Prospects for the continuation of life on Earth, and of the human species

Universal constraints upon laws of evolution as applied to technologically active species, with relevance to the current state of human existence and potentially to unknown other species

In the July 12, 2024 issue of the scientific journal Nature, an article was published by nineteen co-authors, entitled, “The nature of the last universal common ancestor and its impact on the early Earth system.” The article describes the current status of research into the origin of life on Earth, and the latest available evidence, based upon DNA data, the fossil record and isotope tracing. It demonstrates the remarkable, and even astonishing accomplishments of current state-of-the-art scientific inquiry into the origins of life on Earth.

The evidence discussed in the article points to a single Last Universal Common Ancestor (LUCA) as the original organism from which all life existing on earth today is descended, and the appearance of this ancestor roughly 4.2 billion years ago. That ancestor appears to have been what is called a “prokaryote-grade anaerobic acetogen,” in other words, a very simple single-celled organism, neither male nor female and not requiring oxygen to survive. It procreates simply by creating copies of itself. Such cells continue to exist today, and our bodies contain large numbers of them.

As astonishing and significant as this statement is, it is important to recognize what it does not say. First, it does not say that other life forms did not precede LUCA. In fact, these even more primitive life forms (or pre-life chemistry) are presumed to have existed and evolved into LUCA, but we have no traces of them.

Second, LUCA is not presumed to have been the only existing life form at the time, but rather the only one that survived and evolved into all earthly life forms that exist today. To put this into perspective, let's remember that our entire pre-human population of 900,000 years ago fell to only 1280 individuals, and remained that size until 117,000 years later, before starting to increase again. Furthermore, the entire human race today can trace its ancestry to a single woman, who existed around 200,000 years ago. Every human being alive today shares her DNA.

Both of these examples illustrate the fact that not all of the branches of a family tree ultimately bear fruit, so that even if the family is large, many individual members will themselves have no descendants. The continuation of my line, for example, depends entirely upon my two grandsons, who may or may not have children. That’s not unusual. Every family can ultimately trace its line to a single ancestor. In the case of LUCA, therefore, the common ancestor of all life on Earth is simply the one that survived. Others surely existed, but left no offspring that exist today.

The evolution of LUCA and the laws of evolution

Obviously, LUCA did not remain unchanged. It evolved into many other species and forms of life, through the processes first described by Charles Darwin. In fact, as the Nature article sets forth, it evolved into all other forms of life living today on Earth. How did it do that? Simply by following the laws of evolution. These laws have been described by many naturalists and biologists. The most famous of these laws with respect to evolution, is the law of natural selection, first articulated by Charles Darwin in his book, The Origin of Species. With some editing on my part to allow for the more recent discovery of DNA and its role in what Darwin called heredity, it can be stated as follows:

Evolutionary Law #1: Natural selection is the process by which an individual member of a species passes along traits encoded in its DNA to its offspring. To the extent that these traits contribute to the survival of the offspring, they propagate themselves (and therefore the species).

Natural selection operates over generations to select for the traits that help a species to survive, and to select out the traits that do not. This is often called “survival of the fittest,” with “fittest” being a relative term, depending on changes in the environment in which the species lives. In some cases, the entire species dies out, which we call extinction, when, for example a change in habitat is too great or too abrupt for natural selection to save the species. Some examples of extinct species are the trilobite, the Irish elk, and the Hawaii Chaff Flower. In other cases, one species can evolve into more than one, when populations of a species are isolated from each other for a long time in habitats that alter them in different ways. A common example is the donkey or burro and the horse.

The factors at play in evolution and extinction are many. Some examples are:

· Climate change

· Cataclysmic events

· Loss of habitat

· Invasive competing species

· Loss of food source

· Physical isolation of a species, or a population within the species

By the same token, some of the traits by which species propagate themselves in order to adapt to these changes are:

· strength

· speed

· rapid maturation

· defensive mechanisms

· access to prey or nourishment

· aerial flight

· prolific distribution of seed or offspring

· ability to store nutrients

· access to sexual propagation

· ability to survive hardship and deprivation

All of these are fairly obvious, but it is their common thread that can be consequential in ways that are well-known but not yet fully explored. That common thread is competition. All organisms compete with each other – both within and between species – for resources and sustenance, including food, shelter, mates/procreation, protection, etc. This is true for fungi and single-celled organisms as much as for higher species. It is a well-known, universally accepted statement (or law, if you prefer). It permeates the behavior of all life forms, including (obviously) the human species. It can also be stated as a second Law of Evolution:

Evolutionary Law #2: All living things compete for their existence with all other living things

The role of cooperation

But does natural selection operate by competition alone? What about cooperation, such as symbiosis and other mutually beneficial relationships between organisms of both the same and different species?

There's no doubt that cooperation is a factor, but what is its role? We can begin this line of inquiry by examining what eventually happened with LUCA. For well over a billion years, LUCA and its descendants remained prokaryotes. Evolution was not static during this time, but it was exceedingly slow, and dependent to a vastly greater extent upon chance mutations and interactions other than mating, which did not yet exist.

Nevertheless, prokaryotes eventually graduated to eukaryotes - single cells with a nucleus housing the DNA - some time between 2.7 and 1.8 billion years ago. This means that for a minimum of 1.5 billion years, LUCA did not to evolve beyond simple anaerobic single-celled organisms with no nucleus. This is not to say that prokaryotes did not evolve at all during that time, only that before the appearance of eukaryotes, the potential of natural selection was not apparent. This all changed with eukaryotes - a fundamentally new form of life, containing a nucleus housing the DNA.

Eukaryotes were capable of combining with each other to form offspring that were a combination of two parent cells, and not merely copies of a single parent. As a result, the offspring would have combinations of the DNA from the two parents, and thus be different from either of them. This drove faster evolution, and eventually developed into male and female types, as well as a categorical distinction between plants, animals and fungi, starting as early as 1.5 billion years ago, with plants consuming carbon dioxide and expelling oxygen, and animals and fungi consuming oxygen and expelling carbon dioxide. Even more significant, eukaryote cells began to cluster in ways where some could specialize in certain functions - such as digestion and protection - that served other members of the cluster, and vice versa. These colonies of cells with specialized functions exist today in organisms like the Portuguese man o’war, and bear some resemblance to colonies of insects like ants, termites or bees. In any case, these clusters of eukaryotes can be considered early examples of cooperation, and these first cooperative groups of eukaryotes eventually evolved into the first multi-celled organisms, both plants and animals.

Competition vs. cooperation

There is no question that both competition and cooperation are inherent in all life forms on Earth, and that the origin of cooperation may be said to begin with the transition from prokaryotes to eukaryotes, some 2 billion years ago. It is no wonder that they are both part of our DNA, so to speak.

But I would argue that competition is in fact the only driving force in evolution. Why? Let me begin with a reductionist argument. Let us suppose that an organism exists that does not compete for its existence against organisms that do compete? With no motivation to defend itself against other organisms, how fast would it simply cease to exist?

But if that is self-evident, how can cooperation exist at all? The answer is that cooperation confers an advantage to the organisms that engage in it. It was true for the early eukaryotes, and it is true for social alliances today, from wolf packs to human nations and bee hives.

But what is the nature of the advantage that cooperation confers upon the organisms that engage in it? The simple answer is that it enhances the ability to compete. In French they say, “l’union fait la force.” Unity makes strength. Strength for what purpose? To compete.

Ungulates form herds. Why? For protection. Nations form alliances for the same reasons. Criminals form gangs. Wolves form packs. Fish form schools. Bees form hives. Eukaryotes form colonies and eventually multi-celled organisms. But the purpose is always the same: to compete more effectively, to survive and to pass one’s genes to one’s offspring. Cooperation is a means of competition, not an alternative to it, as far as natural selection is concerned. Life does not compete in order to cooperate; it cooperates in order to compete. This may be stated as Evolutionary Law #3:

Evolutionary Law #3: All living things cooperate in varying degrees with each other for mutual advantage over other living things.

Obviously, none of this is directly relevant to questions of morality, ethics, justice or religion. Right and wrong, as well as good and bad, are questions which must be answered in a different type of discussion. The analysis that is presented here is devoted to what is or is not, with respect to evolution and where it is leading the human species, life on Earth, and potentially life throughout the universe. I am not addressing the question of what should or should not be. But it always helps to start with what we know, in order to look at the effects and consequences.

The emergence of technological species

We come now to the question of the human species and its evolution. We know that evolution has led life in many different directions during its long history on Earth. It began in the sea, migrated onto land, and eventually into the air, as well. It has developed life forms that generate poison and perfume, change color at will, grow horns, fangs and armor and many other means and strategies for defending themselves, gaining advantage over other organisms, and propagating themselves. Evolution can be a very powerful process.

We are, nevertheless, at a particularly momentous juncture in the history of evolution. I refer not so much to the development of the human species per se as to the development of technology in the hands of the human species. Humans are of course the primary and almost exclusive agent of technology on Earth, and they are exceptional in its natural history. We tend to think of intelligence as the primary reason for the ascendance of the human species. But we know that other species possess intelligence as well, including cetaceans, corvids, elephants and cephalopods. And we can’t be sure about the power of their intelligence, their linguistic abilities, and their abilities to function in organized groups. Their intelligence and communication skills, as well as their social organization and life cycles may be so different that it can be hard to gauge their capabilities.

But the octopus is the only other intelligent organism that possesses anything like our hands, and cephalopods are handicapped by a very short lifetime and a lack of social structure. Our ability to fashion, with our hands, new and artificial objects and machines and to harness energy, i.e. technology, is unique. We are clearly the first technological species on this planet. This is why I prefer to emphasize the contribution of technology, rather than brain development or intelligence per se toward the age in which we find ourselves. Let us remember that our brains are essentially the same as they were tens of thousands of years ago. The last major change was the development of human language, which required some rewiring of the brain, but not a lot, because it had already proceeded in that direction, as it has in other species. Current estimates are that the capacity for modern language in homo sapiens evolved prior to 135,000 years ago, but actual modern language may not be much older than 100,000 years. On the other hand, tool making is millions of years old. Neither tool making nor intelligence nor language nor even hands are unique to the human species, but the convergence of them is. And clearly, these capabilities have fed off each other in a systematic way, even if none of them has resulted in major physical changes in our species.

Some of this can be inferred from the growth and spread of human population, especially during the last 60,000 years or so. Equally astonishing has been the parallel and roughly simultaneous development of agriculture, urban architecture, and written languages, even in the Americas, which could not have known what was happening on the other side of the world. The reasons for this are not likely to be organic changes, since we are essentially the same organism everywhere on Earth. The process and the convergence appear to be largely self-driving, once all the elements are in place, perhaps when human settlements reach a critical size that creates a level of interaction that is in some ways exponential. No other species achieved these breakthroughs.

The process has now brought about the Age of Technology, which is accelerating at breakneck speed, challenging our efforts to keep up with and adapt to it, and potentially relegating our participation to that of mere cogs in a system controlled by algorithms, technical managers and organizations like Cambridge Analytica, who discovered that humans could be controlled to a significant degree through their electronic devices. The onset of the age may have begun with the first stone tool kits of hominids, millions of years ago, but today it has progressed to where technology increasingly drives itself, with humans as the pollinators of developments such as AI, artificial life forms and exploration of both the farthest and innermost reaches of the universe. We are often unprepared for the consequences. Most of us try to keep up, but it requires increasing vigilance to stay ahead of the forces arrayed to manipulate us and turn us into mere fuel for the vast machinery that is technology today. Think about your interaction with your smartphone. Who is controlling whom?

Perhaps most of this is the inevitable result of the convergence of forces that formed our species and its societal dynamics. Nevertheless, it is in our interest to try to understand what is happening to our species and our planet – and beyond – to the best of our abilities. This is a unique time in the history of life on earth, and it is due to the evolution of our species and its capabilities. Intelligent species existed in the distant past, especially among dinosaurs, but while we have found their remains, we have never found any signs of civilizations or technologies produced by them. And we surely would have, if they existed. Apparently, the convergence of developments that resulted in a species capable of creating a technological society has never existed on Earth until now.

Similarly, we have no confirmed signs of technology from other worlds, either on our planet or on the others that we have investigated thus far. At most, we have speculation about unexplained phenomena that remain unexplained, which has been true since the beginning of time. But we have no objects on Earth that could not have been produced on Earth, whereas we have transported earth-made artifacts to several other bodies in our solar system, which could not have been produced on those bodies. Where is the space junk from extraterrestrial civilizations?

A similar question was famously asked by nuclear physicist Enrico Fermi in 1950 at a gathering of his fellow scientists. After some debate about life on other planets, they concluded that it must exist, because there is nothing particularly unique about Earth. Planets with life may be rare, but there are so many planets in the universe that ours cannot be the only one to produce life. Even one in a million allows for a vast number. Furthermore, even though it took Earth more than 4 billion years to create its first technological species capable of interplanetary – and potentially interstellar – travel, there is no reason to think that we are necessarily the first in the entire universe, much less the only one. In fact, the odds are hugely against this being the case. This is the point at which Fermi asked his famous question, known as the Fermi Paradox, “Then where are they?”

This is more than an idle question. It is a troubling mystery and refers to an uncomfortable fact that deserves an answer. Why is there no evidence of any contact with extraterrestrial civilizations? Why would such civilizations not have left their traces during the billions of years of our planet’s existence? If we can find one-celled organisms from the earliest times, how much easier is it to find alien space junk? Even if aliens found our planet not worth very much of their time, how much more interesting are the moon and Mars, where we left our space junk? It is simply inconceivable that Earth would not have been visited, nor that we are the very first technological species to exist in all the universe.

The answer to Fermi’s question may help give us an idea about where we are headed as a technological species, and I believe it is possible to at least partially provide such an answer using the facts and analysis already discussed thus far. I apologize in advance if the answer is not to your liking; it is not to mine, either.

The evolutionary ceiling

What worries me is that there may be a law of evolution that has the effect of blocking technological species from developing beyond a certain point – that a technological species hits a ceiling above which it cannot rise, and that this law is the same everywhere in the universe, because the laws of evolution operate the same throughout the universe, as do the laws of physics. If we could pass that point, we would make contact with other technological species from other planets. But the available evidence points to the conclusion that no species anywhere in the universe develops beyond that point. Why?

Does it have anything to do with competition being the prime mechanism behind natural selection and cooperation secondary? I don’t know, but the idea that human nature is fundamentally different from the nature of all other life seems flawed and unrealistic to me. We’re not that different. The laws of the universe are universal.

Hollywood is full of films, like Dr. Strangelove and Don’t Look Up, about apocalyptic and post-apocalyptic visions of the world. We all agree that they have a plausible basis, because we know the power of existing weaponry and the potential to use it, as well as the weakness of the human will. Our species is entirely capable of wreaking terrible destruction on our planet, and destroying many of its species, including our own. In fact, a significant number of species already trace their extinction to human activity. Did technological species on other planets and star systems meet the same fate? Is there a law of nature and evolution that dictates that when a technological species reaches a certain point of development, it destroys itself or sets itself so far back in development that it requires a long, arduous crawl to recover, at which time it once again hits its evolutionary ceiling? Perhaps we should take Hollywood more seriously.

We certainly have the means to accomplish such an apocalyptic outcome: nuclear war, climate change, biological warfare (such as experimental disease strains), chemical warfare, even artificial intelligence. If extraterrestrial civilizations have the same experience, this would certainly explain the absence of contact from or with them. But is it a law of evolution?

I believe that a strong case can be made that it is, that it is built into the nature of life and the primary mechanism of natural selection, as a corollary to Evolutionary Law #2, that all living things compete for their existence with all other living things. I therefore propose Evolutionary Law #4 as follows:

Evolutionary Law #4: When a technological species achieves the capability of self-destruction, its primary competitive drive sooner or later causes the exercise of this capability.

Is an evolutionary ceiling hanging over our heads like a sword of Damocles? Do natural laws of evolution dictate that sooner or later we will bring catastrophe upon ourselves? If so, how close are we to that point? In the last 2 million years, have we ever invented a weapon that we have not used? The answer is no, we haven’t.

The spectacular and unprecedented changes through which we are now living appear to be accelerating geometrically and perhaps exponentially. Compared to the period of the existence of life on Earth, the Age of Technology is no more than a split second, but its acceleration seems without constraint. My analysis is a modest attempt to suggest that there may in fact be a limit – an unplanned direction in which we may be headed, and which may be directed by universal laws that we as yet understand poorly.

Let me ask six questions for which I do not have answers but may illustrate the problem.

1. How likely is it that we will stop inventing new means of destroying ourselves, either in part or in whole, whether deliberately or not?

2. How likely is it that all the nations of the world will agree to destroy all technology that endangers our entire species?

3. How likely is it that we will live with the tools of our own destruction for the indefinite future without using them, either by accident or on purpose?

4. If we agree to measures that will make us safe, how long will all the nations of the world abide by them, with no “Samson option” that destroys everyone?

5. If we achieve the previous objectives, how likely is it that we will manage to keep the means of destruction out of the hands of actors that are not party to the agreements?

6. If we manage to adhere to all of these control measures for ten years, how much longer will we be able to do so? Another 10 years? Another 50 years? Another 100 years? Another 1000? 10,000? 100,000? Will we really keep all of these weapons under control indefinitely?

We have no previous experience with this point in our evolutionary history. Nothing to compare it to. If or when we hit the Evolutionary Ceiling, what will it look like? Will we destroy all life on Earth? Will we destroy all human life plus some other species? Will we destroy ourselves only to the point of leaving behind enough population remnants to rebuild slowly, in the absence of the technological tools to which we will have become accustomed? If we succeed in rebuilding, will we find ourselves hitting the same Evolutionary Ceiling as before? In that case, will the result be as bad or better or worse than the first time, or is it totally unpredictable?

As I said, we have nothing to guide us. For us this is the first time in our planet’s history (and possibly the last) to face this situation. We also have no guidance from the rest of our galaxy or universe, at least not yet.

I don't know about you, but I would find it very comforting to receive visitors from other planets telling and showing us that there is another option and explanation for Fermi’s Paradox.

AFTERWARD

A hope, possibly faint

I could end this treatise here, but I want to consider another possibility. I don’t think it’s a very credible one, but I will offer it, nonetheless.

It is a fact that as we learn more about physics, astronomy, cosmology, particle physics and other sciences, they surprise us with strange new and unexpected facts and new laws of the universe. Recently, for example, it has been argued that there is no such thing as time, or that there is no such thing as space, but three dimensions of time. The Einsteinian equations seemed bizarre when they were first proposed, but Heisenberg’s ideas about quantum mechanics seemed even stranger, and entanglement is stranger still. Nevertheless, we plunge ahead, making new discoveries all the time, as we follow the facts.

In fact, there might be whole bodies of knowledge with undiscovered laws and principles. This entire investigation into evolutionary laws is potentially one such example. But in our recorded history and even prehistory on Earth, there are eerie coincidences that point to the potential of undiscovered laws. I pointed out some of them out earlier. For example, there are strange parallels between human activity at a given time in history in different parts of the world which had no communication with each other. Why, for example, did agriculture develop in North and South America, Asia, Africa, and Europe in much the same period? What about the coincidence of the invention of the same types of hunting tools? The building of monumental architecture and city planning? Why do unrelated written languages appear in different places at similar times, and especially languages in cultures that have no contact with each other? Why are these not separated by greater periods of time in different places?

These may be coincidences, or they may have origins that are not obvious to us, such as a “critical concentration” of human population (cities) that unsurprisingly has similar consequences in different locations. But it may also be true that there are undiscovered principles that offer better explanations. If we ever get a chance to see how they operate in other societies and other species on other planets, we might discover such principles.

In the present case, however, it is arguable that just like the coincident timing of events on different continents on Earth, it is conceivable that there is a similar dynamic by which development of species and technology also occurs relatively simultaneously on an interplanetary or interstellar scale, allowing for spacetime constraints. In that case we might expect to meet these species when we are each roughly at the same stage of development, allowing for differences attributable to differences in location on the spacetime continuum, which would be an alternate explanation for Fermi’s Paradox. I would be very surprised if that’s the real explanation, because I know of nothing in the physical and especially cosmological realm that behaves this way. Celestial objects of all sorts have formed at all different times during the existence of the universe. They obey very wide time constraints, if any. But given the fact that we have so little to go on at the present time, I would not want to rule it out completely. If so, it would be a much happier explanation than my worst fear. Nevertheless, I will breathe an enormous sigh of relief when the first alien spaceship makes a visit to our planet, or ours to theirs.