Survival of the Fittest?
In The New York Times bestselling book The Hidden Life of Trees, author Peter Wohlleben describes a way of nature that may be the blueprint for us humans to finally get along.
Charles Darwin’s book On the Origin of Species, written in 1859, proposed that species’ survival is determined by environmental influences that trigger a natural selection of genetic traits needed to better ensure survival of future generations.
Shortly after Darwin’s work was published, Herbert Spencer coined the phrase survival of the fittest to further elucidate natural selection. His theory suggests that only the strong survive, while the weak are genetically weeded out.
While Darwin approved the phrase survival of the fittest, he described it in a later edition of On the Origin of Species to mean, “better designed for an immediate, local environment.” This is not the same as only the strong survive, as we have come to interpret Darwinism today.
As it turned out, at least in the world of trees, survival of the fittest is not how it works. Trees depend on the weak, the diverse, and the different. As you will see, survival of a forest depends on diversity. Maybe we should learn a thing or two from the forests!
Tree Wisdom: Won’t You be My Neighbor?
While we’ve come to believe that our survival is based on superior strength, nature has survived far longer than we, and with a much different philosophy. Trees, for example, have incredible lifespans, with the oldest living tree, a bristlecone pine in the White Mountains of California, still alive after 5,062 years!1 With lifespans of such magnitude, perhaps we can learn a thing or two from the hidden life of trees.2
Giraffes feed on treetops, with a penchant for umbrella thorn acacias. If it were up to them, they would devour all the leaves, weakening or even killing the tree. However, in response to being munched on, the tree starts to produce toxic chemicals into its leaves that the giraffe can’t stand. The giraffe moves on to the next tree, but the acacia also gives off a warning gas, called ethylene, signaling other acacias in a 100-yard range to pump out the same foul-tasting chemical in their leaves, thereby protecting neighbor trees from hungry giraffes.
The giraffes then have to graze further, and work harder. As a result, instead of devouring whole trees, they are forced to take small bites and move on as trees put up their defenses.2
Interestingly, trees respond to threats in slow motion. Chemicals are released at a pace of about 1/3 inch per minute, so it takes about an hour for leaves to ward off a predator. This gives the giraffe a decent meal, but then encourages him to move on. Trees have the ability to produce lethal toxins, but, in general, they work with other forces to protect themselves in order to maintain the balance of nature.
For example, trees can detect the type of insect (by their saliva) chewing on their leaves, and, once again in slow motion (so the insect is fed), the tree releases specific pheromones into the air to attract a predator that will eat the insect! In the circle of life, if the giraffe or insect gets greedy (deciding to eat too much), the tree’s defenses can take over.
In nature, one thing is clear: the greedy don’t survive!
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The Wood-Wide Web
Trees also communicate with other trees, even of other species, through underground fungal networks. The work of Dr. Suzanne Simard at the University of British Columbia in Vancouver shows that trees warn each other by sending chemical and/or electrical messages through their roots into vast fungal networks. These networks are so vast that just one teaspoon of soil can contain many miles of fungal network or hyphae—a network described by Dr. Simard as the wood–wide web!
If the threat is extreme enough, then all the oaks in the forest will start secreting protective chemicals into their leaves. The warnings, however, are not just to protect their own species—the fungal network has open access for all. Warnings from one species are often helpful even for competitors to that tree. Somehow, trees have figured out that the whole is greater than the sum of its parts, and that the forest is key to all of their survival.
While critical to the survival of a forest, fungal networks don’t work in a field with cultivated crops. The ability for farm crops to use this network to protect themselves is lost, and thus they become easy prey for pests.
Trees: Survival of the Friendliest
One would think trees compete for sun above and water below, so the bigger the tree, the more of each they could get. The biggest trees would be the survivors, passing on their genes because they are the fittest.
However, one study measured all trees in a beech forest—big, small, weak, and strong. They grew in different soils—rocky, dry, moist, hilly, flat. To the surprise of researchers, all trees had the same rate of photosynthesis. Little trees with less leaves had the same rate of photosynthesis as big trees with many more leaves. How does this happen if photosynthesis occurs in leaves exposed to sun, as we were all taught in biology class?
The wood-wide web, or fungal network, distributes nutrients from bigger nutrient-dense trees to weaker nutrient-weak trees in order to keep the balance of nature and the forest functioning. Instead of a couple of massive genetically superior trees, nature chooses to keep the genetic diversity of the weak and strong, all an integral part of the whole.
Weaker and smaller trees, along with diverse tree species and shrubs, all fill gaps in the forest. If smaller trees were missing, the canopy would expose the floor to the hot drying sun and alter microbiology of the soil and fungal network. Wind, storms, and freezing temperatures could penetrate and take out trees, leaving bigger gaps and further exposure to the elements.
The forest protects all the parts. The weak, the strong, and the different all make up the whole, which is greater than the sum of its parts.
Perhaps it’s time we too surrender to the fact that we are stronger together than apart! Our diversity may just be our greatest strength.