At the Wall Street Journal this weekend, Alison Gopnik a developmental psychologist and author of a number of books on child and infant learning, pointed to the learning skills of life forms without a brain and offers some insights:

It might seem obvious that you need a brain to be intelligent, but a new area of research called “basal cognition” explores whether there are kinds of intelligence that don’t require neurons and synapses.

Alison Gopnik, “Learning Without a Brain” at Wall Street Journal (July 26, 2020)

If we look at the behavior of slime molds and the blob at the Paris Zoo, it’s not at all obvious that a life form needs a brain to be “intelligent.” Not if all we mean by intelligence is receiving and processing information and thereby adapting to an environment.

She offers the flatworm (Bedford’s flatworm, above right) as an example of intelligence without apparent equipment. This type of worm is flat because it lacks a well-developed respiratory and circulatory system. Otherwise, its cells communicate conventionally, using electrical signals — but with some dramatic results:

Cut one into a hundred pieces and each piece will regenerate into a perfect new worm. (A slime mold-flatworm alliance against the humans would make a great horror movie). But how do the cells in the severed flatworm fragment know how to grow into a head and a tail? …

… In experiments that would make Dr. Frankenstein proud, the researchers altered those electrical signals to produce a worm that consistently regenerates with two heads, or even one that grows the head of another related species of flatworm.

Alison Gopnik, “Learning Without a Brain” at Wall Street Journal (July 26, 2020)

A reasonable conclusion is that there is indeed intelligence involved but it isn’t in the individual flatworm. It is rather implicit in the origin and development of the flatworm. Thus the individual worm doesn’t think and doesn’t need to.

Here’s the open-access paper, by Santosh Manicka and Michael Levin, which is part of a 2019 Royal Society theme issue ‘Liquid brains, solid brains: How distributed cognitive architectures process information.’

In their conclusion, Manicka and Levin aim at something more ambitious than freak flatworms:

Unifications of disparate-seeming concepts and discoveries of fundamental physical dualities have been some of the most powerful revelations in twentieth century science. The time is right for a deep consilience of ideas across several fields, to show that mechanism and meaning (molecular events and information-processing computations/representations) are two facets of the same biological processes.

Manicka Santosh and Levin Michael 2019 The Cognitive Lens: a primer on conceptual tools for analysing information processing in developmental and regenerative morphogenesis Phil. Trans. R. Soc. B37420180369 http://doi.org/10.1098/rstb.2018.0369

But wait: Mechanism and meaning can’t be simply “two facets of the same biological processes.” Mechanism is what a life form is doing. Meaning is constructed by a conscious mind, observing the situation.

An effort to show that “meaning” is one of “two facets of the same biological processes” is an effort to show that the human mind is a physical entity rather than an immaterial entity mediated through a physical entity. And that way lies absurdity. (“If the mind is an illusion, whose arthritis pain is this?”)

The researchers should stick with flatworms. After all, no worm is going to tell them, “I don’t think two heads and no tail is a good idea for me.” If that happened, the worm would truly be an individual thinking entity—and they wouldn’t be allowed to do the experiment.

Other life forms that seem to think without brains:

Is a brain really needed for thinking? The “blob,” now on display at the Paris Zoo, forces the question.

Is an amoeba smarter than your computer? Hype aside, the microbe’s math skills ace the Traveling Salesman problem and may help with cybersecurity

Even bacteria are purpose-driven. The recent finding that bacteria can make individual decisions may help design better antibiotics.

and

Can plants be as smart as animals? Seeking to thrive and grow, plants communicate extensively, without a mind or a brain