Mammoths made apples big and tasty

This 2013 video says about itself:

Going on Mammoth Safari in a Siberian Pleistocene Park

Stewart Brand of the Long Now Foundation details what the future might look like for a parcel of land that is being developed by a ecosystem revivalist, who hopes to reintroduce extinct ice age species to Russia.

Translated from Belgian daily De Standaard, 28 May 2019:

Megafauna helped to make the apple big

Extinct giants such as the cave bear, the mammoth and the giant deer played an important role in the evolution of the apple.

By Senne Starckx

You wouldn’t expect it right away, but fruits like the apple, pear, peach but also strawberry and raspberry all belong to the same family: the rose family (the Rosaceae, the ornamental flower is also a member). The fact that the fruits of this plant family differ so much from each other does not make it easy for botanists to reconstruct its evolutionary history. And, eg, to determine which species are close relatives, and which are only distant family.

But fortunately, there is the DNA. This does not differ too much in terms of structure, and in addition, the letter code betrays the degree of relationship between different species, as well as their evolutionary origin. In 2016, Chinese scientists succeeded in identifying the common ancestor of all three thousand species of Rosaceae on the basis of genetic data: a puny plant with small, hard fruit without even a small amount of flesh. The vegetarians among the dinosaurs – this “rose” grew and flourished just over 100 million years ago – might not have liked it.

Such a large plant family, with such great diversity, that can, of course, only be the result of solid evolutionary control. By birds, insects and other small animals, the traditional pollinators and seed distributors. Or by human beings, who, by domestication and breeding, have immensely put many new species, and varieties on the world.

But larger animals, of which you would not expect it at first sight, can play a decisive role in plant evolution. According to Robert Spengler, paleo and ethnobotanicist at the Max Planck Institute for Human History in German Jena, larger fruits such as the apple have a great deal to thank to big animals, which we do not immediately associate with a juicy piece of fruit. The German analyzed millennia old (mostly charred) apple kernels from excavations in Europe and Asia. The kernels belonged to wild apples that were once picked and eaten by late hunter-gatherers or early farmers. The results of Spengler’s research are described in the journal Frontiers in Plant Science.

In his pits collection, Spengler was able to detect four different wild apple species. After linking the species to the archaeological sites where the kernels were found, he saw a pattern. The geographical spread proved to coincide well with so-called refugias, places where it was still somewhat bearable during the last ice age (thanks to a moderate local climate). According to Spengler, the apple seeds, within the refugias, were mainly spread by (the excrement of) large mammals such as cave bears, mammoths and giant deer – and other specimens of the dangerous but long-extinct “megafauna“. The German botanist is moreover convinced that thanks to these typical “ice age animals” the modern apple is larger than just a blueberry, raspberry or cherry. Their appetite and greed supposedly pushed the evolution of the apple toward ever-greater fruits. Spengler thinks that a similar story can be told about other fruits of size, such as pear and peach. Unfortunately, he does not have old fruit kernels to support that claim as well.

When the ice age ended 12,000 years ago, it was also the end of the megafauna. But don’t mourn, because there were humans. And there were the first farmers who began to improve and refine fruit and other (agriculture) crops. Due to the retreated ice caps, contact was again possible between the areas where the various wild apple tree species grew. And the species could be hybridized. In the end, presumably somewhere along the old silk road in the Tianshan Mountains in Kazakhstan today, the forerunner of the modern apple tree emerged. With big, juicy fruits.