon Age. Koyama’s findings, therefore, remain useful and
generally persuasive, at least until another qualified scholar develops a superior methodology.^7
Nevertheless, Koyama’s is not the only noteworthy demographic work on the long- past
Jōmon era. Kobayashi Kazumasa utilized the wealth of skeletal evidence from this time to infer
life expectancy.^8 Altogether, some 5,000 skeletons survive from the Jōmon period, preserved
because bodies were buried in shell mounds in which the basic chemical composition kept Japan’s
normally acidic soil from consuming the bones. Examining 235 skeletons from different Jōmon
sub- periods, Kobayashi determined that 133 were adult males and 102 were females. Kobayashi
suggested that his sample did not show much variation by period, and argued that men lived to
about 34 and women to 24. Kitō has argued that the difference was due to premature death in
childbirth, but nobody knows for sure. Almost half the individuals in the sample died in their
twenties, and few lived to fifty. Finally, this short lifespan encompassed only those who lived
beyond fifteen. When the whole population is averaged in, life expectancy at birth for both men
and women was only 14.6 years. In other words, during the so- called age of “affluent foragers,”
the population was just barely able to reproduce itself.