Th e main agricultural challenge in the region was lack
of water. All African farmers had to irrigate their crops, and
they invented elaborate systems to transport water to their
fi elds. In areas with narrow rivers and fl at lands, farmers dug
canals and built dikes to channel and contain water. Every
year large numbers of people worked together to clear canals
of debris and repair damage to structures. In the areas closest
to the sea farmers had to ensure that saltwater did not enter
into their irrigation structures and kill their crops.
In areas where fi elds lay above the level of fl oods, farmers
had to use mechanical systems of irrigation. One irrigation
device was the shaduf, or shadoof, a device that lift ed water
in a container. It consisted of a wooden or stone frame with
a long horizontal pole affi xed to a hinge at its top. A farmer
would tie a bucket or skin bag to one end of the pole and at-
tach a stone or clay weight to the other end. If the device was
balanced correctly, it was very easy for the farmer to lift the
bucket or bag of water from a body of water and swing it over
to an irrigation ditch that fl owed into a fi eld. Although irri-
gating a fi eld with a shaduf was less work than carrying water
by hand, it was still slow and laborious; one shaduf could ir-
rigate about an acre a day.
During the Hellenistic Period two more advanced ir-
rigation devices appeared. One was the Persian water wheel
known as a saqiya. Th is device was a large wheel with buck-
ets attached to its perimeter. An ox or donkey turned it to
raise water from a river or pond and transfer it to an irriga-
tion ditch. Th e Archimedean screw, or Egyptian screw, was
a device that raised water by means of a large screw inside a
pipe attached to an inclined plane. Th e lower end of the screw
was placed in a body of water, and laborers turned the screw
by hand. As it turned, it collected and raised water and then
dumped it out at the top. Both the saqiyah and the Archime-
dean screw were large and expensive devices, out of the reach
of most small farmers. Only large landowners could aff ord to
use them.
AFRICAN CROPS
Africans south of the Sahara domesticated several crops that
are not widely grown in other continents. All the African
grains are annuals, plants that complete their life cycles in
one year. Unlike the grains domesticated in the Near East,
however, African grains all show a strong tendency to cross-
pollinate. Near Eastern grains will pollinate themselves,
which results in seeds that produce off spring just like their
parents, a desirable trait for a crop. African grains will cross-
pollinate with wild grains and produce plants that are very
little like their parents. Th is probably made it much more dif-
fi cult for African farmers to domesticate crops than it was for
people in the Near East and Mesopotamia. Th ey would have
had to grow their crops far away from patches of wild grains
that might contaminate the fi elds.
Th e main African grains were sorghum, pearl millet,
and African rice. Africans also domesticated yams, oil palms,
cowpeas, and groundnuts. Sorghum and pearl millet were
domesticated in the dry areas of the Sahel. Rice and yams
grew better in the wet regions of the forest-savanna border
in West Africa. In Ethiopia people domesticated two unique
grains, fi nger millet and tef. Sorghum is a grass grown for its
grain. People made it into couscous (a grainlike type of pas-
ta) and porridge, which they ate with vegetables and sauces.
Sorghum straw was used as a building material, mixed with
mud to form bricks for walls. Sorghum is highly resistant to
drought, an advantage in the dry climate of the sub-Saharan
region. People were gathering wild sorghum for food about
6000 b.c.e. It was domesticated in the Ethiopian highlands of
Africa around 1000 to 500 b.c.e.
Pearl millet is another drought-resistant grain. It grows
wild in the region, and people evidently started gathering
it more than 8000 b.c.e. It produces small seeds and is cur-
rently grown worldwide both as food for humans and as
fodder for animals. Millet contains about 11 percent pro-
tein, about the same as wheat. It does not rise like wheat,
so it cannot be used to make leavened bread. People gen-
erally grind it into fl our to make into fl at bread or boil it
into porridge. Pearl millet probably was fi rst domesticated
in the southwestern Sahara, in what is now Mauritania and
northern Ghana, around 1000 b.c.e. In addition to making
pearl millet into porridge, couscous, or unleavened bread,
people also used the stalks of the plants for building. Pearl
millet traveled from Africa to India around 1500 b.c.e., and
it became a staple crop there as well.
African rice is very similar to Asian rice. Th e ancestor
of African rice resembles the wild rice of Asia and is closely
related to it. Ancient wild African rice grew in holes in the
ground that fi lled with water during the rainy season and
dried out in the dry season, a similar environment to that
in which Asian rice evolved. African rice became the staple
crop in West Africa, where people boiled it and ate it with
vegetables and meats. African rice was domesticated in West
Africa near the Niger River around 200 c.e.
Yams are tubers or roots that grow underground. Peo-
ple prepare them like potatoes, boiling or roasting the fl esh;
certain substances in yams can cause illness if the yams are
not cooked before they are consumed. A single yam can grow
up to seven feet long and weigh 150 pounds. Th ey have thick
skins and brown or pink interiors. Th ey can be stored for sev-
eral months without spoiling, which made them an attractive
crop for tropical climates, where the heat and dampness of
the wet season quickly spoiled grains. Th ey were especially
common in West Africa.
Oil palms grow in West Africa. People domesticated
them to harvest their fruit, which grows in clusters; each fruit
consists of an oily seed surrounded by oily fl esh. Th ey pressed
the fruit to extract the oil. Palm oil is high in calories and
vitamin K, which made it a valuable addition to African diets.
Animals can eat the meal left over from extracting the oil.
Th e cowpea is a type of bean. Th ere are several varieties
of cowpeas today; the best known are black-eyed peas and
crowder peas. Th e cowpea plant can tolerate drier weatheragriculture: Africa 19