A New Law of Biology

A New Law of Biology

I believe I have discovered a new law of biology. I call it “the law of differential adaptation”. It is fairly easily derivable from established principles, but I have not seen it enunciated before. It strikes me as illuminating. We begin by making a distinction: between the animate environment and the inanimate environment. A given organism is adapted to both, and there is a history to these adaptations. The animate environment consists of all the impinging life forms that an organism is subject to, particularly predators, rivals, and diseases. The organism has defenses against these life-threatening factors—ways of surviving in their presence. These ways include things like legs, antlers, and immune systems—for running, fighting, and disease avoidance. The inanimate environment consists of all the non-biological factors that govern an organism’s life: space, time, matter, gravity, climate, oceans, mountains, volcanos, rocks. This is the physical environment as opposed to the biological (and psychological) environment. Now, these two environments show a marked difference: one evolves slowly, if at all, while the other evolves quickly (relatively speaking). The physical make-up of the planet is pretty stable over time, give or take the odd ice age, meteor impact, or volcanic eruption. Once a species is adapted to it its work is done: it doesn’t change, so the organism doesn’t need to. When there is a large change, extinction is likely, because not adapted to. But generally speaking, the rate of adaptive change is slow and equilibrium is readily achieved (judged by evolutionary time). For all intents and purposes, when a species becomes adapted to space, time, and solid objects it has done all the adapting it needs to do—because these things don’t change. They are physical universals (consider the Sun). But it is different with the biological environment—it keeps changing. It evolves rapidly and unpredictably: the biological world evolves differently from the physical world. It does so because of the action of mutation and natural selection. Consider the arms race between predators and prey: each evolves in response to the other—the faster the prey, the faster the predator needs to be, and vice versa. Thus, there has been a lot of change in the biological world since organic evolution began—species come and go, natural selection never ceases, there is a continual biological interaction spurring change. It should now be clear, then, what the new law says: every organism is a locus of slow and fast adaptation—to the fixed physical environment and the changing biological environment. Evolution is double track—a slow track and a fast track. Some characteristics of the environment have been constant over evolutionary time while others have varied. Adaptation to solidity has remained the same but adaptation to predators and pathogens has varied. There has been trait stability and trait plasticity. Two different evolutionary processes have been at work, according as the organism interacts with a constant physical environment and a constantly changing biological environment. For example, lung design hasn’t changed much because the atmosphere is a physical constant, relatively speaking, but escape strategies have evolved quite a bit in response to predator prowess. Just to be concrete, let’s say the rate of adaptation to these two categories is a hundred times faster for the one than the other. Little evolutionary adaptation to the physical environment and much evolutionary adaptation to the biological environment. Natural selection by the biological environment is a hundred times greater than natural selection by the physical environment. The former triggers a lot of adaptive change, the latter not so much. Hence, differential adaptation.[1]

This distinction helps deal with a puzzle: why is it that organisms die a lot from predators and pathogens but not much from purely physical accidents? Have they lagged behind in respect of the former but not the latter, adaptively speaking? How often do fish die from lack of water as opposed to the predatory actions of other organisms? How often do birds die from midair collisions as opposed to wily predators? How often do land-dwelling creatures die from falling off a cliff as opposed to catching a fatal disease? They all seem very good at avoiding physical accidents but not so good at avoiding their biological enemies—rather maladaptive at this. Why can’t they do better? The answer is that the enemy keeps getting one step ahead of them by means of natural biological change, while they struggle to keep up (e.g., viruses). The lion gets faster and more agile just when the antelope begins to outrun it. An animal can be extremely well adapted to avoiding an earlier iteration of a predator, but now it is faced with a new and improved model. It seems as if it has been lazy in the adaptive department, but really it has been working hard to keep up. The appearance of ineptitude is deceptive: actually, the animal is more adapted (fine-tuned) to the biological environment than the physical environment—it is just that the physical environment is relatively static. Adaptations to it are more primitive than in the biological case. The most advanced technology is deployed in the case of adaptation to the biological world; it just looks as if the animal is ineffective in this domain. Thus, animals die of disease more often than from falling over, because the laws of physics stay fixed while microbes keep changing.[2] The physical world is a steady target, but the biological world is a constantly moving target. The pace of evolutionary change would be much less if organisms only had to adapt to the physical environment. But the biological environment is much more dynamic, changeable, challenging to old ways. It is misleading to talk of adaptive change in relation to “the environment” because really the mechanisms at work are quite different for the two cases: there is physically driven adaptation and biologically driven adaptation. The genes for the former have been around a lot longer than the genes for the latter. It is the difference between the tried and true and the continually updated.

Consider the genetic book of the dead, or the phenotypic movie of the past—that is, the records within the organism of its evolutionary history. Some of these recordings depict an unvarying static history but some depict a frantic history full of rapid change. Four limbs have been around forever, but not the peacock’s tail or the owl’s eyesight. Breathing is as old as the hills, but not antler-locking. The movie would be monotonous when it comes to moving on four legs, but it would become action-packed when dealing with predator-prey interactions. Peace is less eventful than arms races. Animals have more to fear from other animals than from rocks and cliffs. The battle for survival is fought more against other animals than chunks of the inanimate world. Thus, there is a deep difference between coexisting with the physical world and coexisting with the biological world—a quantitative difference. The quantity of adaptation to the biological world is much greater (a hundred times greater, let’s suppose) than the quantity of adaptation to the physical world. The biological world acts to accelerate the rate of adaptive change; the physical world tends to produce a constant state of motion (rest). Once the organism is up and running in a physical environment, it doesn’t have any real motive for upgrading its abilities; but an organism that exists in a world of other organisms (predators, rivals, pathogens, parasites) is playing a different kind of game altogether—it has to keep changing or else it is in danger of being done in by other organisms.[3] Hence the law of differential adaptation.

Permit me to talk briefly about the not-so-brief history of the universe. Cosmologists speak of the evolution of the universe, and the word is not out of place. This evolution is slow by any standards, driven by the unvarying laws of physics (mainly gravity). But in one tiny corner of the universe (as far as we know) it has undergone a remarkably rapid evolution—I mean life on earth. Suddenly life began and developed rapidly, by means of mutation and natural selection. New types of entity came into existence overnight (i.e., several millions of years). Then evolution began to pick up the pace big-time: living things started to interact with each other in myriad ways. In a fraction of a second whole species evolved, only to lapse as rapidly into extinction. In the blink of an eye dinosaurs came and went. So, there were three stages of cosmic evolution: first, the physical evolution of the universe; then, its evolution into life on earth; and then, the co-evolution of living things. Evolution accelerated over this time period (14 billion years) achieving speed-of-light evolution in the last billion or so years. There have been three epochs of cosmic evolution, two of them concerning life. I have been suggesting that we carve up organic evolution into two periods or types, corresponding to organism-inanimate evolution and organism-animate evolution. So, there ought to be a further law: the law of differential evolution. This law states that the rate of evolution varies according to whether it is purely physical, organic-physical, or organic-organic. Physical evolution is slow, organic-physical evolution is fast, and organic-organic evolution is super-fast. Evolution in general thus falls into three phases that can be usefully distinguished; it is more fine-grained than we might have supposed. There are varieties of evolution. In fact, evolution evolves in that its nature changes over time. The early post-big-bang phase was relatively primitive and sluggish; the initial life-on-earth phase was more advanced and a lot slicker; the most recent phase really got into its stride and produced cosmic marvels not seen before (lions, humans, etc.). These are the natural kinds of process into which the overall cosmic evolutionary process divides—the evolution of the entire universe, from the very large to the very small. Call it three-fold evolution. We might be in for a fourth phase before too long, as our machines start to evolve on their own account. Then we might get within-a-lifetime revolutions, as machines beget machines.[4]

[1] Consider so-called artificial selection, say of dog breeds. The biological environment of dogs (initially wolves) includes human dog breeders; they have caused an enormous amount of variation in dogs. The changes, genetic and phenotypic, have been extremely rapid. But the changes wrought by the physical environment of dogs have been minimal to non-existent, because it hasn’t changed, or very minimally. The difference between the two sorts of adaptation is conspicuous.

[2] Imagine if gravity were to change its force from time to time: animals would have a devil of a time adapting to its fluctuations and would no doubt die from it (and hence not reproduce) with greater frequency than now. That would be the physical equivalent of predator transformation: stronger gravity, faster predator.

[3] If the physical world evolved by something analogous to mutation and natural selection, then the difference would disappear, or be reduced. For then, it would embed a mechanism of change that lifts it above physical law, causing it to change its nature over time (of course, this is physically impossible). The biological world is inherently a lot more changeable than the physical world because of this mechanism.

[4] Obviously, AI will be crucial: it might start designing and making machines and organisms hitherto undreamt of, capable of producing yet other machines and organisms. Then we will need a fourth evolutionary category—true artificial selection (machines being not part of the biological world). The pace of this evolution might be measured in seconds not millennia and decades—as machines turn out new machines at a dizzying rate.