Sacred Trees and Enclosed Gardens j 8787 87
sheep, and goats. They also irrigated their fields and grew wheat, barley, and lentils. At
the same time, they must have been exploiting wild date palms, which would have been
abundant along the river banks^5 Wild date fruits contained less pulp and sugar, and were
drier and pithier, than later domesticated varieties. During domestication, farmers prob-
ably selected from wild populations those trees producing sweeter, more succulent dates,
and planted them in separate, irrigated orchards. Obviously, whole trees could not be
uprooted, so a means of propagation had to be employed that would preserve the tree’s
desirable traits.
Date palms can reproduce either sexually by seed or asexually by offshoots sprouting
from the base of the trunk. Ubaid date growers undoubtedly were selecting female trees
from wild populations based on the quality of their fruits. However, orchards grown from
seeds would have yielded equal numbers of males and females, defeating efforts to cultivate
only the best fruit- bearing trees. This probably led to the practice of asexual propagation by
means of offshoots. In fact, if the offshoots are not removed, they tend to grow horizontally
around the main trunk, producing a spreading multitrunked tree. Because the trunks are
effectively competing with each other, the multitrunked growth forms are less productive
fruit bearers than single- trunked trees. Wild and feral date palms tend to produce fewer
offshoots, and reproduction is mainly by seed. However, cultivated varieties produce abun-
dant offshoots that must be removed. The practice of offshoot removal probably led to their
use in propagating female trees producing the best fruits. Asexual propagation not only
made it possible to plant orchards consisting only of female trees, it also shortened the time
to maturity. Seed- grown trees typically take seven years to bear fruit, whereas trees grown
from offshoots bear fruit in less than five years.
If the early date palm cultivators had excluded all male trees from their orchards, they
would soon have discovered that the female trees failed to produce fruit, an observation
that eventually would have led to the development of the technique of artificial pollination.
How long might it have taken the first wild date palm cultivators to produce the domes-
ticated variety? Assuming that date palm domestication involved selecting for roughly a
hundred gene mutations (a conservative estimate based on the many phenotypic differences
between wild and cultivated varieties), full domestication probably took hundreds, if not
thousands, of years. Thus, it is likely that the date palm growers of the Ubaid period began
selecting for desirable traits quite early. Consistent with this theory, the archaeological evi-
dence suggests that heavy exploitation of wild date palms in the Persian Gulf region may
have begun as early as 5500 bce, corresponding to the beginning of the Ubaid period in
Southern Mesopotamia.^6Uruk and the Urban Revolution
The Ubaid period ended around 4000 bce, and a new archaeological phase called the Uruk
period (4000– 3000 bce) began. Uruk is the ancient name of the city of Warka (the biblical
city of Erech). Founded early in the Ubaid period, it was sited on the same branch of the
Euphrates River about 75 miles north of Eridu. However, Uruk was larger than any Ubaid
settlement. Estimates of its size range from 300 acres to nearly 500 acres, and it may have
housed as many as 50,000 people. It functioned as an independent city- state, in competition
with other neighboring city- states, such as Nippur.