The Origins of Fruits, Fruit Growing, and Fruit Breeding
from http://hort.purdue.edu/newcrop/origins%20of%20fruits.pdf (excerpt)

Jules Janick, Department of Horticulture and Landscape Architecture, Purdue University

I. INTRODUCTION

In the late Neolithic and Bronze Ages between 6000 and 3000 BCE, the ancient Mediterranean fruits (date, olive, grape, fig, sycomore fig, and pomegranate) were domesticated (Zohary and Spiegel-Roy 1975). Fruits such as citrus, banana, various pome fruits (apple, pear, quince, medlar) and stone fruits (almond, apricot, cherry, peach, and plum) were domesticated in Central and East Asia and reached the West in antiquity. A number of fruits and nuts were domesticated only in the 19th and 20th centuries (blueberry, blackberry, pecan, and kiwifruit). Some well-known fruits, although extensively collected, remain to be domesticated such as lingonberry, various cacti such as pitaya, Brazilnut, and durian. This review will consider the various technologies inherent in the origins of some well known fruits emphasizing factors that led to domestication and the genetic changes that ensued.

A. The Origins of Agriculture

Although precise origins are obscure, the first archeological evidence for a developed agriculture is found in Mesopotamia and shortly after in the Nile and Indus Valleys. Evidence suggests a later development in China, Central America, East and West Africa and, perhaps, New Guinea (Diamond 1997, 2002). In the Mid-East, the change from scavenging, collecting, and hunting to agriculture that occurred about 10 to 12 thousand years ago is rather sudden. Taking into consideration the long history of mankind, the term Neolithic Revolution has been coined for this "rapid" transformation. The domestication of crops was preceded by animal domestication with Nomadism the link between animal agriculture and farming. The first crops domesticated in the Middle East include cereals, such as barley, emmer, and spelt, and pulse crops such as sesame and lentil. Cereal and pulse culture require a number of technologies, including land preparation, planting, harvesting, threshing, and seed storage, that form the basis of crop agriculture.

The enormous morphological changes that can occur with selection associated with domestication is wonderfully apparent with the myriad breeds of dog, all shown to be domesticated from the wolf, and the changes in Brassica oleracea (broccoli, Brussels sprouts, cabbage, cauliflower), and Beta vulgaris (table beet, sugar beet, and chard).

B. Origins of Fruit Culture in the Fertile Crescent

Childe (1958) proposed that a second Neolithic Revolution coinciding with the Bronze Age occurred between 6000 and 3000 BCE involving the change from villages to urban communities. The evolution of urban centers is associated with the development of a settled agriculture. This coincides with the beginning of fruit culture, which involved a long-term commitment to a unique piece of ground. In the case of the date and olive, a fruit orchard can remain productive for over a century. It is fruit culture that bonds humans to a particular piece of land and may be a link associated with the concept of territoriality, the development of city-states, and eventually nationhood.

Information on the ancient origins of fruit culture comes from archeological remains of fruit, and from pictorial and literary evidence. The high culture of Mesopotamia and Egypt produced a rich art in which fruit is a common motif. A trove of paintings and sculpture is found in Egyptian tombs and monuments. The Sumerian discovery of writing in the 3rd millennium BCE, and Egyptian writings somewhat later, inaugurated the literary tradition that survives today as a result of the near indestructibility of the baked clay tablets used for cuneiform script, the wide use of stone carving for hieroglyphics, and the preservation of papyrus in desert tombs.

Perhaps the earliest pictorial evidence of fruit growing occurs in a 1 m tall alabaster vessel known as the Uruk vase found in Jemdet Nasr levels at Uruk that date from about 3000 BCE (Fig. 1). Uruk (Erech) is on the Euphrates just north of Basra, Iraq. The imagery depicts water at the bottom of the vase, followed by plants (barley and sesame) and domestic animals, and men bearing baskets of fruit with offerings presented to a female, perhaps the Goddess Innana, later known as Istar (Bahrani 2002). Unfortunately the fruits cannot be identified, but they tend to be large and of various shapes. Predynastic drawings of fruit trees in Egypt depict the date palm (Fig. 2).

The development of fruit culture in the Fertile Crescent evolved at two loci: the Tigris-Euphrates civilization of Mesopotamia and the Nile valley culture of Egypt. Later infusions of species and technology are from Greece, Persia, Turkey, India and China. By classical times in Greece and Rome fruit culture had achieved a sophisticated level, not exceeded for over a millennium.

II. THE HORTICULTURAL ARTS

Fruit growing involves a more complicated technology than the cultivation of herbaceous annuals such as cereals or pulse crops. Tree crop culture requires a long-term series of horticultural "craft secrets" more or less unique for each species. These include selection of unique clones, vegetative propagation (use of offshoots, cuttings, grafting), continuous irrigation in dry climates, pruning and training, pollination, harvesting, storage, and processing. The cycle of fruit growing is often a year-round activity, and must involve orchard establishment in anticipation of production, which may only ensue after a number of years. Current additions to the technology of fruit growing include the use of dwarfing rootstocks, growth regulators, disease and pest control, long-term storage, protected cultivation, and biotechnology. Here we examine the Neolithic and Bronze Age origins of technologies essential to fruit growing.

A. Species Selection

The first cultivated fruits must have been indigenous species that had obvious human value. This is clearly seen in Egypt where the indigenous date palm was the earliest species cultivated, followed by a succession of introduced fruits such as the sycomore fig and pomegranate (Table 1). The earliest fruit culture in Mesopotamia included the date and olive (4000 BCE), grape, fig, and pomegranate (3rd millennium BCE).

Later fruits introductions, based on literary sources, include the apple, pear, quince, and medlar (Postgate 1987). The small-fruited Malus orientalis and Pyrus syriaca are indigenous to the Fertile Crescent but these were probably not the forerunners of domesticated apple and pear that were introduced from Western Asia probably via Persia. Contacts between East and West date from as early as 1000 BCE as evidence by silk strands on Egyptian mummies, but intensified with the incursions of Alexander the Great (356–323 BCE). Thus, by Greek and Roman eras there was an infusion of Central and East Asian fruits, including the citron and a great variety of stone fruits, including almond, apricot, cherry, peach and plum. In the Age of Exploration in the late 15th and 16th centuries, a great exchange takes place as fruits of the Americas, including the pineapple, cacao, American species of strawberries, and papaya and the fruit-bearing solanums such as tomato and pepper reach Europe, Asia, and Africa while East Asian fruits, such as the banana, mango, and persimmon reach the Americas. Some east Asian fruits, such as kiwifruit, are relatively recent introductions, and a great many tropical fruits of both Asia (durian, mangosteen, salaak) and the Americas (passion fruit, sapote) are still not extensively commercialized.

B. Vegetative Propagation

Although most fruit species can be produced from seed (except, of course, seedless clones), this is usually an inappropriate technique. Most fruit species are highly cross-pollinated (peach is an exception) and therefore highly heterozygous. Thus, open-pollinated seedlings will consist of a highly heterogeneous mixture of fruit types, most of which will be inferior to the selected clone. Furthermore, there is a long juvenile period in trees grown from seed. The Hebrew Bible is full of references to degenerate plants that clearly indicate that the ancients were aware of the hazards of seed-propagated fruit crops. Thus, the basis of most fruit cultivation is vegetative propagation of unique phenotypes (elite clones) with subsequent improvement based on sexual recombination of elites. Vegetative propagation is accomplished from offshoots in date, layers in grape, and cuttings in olive and fig and runners in strawberry. Fruit crops that can be easily propagated vegetatively have been considered preadapted for domestication by Zohary and Spiegel Roy (1975). However, many temperate fruits (apple and pear) do not propagate easily by layers or cuttings and are currently multiplied by graftage.

Grafting is ancient (Vöchting 1892, Mendel 1953) and Childe (1958) has speculated that it was known before 3000 BCE. Although both root and shoot grafting occurs naturally (Fig. 3), the technology is not obvious and must be considered one of the horticultural craft secrets. We know this because much of the Roman writings on grafting often confuse which species are graft-compatible. Pliny describes a number of ludicrous combinations, such as apple on plane tree suggesting that he was not writing from real experience.

Recently, a cuneiform description of budwood importation for grape has been uncovered from Mari, Mesopotamia (Harris et al. 2002) dated to about 1800 BCE, which confirms Childe's (1958) speculation on the antiquity of graftage. The next written evidence of grafting comes from the school of Hippocrates (Pseudo-Hippocrates, about 450 BCE) that discusses the graft union (Meyer 1854), but this reference implies that the technique was very much older. Grafting is discussed in detail by Theophrastus, and all the Roman agricultural writers, including Cato, Virgil, Columella, and Pliny, describe it in detail. Grafting is accurately pictured in mosaics in the 3rd century CE (Fig. 4).

Fruit growing has long been associated with clonal propagation of unique wild seedlings with subsequent evolutionary progress derived from intercrosses of superior clones plus intercrosses with wild races (Zohary and Spiegel-Roy 1975), leading to very high seedling diversity. In a number of species, almond for example, the high diversity of wild clones include segregates that are close to domestic types. This would explain why the ecological adaptation of classic Mediterranean fruits has not exceeded the requirements of their wild ancestors. In most cases, present-day fruit cultivars have undergone far fewer sexual cycles than cereal or pulse crops and some may be only a few generations from wild clones. Thus, many of these crops have not diverged from their progenitors, in contrast to cereals in which selection has operated for thousands of generations. This has been confirmed in apples, where present-day cultivars are not distinct from elite selections obtained from wild stands in Alma Alta, Kazakhstan (Harris et al. 2002; Forsline et al. 2003).

C. Pollination and Fruit Set

In date palms, early farmers discovered artificial pollination, and this is clearly illustrated in Assyrian bas reliefs (Fig. 5), with the practice codified in the Laws of Hammurabi, ca. 1750 BCE (Roth 2000):

§64. If a man give his orchard to a gardener to pollinate (the date palms), as long as the gardener is in possession of the orchard, he shall give to the owner of the orchard two thirds of the yield of the orchard, and he himself shall take one third.
§65 If the gardener does not pollinate the (date palms in the) orchard and thus diminishes the yield, the gardener (shall measure and deliver) a yield of the orchard to (the owner of the orchard in accordance with) his neighbor's yield.

D. Irrigation

The civilizations that developed in the arid climates of the Fertile Crescent are dominated by large rivers—Nile in Egypt and the Tigris and Euphrates in Mesopotamia. In Egypt the regular inundations of the Nile, rising in July until the middle of October, followed by rapid subsidence, permitted a unique horticulture based on basin irrigation (Janick 2002). The system involved a system of dikes to retain the flood and encourage infiltration into the soil. Earthen banks, parallel to the river together with intersecting banks, created a checker board of dike-enclosed areas, between 400 and 1600 ha each. Canals led the water to areas difficult to flood. The flood waters ran through a series of regulated sluices into each basin, flooding the land to a depth of 0.3 to 1.8 m. The water could be held for a month or more; the surplus was drained to a lower level and then returned to canals that emptied into the Nile. The advantage of basin irrigation was that no further irrigation was needed for a winter crop of grain, and the silt, rich in organic matter and phosphates, made fertilization unnecessary.

With fruit tree culture, permanent ponds were an important innovation and the ornamental gardens enclosing ponds testify to their widespread use by the wealthy. In addition, shallow wells, 4 to 35 m in depth, were dug to be replaced later by deeper artesian wells up to 380 m deep. The culture of fruit crops demands constant and controlled irrigation during the spring and summer drought. At first, irrigation was carried out manually with pots dipped in the rivers, carried on the shoulders with yokes, and poured into field channels. By the time of the New Kingdom (1500 to 1100 BCE), the shaduf, a balanced counterpoise, became the irrigating mechanism for gardens. Later, water lifting techniques included Archimedes' screw, the sakieh or chain of pots, and siphons (Fig. 6).

In Mesopotamia, cultivation in the Tigris-Euphrates flood plain is and always has been dependent on irrigation, and the management of this technology may have been the impetus for the development of nation-states (Pollock 1999). Irrigation started as small-scale projects but eventually increased in complexity and involved centralized control. The creation of state-controlled irrigation led to a strong central authority requiring conscripted service (corvée) for canal maintenance. The Laws of Hammurrabi richly describe a legal system enforced to maintain the integrity of an irrigated agriculture:

§53 If a man neglects to reinforce the embankment of the irrigation canal of his field and does not reinforce its embankment, and then a breach opens in its embankment and allows the water to carry away the common irrigated area, the man in whose embankment the breach opened shall replace the grain whose loss he caused.
§54 If he cannot replace the grain, they shall sell him and his property, and the residents of the common irrigated area whose grain crops the water carried away shall divide the proceeds.
§55 If a man open the branch of the canal of irrigation and negligently allows the water to carry away his neighbor's field, he shall measure and deliver grain in accordance with his neighbor's yield.
§56 If a man opens an irrigation gate and releases waters and thereby he allows the water to carry away whatever work has been done in his neighbor's field he shall measure and deliver 3,000 sila of grain per 18 iku of field.

Because of the braiding character of the Euphrates, short canals, about 1 km in length could be dug from the numerous river channels and managed by local groups (Pollock 1999). The natural flow of the river and overflow resulted in natural levees, and in the process the riverbed was gradually raised until it flowed above the level of the surrounding land. This made it relatively easy to cut irrigation channels through the natural levee and allow the water to flow by gravity to cultivated fields and gardens. The natural levees with their good drainage were prized for fruit tree cultivation, but irrigation required water lifting technology. The natural vegetation of the alluvial plain provided pasturage for sheep and goats; it was once home to game animals such as jackals, lions, gazelles, onagers, and hyenas, as illustrated in the hunting scenes in Babylonian bas reliefs now hunted to extinction. Long-term irrigation, however, led to unintended consequences and today much of the area is a vast salty waste as a result of salinization.

F. Processing and Storage

Most of our important domesticated fruits are delicious in the mature state and indeed this is one of the chief virtues of fruit crops. However, this is not the case with all fruits. The olive, in particular, is bitter and inedible, even in the mature state, and some wild species are toxic. Clearly, the key technology must have been derived from the ameliorating practice of soaking the fruits to make them less bitter. Extraction of oil by pressing the fruit transformed olives into the most widely grown fruit crop in the ancient world. The oil was widely used in cooking and illumination; the flame produced from olive oil has a very high luminosity. Fruit crops grown for their fruit or seed oil also include oilpalm and avocado (used for soap in Brazil).

Most fruits have a short life after harvest so that processing is required to have a year-round supply. The perishability of many fruits is one of the limiting factors of commercialization. In the case of the date, the high sugar content of the dried fruit permits extended storage, and dried grapes (raisins) have long been prized for their concentrated sweetness and long storage. Sun drying of many types of Prunus, especially highly sugared plums (prunes) and apricots was facilitated by slicing fruits. The conservation of fruits as jams and preserves was based on the addition of sucrose, a substance unknown until the technology of sugarcane production and processing was developed in the Middle ages. Some wild fruits, such as lingonberry in Nordic countries have long been collected and stored as preserves. The preservation of fruits by heat (canning) was a 19th century technology developed by Nicolas Appert (1750–1841) as a response to the British blockade of France during the Napoleonic wars. Quick freezing and later freeze drying are 20th century technologies.

In more temperate climates, fruit life could be extended by common storage in caves or basements. Caves in Cappadocia (Turkey) maintain a temperature of 12.8°C and are still used to store lemons. The modern transformation of this technique led to refrigerated storage and low oxygen storage (controlled-atmosphere) storage.

The transformation of fruit juice to an alcoholic product (wine), along with bread making, is a Neolithic discovery. Beer making probably predated wine making. This leap into Bronze-age biotechnology was facilitated by the ubiquitous presence of yeast spores. Although wine can be made from various fruits, the choice species is grape, probably because of its combination of sugars, acids, and tannins. At present, the greatest use of grapes is for wine manufacture. In the East, salting and fermentation technologies were developed as a means of whole fruit storage. A few tropical fruits (e.g., plantain and breadfruit) are staple starch crops and require cooking.

III. ORIGIN, DOMESTICATION, AND EARLY CULTURE OF FRUIT CROPS

A. Mediterranean Fruits

1. Date Palm. The date palm (Phoenix dactilifera, Arecaceae) is a dioecious palm, thought to be indigenous from Northern Africa through the Arabian peninsula to northern India (Goor and Nurock 1968; Zohary and Spiegel-Roy, 1975; Smartt and Simmonds 1995). In antiquity, the date palm was esteemed from India through North Africa for its sweet fruit consumed fresh or dried, for its valuable wood and leaves, and for its long life. As a result of its many virtues, the date was transformed into a sacred tree, symbolically referred to in Babylonian and Assyrian iconography. It may have been the first cultivated fruit and was well-established in the Middle East during the Bronze Age. The precise origin of the cultivated date is open to conjecture. Vavilov considered the origin of the date to be the mountains of northeastern Africa in Ethiopia and Eritrea but there is evidence that the first cultivation occurred in the Lower Mesopotamian Basin. Archeological evidence places date stones in the Ubaidian horizon (about 4000 BCE) in Eridu, lower Mesopotamia. A predynastic representation of a palm tree (perhaps a date) with gazelles has been dated 4000 to 3000 BCE (Fig. 2).

The date palm is adapted to long, extremely hot, summers with little rain and low humidity from pollination to harvest but requires a source of underground moisture. All cultivated dates set fruit only in dry desert conditions, in contrast to a number of wild species which do not produce suckers and may be adapted to rainy conditions. Since the plant is a monocot and lacks a deep root system, irrigation is essential. An Arab proverb describes the date palm as "its feet in running water and its head in the fire of the sky."
The cultivated date palm is easily propagated from seed and, unlike its wild relative, can be vegetatively propagated from offshoots (suckers) at the base of the plant (Fig. 8). Clearly the production of offshoots is one of the principal characteristics of domesticates. At present, all cultivars can be propagated in this manner and one to several suckers may be removed each year. Offshoots can be planted without roots, but mounding of soil around the base of the mother tree facilitates their rooting. Irrigation is essential to insure survival of offshoots and high productivity.

Since the date is dioecious, production of fruit by pistillate clones requires the presence of a source of pollen. In present-day commercial plantations, one male tree to 100 females is sufficient if pollination is performed by hand. In some cases twigs or branches of the male inflorescence from 10 to 15 cm long and bearing 30 to 50 flowers are tied on the female cluster, but this process must be repeated because of variation in time of maturation of pistillate flowers. Pollen has also been distributed by airplanes or helicopters.

By the time of Hammurabi the problem of the division of the crop between the landlord and the tenant gardener, who acted as a sharecropper, was defined and penalties for lack of pollination were assessed (see IIC). The practice soon took on religious significance as illustrated by bas reliefs showing pollination of sacred trees by kings and gods (eagle-headed genii) (Fig. 5). The sexual nature of the pollination process was probably known as the date palm became a symbol of fertility. Theophrastus writing in the 3rd century BCE, clearly mentions the parallels and refers to the pollen bearing plant as male and the fruit-bearing plant as female.

Wild date palms often produce small and nonpalatable fruits, while the domesticates are associated with larger size and considerable amounts of sweet pulp. Increased size and quality of the fruit is associated with selection carried out under domestication.

2. Olive. Olive (Olea europea, Oleaceae) is a slow-growing, long-lived, evergreen tree uniquely adapted to the climate of the Mediterranean basin and considered a defining feature of this climate (Smartt and Simmonds 1995). Indigenous types are still widely found with archeological evidence as far back as 12,000 years ago (Blazquez 1996). The cultivated olive originated about 6000 years ago in Asia Minor, but was generally unknown to the Babylonians and Assyrians whose source of oil was sesame and walnut. The olive was long known in Syria and the Holy Land and was introduced to Egypt from Syria between 3000 and 1800 BCE (Goor and Nurock 1968). By 2500 BCE, the ancient city of Elba in northern Syria had fields containing between 500 and 1000 olive trees, producing and exporting various types of olive oil. According to Hittite texts olives were cultivated in Anatolia and imported to Egypt from the time of Ramses II (1197–1165 BCE), where there is mention of the use of olive oil for illumination and as a skin emollient for cracks and sunburn. The olive moved from Egypt to Carthage in North Africa, reaching Italy in the 7th to 6th century BCE.

Olive along with grape is the most mentioned fruit in the Hebrew bible. Its importance has permeated the Western world and the olive tree and oil are symbols of beauty, freshness, fertility, wealth, fame, and peace. Greek myths associated with the olive involve Hercules and Athena. The importance of oil is reflected in its widespread use for religious purposes such as consecration ceremonies (anointing) in Judaism and Christianity; the word messiah (Christ) literally means "the anointed one." Olives were introduced to South America in the 16th century and introduced to Mexico, California and Australia in the 20th century.

In Mediterranean climates, the olive is often grown without irrigation, although yields are low. Moderate pruning is performed to shape trees and to remove unfruitful wood. Harvest is usually carried out by hand, with the time depending on the use (Fig. 9). Olives have been propagated from grafting since antiquity (see Vegetative Propagation). Many present-day cultivars are considered to be thousands of years old.

There are two processing steps involved in olive utilization. The first is transformation of the bitter fruit to an edible form and the second is oil separation. Somehow, Neolithic humans learned to consume a small, bitter fruit, almost inedible and somewhat poisonous as a result of the phenolic glucoside eleuropein found in various concentrations in all olives. This was accomplished by soaking, a technique still used. Further steps in detoxification included pounding, addition of lye (sodium or potassium hydroxide), or lactic acid fermentation induced by sodium chloride (Colmagro et al. 2001). There is ample evidence that so called "primitive" societies learned to leach a number of foods to reduce their content of bitter substances. Australian aborigines used a combination of soaking and roasting with many native fruits and seeds (Crib and Crib 1974).

Later in the Bronze Age, olive processing technology was invented to separate the oil. Olive became the first great industrial crop, grown more for its oil—as a medicinal, for cooking, and for illumination (the light is very bright)—than for direct consumption. The religious practice of anointing probably derived from the medicinal use of olive oil.

The earliest process of oil extraction was by crushing the fruit in water and spooning the floating oil. Later improvements were the use of oil presses of various types. Typically water was added and the oil removed by decantation. At present 90% of the world olive crop is pressed for oil which is used for culinary purposes; the remainder is used as table olives, a fermented product. Recently, olive consumption has increased with the recognition of the beneficial properties of oleic acid and the increase in consumption of various types of table olives as a gourmet product.

3. Grape. Wild grapes of the Old World (Vitis sylvestris, Vitaceae) are indigenous to the south Caspian belt, Turkey, and the Balkans, and were widely distributed in the northern Mediterranean area including the Black and Caspian Seas (Zohary and Spiegel Roy 1975; Smartt and Simmonds 1995; Reisch and Pratt 1996). Wild grapes are dioecious, perennial, forest vines and thrive in cooler and more humid conditions than do olives. Harvest of wild grapes long preceded domestication, as evidenced by carbonized seed in numerous prehistoric sites in Europe. Presence of the wine grape in the Near East is dated as early as the 8th millennia BCE but eastward expansion was limited by lack of winter hardiness and poor adaptation to high summer rainfall. Toward 5000 BCE, and perhaps earlier, the domestic grape, V. vinifera, migrated from Anatolia to Syria and thence to the Holy Land. Signs of Bronze Age domestication are found in Mesopotamia, the Holy Land, Syria, Egypt, and the Aegean. By the 2nd millennium BCE there is evidence of vessels for wine storage as well as of raisins. A number of grape species are found in the New World and these types were domesticated after the European encounter with America (Reisch and Pratt 1996). One American species, V. labrusca, known as the fox grape, was rapidly domesticated while others were hybridized with V. vinifera to develop Phylloxera-resistant rootstocks. Muscadines (V. rotundifolia), native to the southern United States, were preserved by Native Americans by drying (Olien 2001) but was not cultivated and can be considered a recent domesticate.

The seedless grape 'Sultanina', known as 'Thompson Seedless' in the United States, is an ancient Turkish cultivar and still one of the most widely grown for table grapes or wine. Grapes were preserved in two ways. The simplest was sun drying, and the dried fruit (raisins) were prized for their concentrated sweetness, and long term storage (Fig. 10). The transformation of grape juice to wine occurs almost naturally but requires anaerobic conditions. The fermentation of juice into wine was probably based on beer technology, an older practice.

4. Fig. Figs, borne on small trees, are considered one of the classic fruits of the Mediterranean basin. Signs of fig cultivation are found at various Neolithic and late Neolithic sites (Zohary and Spiegel-Roy 1975), and from Bronze Age sites in the 4th millennium BCE. Domestication was generally contemporary with olive and grape in the Eastern Mediterranean basin; it was mentioned by King Urukagina ca 2900 BCE and became known to the Assyrians as early as 2000 BCE. Egyptian records indicate fig cultivation in Canaan in the 3rd and 2nd millennia BCE (Goor and Nurock 1968) and there are many paintings of fig from antiquity (Fig. 11, 12). The fig is easily propagated by seed, as well as by cuttings or layers. Propagation by grafting and budding was described by Cato in the 3rd century BCE.

The fig is marvelously adapted to insect pollination (Condit 1947; Storey 1975). Pollination is carried out by this tiny (about 1 mm) wasp, an association described by Theophrastus. The insects overwinter in the larval stage in the pistillate flower, pupate in early spring, and emerge as adults within the synconium. The wingless male impregnates the female inside the ovary and then perishes. The winged female exits the synconium through the ostiole, where she is covered with pollen from staminate flowers clustering around the orifice. The winged female then migrates to other small figs, deposits an egg in each of a number of pistils and then dies. However, when the female enters the common fig which contains only long-styled pistils which are not adapted to oviposition, the insect perishes, but not before pollination has been accomplished.

There are as many as three crops of figs in each season. The first crop, called profichi, are formed on wood of the previous year's growth. They may contain the wasp or, if uninhabited, are called blanks. The inhabited profichi are usually dark green, firm and plump, while the blanks are yellowish green, ribbed and inclined to be spongy. The next crop, called mammoni, are produced in the axils of the current season's growth and are often pollinated by wasps from the profichi crop. The last crop is called mamme and remains on the tree during the winter season. Figs are consumed fresh or dried and are often processed as a paste for pastries or canned. The fruit can be fermented and distilled into alcohol.

5. Sycomore Fig. [not grown commercially today, smaller than figs grown commercially] The sycomore fig (Ficus sycomorus, Moraceae) originated in the savannas of eastern Central Africa where they grow spontaneously and reproduce by seed. The tree is easily propagated by cuttings. It was introduced to Egypt in predynastic times, before the 3rd millennium, and became an important cultivated plant in the Early and Middle Kingdoms. Although the fruit was not considered exceptional, the tree was highly prized and held sacred, especially to Hathor, goddess of love, and representations of fruit and tree are found on basreliefs and commemorated in song. Fruit and leafy branches were placed in funeral offerings. The wood is decay resistant and esteemed for household utensils, construction, boxes, and coffins. The tree was introduced to the Levant, present-day Israel, Lebanon, and Syria as well as Cyprus. It was well known in Biblical times and became a food for the poor.

Flowers are pollinated by the chalcidoid wasp, Ceratosolen arabicus, but the plant was introduced to Egypt without the wasp. Although fruits developed parthenocarpically they did not enlarge or ripen successfully unless wounded. This fact is found in a famous quote from the Hebrew Bible (Amos 7, 14): I was no prophet, neither was I a prophet’s son but I was a herdman and a “piercer” (mistranslated as “gatherer” in the King James translation) of sycomore fruit. The phrase refers to the practice of ripening the fruit by scraping it (Fig. 13). Wounding of the fruit results in ripening through the release of ethylene. This remarkable technological discovery was known to Theophrastus who writes: The sycamore cannot ripen unless it is scraped but the Egyptians’ scrape it with iron claws, the fruit thus scraped ripens in 4 days.

6. Pomegranate. Pomegranate (Punica granatum, Punicaceae), native to the southern Caspian belt (Iran) and northeast Turkey, is a Bronze Age fruit that has been cultivated for 5000 years (Goor and Nurock 1968; Zohary and Spiegel-Roy 1975). Its presence in Syria, the Holy Land, Egypt, and Mesopotamia indicates domestication. The Latin name Punica refers to Carthage and the fruit was once known as the apple of Carthage. Remains are found in Nimrud, Arad, and Jericho. The pomegranate was introduced into Egypt from Syria about 1600 BCE before the 19th Dynasty during the inflow of Semitic people (Hyksos). The fruit is commonly illustrated in Egyptian art (Fig. 14) from the New Kingdom and widely found in Jewish and Greek art. The pomegranate is easily propagated by hardwood and softwood cuttings. Domestication is associated with increased fruit size, and sweetness, and a shift to clonal propagation. Some types have degenerate embryos and are called seedless.

In Egypt, juice from the pomegranate was consumed and converted to wine. The rind was prescribed as a medicinal and the flowers were crushed to make a red dye for leather. Based on extensive iconography the pomegranate seems little changed from antiquity. Peel color varies from bright red to leathery brown.

B. Central Asian Fruits

1. Pome Fruits. Pome fruits of the Rosaceae include apple, pear, quince, and medlar, of which the apple is the most important tree fruit of the temperate world. The trees require an annual period of chilling to break dormancy for proper growth, and the seeds require a period of cold stratification before they will germinate, and must be separated from the placental tissue of the fruit to germinate.

Apple. The apple is cross-pollinated and most cultivars are self-incompatible. Most cuttings of apple and pear trees do not root from cuttings so that vegetative propagation is difficult without grafting. There are 24 primary species of Malus, distributed in Europe, Central Asia, and Eastern Asia and three in North America (Way et al. 1990). Most of the wild apples are small and bitter. However, the large, sweet-smelling domestic apple (Malus ×domestica) clearly originated in Central Asia, specifically Almaty, Kazakstan (Dzhangaliev 2003) and was introduced to the West via Persia in antiquity. Recent explorations in Kazakhstan (Forsline 2003) support Vavilov’s suggestion that Malus sieversii = M. pumila is the major progenitor of the cultivated apple, and this has been confirmed by recent work with molecular markers (Harris et al. 2002). The explorations in Kazakhstan also indicate that elite wild material contains all the characters of modern apples (Fig. 15) including size, quality, and various colors from red to yellow to green. Barrie Juniper (pers. commun.), has made the intriguing observation that the selection mechanism for large size may not have been human but rather the result of millions of years of
selection for large size by bears endemic to the area who consume large numbers of apples; their droppings provide a unique germination medium. All of the other species of apple appear to be distributed by birds, providing no selection mechanism for large size.

Fruits of wild relatives of the domesticated apple occur in the Mideast and Europe and were frequently collected by Neolithic and Bronze Age farmers. However it is difficult to know precisely when the larger, sweeter apples of central Asia reached the West because reference to apple (hazur) in the early Sumerian literature may in fact refer to the indigenous, bitter, smallfruited species, Malus orientalis. The earliest archeological evidence (early dynasty III, about 2200–2100 BCE)of dried apples are rings of small fruits (11 to 18 mm in diameter), possibly threaded on a string, on saucers in Queen Pu-abi’s grave at Ur near present-day Basra, Iraq (Postgate 1987; Renfrew 1987). Apples lose their bitterness when dried (Barrie Juniper, pers. commun.), and if wild M. orientalis were harvested it might have been consumed in this manner. A Sumerian cuneiform literary manuscript, entitled Disputation between the Hoe and the Plow (Vanstiphout 2000), dated about 1900 BCE, refers to gardens of apples. In Anatolia (Turkey), the Hittites, who rose to dominance in the 2nd millennium BCE, referred to 40 apple trees on one estate. Later biblical references to sweet-smelling apples such as in the Song of Songs, written probably no earlier than 1000 BCE, suggest introduction before the 1st millennium BCE. In any case, by the 1st millennium BCE apples were a part of western agriculture. Homer (8th or 9th century BCE) refers to apples in the gardens of the King Alcinöus, the king of the Phaeacians, a legendary country. Apples, however, were unknown in Egypt until Greco-Roman times.

How did the apple reach the west from Central Asia? Because apples and pear do not propagate easily from cuttings, the most likely explanation is the introduction of seed carried in saddle bags by caravans along the trade routes, passing through the fabled cites of Bukara and Samarkand to Persia, perhaps facilitated by seed germination in horse droppings, but propagation from root suckers is another possibility (Fig. 16). Another explanation is that grafting technology, dated as early as 3800 years ago (Harris et al. 2002), may have been involved with Persia as an intermediary stop. Persia is clearly the source of many fruits from Central Asia and China.

Whatever the precise mechanism, the apple clearly passed through Persia and Greece, and, by the time of the Romans, apple technology including grafting, pruning, storage, and selection of unique adapted clones was perfected. Even the use of specific rootstocks seems to have been discovered (a low growing type is described by Theophrastus) and it is no coincidence that these easily-rooted dwarfing clones are called Paradise, the Persian word for garden.

The apple cultivated by the Romans was transported throughout the empire and became naturalized throughout Europe, resulting in thousands of unique types. Possibly some intercrosses with the small, astringent Malus sylvestris native to northern Europe, gave rise to cider apples that are still cultivated. Interestingly, a secondary center of diversification was established in the United States in the 18th and 19th centuries as seed from European cider mills was imported resulting in a new cycle of selection by fruit growers (see IV C). As a result, most of the new cultivars of apple now grown worldwide derive from American and Canadian selections.

The technology of apple production led to improved methods of storage in cool areas, first underground storage, later cooling with ice and, finally, refrigeration in modern times. Special methods to control diseases and insect pests which have always been a problem were sought but were largely unsuccessful until the 19th century when the fungicidal properties of lime sulfur was discovered and used to control such diseases as apple scab, and lead arsenate was used to control codling moth, a practice that is now illegal. The original apple processing consisted of drying; later juice was extracted and converted to a fermented product called cider, then distilled into a liquor (calvados or apple jack). Apples are now consumed fresh, or cooked, whole or as a sauce, and especially popular in pastries.

Genetic changes in apple include the selection of triploids derived from unreduced gametes, parthenocarpy, mutations involving growth habit, particularly spurry and short internode types, and various forms of pest and disease resistance. Fruit changes include shape, and various quality factors such as flesh firmness, sweetness, acidity, flavor, and shelf and storage life (Janick et. al. 1996). Triploidy seems to confer an advantage to cultivated apples for about 10–20% of cultivars are triploid yet nonreduction occurs in only about one in a thousand seed. The ability of layered shoots to root is advantageous in rootstocks, which are propagated by mounding soil around the bases of shoots (stooling). Differences in tolerance to many pests are observed in any large collection of apples. Immunity to apple scab has been transferred from Malus floribunda by backcrossing, but the problem of races has also appeared in some areas. This places the durability of this gene (Vf) in question, although it has held up for many years in the United States (Janick 2002b).

Pear. The pear has a story similar to that of the apple except that the domestication of the pear followed two separate paths. Pyrus communis, native to Central Asia, gave rise to the European pears characterized by intense flavors, flesh softening after the climacteric, and a wide range in sizes and shapes. The European pear is described by Homer as one of the fruits in the garden of Alcinöus, and the Roman agricultural writers Cato, Varro, and especially, Pliny describe many types (Hedrick 1921). In eastern Asia, the crisp, sweet-fleshed fruit of Pyrus pyrifolia, P. bretschneiderii, and P. ussuriensis are round, aromatic, and crisp-fleshed, and now known either as Asian pears or under the Japanese name nashi (Watkins 1995; Bell et al. 1996). The pear has been known in China for 4000 years (Wang 1990).

Systematic breeding of European pear was first carried out by Jean Baptiste Van Mons (1765–1842), a Belgian physician, pharmacist, and physicist and an early apostle of selection in plants. He systematically collected clones of pear, planted (open pollinated) seed of the best material and made selections for eight generations. In an early fruit book, The American Fruit Culture (1863), John J. Thomas (1810-1895) stated that the mean time from seed planting to fruiting in the first cycle was 12 to 15 years, 10 to 12 in the second cycle, 8 to 10 by the third, 6 to 8 by the fourth, and 5 by the fifth. By the 8th generation several fruit trees fruited at the age of four years (emphasis by the author, presumably based on correspondence of Von Mons). This may be the first example of data on long-term selection in plants. Sexual hybridization to produce new pear cultivars (as well as apple, cherry, strawberry, red currant, plum, and nectarine) was first attempted by Thomas Andrew Knight (1759–1838).

2. Stone Fruits. The genus Prunus,