Where is intelligence situated? Our conceptions of intelligence are based on animal models and a kind of “brain chauvinism.” Every animal, from the flatworm to the black bear, has a brain, central meeting place of sensation, and coordinated response. Because animals are mobile autonomous beings who must pursue their food, the brain must itself be compact and portable.
But a centralized brain is not needed for plant intelligence. Rapid movement is not necessary when the food comes to you. For an autotrophic, sessile being, bathed in the needed resources, networked in intimate relationships with myriad others above and below ground, a very different system of sensation and response might well evolve, which looks nothing like the animal model.
If food becomes abundant, no animal can grow more legs to chase after it or a new mouth to eat more. In times of shortage, most cannot cast off a limb that it has no energy to sustain. The whole organism is static in form and flourishes or suffers within those constraints. Not so for plants, who can adaptively alter their circumstances by growing additional parts or losing unneeded ones. Decision-making at tree pace looks like passivity to us herky-jerky animals, accustomed to our own short lifespan. But pine behavior is a slow-motion pursuit of adaptive solutions. Plant intelligence or “adaptively flexible behavior” may be manifest in their extraordinary capacity to change form in real time by altering their allocation of carbon to different functions in response to changing needs.
This slow dance of parts emerging and disappearing is the tree-paced equivalent of movement. Branches expand into light-filled gaps and retreat from dense shade, adjusting their architecture to optimize light capture. Roots are deployed in new directions to follow changing gradients of water and minerals, not randomly but with purpose. They are hunting light and grazing for phosphorous by differential deployment of apical meristems.
Plasticity is possible because trees have myriad growing points, or meristems, a reservoir of adaptation poised to respond to changed circumstances. Tissues that animals never dreamed of, meristems—like totipotent stem cells—can be modified into the new tissues that best suit the conditions. Trees like white pine also have a lateral meristem, the vascular cambium, which gives rise to the cells that increase the diameter of the stem. It is an entire body stocking of meristematic tissue, perpetually embryonic. This nexus of nutrients and hormones and sensory chemicals, and creative cell making, is perhaps a fertile location to search for the decentralized seat of pine intelligence.
Myopic animals mistaking our herky-jerkiness for intelligence!
(Yes, the picture of the white pine above leaves out most of the tree's brain...!)
