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Plants have sensibilities, but are they conscious?

They experience reality differently than we do.

  • The field of plant neurobiology studies the complex behavior of plants.
  • Plants were found to have 15–20 senses, including many that humans have as well.
  • Some argue that plants may have awareness and intelligence, while detractors persist.


Do plants have feelings? Not in a poetic, metaphorical sort of way but real feelings? Can they hate, love, or be bored? If you go around plucking flowers or mowing grass down with your lawnmower, are you causing these organisms pain? A rising field of plant neurobiology may answer these provocative questions.

This area of study was perhaps jolted into existence by the series of experiments carried out in 1966 by a former C.I.A. polygraph expert named Cleve Backster. He was, in turn, inspired by the work physicist Jagadish Chandra Bose, who found that playing different kinds of music near plants made them grow faster

Backster hooked up a galvanometer to a houseplant and found that the plant's varying electrical activity seemed to correspond to the thoughts from Backster and his colleagues. The experiment appeared to show that the plants reacted to whether the thoughts were positive or negative.

In one such trial, written up in the International Journal of Parapsychology in 1968, Backster's team connected plants to polygraph machines and found that a plant that saw someone stomping on another plant, essentially killing it, could pick out this "killer" out of a lineup. It registered a surge of electrical activity then this person appeared before it.

Cleve Backster using a lie detector on a household philodendron. 1969.

Credit: Gay Pauley

While Backster's findings were not duplicated by others, especially as he went on to find plants communicating telepathically, the area of study got a further boost in a 2006 paper published in Trends in Plant Science, where a team of biologists argued that the behavior you can see in a plant are not just a product of genetic and biochemical processes.

The authors, who included Eric D. Brenner, an American plant molecular biologist, Stefano Mancuso, an Italian plant physiologist, František Baluška, a Slovak cell biologist, and Elizabeth Van Volkenburgh, an American plant biologist, declared that a new field of plant neurobiology must be born to further understand plants. This area of biology research "aims to understand how plants process the information they obtain from their environment to develop, prosper and reproduce optimally," wrote the scientists.

They explained their observations that plants show behaviors that are coordinated by some type of "integrated signaling, communication and response system" within each plant. As profiled by Michael Pollan in the The New Yorker, these behaviors include responding to numerous environmental variables, such as light, temperature, water, microbes, and soil components like nutrients and toxins, and even gravity.

What's more, the plants utilize electrical signal and produce chemicals similar to neurons in animals, allowing them to respond to other plants. This led the authors to propose that plants exhibit intelligence, allowing them to react to their environment for both present and future actions.

In fact, studies showed that plants evolved to have between 15 and 20 separate senses including the human-like abilities to smell, taste, sight, touch and hear.

Does that mean plants, which compose 80 percent of the biomass on Earth, have complex nervous systems or even brains?

Maybe not brains like we understand them but intelligence. While brains are useful for problem solving and complex tasks, they are not the only way for organisms to interact with their environments. Humans tends to overestimate the relative greatness of their brains and faculties.

Stefano Mancuso, who was involved in the 2006 paper and runs the International Laboratory of Plant Neurobiology near Florence, Italy, contends that plants think, just differently, utilizing distributed intelligence. They gather information from their environments and respond in ways that are good for the whole organism. They also communicate, having 3,000 chemicals in their "chemical vocabulary".

Check out this TEDx talk with Stefano Mancuso

Many plant scientists over the years have pushed back against the field. One of its most ardent critics has been Lincoln Taiz, a now-retired professor of plant physiology at U.C. Santa Cruz. He believes that plant neurobiology ultimately leads down a slippery slope implying that plants can feel emotions like happiness or pain, can make decisions with purpose and perhaps even have consciousness. Chances of that being true are "effectively nil," writes Taiz in the recent paper "Plants Neither Possess nor Require Consciousness," published in the August 2019 issue of Trends in Plant Science.

While plants may exhibit sophisticated behaviors, their nervous systems are not comparable in complexity to those of animals and they have no similar brains, asserts the biologist. In fact, they have no need for consciousness, as it would require expending too much energy for their sun-oriented lifestyles.

He uses the case of a forest fire to point out the horror of what it would mean for plants to have sentience:

"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," writes Taiz.

Indeed, the idea of plants having self-awareness might seem too daunting and not yet supported by enough credible research, but the overall project of the field of plant neurobiology has already challenged the overly human-centric understanding of nature.

Hulu's original movie "Palm Springs" is the comedy we needed this summer

Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.

Gear
  • Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
  • As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
  • The film is perfectly timed for a world sheltering at home during a pandemic.
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Two MIT students just solved Richard Feynman’s famed physics puzzle

Richard Feynman once asked a silly question. Two MIT students just answered it.

Surprising Science

Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.

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Our ‘little brain’ turns out to be pretty big

The multifaceted cerebellum is large — it's just tightly folded.

Image source: Sereno, et al
Mind & Brain
  • A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
  • The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
  • This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.

Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).

A neural crêpe

A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.

So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.

The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."

Study's cross-sections of a folded cerebellum

Image source: Sereno, et al.

A complicated map

Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."

That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.

It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."

This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."

Bigger and bigger

The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.

"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."

As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."

Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."

Economists show how welfare programs can turn a "profit"

What happens if we consider welfare programs as investments?

A homeless man faces Wall Street

Spencer Platt/Getty Images
Politics & Current Affairs
  • A recently published study suggests that some welfare programs more than pay for themselves.
  • It is one of the first major reviews of welfare programs to measure so many by a single metric.
  • The findings will likely inform future welfare reform and encourage debate on how to grade success.
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