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This Brainless, Single-Celled Blob Can Make Complex 'Decisions'

S. roeselii is shown here contracting down to where it's holding onto a surface.
S. roeselii is shown here contracting down to where it's holding onto a surface.
(Image: © Courtesy: Bill Porter)

Tiny, brainless blobs might be able to make decisions: A single-celled organism can "change its mind" to avoid going near an irritating substance, according to new findings.

Over a century ago, American zoologist Herbert Spencer Jennings conducted an experiment on a relatively large, trumpet-shaped, single-celled organism called Stentor roeselii. When Jennings released an irritating carmine powder around the organisms, he observed that they responded in a predictable pattern, he wrote in his findings, which he published in a text called "Behavior of the Lower Organisms" in 1906.

To avoid the powder, the organism first would try to bend its body around the powder. If that didn't work, the blob would reverse the movement of its cilia — hairlike projections that help it move and feed — to push away the surrounding particles. If that still didn't work, the organism would contract around its point of attachment on a surface  to feed. And finally, if all else failed, it would detach from the surface and swim away.

Related: Images: Tiny Life Revealed in Stunning Microscope Photos

In the decades that followed, however, other experiments failed to replicate these findings, and so they were discredited. But recently, a group of researchers at Harvard University decided to re-create the old experiment as a side project. "It was a completely off-the-books, skunkworks project," senior author Jeremy Gunawardena, a systems biologist at Harvard, said in a statement. "It wasn't anyone's day job."

After a long search, the researchers found a supplier in England who had collected S. roeselii specimens from a golf course pond and had them shipped over to Gunawardena's lab. The team used a microscope to observe and record the behavior of the organisms when the scientists released an irritant nearby.

First, they tried releasing carmine powder, the 21st century organisms weren't irritated like their ancestors were. "Carmine is a natural product of the cochineal beetle, so its composition may have changed since [Jennings'] day," the researchers wrote in the study. So they tried another irritant: microscopic plastic beads.

Sure enough, the S. roeselii started to avoid the beads, using the behaviors that Jennings described. At first, the behaviors didn't seem to be in any particular order. For example, some organisms would bend first, then contract, while others would only contract. But when the scientists did a statistical analysis, they found that there was indeed, on average, a similar order to the organisms' decision-making process: The single-celled blobs almost always chose to bend and alter the direction of their cilia before they contracted or detached and swam away, according to the statement.

What's more, the researchers found that, if the organism did reach the stage of needing to contract or detach, there was an equal chance that they would choose one behavior over the other. 

"They do the simple things first, but if you keep stimulating, they 'decide' to try something else," Gunawardena said. "S. roeselii has no brain, but there seems to be some mechanism that, in effect, lets it 'change its mind' once it feels like the irritation has gone on too long."

The findings can help inform cancer research and even change the way we think about our own cells. Rather than being solely "programmed" to do something by our genes, "cells exist in a very complex ecosystem, and they are, in a way, talking and negotiating with each other, responding to signals and making decisions," Gunawardena said. Single-celled organisms, whose ancestors once ruled the ancient world, might be "much more sophisticated than we generally give them credit for," he said.

The findings were published Dec. 5 in the journal Current Biology.

Originally published on Live Science.

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  • sciencezen
    Might this have implications for the concept of "consciousness?" Does it originate in the brain or is the brain a receiver?
    Reply
  • noreality
    I think it's more of a case where the irritant causes the organism secrete a different hormone which affects and changes it's movement.
    Reply
  • Anonwriter
    Stentors are not blobs. They may be single celled but they are complex and beautiful.
    Reply
  • info addict
    sciencezen said:
    Might this have implications for the concept of "consciousness?" Does it originate in the brain or is the brain a receiver?
    Definitely makes the case for consciesnes being outside the body.
    Reply
  • S. Taylor
    sciencezen said:
    Might this have implications for the concept of "consciousness?" Does it originate in the brain or is the brain a receiver?
    The current scientific research, primarily from peer reviewed Chinese papers on bio-sciences and neurology, provides significant data supporting the hypothesis that the brain is a data storage, data organization, and and data delivery organ. Obviously, the "code and information" that controls data retrieval, organization, and transmission (thoughs and memories) could possibly be occur elsewhere in the human body. That is an area of future studies.
    Reply
  • sward
    Hi folks, know how tempting it is, but friendly reminder that the Live Science forums are for discussing science, not politics. We've removed some off topic political commentary from this thread. :)
    Reply
  • netdragon
    info addict said:
    Definitely makes the case for consciesnes being outside the body.
    Or that the cell and we are constructs of consciousness (once we have a scientific definition for consciousness)

    S. Taylor said:
    The current scientific research, primarily from peer reviewed Chinese papers on bio-sciences and neurology, provides significant data supporting the hypothesis that the brain is a data storage, data organization, and and data delivery organ. Obviously, the "code and information" that controls data retrieval, organization, and transmission (thoughs and memories) could possibly be occur elsewhere in the human body. That is an area of future studies.
    We're pretty much getting close to that point already. However, the brain is so sophisticated, that it can model most of our processes and even image recognition and some "intentional" behavior that it continues to not be ruled out as the sole cause of "mind". Beyond the "turing machine" look, or bio-electrical, it is possibly a quantum computer as well. So it is very sophisticated and has an emergent property. But there's probably more than the brain to our mind. The problem is, we don't have a good enough way to experiment around alternatives. We're missing some tools to get there right now. I suspect some path of quantum computation will get us there.
    Reply
  • carole4Jesus
    Hi, great video... I was wondering if anyone can spot the coccidioides immitis within the specimen? It may be the cause of the movement. I have this too, and have been researching for a couple of years. It is quite painful at times, and I was wondering if the S. Roeslii can respond to stimuli. I also am curious about the tiny mobile 'creatures' swimming around outside... can anyone i.d. them? I have a video of them *it may also be cocci... swimming inside of a fiber ball, dipped in alcohol... 1000x . They are quite fast and obviously aggitated by the alcohol, however it doesn't kill them.
    Reply
  • carole4Jesus
    carole4Jesus said:
    Hi, great video... I was wondering if anyone can spot the coccidioides immitis within the specimen? It may be the cause of the movement. I have this too, and have been researching for a couple of years. It is quite painful at times, and I was wondering if the S. Roeslii can respond to stimuli. I also am curious about the tiny mobile 'creatures' swimming around outside... can anyone i.d. them? I have a video of them *it may also be cocci... swimming inside of a fiber ball, dipped in alcohol... 1000x . They are quite fast and obviously aggitated by the alcohol, however it doesn't kill them.
    After review, the whole artifact that has captured the S. Roeslii is in fact coccidioides immitis. I have many photos of the various stages. You can spot them in the photo in various places. I believe the cocci. has captured the S. Roeslii, and is driving it so to speak... its a very invasive dimorphic fungi. 202221
    Reply
  • carole4Jesus
    3839Here are 2 stills from the video. This is the very organism that I am infected with. It seems to know no bounds unfortunately. After discovering this cocci. 12 7 yrs. ago, there still is no vaccine, nor a cure. Dogs, cats are even more susceptable to the infecion than humans. The numbers are rising rapidly. In 2013 5,500 were reported, now 15,000 reported yearly. And many more (like myself) are unreported.
    Reply