David's theory of evolution;Two; Shapiro's theory extended (Evolution)

by David Turell @, Saturday, December 07, 2019, 22:12 (211 days ago) @ David Turell

Protozoa act like bacteria in the way they respond to stimuli. Note both are free-living and must be able to care for themselves for survival:

https://www.the-scientist.com/news-opinion/single-celled-organism-appears-to-make-decis...


"Reproducing the results of a 100-year-old discredited study, a paper in Current Biology today (December 5) confirms that the pond-dwelling protozoa Stentor roeseli can make complex and predictable behavior modifications to escape harm.

“'What [the paper] shows is that a single cell can have several different possible responses and then choose among them in a defined order,” says cell geometrist Wallace Marshall of the University of California, San Francisco, who was not involved in the study. “Jennings had reported this more than a century ago but nobody really believed it, so showing this result again using modern methods is really exciting in my opinion,” he continues.

***

"[They] found that microscopic polystyrene beads “elicited reproducible avoidance behaviors”—indeed, all of the four behaviors that Jennings himself had noted. It’s not clear why the carmine didn’t work, but it’s possible the composition of the product may have changed since the early 1900s, the authors suggest.

***

"Computational analysis of the assembled data revealed that, as Jennings had seen, the behaviors tended to occur in a hierarchical order. However, this hierarchy was only observed at the population level. In any individual organism, the reversal of cilia direction, bending, or contraction could occur in any order. In the cases where an organism detached, however, a contraction was always the immediately preceding behavior.

"Although its not yet clear how S. roeseli switches between behaviors, “now we’re pretty sure that [Jennings’s result] really is true. . . . It puts it into the realm where people could start to investigate it at a more mechanistic level,” says Marshall.

“'It’s fantastic that they were able to repeat [the findings],” says mechanical and biological engineer Sindy Tang of Stanford University who was not involved in the study. “It’s fascinating . . . that a single cell that is not a neuron has everything you need to make a decision.”

“'This paper nicely settles a debate between those [researchers] willing to accept that non-neuronal organisms are also capable of processing information and acting on that information, and those that stick to the idea that only neuronal organisms are capable of complex decision making,” Madeleine Beekman, an evolutionary ecologist at the University of Sydney who was not involved in the study,"

Comment: What is amazing these research folks don't seem to know Shapiro's work and are surprised by these behaviors that mimic his bacterial studies. Obviously I think all single-celled organisms are programmed for survival with automatic responses, just like bacteria.


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