388 
There is a fourth region of the same 
type in eastern North America, which 
is comparable in extent. But, since it 
has been accessible to civilized man 
for only a few generations, it is not yet 
fully occupied; and it carries only the 
moderate population of about 130 
millions on a little less than 2 million 
square miles of land. 
Nowhere else on the earth is there 
any similarly large mass of dense popu- 
lation; though the island of Java is as 
densely peopled as England, and parts 
of West Africa have more than 40 in- 
habitants per square mile. In other 
regions there are a few dense clusters 
on small areas around large cities, es- 
pecially in South America and Aus- 
tralia. But outside the four great 
populous regions which have been 
noted the remaining six-sevenths of 
the available land is very thinly 
peopled. 
Tassie 3.—The four major human regions 
Area in Population 
Continuous habit- caus Central 
able region square U Per | latitude 
mites | gmt, | square 
Buropeseeisee: 2.8 | 520 186 | 50°N 
Eastern North 
America.... WAY |) EKO 52 | 40° N 
IOP IBRISES ooo oe fo S008 e292, Ss 5caNi 
India? ss fee orn. 1.0 | 400 400 | 25°N 
Next we may briefly consider the 
reasons for this, at first sight peculiar, 
distribution. Rather more than three- 
fourths of mankind dwell in the Old 
World, by which is meant that part of 
the earth which has been accessible to 
civilized men during all the historic 
period, in contrast to the New World 
which has been similarly accessible 
only since the Age of Discovery at the 
end of the fifteenth century. The Old 
World, as thus defined, includes most 
of Asia, Europe, and Africa north of 
the Sahara, and nearly half of the 
available land. 
Over this vast area the population is 
in fact distributed in general accord- 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
ance with the food-producing capacity 
of the various regions. The fertile 
areas are densely peopled—the barren 
lands are comparatively empty. All 
the oases of the deserts are, or have 
been, occupied; and many of them are 
crowded. By a process of trial and 
error, which has already extended over 
some thousands of years, men have suc- 
ceeded in establishing themselves in 
all the parts of these lands which can 
be made to provide subsistence. 
Though the knowledge and equip- 
ment gained by Western civilization 
in the last two centuries has made it 
possible to utilize lands which could 
not be occupied by civilized man be- 
fore, as for instance in Siberia, yet the 
general adjustment of population to 
natural resources in the Old World is 
the best available guide to the possi- 
bilities of maintaining any compara- 
ble masses of population in the newer 
lands of the earth. 
Elsewhere ® I have estimated the 
extent of the cultivable land of the 
world at 30 percent of the total land 
area, i. e., about 16 million square 
miles or 10,000 million acres. Hence 
I assume in the rest of this address 
that that area, less than a third of the 
available land, is cultivable. Another 
30 percent may be classed as produc- 
tive but not cultivable; and the rest 
(40 percent) is occupied by the deserts 
(cold and dry). (See fig. 2.) 
The productive but uncultivable 
third of the land is mainly divided be- 
tween areas of forest and poor grazing 
land, such as the mountain and hill 
pasture of northwest Europe and the 
semiarid range or bush of North 
America and Australia. The wetter 
areas of this land are often suitable for 
forest; so are some considerable areas 
on the margins of the tundra, where 
the hardier conifers can grow although 
the lack of sufficient summer heat 
prohibits agriculture. The semiarid 
regions, and the summer pastures of 
the tundra and the high mountains, 
are likely to remain grazing lands. 
15 Geographical Journal, December 1930. 
