seeds, but wild teosinte is not an impressive source of food. It
grows throughout Mexico, Guatemala, and Nicaragua. Th ere
are fi ve diff erent species, some of which are annual (complet-
ing their life cycle in one year) and others perennial (living
several years). Archaeologists believe that two of the annual
spec ie s t hat g row i n t he Tehu ac á n va l le y i n Mex ico were prob -
ably the ancestors of corn. Th e fi rst primitive cobs of what ap-
pears to be domestic corn grew between 2700 and 2600 b.c.e.
near inhabited caves in the Tehuacán valley. Th e inhabitants
were still hunter-gatherers who moved about with the sea-
sons, but they grew a small crop of corn to give themselves a
little food security.
Th is early corn was nothing like the large ears grown
today. It had tiny ears with small kernels and resembled a
modern crop known as Argentine popcorn. Its ears were only
slightly bigger than those of teosinte. Nevertheless, scientists
know this corn was domesticated, because it had kernels that
could not release themselves from the cob; it could be reseed-
ed only when humans removed the kernels and planted them.
Cob sizes increased; between 500 b.c.e. and 1 c.e. cob length
doubled in size.
Corn gradually spread through the Americas. Th e same
small, primitive corn appeared in northern South America
1000 b.c.e., near the Pacifi c coast in Ecuador between 1200
and 800 b.c.e. and along the Orinoco River in Venezuela
about 800 b.c.e. People in the southwestern United States
were growing corn by about 1000 b.c.e. Small-kerneled
corn reached the mountains of Peru by 450 c.e. Corn was
not initially a staple of most peoples’ diets; historians be-
lieve that much of the earliest domesticated corn was used
to brew beer. As the years went by, however, corn provided
an increasingly larger share of the calories of many Ameri-
can diets. Corn can be eaten whole, from the cob, but it was
most important dried, which made it a source of food that
could be stored year-round. People used stone mills to grind
it into cornmeal and made this meal into fl at bread or por-
ridge. Corn is not an especially nutritious grain because it
lacks two essential amino acids (the building blocks of pro-
teins). Early Americans solved this problem by adding ashes
to cornmeal to increase the niacin content and by combin-
ing corn with beans.
Beans form the second component of the trinity and
supplied the protein that corn lacked. Lima beans appear
to have been domesticated fi rst, followed by the beans now
called common beans, which include navy, kidney, and
red beans, among many others. Ancient common beans
evolved into the more than 100 types of domestic beans
known today. Common beans and the lima beans were all
widely cultivated in the Americas long before Europeans ar-
rived. Scientists can tell that the beans were domesticated
because, just as with domesticated corn, these beans can-
not expel their own seeds; humans must do that in order to
plant the next crop. Beans appear to have been domesticated
later than corn. Historians had long theorized that corn and
beans were domesticated simultaneously, but that does not
now seem to have been the case.
Mexican and Andean Americans domesticated lima
beans independently of one another. Historians currently
believe that people in the Andes may have started growing
lima beans around 2000 b.c.e. Earlier research into this area
led to speculation that humans may have domesticated limas
around 5600 b.c.e., but these dates are now considered inac-
curate. Th e Andean lima was a large-seeded variety. It had
spread along the Pacifi c coast of Chile and Peru by about 400
b.c.e. Th e smaller-seeded Mexican lima bean appeared later,
around 800 c.e. Large-seeded lima beans predominated at
higher altitudes, while small-seeded varieties grew at lower
altitudes. Lima beans are high in protein and fi ber; people ate
them fresh or dried them to save for later. Th ey cooked dried
beans by boiling them.
To trace the ancestry of various types of common beans,
scientists have analyzed the protein content of domestic and
wild beans in Mexico, Central America, and South America.
Th ey discovered that common beans were domesticated twice,
in two diff erent places. One type of bean was domesticated in
Mexico, and another type was domesticated in the Andes. Th e
earliest known domestic common beans were grown about
300 b.c.e. in Mexico. Common beans, similar to lima beans,
provided necessary protein to ancient diets, especially when
combined with corn. Common beans keep well when dried,
so people could count on eating them year-round.
Squash formed the third component of the trinity. Hu-
mans cultivated several varieties of squash that still exist to-
day as acorn, spaghetti, and patty pan squashes; pumpkins;
and zucchini. Green and yellow squashes came from the east-
ern United States, and orange pumpkin squashes came from
Mexico. Historians know little about the process by which
humans domesticated squashes. Some experts believe squash
cultivation may have occurred simultaneously with corn cul-
tivation, perhaps around 3000 b.c.e.MESOAMERICAN CIVILIZATIONS
Agriculture facilitated the rise of the great Mesoamerican
civilizations, which built large cities with complex bureaucra-
cies and religions. Th e Olmec lived on the coast of the Gulf of
Mexico between 1500 b.c.e. and 400 c.e. Th ey worshipped a
rain god, a sign that rain was extremely important for grow-
ing their crops. Th e city of Teotihuacán, near modern Mexico
City, was inhabited from 150 b.c.e. to 750 c.e. In its heyday
it was the size of Rome. Its inhabitants also worshipped a
weather deity, a fanged storm god who would release the rains
to grow the crops of corn, beans, squash, and peppers.
Th e Maya, a civilization that lasted from about 1800 b.c.e.
to the 17th century c.e., had a vast empire that encompassed
parts of Guatemala, Mexico, Honduras, and Belize, with sev-
eral regional capitals. Th eir kings and bureaucrats oversaw a
large population of citizens, most of them farmers. To feed
the population, Mayan farmers maintained vast permanent46 agriculture: The Americas