Apples are integrated into Adams County and Pennsylvania culture, economy and history. In fact, they play a large part in the Pennsylvania Farm Show, where they are displayed in the Main Hall and in a dedicated booth in the food court. These booths show just a miniscule number of the 7,500 existing cultivars (plants selected for a specific trait) of culinary and eating apples. Currently, apples are the most popular fruit in the United States, although just 15 types make up 90 percent of apples grown throughout the United States. Collectively, they are called Malus domestica.

The genus malus originated approximately 12 million years ago in southern China (specifically in Chuan Dian Palaeoland), Northern Vietnam and Northern Laos. To be exact, it originated in the Tian Shan Mountains of Kazakhstan in Central Asia and still grows in this location, which is the geographic center for over two thirds of all extant species.

The ancestor of these trees is the Malus sieversii, which was identified by Nikolai Vavilov in 1929 by tracing its genome. These results have been confirmed by more recent DNA testing. However, another theory suggests that the ancestor originated farther south than this region because warmer temperatures were better suited for its growth. The tree adapted to colder climates over multiple millennia and spread northward to Kazakhstan.

However, in order for any seeds to spread in any region, these trees had to find a method of distribution. Fruit dropping from branches would cause saplings to grow too close and cause competition with the parent tree. Therefore, they developed large fruits, which attracted and were eaten by megafauna, such as reindeer, wild horses, woolly mammoths, and wooly rhinoceros, during the last Ice Age. The result was that the seeds were distributed at greater distances, farther than water or wind could carry them. In fact, large-fruiting wild apples, such as Malus orientalis Uglitzk, M. sieversii, and M. sylvestris Mill, display traits that indicate that they co-evolved with megafauna. Specifically, the seed (hard and pear-shaped with a smooth surface) developed to pass safely through the digestive systems of large mammals. Fossil and genetic evidence demonstrate that this size evolved several million years before humans began apple cultivation.

This distribution technique worked. During the advance and/or retreat of the glaciers, plants and trees that were able to spread their seeds further than others survived for a longer time or possibly permanently. Some seeds found glacial refuges, isolated places with a climate still favorable to them. However, when the megafauna became extinct around 12,000 years ago at the end of the Ice Age, apples lost their primary method of dispersal and the area of seed distribution grew smaller.

Inadvertently, humans became the new seed distributors. As farming began at the end of the Ice Age, forests were cleared for planting, and later, existing fields were abandoned or left fallow. As an early successional species, apples began to grow in and around these open spaces.

At this point, human history and agricultural history became intertwined. Although apple seeds have been located in archaeological sites in Asia and Europe, which date to approximately 10,000 years ago, the earliest known cultivation of this fruit happened in the Tian Shan Mountains of Kazakhstan, where Malus sieversii was grown about 1000 B.C.E.

Later, apples were spread east and west along the Silk Road (30 B.C.E. to 1453 C.E.), whether by discarded apple cores or purposeful transportation of seeds and plants. Bees and other pollinators were attracted; different species were cross-bred; hybridization occurred. Also, possibly humans could have crossed these trees with the wild crab apples from the Caucasus and/or Siberia

However, apples were domesticated differently than other crops because they are heterogenous, which means that their genetic traits are not fixed. If a seed is planted, the resulting sapling would not retain its parent’s exact characteristics but would develop its own. A high genetic variability exists, resulting in inconsistencies in fruit.

During cultivation, humans noticed specific desirable traits of the fruit, such as color, firmness, size, sweetness, and texture. These characteristics must be artificially maintained by grafting branches onto a root stock (the base and roots of another tree which has also been selected for its characteristics). The resulting trees have less mutations and selection than wild ones. However, limited natural reproduction occurs.

Evidence exists for grafting in the ancient Near East and China circa 200 B.C.E. Later, the crusaders might have brought this technique into Europe when they returned in the 1200s. The first known literary account of the process in English was written by Leonard Mascall in 1592 with a title that is 12 lines long and begins "A book of the arte and manner how to plant and graffe all sorts of trees."

In summary, the apple has a long and complex history. Genetically, Malus domestica is actually a hybrid of at least four separate species, including Malus baccata, Malus orientalis, Malus sieversii and malus sylvestris, with Malus sieversii providing most of the genetics. Two thousand years of intense and purposeful apple cultivation have created many modern varieties. However, small isolated areas of genetic diversity and late Holocene apple breeding zones remain in the villages in the Karaman region of Turkey and Iran. Culturally, the apple has traveled around the world. It has thrived, since its characteristics appeal to humans. It grows in temperate environments. The fruit became a source of food, especially because it can be consumed in different forms such as eaten fresh, drank as juice, cooked in dishes, and processed for preservation. It is not easily perishable and can be transported over long distances. Overall, it has become a much-loved fruit.

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