The Adena were a prehistoric farming society in North America who left evidence of their lives in the mounds they constructed.

The Eastern Woodland period, which began around 1000 b.c.e., was characterized by several developments, the most notable of which was the introduction of an early form of agriculture. The Adena were an Early Woodland people who lived around the Ohio River Valley from about 1000 b.c.e. to 100 c.e. Evidence of Adena settlements has been found in Ohio, Indiana, Illinois, West Virginia, Kentucky, New York, and Pennsylvania. The Adena lived in an environment of dense forests, rich with game and foraging foods, drained by numerous rivers and streams. The weather changed significantly during the year from cold, harsh winters to hot summers. However, the length of the growing season, the rich soil, and ample rainfall proved well suited for farming.

The Adena are most noted for the hundreds of earthen effigy mounds they left behind. These large hills varied in size from a few feet to hundreds of yards across and hundreds of feet tall. Most Adena mounds are circular, but some were constructed in geometric and animal shapes, and others were surrounded by moats, walls, or embankments. The most famous of these and one of the longest, the Serpent Mound near Cincinnati, Ohio, is a series of mounds, 20 feet (7 meters) wide and 5 feet (nearly 2 meters) tall, that stretch almost a quarter of a mile (nearly half a kilometer). From the sky, the mound appears to be an open-mouthed snake.

Thousands of mounds once dotted the Ohio River Valley. Over the years, many were destroyed, cleared away by early nonnative farmers or raided by the curious. Hundreds remained, however, and both professional and amateur archaeologists have excavated many of them. Through the examination and study of the artifacts found inside, archaeologists and anthropologists have learned much about the foods the Adena ate, the clothing and jewelry they wore, the tools they used, and even how they may have worn their hair.

A great deal of labor and organized community effort was used to construct the mounds. The Adena moved thousands of tons of earth to the sites using only woven baskets to carry the soil. The mounds were constructed for various purposes. Some were dumping places for tribal garbage. Some mounds are believed to have had religious or ritual significance, and celebration headdresses and masks were unearthed from small interior dwellings that were possibly ceremonial rooms or buildings. The mounds might have begun with a round dwelling house that was converted into a mortuary.

Most Adena mounds were used as burial sites for the dead and contain human and animal remains along with various grave goods, including copper beads and bracelets, carvings on stone tablets, river pearls, mica, weapons, tools, cooking utensils, and pipes. Some pipes, weapons, and bowls were decorated with carvings of animals and humans. The human remains have provided scientists with clues as to the age, sex, and size of the Adena; when they died; and the causes of their deaths. Bodies of some of the dead were cremated before their ashes were placed in the mounds. Others were cached in hollow tree trunks or logs. Several graves contained small vaults constructed of wood or bark. A few of the bodies were decorated with headdresses, helmets, bracelets, pendants, and rings. Bodies dating to the end of the Adena era, c. 100 c.e., have been found sprinkled with powdered ocher derived from a red clay in the area that was also used to decorate pottery.

Some mounds were not completed after the first group of remains was interred. They contained multiple layers and dozens of bodies buried over many generations. The bodies were interred, sealed, and covered with another layer of earth. By excavating the mounds in horizontal slices, anthropologists have been able to track the progression of Adena culture over the years, revealing that as the centuries passed, the Adena developed more advanced tools and weapons, produced more refined jewelry, and made advancements in agricultural methods.

The Adena were some of the earliest Native American farmers. Cultivation may have begun when tribal people stuck seeds or nuts from foods they already gathered into the ground. If they bore fruit, the people planted more in areas closer to their villages. Agriculture supplemented the diets of the Early Woodland people rather than acting as their main source of nutrition. The Adena diet included hazelnuts, walnuts, and hickory nuts. They also appear to have eaten grown sunflower and goosefoot seeds, raspberries, strawberries, knotwood, and grapes. Toward the end of the period, there is evidence that the Adena were planting the corn and squash that would later become staples for many Eastern American tribes.

The Adena continued to hunt and gather to supplement their diet. Many different animal bones were found in the mounds. Evidence suggests the Adena hunted deer, bear, elk, wolf, and small game such as raccoon, squirrel, and beaver. Fish and wild birds such as turkey, duck, and grouse were also a part of their diet. The Adena broiled or grilled their food over an open fire or boiled it in leather or wooden containers. Meals were eaten from wooden or stone bowls. Gourds were dried and used as bowls and spoons as well as eaten.

Hunting tools included spears with pointed flint blades and stone knives for cutting and scraping. Spearheads were sharpened to a point by chipping away at flint with knife blades or other stones. Hides from hunted animals were used for clothing and blankets. Evidence indicates the Adena wove and twined local grasses for mats and sandal-like footwear.

The Adena lived in small, semipermanent villages. They used lumber from the forests around them to construct circular wooden homes. The outside walls were erected with sunken wooden tree posts that were pointed outward to support the roof. The outside walls were covered with bark or long, thin sticks interwoven into wattle for support and insulation. The conical-shaped roof was also constructed of wooden poles and covered with slabs of bark. Each home was approximately 18 to 40 feet (6 to 12 meters) in diameter.

Pottery was found in a number of mound sites. Some anthropologists believe the Adena were one of the first tribes in the eastern United States to make pottery. Pottery was made from carved stone or clay that was abundant in the area. Clay was gathered from nearby creek beds, formed into bowls and pots, and dried in the sun. Many vessels were decorated with geometric and animal shapes. Serpent decorations were found carved into bowls and pipes and painted on pottery. Pottery was used for cooking and storing food and as eating utensils.

Evidence suggests that the Adena traded extensively with other tribes, including tribes hundreds of miles away. Grizzly bear teeth and obsidian from the Rocky Mountain region were found in the burial mounds along with copper from north of the Great Lakes and seashells from the coastlines of both the Atlantic Ocean and the Gulf of Mexico.

It is not known why the Adena civilization disappeared. Somewhere around 100 c.e., the Adena may have dispersed or been driven away to other regions. They may have merged with the Hopewell tribe, another mound-building Eastern Woodland group that later occupied the same areas of the Ohio River Valley. The Hopewell constructed more refined metal tools and ornamentation and produced mounds that were even more elaborate than those of the Adena. However, the artifacts the Adena left behind in the mounds they constructed provided future generations with vital clues about their culture and way of life.

• Ceram, C. W. The First American: A Story of Native American Archaeology. New York: Harcourt, Brace, Jovanovich, 1971. Describes mounds and the artifacts that have been found in them.
• Jennings, Jesse D. Ancient Native Americans. San Francisco: W. H. Freeman, 1978. Provides information on the Adena way of life. Bibliography and index.
• Kennedy, Roger G. Hidden Cities: The Discovery and Loss of Ancient North American Civilizations. New York: Free Press, 1994. Describes Native American architecture, its excavation, and prominent theories.
• Silverberg, Robert. Mound Builders of Ancient America: The Archaeology of a Myth. Athens: Ohio University Press, 1968. Maps and details the excavation of mounds.
• Webb, William S., and C. E. Snow. The Adena People. Reprint. Knoxville: University of Tennessee Press, 1988. A classic study of the Adena originally appearing in 1945.
• Woodward, Susan L. Indian Mounds of the Middle Ohio Valley: A Guide to Adena and Hopewell Sites. Newark, Ohio: McDonald & Woodward, 1986. A brief but valuable guide, including a bibliography.