Home / Opinion / Columns /  The amazing ‘Wood Wide Web’ that could inspire deep learning
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As artificial intelligence (AI) becomes all-pervasive and attempts to approach the intelligence of humans, a key AI technology enabling this is deep learning. At the heart of deep-learning algorithms are neural networks, a technology inspired by the human brain, mimicking the way that biological neurons in our nervous system send signals to one another. It was a revelation to me that these networks in turn perhaps mimicked an even more ancient structure: an underground partnership of tree and fungi (what scientists call ‘the mycorrhiza’).

We typically think of trees, even if in a forest, as solitary creatures in a Darwinian competition for resources, sunlight and space, but otherwise unaware and indeed unconcerned about one another. This is not so, it seems. A forest is a vast, primeval and complex society connected in an unlikely way—through a web of fungi. As The New York Times writes in ‘The Social Life of Forests’ ( ), “There is conflict in a forest, but there is also negotiation, reciprocity, and perhaps even selflessness. The trees, understory plants, fungi and microbes in a forest are so thoroughly connected, communicative and co-dependent that some scientists have described them as superorganisms."

This was not the general idea until a seminal research paper published by Suzanne Simard in Nature took root in the scientific world. It has been known that threadlike fungi live symbiotically with trees, surrounding and fusing with their roots and helping them extract life-giving phosphorous and nitrogen from the soil, in return for carbon-rich nutrients that trees manufacture using photosynthesis. Simard discovered that this intricate web of fungi connect every tree to every other, irrespective of species. Trees can transport carbon, water, nutrients and even send alarm signals and hormones to one another through these circuits, with the oldest trees donating resources to the youngest. Another piece of research done by professor Tamir Klein quantified this: “In a patch of forest the size of a rugby field, the trees trade around 280 kilograms of carbon every year. That’s around 40% of the carbon in their fine roots, and about 4% of what they produce in total through photosynthesis. Mycorrhizas supplied trees and other plants with up to 40% of the nitrogen they received from the environment and as much as 50% of the water they needed to survive. Below ground, trees traded between 10% and 40% of the carbon stored in their roots."

The interdependence goes beyond carbon and water. A tree attacked by parasites, for instance, passes chemical alarm signals to trees around it, pre-warning them to manufacture their own chemical defences. Research has indicated that plant roots grow toward the sound of running water and that certain flowering plants sweeten their nectar when they detect a bee’s wing beats. A tree about to die may even bequeath its stored carbon to a younger tree through this amazing network. Simard believes that veteran trees “send messages of wisdom on to the next generation of seedlings", and she posits the concept of a forest having several mother trees, the ones that are the oldest and most interconnected (incidentally, her book is called The Mother Tree). The concept of a mother tree is not new: Central American mythology talks of an immense tree that grows at the centre of the universe; Norse cosmology has a similar tree called Yggdrasil.

This coexistence has interesting possibilities. Dr Franciska de Vries of the University of Manchester says that forests “might be more socialist than we thought" and not necessarily follow Darwin’s philosophy of ‘survival of the fittest’. Interestingly, Darwin, who was inspired by the writings of Thomas Malthus and Adam Smith, believed that all life was locked in a relentless competition for limited natural resources. “Darwin’s theory of evolution by natural selection is obviously 19th-century capitalism writ large," wrote biologist Richard Lewontin. At one point, Darwin worried that the kind selflessness that he saw among trees and other creatures would be “fatal" to his theory.

Trees clearly seem to be more cooperative than competitive. Simard, in fact, believes that a forest might be one single organism rather than a collection of trees. Another naturalist Merlin Sheldrake believes that these amazing fungal webs create the ‘social network of plants’. It is not surprising, therefore, that when Nature published Simard’s ground-breaking research, it gave it the title ‘The Wood Wide Web’—not just an inspiration for neural networks, but even for the internet.

Jaspreet Bindra is the chief tech whisperer at Findability Sciences, and learning AI, Ethics and Society at Cambridge University.

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