GREAT MALUS (APPLE 2)
In our final installment of Completely Arbortrary’s Excellent Adventure, we take it all the way back to the year 0, Kazakhstan, where we discuss the wolf to our apple’s dog, the Wolf apple (Malus sieversii). Today, we know apple as a supermarket produce section monopolizers, but these are simply the domesticated version of the wild animal that is sieversii, a Kazakhstani native from a different time.
The Wolf Apple
(Malus sieversii)
Few fruits are as well known in the Northern Hemisphere as the apple. It’s the temperate equivalent of the tropical mango or banana: it’s so ubiquitous that you assume it as a given constituent of any fruit stand or produce isle any time of year.
The apples that most people are familiar with from these fruit stands are all variations of a single species we today call the domestic apple, Malus domestica. This is the tree that gives us such vacuous delights as the Gala, Red Delicious, Honey Crisp, and ol’ Granny Smith. The domestic apple has been carried across the world and, due to its extreme heterozygosity [link to old apple episode], has been wildly successful at growing wherever it’s planted and at producing new and interesting fruit.
Heterozygosity describes how differently a plant’s genes are expressed between offspring and parents. An extreme heterozygote is a plant whose offspring, grown from seed, can exhibit wildly different traits as compared to those of its parents. Indeed, each seed fertilized from the same two parents could grow up to be so different in form and appearance that you would have no idea they are essentially siblings.
Humans have used this trait in apples to develop the thousands of varieties that we have today growing all over the world. The domestic apple, though, as its name would suggest, is not a wild apple. Though growing everywhere, it’s native to nowhere. The domestic apple is an artifact of humanity.
You won’t find a Malus domestica with big, juicy, lustrous red fruit just growing wild out your door. And if you did, you can be certain that it was planted there by some human. The apples that most people know, those that you have growing in your backyards and orchards, those that you find in the supermarkets, those apples have had a history akin to that of the domestic dog.
The domestic dog (Canis lupus familiaris) is a descendent of the wild wolf (Canis lupus), and they have been bred into a stunning array of forms, from the wildly flamboyant to the imminently useful. But wherever you see a dog, whether it’s a husky or a dachshund or a retriever, you know immediately that it is an artifact of human intervention. As with the dog, so with the apple, which begs the question: who are the apple’s wolves?
The apple’s proverbial wolf is the wild apple of the Tian Shan Mountain of Kazakhstan, whose scientific name is Malus sieversii, but which henceforth we will call the wolf apple. The wolf apple is one of the lucky few trees whose evolutionary wager on big animals’ appetites really paid off.
Just like the Osage-orange and the Kentucky coffeetree, the wolf apple developed outsized fruit for outsized animals long before humans came on the scene. The same highly variable traits that allowed us humans to cultivate numerous giant apple varieties gave the wolf apple the ability to swiftly adapt to the preferences of megafauna in the mountains of Central Asia. Some of these species are still alive today, like Asian horses, but others went extinct long ago, like aurochs, mammoths, and others. Luckily for the wolf apple, when these animals went extinct, humans were there to take up the mantle.
The wolf apple had success where other trees did not, and it may have to do with the extraordinary genetic plasticity of the species. That extreme heterozygosity allowed the wolf apple to mold itself into the tree du jour for whoever was around to eat it. When humans picked up where the ice age mammals left off, they began transporting wolf apples down from the mountains and along the famous Silk Road trading routes where it was introduced to and hybridized with apple species from Europe and East Asia. Thus, the process of domestication began.
Over the next few thousand years, humans learned to breed and graft apples together, selecting and cloning the varieties that we liked best. Because apples of any variety rarely if ever grow true from seeds, we culled the wild apples from our orchards and planted only our cloned breeds, calling these new forms the domestic apple, Malus domestica.
Luckily, we have not lost the wild ancestors of the domestic apple, our wolf apple. They still thrive in the Tian Shan Mountains where they hold the pool of wild genes that are still consorting and conspiring with the local fauna (including humans) to make sure that, whatever the change in fashions, there will be an apple to suit the times. But we’d be remiss if we failed to remember that we haven’t lost the wild ancestors even in our domestic apples. Inside each seed lays the heart of the wolf apple just waiting to come out.
Completely Arbortrary is produced and hosted by Casey Clapp and Alex Crowson
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Cover art by Jillian Barthold
Music by Aves and The Mini-Vandals
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Additional Reading:
The Wolf Apple (Malus sieversii)
Origins of the Apple
The History of the “Forbidden” Fruit
Where do apples come from?