French, Israeli researchers explore chemical origin of biological cognition

How human beings developed the capacity for cognition has been a scientific topic of speculation for centuries.

If life emerged from non-life, as many scientists hold, how did this dead matter begin to think? Two longtime chemists discussed this question in a perspective published in the Dec. 3, 2022, issue of the journal Life.

Robert Pascal is an emeritus professor of chemistry at Aix-Marseille University in France. Addy Pross, the lead author, is an emeritus professor in the department of chemistry at Ben Gurion University of the Negev in Israel. Their research has long focused on basic aspects of the origin of life problem.

For a lay reader, the article usefully reviews the scientific development of ideas about life's special properties, going back to the late 19th Century, and describes the conceptual and research advances of the scientists involved. The authors give a good sense of how science advances, and where their own views are grounded.

They start with Charles Darwin's theory of evolution, which involved both "corporeal and mental endowments," as Darwin put it.  In other words, Pascal and Pross say, "it took place along both physical and mental axes, [and] both facets would necessarily have been present from the beginning of the evolutionary process."

Dynamic kinetic stability (DKS)

The authors highlight the more recent concepts of dynamic kinetic stability (DKS) and dynamic kinetic chemistry, the chemistry of systems in that DKS state. The DKS state is a recently discovered non-equilibrium state, which crucially depends on a continual supply of energy and other inputs from the environment. But once such a chemical system becomes replicative, the conceptual gap separating chemistry and biology begins to narrow. 

The article reviews recent research on replicative processes in biology and chemistry and find it merges with established biological thinking in the concept known as autopoiesis. This comes from the Greek works for self (auto) and creation or production (poiesis). 

The beginnings of autonomous behavior, at the heart of autopoiesis, can be found in chemistry. And natural selection, they assert, is in effect "just the biological term for kinetic selection."

Regarding the question of cognition, the authors review work showing the cognitive behavior of bacteria. 

"This simplest of life forms is able to sense its internal condition, coordinate with neighboring organisms, and routinely activate elaborate response systems in response to ongoing challenges," they write. "Thus, remarkably, life's mental capability is already apparent at that simplest life level." 

The authors then consider the process in terms of chemistry. Further, mind-like qualities, they suggest, "would have been initiated in chemical pre-life."  The authors describe the differences between the way an inanimate system and a DKS system interact with the environment.

An ‘inside-outside’ relationship

The DKS system has an ontological relationship with its environment, which they describe as an ‘inside-outside’ relationship. "In other words," they write, "the physical emergence of the cell membrane in evolution could be understood as a material consequence of that `inside-outside' ontological relationship rather than its cause."

This is the beginning of biological information transfer, they say. How might this happen? 

"It would only be through an evolutionary process, whereby a replicative DKS system would be able to evolve, that explicit cognitive function could begin to emerge--perception, memory, and learned response," the researchers noted.

The final section of the article discusses how the DKS system is not mechanical but "a dynamic energized system with an obligatory dependence on its surroundings with inherent cognitive capabilities."

Pascal and Pross conclude, "The actual physical pathway by which early mental manifestation was able to evolve into the full-blown consciousness of advanced life forms is likely to preoccupy researchers for decades to come."

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Robert Pascal & Addy Pross. "On the Chemical Origin of Biological Cognition." Life, Dec. 3, 2022. https://doi.org/10.3390/life12122016

An interview with Addy Pross

The chemical roots of biological cognition

Your article reviews the evolution of scientific thought about the origin of biological cognition and you note that there are new research developments indicating that cognition has a chemical origin. What are some of the new concepts that led you to this view?

Two recent developments are of special significance. The first, in biology, is the dramatic realization that bacteria, the simplest of all life forms, are highly cognitive. Biologists now claim that bacteria do the equivalent of "think," "decide," "talk," "listen," "cheat," "eavesdrop" and "lure." That realization was an eye-opener.

Cognition is there from the very beginning, quite remarkable. No brain or neural system required. But that realization hints at cognition’s origin within chemistry. After all, a bacterial cell is nothing more than a microscopic smidgen of physical/chemical "stuff."

The second significant development, in chemistry, was the 2010 discovery of a new dimension in chemical possibility. This was also, quite dramatic. Think of it as equivalent to the discovery of a third spatial dimension that enabled flight.

Chemical aggregates once activated in that newly discovered energized dynamic kinetically stable (DKS) state were found to take on properties that do not exist in the "regular" thermodynamic world. Living entities with their unique emergent properties, including cognition, are now understood to lie within that newly discovered chemical dimension.

Life chemistry finally has a characterizable physical/chemical home. Some aspects of biological thinking will need to be revised to incorporate that newly acquired chemical understanding.

How do you define cognition and its physical basis?

If you want to stress a biologist, ask them to define cognition; it's a highly contentious issue. Nevertheless, one common, though limited, definition is a system that is "able to acquire, process, store, and act on information from the environment.” This is adequate for our purpose.

Categorizing life’s physical basis in DKS terms enables the chemical origin of cognition to be uncovered. A DKS system’s absolute dependence on resources and its responsiveness to changes in resource availability can be seen as the beginnings of a cognitive capability.  The emergence of ‘self’ can also be understood in those terms.

A DKS system can be thought of as an inside in continual interaction with its outside, the resource-providing environment. And a DKS system that has acquired a replicative capability can undergo an evolutionary process toward enhanced management of its resources, toward systems of greater dynamic kinetic stability.

Contrary to common evolutionary thinking, evolution does have a physical directive: the drive of DKS systems toward greater dynamic kinetic stability.

Can you say more about the concept of dynamic kinetic chemistry and how it is helpful in understanding the emergence of cognition.

Dynamic kinetic chemistry is the unique chemistry that takes place within this newly discovered chemical dimension to which all living systems also belong. As I mentioned, DKS systems are totally dependent on resources external to the system for their continued existence, and that’s why the emergence of cognitive capabilities comes to be. 

One could think of this dependence as the beginnings of a mental state. To be clear, mental states, despite being "mental," are physically based, and we now are beginning to better understand that physical-mental relationship. 

What is the importance of the exchange of information of DKS and the environment, the inside-outside relationship?

It's very important. Life’s very existence, together with all its associated properties, derives directly from that exchange of information. It is that ongoing exchange that manages the inside-outside relationship, enables the emergence of self, and drives the evolutionary process.

Stop that on-going exchange and it immediately leads to collapse of the DKS state – to death. That’s why the life-to-death transition is so easy and the reverse direction is a lot harder.

What are your next steps with this research?

Once we understand what life is, a means of synthesizing proto-life systems opens up, an ultimate challenge in science. Preparation of a replicative system in the DKS state would be predicted to undergo an evolutionary process toward increasing DKS stability through increasing complexity, increasing cognitive capability, increasing functionality, increasingly lifelike. 

But the synthetic challenge is considerable. Fifty years of replicative chemistry have taught us that replication alone does not lead to the evolution of life-like systems. A system that is both in the energized DKS state and replicative is required.

The problem is that chemists still do not know how to activate a replicative system into the DKS state. I’d say that’s the major experimental challenge before us.

You list function, agency, purpose, and mind as inconsistent with an objective universe governed by natural law. Do you think some of these are closer to being solved than others?

Life’s special properties, including function, agency, purpose and mind, are expected to become explicable through DKS characterization.

While the exploration of life as a concept has focused on the origin of cognition, similar thinking would allow for the physicalization of function, agency, purpose, and mind.

Paradoxically, it turns out that life’s purposeful character derives from objective reasons. Maybe, just maybe, a two-millennia mystery could be edging toward resolution: Is nature objective or teleological? The simple answer may be that it is both.

How does your concept of the Persistence Principle fit in here?

Whereas regular chemistry is fundamentally governed by Second Law of Thermodynamic considerations, change in dynamic kinetic space is more usefully understood through what (Robert) Pascal and I have termed the Persistence Principle. This is a more generalized form of the Second Law, the drive toward increasingly persistent forms.

The Persistence Principle is a broader physical statement that contains within it the Darwinian biological principle of "survival of the fittest." It’s all part of the goal of physics-chemistry-biology merging.

 What has the reaction been to your article?

Some encouraging responses have been received but it’s early days. It is clear, though, that bridging between the physical and biological sciences is not for the faint-hearted. 

Physical scientists feel uncomfortable with biological concepts such as purpose, agency, cognition or mind; these concepts simply don’t exist in physical terminology. Biologists are generally unfamiliar with the intricacies of chemical reaction theory. The chasm separating those two approaches for understanding the natural world is wide and it will take time to bridge. But the ultimate goal is unambiguous: the conceptual merging of the physical and biological sciences. Nature, after all, is one. There is still a ways to go."