Farming, from Ancient to Zoo - National Zoo| FONZ

Farming, from Ancient to Zoo
A Glimpse into Farming History at the Kids' Farm

By Shannon Lyons and Emily Huhn
July/August 2004

kid's farm barn at the national zoo:http://nationalzoo.si.edu/Publications/ZooGoer/2004/4/kidsfarmside.cfm

Kids' Farm at the National Zoo houses cows, goats, donkeys, chickens, and ducks. (Jessie Cohen/NZP)

Insects have been farming for tens of millions of years, cultivating fungi and managing herds of aphids and mealy bugs. Humans, on the other hand, are relative latecomers to the farming scene. Scientists estimate that people in the Fertile Crescent region of Southwest Asia began domesticating plants and animals around 11,000 years ago, although we may have been "proto-farming," or managing wild plants and animals, as far back as 40,000 years ago.

In that short time we've raised farming to an incredible level of sophistication. To date, human farmers have domesticated about 40 animal species and several hundred plant species; invented machines that can sow, tend, and harvest massive crops efficiently; and manipulated the genes of plants and livestock to make them disease-resistant, tastier, and higher-yielding.

The animals and plants on exhibit at the Smithsonian National Zoo's new Kids' Farm, from goats to green peppers, are a testament to our reliance on farms for food. They're also a reminder of how domestication has shaped and been shaped by human societies for millennia.

Nigerian dwarf goat at Kids' Farm. (Jessie Cohen/NZP)

Goats
Of all the animals at Kids' Farm, the ancestors of the goats (Capra hircus) were among the first to be domesticated. People hunted wild adult goats in the highlands of present-day Iran long before the Neolithic period began. Hunters targeted adult goats because they were larger than their young counterparts, and so yielded more meat. But goat bones found at the Ganj Derah archaeological site in Iran indicate that around 8000 B.C.E., people began to slaughter male goats at a younger age, while keeping females and a few males alive longer so they would breed and produce a herd. Melinda Zeder, a curator at the Smithsonian's Museum of Natural History, and Brian Hesse of the University of Alabama at Birmingham, studied the bones and say they are evidence that humans began to shift from hunting goats to herding them, using a technique of selective killing that farmers still practice today. Moreover, the herders' reliable source of goat meat enabled them to expand to new areas, and they introduced goats to the lowland regions of Iran. Not only did hunting subside as herding grew, but the goats literally chewed through, and altered, lowland plant communities.

Domestic goats were also present in ancient societies in China and India, and are used for meat and milk around the world. The Kids' Farm goats—two Nubians and two Nigerian dwarfs—come from northeast African and West African breeds, respectively.

Wheat and Kids' Farm's Pizza Garden
Kids' Farm features a pizza garden in which plants used for pizza ingredients are grown. One such plant is wheat (Triticum spp.), which, like goats, was probably first domesticated in the Fertile Crescent about 10,000 years ago. Long before then, wheat made its mark on humanity: Hunter-gatherers had been collecting and storing wild wheat seeds for consumption throughout the year, which enabled them to settle into permanent villages instead of roaming nomadically in search of food.

Domestic wheat.

In his 1997 book Guns, Germs, and Steel, Jared Diamond explains that a genetic mutation was responsible for the domestication of wheat. Wild wheat grows on stalks that shatter when their seeds are ripe, thus scattering them on the ground. But a mutated gene caused some wheat stalks not to shatter, and humans could easily harvest ripe seeds from these stalks. They then planted the seeds and propagated the genetic mutation, which would otherwise have been an evolutionary deadend for a plant that relies on scattering its seeds to reproduce. Thus, wheat changed humans by giving them the means to quit roaming, and humans changed wheat by cultivating a mutation that could only survive with their assistance.

According to Diamond, "...the earliest known cultivated emmer wheat comes from the Fertile Crescent around 8500 B.C. Soon thereafter, the crop appears progressively farther west, reaching Greece around 6500 B.C. and Germany around 5000 B.C." Wheat was a staple food to ancient Egyptians, and to Romans who imported it from around their empire. It was a rich man's grain in the Middle Ages in Europe because it was too expensive for the commoner to use undiluted in his bread. The Spanish brought wheat to North America and began growing it in Mexico in 1529, and today the United States is one of the world's leading wheat producers.

Cattle and Kids' Farm's Cows
Both of the Kids’ Farm cows, a Holstein-Friesian and a polled Hereford—and, in fact, all modern domesticated breeds of cattle—likely descended from wild ox-like animals called aurochs (Bos primigenius) that once roamed over large areas in Asia, Europe, and North Africa.

Clues about the origins of cattle domestication first came from the archaeological record. The distinction between wild and domesticated animal remains is not always clear, but scientists looked for groups of bones with characteristics suggestive of life in a tended herd. For example, cattle from a domestic herd were more likely to be of similar age when slaughtered than wild varieties, and groups of males were more likely to be killed than offspring-producing females. And, like many other domesticated animals, cattle became smaller after several generations of domestic life.

Most scientists have long agreed that aurochs were first domesticated 8,000 to 10,000 years ago, and the archaeological record shows the Fertile Crescent of the Near East to be a major domestication center. But a question remained: Were cattle domesticated just once in the Near East before expanding into Europe and Africa, or were they domesticated independently in different locations?

This Holstein-Friesian hiefer is one of two cows at Kids' Farm. The cows are washed daily with help from visitors. (Jessie Cohen/NZP)

Conventional wisdom held that African, European, and Indian cattle descended from aurochs domesticated in the Near East, from which two types of cattle, the humped Bos indicus and the humpless Bos taurus, evolved subsequent to domestication. The two cattle types are named as separate species, but their taxonomy is still debated, and some scientists argue they should be classified as subspecies.

However, recent DNA evidence suggests that cattle evolved into different types before they were domesticated. The authors of 1994 and 1996 papers in the Proceedings of the National Academy of Sciences believe Indian cattle diverged about 200,000 years ago and formed a genetically distinct group (B. indicus). Long before Near Eastern cattle were domesticated, the remaining group split again about 25,000 years ago into two groups that are the forebears of African and European cattle.

The data suggest that not all modern cattle breeds are descended from Near Eastern cattle, and that there was not a single original domestication event. Rather, cattle were independently domesticated in what are now India and Pakistan, in the Fertile Crescent, and possibly in Africa.

European cattle are most likely related to those domesticated in the Fertile Crescent. However, the origins of African breeds appeared a bit more complex. While African cattle share some genetic traits with European cows that correspond most closely with B. taurus, many of today’s African cattle look more like humped B. indicus. It is possible that European and African cattle originated as two separate lineages that eventually interbred.

In 2002, scientists proposed that African cattle stem from the domestication of a B. taurus type of auroch that lived in northern Africa when the Sahara was much less dry and arid than it is today. Based on genetic analysis and mapping, they reported in the journal Science that the number of B. indicus genes detectable in modern African cattle peaked on the east coast of Africa, suggesting that large numbers of B. indicus may have been imported to Africa by sea from South Asia. In fact, the cattle with the most pure B. indicus genes live on the island of Madagascar, further supporting the idea that B. indicus cattle came to Africa by sea. Since they arrived, Indian cattle genes have spread throughout the African continent.

Jared Diamond, author of the 1997 book Guns, Germs, and Steel, supports both genetic divergence and dual domestication: “…genetic analyses show that the ancestors of modern Indian and western Eurasian cattle breeds diverged from each other hundreds of thousands of years ago, long before any animals were domesticated anywhere. That is, cattle were domesticated independently in India and western Eurasia, starting with wild Indian and western Eurasian cattle subspecies that had diverged hundreds of thousands of years earlier,” he says.

In order to trace cattle ancestry, scientists compared mitochondrial gene sequences from hair follicles and blood samples of modern cattle. Because scientists know the rate at which certain DNA sequences mutate, studying the accumulation of mutations in cattle DNA samples helps them create a timeline from which they can estimate the point when ancestral lines diverged from one another. Gene sequences can also help illuminate how herds may have spread outward from domestication centers.

Scientists believe that cattle divided into different genetic lineages before their domestication. (USDA)

Now extinct, remnant populations of wild European aurochs existed until 1627. Curious about whether the wild aurochs of Europe interbred with domestic cattle that came from the Near East, scientists studied DNA sequences from four auroch bones discovered in Britain that were between 3,000 and 8,000 years old. In 2001, they revealed in Nature that while the British auroch sequences were closer to that of B. taurus than to B. indicus, they were very different from modern domesticated European cattle. This showed that wild aurochs roaming Europe did not interbreed with domestic cattle and supports the idea that the ancestors of European cattle were imported from the Near East. As Daniel Bradley, a coauthor of the study, explains in Natural History Magazine, “Today, a British cow’s mitochondrial genes are much more similar to the genes of a cow—ancient or modern—from Syria or Turkey, than to the genes of the wild ox that used to roam the island.”

By 3000 B.C.E. domestic cattle were firmly established in ancient Egyptian farming, religion, and culture. Egyptian tomb paintings depict cattle as sources of meat and milk and as beasts of burden working in fields. The Egyptian cow goddess Hathor was a powerful deity: She was a symbol of creation, motherhood, love, and thought to be the guardian of the dead.

Domestic cattle are versatile animals. Their milk and meat have fed humans for millennia. Their dung has been used for fuel and even as money, and their manure is still a major fertilizer of the world's crops. As plow animals, they have enabled people to farm land that would otherwise be unusable, and have thus helped spread agriculture to far-flung places. One such place is the American West, where cattle, which were introduced to North America by Spanish explorers, gave rise to ranching, cowboys, and range wars. Their worldwide popularity has not been without consequence, however. Millions of acres of tropical rainforest are cleared each year to make way for cattle to graze.

Kids' Farm
A stroll through Kids' Farm unravels the fantastic history of several other important domesticated animals and plants. At the Caring Corral, visitors can help care for the goats and four miniature Mediterranean donkeys (Equus asinus), whose ancestors were first domesticated in Egypt around 4000 B.C.E. for transportation and field work.

Kids play on a giant foam pizza at Kids' Farm. (Jessie Cohen/NZP)

Chickens and ducks are among the world's most abundant domesticated animals and have provided meat, eggs, and feathers to humans. Kids' Farm has six varieties of chickens (Gallus gallus). According to a 1996 paper in the Proceedings of the National Academy of Sciences, DNA evidence suggests that red jungle fowl from Thailand are the matriarchal origin of all domestic chickens. But there is some question as to whether they were first domesticated in Thailand. The earliest remains of domesticated chickens, which date to about 7,500 years ago, were found in northeast China along the Yellow River, and other remains have been found in Pakistan, the Ukraine, and Spain. The three varieties of ducks (Anas spp.) that inhabit the Kids' Farm duck pond are descended from mallards that were domesticated in China or Southeast Asia about 2,000 years ago.

At the Pizza Garden, plants such as onions, green peppers, and tomatoes grow. Each is an example of how humans have adapted plants to meet their needs. At the giant 22-foot foam pizza playground, kids can climb through a humongous olive—the first fruit to be domesticated, in the Mediterranean in 4000 B.C.E.

One of the most important lessons of Kids' Farm is that farming is hard work. The first farmers struggled with their newfound opportunities and were in some places "...smaller and less well nourished, suffered from more serious diseases, and died on the average at a younger age than the hunter-gatherers they replaced," says Diamond. But they persevered. At first they supplemented their hunts and foraging expeditions with small amounts of domesticated foodstuffs, but it took thousands of years of experimentation and accidental discovery for farming to become our primary source of food. Along the way, it shaped our destiny.