Another rather interesting trait of slime molds and related organisms is that they are capable of rather impressive feats traditionally thought to be limited to “higher” animals. These include behaviors like problem-solving skills and the ability to learn. Amazingly, they also display the ability to anticipate environmental changes based on prior experience. Still, just like bacteria, the amoeba-like cells in slime molds do not possess an actual animal-like nervous system. If we think about it, from our admittedly biased perspective, the absence of a nervous system makes the behavioral repertoire of bacteria and slime molds even more astonishing.
Oné Pagán: The First Brain: The Neuroscience of Planarians (2014),

I looked up at the sky and all around and saw no sign of any birds. I was standing on a rocky beach in Maine. I had a bucket of lobster shells, which I threw onto the beach. A minute later two seagulls arrived from somewhere and began to feed. I knew this would happen (I had been disposing of lobster remains this way for many years), and I knew that the long-distance visual capability of seagulls was remarkable.

So is the vision of hawks, the strength of spider webs, the speed of deer, the cunning of squirrels, and so on. I know that all these features and every other characteristic of  living creatures are the product of evolution by natural selection. But I can understand why some people see the hand of an intelligent designer in the amazing structures and function of flowers, bees, and all of life.

And I now believe they are right. I think there is in fact an intelligent designer at work that explains all the magnificent beauty of biological life. But when I use the word intelligence, I mean something different than the kind of intelligence we are most familiar with.

We solve problems with our intelligent brains, as do many other animals. But is brain-centered intelligence the only form of intelligence that can exist? Apparently not, since we already know the brilliant things that computers and automated machines can do. We might be able to imagine other forms of intelligence that have nothing to do with the complex neural electrical circuits that are the components of smart brains.

Actually, all living creatures, including single-cell organisms like bacteria, possess a form of intelligence that is not remotely conscious or like anything based on brain function. The dictionary definition of intelligence is the capacity for learning, reasoning, and understanding. Clearly a single bacterium, or even a single ant, is unlikely to exhibit any degree of reasoning or understanding. But populations of bacteria and other “primitive” creatures do show the capacity to learn, and, depending on how one defines the words, to reason and understand. When observing these organisms, we are tempted to describe their behavior in anthropomorphic terms, because they seem to resemble familiar human characteristics.

For example, the quote by my friend, Dr. Pagán illustrates the remarkable way that slime molds can behave. Thousands of individual M. Xanthus bacterial cells can coordinate their behavior in order to more effectively attack and degrade other bacteria.  Many bacteria living in soil, with restricted mobility, solve the challenge of migration by growing in a pattern that results in net migration in a particular direction. Some single-cell amoebae are able to construct shells of glass from sand grains. The idea of a single cell building its own shell is remarkable.

The intelligence of “lower” creatures is not related to neural electrical impulses – it uses a completely different platform. What we see in all living creatures, no matter how simple and small, is biochemical intelligence. Bacteria, amoebae, ants, and plants communicate and perceive through chemical signals, not electromagnetic ones.

Bacteria use biochemical signals and receptors for those signals to communicate to those around them that they are there, and when a critical mass appears, the community of bacteria take the appropriate action (produce light, or virulence, etc.). Plants of all kinds also use biochemical signaling both for internal and external communications. No tree, flower, or grass possesses any neural systems.

Even in advanced, large creatures like us, most of the cells in the body act on signals from neighbors and hormones. The great majority of the activity of liver, skin, intestinal mucosa, and other somatic cells is invisible to the brain, and the very existence of a large intelligent brain is irrelevant to most somatic cells.

Biochemical communication between cells, the foundation of intrinsic biochemical intelligence, depends on the production of very specific proteins, which can act as signals and receptors, as well as on enzymes involved in the synthesis and degradation of these signals. Like all proteins, those involved with communication are produced in the ribosome according to the program of the DNA sequence and the genetic code. The genome determines not only what signals are produced and what the receptors do in response to binding to a signal, it also determines when this happens, thanks to intricately complex gene regulatory networks.

The actions of the signaling proteins and their receptors are automatic and preprogrammed. The organism has no choice in what happens when a signal is bound to a receptor and the bound receptor initiates some action by the cell. This might call into question whether we should really consider this to be intelligence, any more than we deem a computer intelligent.

But, in fact, there is more to IBI than chemically predetermined actions following the receipt of a chemical signal. When it comes to animal intelligence, we consider interaction with the outside world as an important part of intelligent decision-making and the exercise of will. Animals interact with the environment by means of their senses, and feedback from sensory stimuli is an essential part of neurological intelligence. Such feedback tends to be swift and in real time. A fox smells a rabbit, approaches slowly, sees the rabbit, and decides to give chase. The sensory input leads to the intelligent decision to pursue the prey.

Cells also have a way to get feedback from their environment that allows for intelligent choices and decision-making, but it is vastly different from animal sensory perceptions. The way bacteria and other simple organisms get the feedback they need is by dying.

Put another way, the feedback that tells cells whether their communication, defense, and other systems important to their lives are working well or need to be improved is natural selection. The best way to see this in action is the “viral” video from Harvard that shows bacteria evolving and expanding into zones of increasing concentrations of poison. As the bacteria spread, most of them die, and the survivors have undergone mutations allowing them to thrive in higher poison concentrations. It is this same process of evolution by natural selection (environmental feedback) that allows for the origin of the protein signals and receptors and is responsible for their continuous improvement and adaption to changing environments. The feedback here is extremely slow compared to sensory feedback, but it has the same effect. Remember, it isn’t the individual bacterium or social insect that counts, but the whole population.

This means that the intelligent designer is actually every biological population of organisms, and the method of design is populations using their intrinsic biochemical processes of communication and protein synthesis, coupled with input from the outside world by means of natural selection to give feedback regarding what works and what doesn’t. This is design by intrinsic biological intelligence.