Lincoln Taiz is peeved. Over the last decade or so, the retired plant biologist has watched the rise of the field of “plant neurobiology” with growing dismay.
That controversial field, which debuted in a 2006 article in Trends in Plant Science, is based on the idea that plants — which do not possess brains — nonetheless handle information in ways that resemble sophisticated animal nervous systems. This thinking implies that plants could feel happiness or sorrow or pain, make intentional decisions and even possess consciousness. But the chances of that are “effectively nil,” Taiz and colleagues write in an opinion piece in the Aug. 1 Trends in Plant Science.
“There’s nothing in the plant remotely comparable to the complexity of the animal brain,” says Taiz, of the University of California, Santa Cruz. “Nothing. And I’m a plant biologist. I love plants” — not because plants think like humans, he says, but for “how they live their plant lives.”
Some plants are capable of sophisticated behavior. Wounded leaves can send warning signals to other parts of the plant, and noxious chemicals can deter munching predators. Some plants may even have a version of short-term memory: Tiny sensing hairs that line Venus flytraps’ insect prisons can count the touches that come from a bumbling insect (SN Online: 1/24/16). But plants perform these feats with equipment that’s very different from the nervous systems of animals, no brain required, Taiz contends.
He and colleagues point out methodological flaws in some of the studies that claim plants have brainlike command centers, animal-like nerve cells and oscillating patterns of electricity that are reminiscent of activity in animal brains. But beyond the debate over how these studies are conducted, Taiz’s team argues that plant consciousness doesn’t even make sense from an evolutionary point of view.