Anthropocentric Trophic Webs:
Plant & Animal Domestication in the New World
What happened? The Long-Term Effects of Plant & Animal Domestication:
o Hunting-Gathering (foraging) way of life has almost completely
disappeared
99% of humankind’s existence has been as hunter-gatherers
Humans were tied to the seasonal cycles of plant availability, animal
movements, and the ebb and flow of aquatic resources

Human populations have expanded enormously
Human population on Earth will reach 7 billion in 2011
Roughly 1.3% annual growth; 400,000 babies born each day
World human population is projected to reach 9-10 billion by 2050
o Complex, hierarchical societies have come to dominate the world
Egalitarian and Chiefdom-level societies, with simpler forms of economic, social and
political organization, are now fairly rare
* Domestication involved the creation and maintenance of mutually interdependent
relationships between plants, animals & humans *
Thousands of plant species and numerous animal species have been
domesticated over the past 10,000 years in both the Old World & the New World
Only a few, though, have become major staples
Old World
Goats, wheat,
sheep, cattle, rice
New World
Maize (Mesoamerica),
potato (S. America)
How did plant domestication occur? What strategies did people use?
The process: Artificial Selection for:
o Plants that were more productive & palatable
o Plants that were more tolerant of greater extremes in temperature & soil
quality
o Animals with more meat, more wool, were more resistant to disease, had
more docile temperaments
Slow, very gradual transition from hunting-gathering lifestyle to a fully
agricultural lifestyle o At least 2,000 year transition period in the Near East
o It took 4-5,000 years to complete the transition in Mesoamerica
Why? Because many generations of selective breeding were necessary in order
for wild species to become significantly more useful than wild foods
Domestication of plants and animals is still on-going: “genetically-engineered
foods,” pure-bred horses & dogs (American Kennel Club/AKC-registered)
Plant domestication probably began to occur by enhancing the productivity of
wild plants.
Julain Steward, who is widely credited with developing the concept of Cultural
Ecology, observed Paiutes of the Great Basin in Nevada (H-G group) irrigating
fields of wild sunflowers (Helianthus bolanderi), goosefoot (Chenopodium spp),
sage (Salvia columbariae), and wild rice (Oryzopsis hymenoides).
Domestication Strategies:

Mutant forms (those with favorable mutations, of course) – isolated from
other wild plants & then planted together with other mutant forms having
those desirable characteristics in order to cross-breed these plants
 “Seedbed selection” – where plants that germinate & grow more slowly
are weeded out from wild crops, as at Guilá Naquitz, Mexico.
Sites with evidence of very early plant domestication:
Guilá Naquitz – dry cave in Oaxaca, Mexico
Excavated in 1960's by archaeologist Kent Flannery
o 6 separate human occupations, 10,750-8,600 BP
o First plants domesticated there – squash (Cucurbita pepo) - 8,9906,980 BP: rinds thicker, stems bigger than in wild specimens; seeds rich
in complex plant starches, probably used also as containers (we’re prepottery here)
o Corn remains at Guilá Naquitz: pollen – 8,800-7,500 BP; cobs 6,300
BP
o Seasonal occupation of cave by mobile hunting-gathering
microbands; variety of both wild plants and animal consumed
Tehuacán – highland valley northwest of Guilá Naquitz
Multidisciplinary field project conducted in 1960’s by Scotty MacNeish
o Excavations at 12 rockshelter & cave sites in valley
o Earliest maize cobs (direct dating of cobs themselves) – 5,500 BP;
maize probably introduced to Tehuacán Valley from elsewhere in
Mexico, possibly the Rio Balsas region (see below)
o Over 24,000 maize specimens recovered from Tehuacán Valley caves
o Earliest cobs – 2” long – could not disperse their seeds naturally
(without human intervention), a clear sign of domestication
o By 8,000-7,000 BP avocados were being cultivated in the valley;
evidence: increased size, change in seed shape from round to eggshaped
o Wild beans probably domesticated by 6,000-5,000 years ago
Xihuatoxtla rockshelter – Rio Balsas region of West Mexico, state of
Guerrero. Recent investigations by Dolores Piperno and colleagues
(2009 PNAS)
o
Maize determined to be present here by 8,700 BP. This is the
earliest date for domesticated maize discovered to date.
o Phytoliths (plant silica) recovered from 19 grinding stones and 3
chipped stone tools during starch grain analysis. Maize found to be
dominant starch grain type on every tool, accounting for 90% of all
grains recovered
o
Phytoliths from domestic squash (Cucurbita spp.) were recovered
from both sediments and stone tools in every layer, again including the
Early Archaic and Paleoindian layers.
Maize (Zea mays)







Perhaps the best known example of artificial selection among
domesticated plants
THE major staple crop for most native North Americans and
Mesoamericans
Probably derived from teosinte (Zea mexicana), a tall, annual grass
native to Mexico. Teosinte is now widely believed to be the wild
progenitor of maize. Teosinte means “mother of corn” in Nahuatl,
language of the ancient Aztecs (Mexica) and other indigenous peoples
in the Basin of Mexico.
Tripsacum (Zea tripsacum) a relative of maize distributed throughout
North & South America - not as closely related genetically to maize as
teosinte, but when crossed with teosinte it resembles some of the
oldest maize specimens found in archaeological contexts
Where was maize first domesticated? Researchers are still debating
this important point, as it is clear from cob shapes from the Oaxacan
and Tehuacán sites that some evolution had already occurred by the
time maize reached these areas of Mexico. It may have originated in
Guerrero in the Central Balsas region (see above)
Maize used in the southwestern United States by about 3200 years ago,
and in eastern United States beginning about 2100 years ago. By 700
AD, maize was well established up into the Canadian shield. DNA
studies suggest that purposeful selection for various traits continued
throughout this period, leading to the wide variety of species today. For
example, 35 different races of maize have been identified in
precolumbian Peru, including popcorns, flint varieties, and varieties for
specific uses, such as chicha beer, textile dyes, and flour.
The importance of maize domestication cannot be underestimated.
"This was indeed the most crucial step along the road leading to the
great precolumbian civilizations" (Micahel Coe and Rex Koontz
2002:33). These authors are talking about the Olmec, Maya, Zapotec,
Aztec and other complex societies that developed in Mesoamerica, not
to mention those in North America, such as the Mississippian
chiefdoms, like Cahokia, and the Anasazi and Hohokam, in Four Corners
region and Arizona, respectively.
Other important plants domesticated in the Americas:
o Beans (numerous varieties)
o Chile peppers (yes, the red hot kinds)
o Cacao (favored chocolate drink of Maya nobles)
o Sweet potatoes (delicious anytime)
o White potatoes (many, many varieties) NOTE: most varieties of potatoes
belong to a single species, Solanum tuberosum, about 10 other Solanum species
have been cultivated, and 200 wild species have been recorded
Other notables - cotton, manioc, tobacco, tomato, vanilla, pumpkin, cashew,
peanut and agave
“We no longer think of the preceramic plant collectors as a
ragged and scruffy band of nomads; instead, they appear
as a practiced and ingenious team of lay botanists who
knew how to wring the most out of a superficially bleak
environment.” KENT FLANNERY