'Plants are intelligent too’ say scientists

Feed me: The Little Shop of Horrors’ nightmare view of a thinking plant © The Geffen Company

Recent botanical discoveries are leading some scientists to the conclusion that plants might be intelligent beings. But how can it be possible to think without a brain?

Communication, decision-making, memory and senses are signs of intelligent life, present in man and beast. They are not things you would associate with the plant world.

Now, according to research explored by Richard Mabey in his new book, The Cabaret of Plants, scientists are discovering that plant behaviour may be motivated by more than a biological drive for nutrients and sunlight.

The idea that plants might be ‘intelligent’ is not new. A 1973 study convinced many people across the world that plants preferred classical music to rock, and that they could have emotional responses to negative feelings. The scientific methods used to support these ideas have since been almost entirely discredited, but new findings point to the possibility that plants might just be intelligent after all.

Until now, the scientific community has agreed that a brain is necessary for thought, but the expanding field of plant neurobiology suggests otherwise. An experiment conducted by a lab in Florence showed how a Mimosa pudica — known as a ‘shy plant’, for its ability to quickly draw in its leaves when touched or moved — could be trained not to respond to a threat after the threat had been proved harmless through repetition.

To do this, scientists dropped the plant from a height of 15 centimetres 60 times, until it stopped drawing in its leaves. Remarkably, the plant not only continued to respond to other types of stimuli, like shaking, while ignoring the drop, but also it still ‘remembered’ that being dropped presented no danger 28 days after its ‘training’.

For Richard Mabey, discoveries like this disrupt the idea that plants are passive, solely reliant on the right conditions and luck for their development; but rather they are, as he puts it, ‘individuals — active and adaptive agents.’

For scientists, the new discoveries are challenging. Many agree that there’s more to plants than previously thought, but they reject the use of words like ‘learning’ and ‘intelligence’ as inappropriate, highlighting the difference between thought and instinct.

Leaf it out

Scientists agree that plant consciousness is fanciful. But for some the idea that an organism without a brain can make decisions offers exciting insights into our own consciousness — after all, it’s accepted that the brain is the centre of thought, but where and how thought is formulated within it remains a mystery.

For others, this is rubbish. Not only is it patently incorrect that plants have any capacity for an intelligence resembling that found in the animal kingdom, but the research into it is a waste of time and resources, distracting from more pressing concerns and misleading the public with false impressions.

You Decide

  1. Do you think plants have personalities?
  2. If plants are conscious, what do you think the ethical impact is for vegetarians?

Activities

  1. Write a list of five questions you would ask a plant. With a partner, discuss what you think their answers might be.
  2. Plant a seed. Experiment with moving the growing plant in relation to its light-source. Take a picture every day, and record your observations in a diary.

Some People Say...

“Plants deserve rights.”

What do you think?

Q & A

Does this mean it’s wrong to eat plants?
No. Just because there’s an argument that plants are intelligent, that doesn’t mean that they experience any of the world in the same way as humans and animals. Without nerves, a brain and pain receptors, it seems pretty unlikely that they’re suffering. Besides, many plants evolved — and have been developed — to be eaten. There’s a reason fruit is delicious.
Assuming it’s true, how does it change things?
The type of intelligence that some scientists argue plants display actually offers some pretty good solutions to various problems. Additionally, thinking from a plants perspective offers new and valuable insights into things like robot design and network technology. For more information see the New Yorker piece in ‘Become An Expert’.

Word Watch

1973 study
The Secret Life of Plants attracted a widespread following, but was dismissed by the scientific community for its poor experimental practices and pseudoscience.
Mimosa pudica
See ‘Become An Expert’ for a video of the plant reacting to touch.
Agents
In this context, agent describes someone or something capable of acting with ‘agency’. That is, the ability to behave according to its own will in an environment.
Thought and instinct
There’s an argument to be made that intelligence can in fact be separated into two strands; intelligence as it appears in humans and some higher mammals — like dolphins and gorillas — is characterised by things like reason and self awareness, and definitely requires a brain. The other type of intelligence is less abstract, and more about the ability to respond in the best way to the challenges of an environment.

Subjects