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.â€
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 brain like 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.
Sophisticated animal brains evolved in part to help
an organism catch a meal and avoid becoming one, Taiz says. But plants are
rooted to the ground and rely on sunlight for energy, a sedentary lifestyle
that doesn’t require quick thinking or outwitting a predator — or the
energetically expensive nervous systems that enable those behaviors.
“What use would consciousness be to a plant?†Taiz
asks. The energy required to power awareness would be too costly, and the
benefit from such awareness too small. If a plant fretted and suffered when
faced with a threat, it would be wasting so much energy that it wouldn’t have
any left to do anything about that threat, Taiz says.
Imagine a forest fire. “It’s unbearable to even
consider the idea that plants would be sentient, conscious beings aware of the
fact that they’re being burned to ashes, watching their saplings die in front
of them,†Taiz says. The horrifying scenario illustrates “what it would actually
cost a plant to have consciousness.â€
Besides, plants have plenty to do without having to be conscious, too. With sunlight, carbon dioxide and water, plants create the compounds that sustain much of the rest of life on Earth, Taiz points out. “Isn’t that enough?â€
From Source: https://www.sciencenews.org/article/plants-dont-have-feelings-and-arent-conscious-a-biologist-argues
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