By Steve Davis
In 1943 the eminent physicist Erwin Schrodinger gave a series of lectures in Dublin that were later published in book form under the title What Is Life?
Its success was considerable as it kick-started the new field of molecular biology, but Schrodinger deliberately avoided an investigation into a definition of life, believing that the time was not ripe.
In more recent times, Fred Adams, Professor of Physics at Michigan University, in The Origins of Existence – How Life Emerged in the Universe, wrestled manfully with this question, but he eventually concluded that:
“Achieving a universal definition of life is unquestionably of fundamental importance, but no such definition has yet been forthcoming.”
There is a noticeable reluctance among scientists to grapple with this question of life. All are happy to speculate about the conditions necessary for life to originate, but none seem inclined to actually define life itself. In The Selfish Gene for example, Richard Dawkins devoted a page or so to explaining the conditions necessary for its origin, then stated that “At some point a particularly remarkable molecule was formed by accident.” He then went on to speculate about the further development of this molecule he calls a replicator, but failed to explain to his readers what life actually is.
A strident critic of Dawkins, Professor Gabriel Dover, in his wonderfully quirky and scientifically illuminating Dear Mr Darwin, described the conditions necessary for life from a galactic viewpoint, but like Dawkins he omitted a definition.
Professor Freeman Dyson, another critic of selfish gene theory, in his excellent Origins of Life, did go so far as to provide the characteristics of life, as did Fred Adams, but these provide a description, not a definition.
These approaches seem to typify the attitude of the scientific community to what appears to be perceived as a difficult subject, but as we press on I hope to show that perception to be misplaced.
Adams specified reproduction and metabolism as the characteristics of life, while Dyson took a similar position but quite pointedly differentiated himself from the selfish gene view of life, first stating that:
“… the essence of life from the beginning was homeostasis based on a complicated web of molecular structures… The tyranny of the replicators was always mitigated by the more ancient cooperative structure of homeostasis that was present in every organism,” and with an admirable touch disclosed a personal aspect to the question with the following: “I have been trying to imagine a framework for the origin of life, guided by a personal philosophy that considers the primal characteristics of life to be homeostasis rather than replication, diversity rather than uniformity, the flexibility of the genome rather than the tyranny of the gene, the error tolerance of the whole rather than the precision of the parts.”
If we take the three specifics highlighted by Adams and Dyson, homeostasis reproduction and metabolism, (homeostasis is the ability to maintain a constant chemical balance in a changing environment, metabolism is the chemical processes that occur in cells in particular the consumption of energy, reproduction can be as simple as cell division but can involve a cell dividing in accordance with a code of instructions) we see that all of the characteristics of life require cooperation, either within a cell between its parts, or between combinations of cells.
If we are to examine this from a philosophical viewpoint as Dyson suggests and as I believe we should, then instead of just using physiological processes to explain life we must go one step further and look in turn to their essence.
We must ask what it is that drives or organises the life processes.
It’s clear from the work of Dawkins and all other biologists’ descriptions of the endless and complex cooperative arrangements that exist in nature, from the level of molecules and compounds through to organisms and societies, that cooperation is the common feature behind the organisation of life activities, no matter the form of the living entity. This is consistent for cell, for organism, and for society.
Further, that natural selection (the elimination of less fit organisms) has ensured that those organisms having superior life processes survive and reproduce to an extent that permits them to proliferate.
It’s also clear that the cooperation engaged in by those first replicating molecules is evidence that group selection is not just a theoretical possibility that lacks evidence from the natural world as the W.D. Hamilton school of thought maintains; rather it is the very mechanism that facilitated the initial evolution of life forms.
Group selection would appear to be the dominant evolutionary principle.
Can we extract from this a useful definition of life?
Can we go deeper than a description of the physiological processes outlined by Adams and Dyson?
It seems inescapable that life at the molecular level is actually a remarkably simple and basic concept – life is cooperation.
The key here is to return to the very beginning, to the “primordial soup” that is assumed to be the site of the origin of life forms, and consider the process that saw lifeless molecules assume life.
At what point we must ask, did they assume life?
Unquestionably, when the first molecules began coalescing, then began cooperating with something as simple as replication, that was the point at which they began living, for it’s at that point that they began performing those functions that we generally consider to be the characteristics of life.
Cooperation began life, nurtures life, and expands life, and so can be considered as the definition of life.
Life is not an item, an object. It is not measurable; it’s a process.
There seems to be no good reason why a definition of life at the molecular level should not hold true as life forms slowly increased in complexity.
Indeed, there is nothing about organisms, nothing about the myriad social arrangements existing in the natural world that undermines this definition.
All are wholly dependent on cooperation for survival, and all, even groups or societies, demonstrate homeostasis, metabolism and reproduction in one form or another. (The forms may differ, but all have mechanisms for maintaining stability, for intake and consumption of energy, and for reproduction.)
If the definition of the first biological life is cooperation among molecules, then possibly a useful general definition is that life is just simply cooperation. We can test this by asking the reverse question.
If life is cooperation, is cooperation therefore life?
It strikes me that such a case could be mounted as long as conditions are attached.
For instance, an engine demonstrates cooperation between its various parts to achieve a particular end, but we would only refer to it as being alive in a metaphorical sense, as an engine needs external inputs for initiation and for sourcing of energy.
The limitations of the engine example however, lead us in the right direction for a useful general definition.
We can conclude as a general rule that independent spontaneous cooperation is life.
Why is it important to define life?
Perhaps “define” is not even appropriate for a process.
Perhaps “explain the essence” is more suitable.
No matter the term or phrase used, if cooperation was to gain widespread recognition as the most important and indispensable aspect of all life, this would revolutionise the world in which we live.
Economics for example, would no longer be the study of scarcity and competition — it would become the study of the advantages to be gleaned from working together rather than grudgingly co-existing in a state of constant confrontation.
As Professor Fred Adams said:
“Achieving a universal definition (explanation) of life is unquestionably of fundamental importance.”
Possibly, in more ways than he realises.
Notes
As almost twenty years have passed since a version of this was first published, I thought it might be prudent to see if progress had been made in defining life.
It turns out that although some of the old thinking is still influencing progress, there seems to be a younger generation of physicists and biologists doing good work in this area.
Interesting articles can be found here:
Scientists have come up with a new meaning of life – and it’s pretty mind-blowing
Radical New Theory Gives a Very Different Perspective on What Life Is
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We all know the answer is 42. But what is the question.
Suppose that an AI robot followed its own blueprint to make another AI robot and together they made another AI robot to that (now) common blueprint and this process continued.
Would that count as life?
It has all the criteria this article puts forward for it to be: cooperation, replication, stability in a changing environment (homeostasis) and the intake and consumption of energy (metabolism).
Perhaps a fifth criteria to the definition is in order: biology.
Life is biological.
** Not so long ago a scenario such as I described was confined to the realms of science fiction but today that position has shifted considerably. While we’re not yet at the point of it being a certain outcome we’re definitely well past it being either impossible or improbable.
“It has all the criteria this article puts forward for it to be: cooperation, replication, stability in a changing environment (homeostasis) and the intake and consumption of energy (metabolism).”
Interesting comment, Joel.
The natural instinct of all species is to survive and multiply. You ticked that box.
Take to coronavirus as an example. It was never going to survive if it killed its host, so it evolved into something less lethal.
“Suppose that an AI robot followed its own blueprint to make another AI robot and together they made another AI robot to that (now) common blueprint and this process continued. Would that count as life?”
It’s a great question Joel, and it brings to the fore the idea that a “definition” of life is too restrictive, and that an explanation is preferable. (I only changed my opinion on that point during the preparation of this piece for AIMN, having clung to a definition for almost twenty years.)
In this case I think you’re right — that life is biological.
That was well put by a fellow blogger years ago who was commenting on an article about AI, and he made this point; Intelligence is biology, because at the end of the day, you can build any kind of machine you like with whatever degree of sophistication technology allows and it can excel at its assigned task. But until you can build a machine that gives a damn, it is nothing but a set of human induced rules.
Another aspect to your question is that the first robot in such a chain is not alive as it did not arise spontaneously from its environment. It was consciously manufactured, so it might be a stretch to allow that its creations are alive. But that’s merely my opinion — a “pet” condition if you like.
You’ve nicely introduced the theme of the follow-up article — the place of intelligence in the story of life.
I’d better get to work.
“Achieving a universal definition of life is unquestionably of fundamental importance, but no such definition has yet been forthcoming.”
Maybe because that’s an individual thing for every person, just like their cultural, emotional, familial, spiritual bonds and the personal relationships they build, and how they encounter the world in their travels thru life and the choices they make in those circumstances as they travel thru those varying phases with emphasis on the building bit.
As for scientists attempting to explain life, they are still trying to figure out the Big Bang! IMHO somewhere along that chain of chaos two aspects met and formed some kind of biology that has transmuted over billions of years to what we know today what I call the God particle.
A simple explanation that I found many years ago as I’m a simple person https://www.youtube.com/watch?v=uaGEjrADGPA
And here’s some detail about M87, huge galaxy that we are a small tiny dot of so we have a ways to go….
https://en.wikipedia.org/wiki/Messier_87
Heather, you make a good point.
Our tendency to confuse our consciousness (very personal) with life, has hobbled our ability to distance ourselves from looking at the underlying features of life at the material level.
You mention The Big Bang.
That raises the odd fact that most of the realistic consideration of the essence of life is being done by physicists, not biologists.
Perhaps that’s because physicists have become accustomed to tackling tough questions such as the origin of the universe.
This has been a question that begins to merge with the most profound of metaphysical considerations, and biologists do not seem to have the background to venture there.
Let us have more conversation between physicists and biologists, whereby we scribblers may be better listeners…learning.
Thanks Steve for a stimulating essay.
In thinking upon the content I was reminded of an incident several years ago when a good mate, with the help of a very large rum, began to wax lyrical. Spying his 5yo great-grandson close by, he asked the youngster: “What is life?” A reply was given immediately: “It is what you make of it”. Out of the mouths of babes indeed!
Having recovered somewhat from our joint astonishment at this, we thought to contemplate the matter further by assuming that however life might be said to have begun, its continuation (upon any level) would appear to require some form of biological input, without which the ‘system’ fails.
As humans are clearly an important biological component of life upon earth, does our mere presence affect those systems which are said to sustain us? I think it can be argued that how we collectively think and act does indeed affect our material environment, if not ultimately the very survival of our species.
For example, we are now beginning to more fully understand the effect of our actions upon, say, the climate cycle together with the accelerating depletion of the earth’s resources.
That’s looking at matters on perhaps the largest level. But what of the individual?
Does the same hold true here? Do our individual thoughts and actions have a direct bearing (or outcome) upon our lives, upon our individual circumstances, such as our health, our financial circumstances, our relationships, and so on? I think the short answer has (in large degree) to be yes, in which case our individual lives are a continuous process of creation; and, I assume, the same to be true of the collective.
The final question then is: to what end is all this human endeavour? Leaving aside what precisely drives the effort (or causes it to happen), what is the intrinsic purpose of such individual and collective thought and effort? Do we actually have an end result in mind, and if so, what is it?
Julian, many thanks for your interest, and for digging deeper.
Discussions along these lines almost force us to go deeper.
The result is that physicists, who as I mentioned in an earlier comment have become accustomed to digging deeper, have found that their tentative conclusions (some might call them speculations) from quantum mechanics have overlapped with Eastern spiritual teachings.
And so we see the emergence of books such as The Tao of Physics, that I think Kanga might have mentioned on another thread. The author Fritjof Capra stated that “Science does not need mysticism and mysticism does not need science. But man needs both.”
Your question “to what end is all this human endeavour?… what is the intrinsic purpose of such individual and collective thought and effort? Do we actually have an end result in mind, and if so, what is it?” is evidence for the view of Capra that we need both science and mysticism.
There is a universal and deep inner need to ask “WHY?”
There will be a follow-up piece that edges a little more in that direction, so perhaps we should look at your question there.
Yes Steve,
I’ll lay claim to the (several) references in AIMN to Tao of Physics by Fritjof Capra (albeit Kanga may have too).
I read it out aloud to my girlfriend in the late 70s, although she did snore through some of it. Then I re-read it in the 20teens after much time spent throughout the subcontinent, and closer association with the mystics. My delight with it hadn’t waned.
I luv the energetic probability in “Science does not need mysticism and mysticism does not need science. But man needs both.”
I look forward to your follow-up piece.
Clakka, thanks for your interest.
Capra has copped criticism from a section of the physics community, but the tone of the criticism is rather like that which was dished out to Nowak Tarnita and Wilson when they declared that Hamilton’s inclusive fitness concept was dead.
Emotional responses are rarely factual.