The domesticated apple is a remarkable tree having been used for millennia as a dessert and cooking fruit, and as the raw material for brewing cider and distilling calvados. The apple, with its gastronomic, symbolic, religious, decorative and patriotic appeal, is culturally and biologically adaptable.
Malus is a small genus of approximately 30 species distributed across northern temperate regions, although the number of species is difficult to determine because closely related species readily cross, producing complex hybrids, whilst cultivated and wild apples frequently cross to produce highly variable wildings.
The apple we eat is not European; it is native to Central Asia, and people have speculated about its origin for centuries. Over the last century, the combination of intensive fieldwork, experimental and commercial breeding, and genetics has allowed us to disentangle the intricacies of the apple-human relationship and the origins of domesticated apple.
The Central Asian wild apple (Malus sieversii) is common in the region's remarkable fruit forests. These deciduous, mid-elevation forests once extended west from China in a narrow strip along the Tian Shan to the Black Sea; today only fragments remain. Central Asian wild apple is naturally very variable in tree height and form, and in fruit size, shape, flavour and colour. From this pool of natural variation, people selected and propagated their favourite types, which some four to ten thousand years ago produced a distinct species; Central Asian wild apple had been domesticated. Over the next four millennia, as the apple moved west out of Central Asia, perhaps by nomadic horsemen and people trading along the Silk Roads, further selections were made as the domesticated apple picked up genes from the western Asian wild apple (Malus orientalis) and the European wild apple (Malus sylvestris) through hybridisation. Such unconscious efforts, together with the conscious efforts of generations of European apple breeders since the early nineteenth century, have produced thousands of named apple cultivars across western cultures.
Propagating particular apple cultivars from seed is a waste of time. A single apple tree will not mate with itself but produces seed by crossing. To produce identical trees a vegetative propagation technique (grafting) must be used. Grafting, where the scion of one tree is attached to the rootstock of another, was invented about four thousand years ago in Mesopotamia. Grafting, and the ability to bulk-up particular apple types, probably played a key role in establishing apple as a major fruit crop.
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