There’s another text, or rather a collection of texts, dating to slightly later, which perhaps provides more dependable evidence for grafting. The Hebrew Bible consists of a compendium of stories and histories which were written and collected together over a thousand years, between 1400 BCE and 400 BCE, spanning the last centuries of the Bronze Age, into the Iron Age. Although grafting isn’t referred to specifically, it’s certainly implied, in several parables where cultivated vines reverting to wild forms are mentioned. It’s highly likely that the Persians – whose empire stretched around the eastern Mediterranean and into India and western Asia – would have used grafting in their orchards, but there’s no clear reference to this practice.
It’s Ancient Greek literature that provides us with the earliest, unequivocal description of grafting. A passage from the Hippocratic Treatise, dating to the late fifth century BCE, runs: ‘Some trees grow from grafts implanted into other trees: they live independently on these, and the fruit which they bear is different from that of the tree on which they are grafted.’ The Romans planted orchards of sweet apples in Italy, along with cherries, peaches, apricots and oranges. By the time the Romans were becoming a force to be reckoned with throughout Europe, references to grafting abound. And it was the Greeks and then the Romans, through their trade networks, colonies and empires, who spread apples and orchards and the knowledge of grafting right across the continent. A wonderful mosaic from Saint-Romain-en-Gal in southern France, dating to the third century CE, shows the orchard year – from planting, grafting and pruning to harvesting and cider-making. For the Romans, cultivated apples were a sign of civilisation. Tacitus, writing in the third century CE, recorded the Germans eating agrestia poma – peasant, rustic or wild apples – in contrast to the urbaniores – the urbane, cultured, sophisticated fruit – that the Romans preferred. But, as the civilising influence of Rome spread across Europe, so did the cultivated apple. At least, that’s probably what the Romans would have liked us to think. There’s a chance, though, that cultivated apples arrived in Britain and Ireland much earlier than that. During excavations of Haughey’s Fort, a late Bronze Age hillfort in County Armagh, Northern Ireland, archaeologists found what appeared to be a large, 3,000-year-old apple. It caused much excitement – but further inspection revealed it to be a puffball. A 3,000-year-old puffball.
So far, then, there’s no direct evidence of pre-Roman apples in this corner of north-west Europe. But it’s not such an extraordinary suggestion – there were extensive trade networks across Europe long before the classical civilisations took off. Indeed, some of the tin for making bronze may have come from Cornwall. Throughout Spain, France and Britain there are Celtic place names – which may have taken root in the Iron Age, if not before – that suggest the presence of apples in the ancient, pre-Roman landscape. From Avila in Spain, to Avallon, Availles and Aveluy in France, to the elusive Isle of Avalon or Ynys Avallach – somewhere in Britain – appley names could imply an even more ancient link to those ur-orchards in Kazakhstan. But this is still just conjecture. Those apple names could, presumably, just as easily relate to local, wild apples.
When Romans first arrived in Britain, Ireland, France and Spain, the native inhabitants would have been well used to exploiting their own local crabapples – just as they were in Germany. In a pit in Devon, archaeologists found a collection of baked-clay loom weights and an astonishingly well-preserved collection of pips, stalks and even whole wild crabapples, dating to the early Neolithic – nearly 6,000 years ago. Crabapples have also been found, threaded on to strings, at the 4,500-year-old tomb of Queen Puabi at Ur in Mesopotamia. But traces of apples have been discovered at even earlier archaeological sites, dating back to the Mesolithic, in Scotland. And in the Upper Palaeolithic site of Dolni Vestonice in the Czech Republic, crabapple remains have been found dating to around 25,000 years ago. It seems reasonable to assume that our ancestors have been eating wild apples for as long as there have been humans and apples in the same place. While crabapples seem to have formed part of the ‘paleo diet’, there were other uses for them – medicinally and in cider-making. And of course, crabapples are still used in their wild form. They’re planted in orchards to help with pollination of cultivated apples. Their fruits are cooked and served with meat, or made into sauces and jellies – and are still used to make cider. And they’re pretty. Alongside my own four urbaniores, I have a beautiful little agrestia poma, a pink-flowered, yellow-fruited, crabapple in my own garden.
The spread of sweet, plump cultivated apples, from the Near East, throughout Europe in the Bronze and Iron Age – carried out, if not exclusively, under the aegis of the Roman Empire – may be thought of as the first major diaspora. With the collapse of the Roman Empire, orchards were abandoned. But, in western Europe, apples survived in the gardens of monasteries, spreading across Europe again with the expansion of the Cistercian order in the twelfth century. In 1998, a single apple tree with red-golden apples was found growing on Bardsey Island – probably the last survivor of the monastic orchards there, and it’s now being cultivated again. In eastern Europe, apples survived the fall of the Byzantine Empire in the eighth century, and were carefully curated and cultivated in the Muslim world. In the sixteenth, seventeenth and eighteenth centuries, the second major diaspora took place as European colonisers started to plant cultivated apples in the Americas, South Africa, in Australia, New Zealand and Tasmania. In 1835, when Darwin landed in Chile, he found the port of Valdivia surrounded by apple orchards. Tasmania would later become known as the ‘Apple Isle’ – an antipodean Avalon.
This second apple diaspora resulted in a great variety of apples – suited to diverse environments across the temperate zone. The success of apples in North America seems to have involved a ‘return to the wild’. Apples were planted from seed and natural selection got down to work, weeding out individuals that could not thrive in the new habitat, with its harsh winters. New varieties emerged out of that sifting, whilst cultivars undoubtedly hybridised with native American crabapples too, borrowing useful local adaptations. The apple was able to remake itself, to fit its new habitat. It was out of this global spread of apples, and the winnowing of selection acting on seedlings once again, that our familiar modern cultivars began to appear in the nineteenth century. The McIntosh or ‘Mac’ (the namesake of the Apple Macintosh computer) emerged in 1811 in Canada; Cox’s Orange Pippin appeared in 1830 in Buckinghamshire; Egremont Russet in 1872 in Sussex; Granny Smith in 1868 in Australia. In the twentieth century, selection became even more directed, precise and brutal. An incredible diversity was pruned back to just a few brand-names that would corner the global market in apples. And yet new varieties continued to be born – of which some would become immensely successful: Golden Delicious appeared in West Virginia in 1914; Ambrosia in the 1980s in Canada; Braeburn in 1952, Gala in the 1970s and Jazz in 2007 in New Zealand.
Diversity has been reined in amongst our modern cultivated apples – but it’s still impressive, especially compared with other species. The botanical expeditions of the late twentieth and early twenty-first century seemed to confirm what Vavilov had concluded on his 1929 visit to the orchards around Almaty – that all the huge variety we see in our modern apple cultivars could be traced back to those ancient ur-orchards of Kazakhstan.
Genetic revelations
Similarities in the shape of trees, and their flowers and fruit, together with clues from written history, all pointed to the foothills of the Tian Shan as the birthplace of domesticated apples, Malus domestica. In the 1990s studies of mitochondrial DNA – and chloroplast DNA, which is also inherited down the maternal line – confirmed the hypothesis that the Asian wild apple, Malus sieversii, was the ancestor of the modern, domesticated apple. There had always been the possibility that interbreeding with other wild-apple species had been instrumental in the development of domestic apples, but the geneticists uncovered what looked like an unbroken, fairly unsullied ancestral line going right back to the wild apples of Ka
zakhstan. It seemed that the DNA of our familiar eating apples was still, in the main, Malus sieversii. Given that this wild-apple species was so spectacularly variable in the wild, it didn’t seem unfeasible that all – or nearly all – the variation seen in domestic apples could quite easily come from this single source. Some botanists even went as far as to put domesticated apples and the central Asian apple into the same species, Malus pumila.
But a huge new study of apple varieties published in 2012, led by French geneticist Amandine Cornille, has painted a new and unexpected picture of apple origins. This new analysis looked at large numbers of cultivars, from China to Spain, and used more complete samples of DNA than previous investigations – and revealed a surprisingly prodigious level of variation. Whereas most domesticated species contain just a fraction of the diversity seen in wild relatives, cultivated apples are just as diverse as most wild Malus species. But it was when Cornille and her colleagues drilled down into the variation, and carefully looked at comparisons between the domesticated apples and wild species, that they revealed the well-hidden secret of the apple. The geneticists found that cultivated apples did indeed come from the wild apples of Kazakhstan – but not exclusively. They discovered that cultivated apples had clearly bred with wild crabapples as the cultivars spread along the Silk Road. Apples had not emerged from a single geographic origin, over a short time period, but had continued evolving – and interbreeding with close cousins – over millennia. Throughout the apple’s history – and despite the use of grafting to clone and genetically constrain apple populations – improvements have arrived on the scene through human selection of good-looking apples created by natural, open pollination. It’s always been possible for wild cousins to add their own contributions to the gene pool. And those contributions just arrived – there was nothing intentional on the part of humans to orchestrate those crosses.
This interbreeding with wild apples wasn’t just about adding details to the story of the domesticated apple; it subverted it. The original progenitor of cultivated apples was still Malus sieversii – with the origin of domesticated apples estimated to have occurred between 4,000 and 10,000 years ago. But the influence of other wild apples – particularly Malus sylvestris, the European crabapple – has been profound. The study showed that our modern, domesticated apples actually owe more of their genetic make-up to crabapples than to the original central Asian apples.
It’s an extraordinary revelation, but echoes what has recently been found in quite a few other species – including other woody, domesticated plants such as grapes and olives. And it’s much like the story of maize: cultivated Zea mays is genetically more similar to the highland wild varieties than to the originally-domesticated, lowland teosinte.
A few botanists had suggested in the past that cider apples might have been produced by crosses with crabapples, to introduce a desirable bitter, astringent quality. While the Cornille study showed that interbreeding had definitely occurred, it didn’t show any difference between modern cider apples and eating apples. Both had roughly equal, considerable amounts of Malus sylvestris in their ancestry. If anything, the sweet, dessert apples had more. Geneticists have already begun to dig into exactly what these different sources of their heritage, of their DNA, means in practice. Genes for fruit quality have been inherited – and preserved – from that original progenitor, Malus sieversii. In contrast, genes from local wild species have contributed adaptations to the new environments that the domestic apple found itself growing in, as it spread from the forests of the Tian Shan.
The 2012 Cornille study also showed plenty of gene flow in the opposite direction, from cultivated apples into wild ones. So domestication has influenced the evolution of apple species that haven’t even been domesticated (just as it’s done with horses and wolves). This evidence – of gene flow in both directions – has emerged so recently that agronomists and conservation biologists are still trying to get their collective heads round the implications. What about the wild apples – are they threatened by the penetration of domestic genes into their genomes? This exchange of DNA isn’t a new phenomenon – it must have been happening since the dawn of domestication. It’s easy to leap to conclusions, and imagine that all introgression from domestic into wild species is deleterious and undesirable. But it’s also possible that some domestic genes could be beneficial. We need to invest in answering these questions in order to direct our conservation efforts and protect wild species to the best effect. Conservation seems morally right, and an altruistic endeavour, but we also have more selfish reasons to care about the health of wild species. Genetic analyses of our modern apple cultivars show that some of them seem to be dangerously closely related: the equivalent of second or even first cousins – or sometimes even siblings. This increases the chance of genetic diseases becoming serious – because it brings rare variations in genes together. The genetic diversity across modern, domesticated apples looks impressive when compared with other tamed species – there is no detectable domestication ‘bottleneck’ – but the total diversity hides a more troubling reality. Apple production is based on cloning. There might be plenty of genetic difference between clones, but absolutely none within them. Although there are millions of domesticated apple trees growing in the world, these actually represent just a few hundred clones – a few hundred actual individuals. Some are fruiting scions, some are rootstock. It means that apples are quite seriously threatened by alterations to their environment – such as the emergence of new pathogens and changing climate.
So it’s even more important to maintain a healthy pool of genetic diversity amongst wild apples – we may well need to tap into it to keep our domesticated apples healthy. In fact, we undoubtedly will. Wild apples might also hold the key to tackling some of the common problems that are already affecting our domestic apples. Botanists visiting the wild-apple forests of Kazakhstan have noticed that some of the trees seemed to be unscathed by canker and scab – apparently resistant to these diseases. Some also appeared to be able to grow in extremely arid conditions – a drought-resistant trait which could be immensely useful for some cultivated apples. It’s also clear that whatever happens in the lab, this needs to be supported by expeditions into the field. We still need the Vavilovs, the Forslines, the Junipers to trek out into the ancient places, the wild places, and bring back their precious samples. Out there in the wilderness may exist the genetic answers to some of the challenges facing our orchardists today, and some problems that we haven’t even thought of yet.
Genetics is shining a bright light on ancient origins of many species. We get clues from archaeology and history, but sometimes these clues can be misleading. The evidence is always patchy. Interrogating DNA, both modern and ancient, gives us the chance of filling in some of the gaps, by offering us another perspective on the past. As sequencing entire genomes becomes easier and quicker, we’re now gathering in armfuls of unexpected insights into the histories of our domesticated species, from the astonishingly ancient origin of domesticated dogs – to amazingly early traces of wheat in Britain; from identifying lowland Balsas teosinte as the original ancestor of maize – to the real crabapple nature of apples. But one of the most surprising genetic revelations of all has involved a very familiar species: Homo sapiens.
10
HUMANS
Many historical problems can be understood only because of the interaction between man, animals and plants.
Nikolai Vavilov
Professor Busk’s Grand, Priscan, Pithecoid, Mesocephalous, Prognathous, Agrioblemmatous, Platycnemic, wild Homo calpicus
In 1848, a skull was discovered during British mining operations at Forbes Quarry on the north face of the Rock of Gibraltar. It was presented to a meeting of the local Gibraltar Scientific Society, but no one could make sense of this odd, heavy-browed, thick-set cranium with its gaping eye sockets. It was left on a shelf to gather dust.
Eight years later, another skull was found, along with some bones, in another quarry – th
is time in Germany. The remains were unearthed in the Feldhofer Grotte of the Neander Valley near Dusseldorf. Workmen clearing the mud from caves prior to quarrying found what they thought were cave-bear bones – but a local teacher recognised that they were human and collected them up. Professor Mayer, at Bonn University, suggested that the bones may have belonged to a Mongolian military deserter, who had died from rickets, frowning in agony with the pain and forming heavy brows in the process. But Professor Schaaffhausen, at the same university, thought that the Feldhofer skull and bones were normal – not pathological. As the remains had been found alongside the bones of extinct animals, he reasoned that this human must have been a very ancient inhabitant of Europe. In 1861, London anatomist George Busk translated Schaaffhausen’s paper on the Feldhofer fossils – he agreed that the skull was potentially that of an ancient type of human, and he called for more fossils. The next year, the Forbes Quarry skull was duly packed up and sent to London.
Come 1864, Busk published his report on the ‘Pithecoid Priscan Man from Gibraltar’, in which he claimed that it resembled ‘the far-famed’ Feldhofer fossil. The remains from Gibraltar and the Neander Valley weren’t mere oddities, he argued, but representatives of a lost tribe that had roamed ‘from the Rhine to the Pillars of Hercules’. Darwin saw the ‘wonderful Gibraltar skull’ in that same year, but he neglected to make any further comment on it. Busk’s friend, Hugh Falconer, wrote to him on 27 June, suggesting a name for the specimen:
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