On the memory of trees.

Scientific American looks at the work of ecologist Suzanne Simard, and her efforts to preserve “mother trees,” which have intelligence, memories, and even look out for their kin:

You also found that birches give sugars to fir trees in the summer through the mycorrhizal networks and that firs return the favor by sending food to birches in the spring and fall, when the birches lack leaves.

Isn’t that cool? Some scientists were having trouble with this: Why would a tree send photosynthetic sugars to another species? And to me, that was so obvious. They are all helping one another to create a healthy community that is of benefit to everyone.

Nowadays we look at things like the human genome and realize that a lot of our DNA is of viral or bacterial origin. We now know that we ourselves are consortiums of species that evolved together. It’s becoming more mainstream to think that way. Likewise, forests are multispecies organizations.

Your use of the word “intelligent” to describe trees is controversial. But it seems like you are making an even more radical assertion—that there is an “intelligence” in the ecosystem as a whole.

You used the word “controversial.” That comes from me using a human term to describe a highly evolved system that works, that actually has structures that are very similar to our brain. They are not brains, yet they have all the characteristics of intelligence: the behaviors, the responses, the perceptions, the learning, the archiving of memory. And what is being sent through those networks are [chemicals] like glutamate, which is an amino acid that also serves as a neurotransmitter in our brain. I call the system “intelligent” because it is the most analogous word that I can find in the English language to describe what I am seeing.

Some people challenge your use of words like “memory.” What evidence do we have that trees are actually “remembering” what happened to them?

The memory of past events is stored in the tree rings and in DNA of the seeds. The width and density of the tree rings, as well as the natural abundance of certain isotopes, holds the memories of growing conditions of previous years, such as whether it was a wet or dry year, or whether there were nearby trees, or if they had blown over, creating more space for the trees to grow faster. In the seeds, the DNA evolves through mutations, as well as epigenetics, reflecting genetic adaptations to changing environmental conditions.