What is Life?

Posted on May 28, 2020 by Martin van Creveld

The question how dead matter could have given rise to conscious, sentient living beings such as ourselves has been preoccupying people for millennia past. So much so, indeed, that our inability to answer it remains one of the great constants of our history. Just think of the book of Genesis which has God first making man and then breathing into his nostrils “the breath of life.” Thereby turning him into “a living soul” out of whose rib He later fashioned a woman, too; meaning, perhaps, that the process by which Adam was created “out of the dust of the ground” was one of a kind which not even He could replicate

However, many of us moderns do not believe in God and may not even be familiar with the Bible. Let alone know what the Buddha, Plato, St. Augustine, Descartes, and many other philosophers and/or psychologists, biologists and computer engineers had to say about the matter and do so still. So I thought I would try to put together a short list of things which, by their presence or absence, will indicate whether X, or Y, or Z, is or isn’t alive. If not for the benefit others, at any rate for my own.

Cellular structure. Starting with germs—but not including viruses, which for that very reason are not always included under the rubric, life—all living matter is made up of cells. Cells fall into two basic types, prokaryotic and eukaryotic. Prokaryotic cells do not have a nucleus; eukaryotic ones do. Living organisms are built either of single cells, as bacteria and amoeba are, or of multiple ones.
Self-repair. A cardinal quality only life has is its ability to repair itself. A locomotive, or an automobile, or a computer for that matter, cannot do this. Once something goes wrong, it will either stay wrong or get worse. Not so living organisms. A wound, provided it is not too serious, will start healing itself almost as soon as it is inflicted. Provided there is no infection, a hard object embedded in our flesh will be surrounded by scar tissue and can remain in place for many years without giving rise to any further trouble. In quite some animals even the loss of a tail, or tentacle, or limb, or teeth, will be compensated for by new growth. These are things no inanimate object, natural or artificial, can do. Or, presumably, will ever be able to do.
Metabolism (from the Greek: beyond change); meaning, the sum total of life-sustaining chemical reactionsin organisms. It is generally divided into three parts. First, the conversion of food/fuel into energyon which all physiological processes run. Second, the conversion of food/fuel into building blocks for various kinds of tissue of which the body consists. And third, the elimination of wastes. These enzyme-catalyzed reactions allow organisms to grow, reproduce, maintain their structures, and respond to their environments. All living organisms necessarily have such chemical reactions; non-living ones do not.
Growth. Given the opportunity, i.e food and a favorable environment, all living creatures grow. A chicken grows into a chick, a human baby into a man or woman many times its size and weight. This is not simply a matter of material being added from outside, as when two or more droplets, bubbles or particles merge during contact to form a single daughter droplet, bubble or particle. Nor of crystallization, as when a solution of certain materials, such as Epsom salt in boiling water, is allowed to cool, causing the salt atoms to run into each other and join together in a crystal. Rather, of a creature growing according to its own internal laws as embedded in its DNA.

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Reproduction. Starting with germs and ending with trees and whales, what all living creatures have in common is their ability to reproduce, i.e make more or less faithful copies of themselves. Not so inanimate objects, not one of which has ever performed that feat. A spoon does not divide to form two spoons, a telephone does not become pregnant and give birth to another telephone. True, a three-dimensional printer can be used to produce as many copies as desired of many objects, parts of itself specifically included. Two printers can even made to work in tandem, producing parts that can then be used to build a third not identical to either of them. What they cannot do is assemble those parts until they form a third printer; that must be done by hand. As long as this is the case the story of the sorcerer’s apprentice, where a broom is first broken in two and then starts reproducing itself and refuses to stop, will remain just that—a story.
Evolution. Reproduction means creating more organisms of the same kind. Not so evolution which, over time, results in the emergence of organisms that, on occasion, can be so different from the original as to be barely recognizable. As, for example, when terrestrial animals evolved out of maritime ones, birds, out of dinosaurs, and humans, out of some ape-like ancestor.
Changes brought about by evolution are hereditary, which means that they are not simply the product of the natural environment and the organism’s attempt to adapt to it. As far as present-day scientific knowledge goes, what drives evolution is random changes (mutations). Such changes are brought about by errors in a creature’s DNA. The errors themselves can be caused by a. External factors, i.e certain chemicals or high energy particles hitting the DNA molecule in question; b. DNA’s failure to properly mate with its opposite number during conception; and c. DNA being an extremely complicated molecule, it may fail to replicate (copy) itself properly during cell division. Provided they are beneficial rather than harmful, in which case the creature that carries them will be selected out, a long sequence of such changes, known as genetic drift, can result in a new species emerging, at feat no non-living object has ever been able to emulate. That even applies to the so-called evolvabots built by robot-engineer John Long. Evolvabots do mimic some aspects of living systems such as sensing gradients, foraging, maneuvering, evading predators, and attacking prey. However, not one of them has ever changed themselves into something it was not
Consciousness. Just what consciousness is no one knows. Starting with Democritus around 450 BCE, many philosophers and scientists have gone so far as to insist that it is an illusion and that, “in reality,” there is no such thing; all there is are patterns of electric (and chemical, a point that those who claim that brains are just computers often overlook) activity in the brain. However, few if any of them would agree that they themselves do not have it.
Consciousness is what accounts for our ability to think—cogito ergo sum, as Descartes put it. Not just to answer questions, which properly programmed computers can do as well as, and much faster than, we, but to formulae them. Also, which may be even more important, to experience such feelings as awe, elation, fatigue, fear, joy, hatred, hunger, love, pain, pleasure, and any number of others right down to the end of the alphabet. Though one may doubt whether all these are present in all living creatures—whether, for example, germs can think and trees, experience fear—one thing seems abundantly clear: inanimate objects to not have it.
Purposefulness. Two things can cause the status quo to change; a cause, and a purpose. A cause is exemplified by a push we get from behind, making us move, stagger or fall down. A purpose is something we first set up for ourselves and then, relying on our will, pursue. A cause works from the past into the present; a purpose, from the present into the future. A cause can affect both an inanimate object and a living one. Not so a purpose, which is limited to the latter alone. Whether all forms of life act on purpose we do not know. Some, however, clearly do.

Conclusion: Note that each one of the above articles refers to an essential characteristic of life. Joined together in a single object, or contraption, or organism, they would actually be life. Yet we still do know how life grew out of inanimate matter. Let alone what it is. Whether or not it is based on ignorance or on fact, it is this gap which, by forcing us to resort to the idea of the free will, governs our systems of education, morality, justice, trade, and much more. As long as it persists, so will we.

What Has Not Changed

Posted on July 2, 2015 by Martin van Creveld

Currently I am reading Maps of Time: An Introduction to Big History (2005) by David Christian and William H. McNeill. It traces the evolution of the world from the big bang to the moment in which we humans find ourselves today. One of quite a number of recent books of the same kind, and not the worst of the lot.

It made me think. A higher compliment no book can get or should get. However, seen from the authors’ point of view, it made me think about the wrong things. Perhaps that is another compliment to their work. I did not think about how we changed and why we changed and how else we might have changed and where change is taking us a d whether change is good or bad. But about all the ways in which we did not change. In other words, what it means to be human.

Homo Sapiens (skull & lower jaw) from the Human Evolution Gallery (tracks through time)
Age: 18,000 years old
Locality: Upper Cave, Zhoukoudian near Beijing, China

Before I start, a qualification. We humans are supposed to have evolved from ape-like ancestors who lived several millions of years ago. The question as to just when we became “modern” and “fully human” is very much one of definition. I cannot and will not go into all the different creatures that linked us to the ape in question. The more so because paleontologists themselves never stop quarrelling about their nature, the reasons why they appeared, the time at which they appeared, and the sequence in which they did so. That means I am going to limit myself to the last fifty thousand years or so. To my admittedly limited knowledge, no one has argued that our ancestors of that period were not “fully” human.

So here are a few of our outstanding characteristics.

To be human is to be a land animal (even if, in the future, we succeed in providing ourselves with artificial land-like environments under water, in the sea, and in outer space). That has some very important implications for the way we live.
To be human is to reproduce sexually (as opposed to some other creatures which use different means to the purpose). In other words, a division of roles between males and females, with everything that entails.
To be human is to be a mammalian. That has some very important implications for the way we are fed and raised during our early years.
To be human means that we need our rest and can only do so much within a given time. Are you listening, all you hard-driven, hard-working, Protestants and other go-getters?

So far, I have been listing the things we have in common with a great many other species. Still, they form part of our humanity. Take them away, and God only knows what we become. Fish, perhaps? Or mushrooms? Or reptiles? Or robots? But there are also quite a few things other species do not share with us, of which they share only to a very limited extent. To wit:

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Bipedalism. Humans are the only mammalians who walk on two legs instead of four. The outcome has been to free our hands for other kinds of activity. Including a great many such as only humans engage in.
To be human is to be prematurely born. Partly because bipedalism has caused the birth channel to become narrower, partly because the fetus’ head has become enlarged so as to contain the developing brain, human babies are born before their time. The outcome is that they are less independent, and need a longer period of rearing, than the young of any other mammalian species. The implications for family structure are obvious.
To be human is to have language. Not just a smaller or greater number of signs, as many animals also do. But a system of sounds that stand for—symbolize—objects, qualities and actions in ways others of our species who share the same language will understand.
To be human means to produce things. Not just using natural objects, such as sticks or stones, for this purpose or that. But actively modifying them, or even creating them ex novo, for our own purposes. Broadly speaking, the things may be divided into two kinds. Those that serve some kind of useful purpose; and those that provide us with aesthetic enjoyment. Very often the two kinds are combined in the same objects.
Not only do we produce things, but we also exchange them. That is true both inside societies and among them. A group of people so isolated as to be unaware of others of its kind and unable to engage in exchange with them has probably never existed. Had it existed, in all probability it would have come to a relatively rapid end.
Exchange implies contact, and contact implies occasional disagreements. Some disagreements lead to war, or, at any rate, some kind of socially-sanctioned violence between different groups.
To be human is to have self-consciousness, to recognize one’s own existence. As by looking into a mirror and identifying oneself. That is something computers do not have and, perhaps, will never have.
To be human is the ability to look into the future so as to link means with ends. In other words, to understand the meaning of “in order to.” That, again, is something computers do not have and, perhaps, will never have.
To be human means to be able to distinguish between the things we do and those we ought, or ought not, to do. It is, to use Biblical terminology, having eaten of the Tree of Knowledge.
To be human is to have some kind of religion. Even if it is not really a religion, as in the case of Buddhism and Confucianism, or, some would say, animism (which is probably the earliest form of religion of all). To be sure, using a few pieces of bone and some crude stone artifacts to determine this beliefs of our Stone Age ancestors is like trying to recover the text of Hamlet from the rusty remains of the hero’s sword. To the extent that it can be done, though, it would appear that religion has accompanied humanity for as long as the latter has existed. And it does so now. Even if, since many of us think God, is dead, we call it human rights; or the liberation of women; or health consciousness; or environmentalism; or whatever.
Finally, to be human means to be conscious of death, i.e. that our existence here on earth will one day come an end.

The reason why I am listing these points is not simply to look into the past and confirm the unity of mankind, as so many before me have done and are still doing. Rather, it is to peer into the future “far as human eye [can] see” (Lord Tennyson). And my point is that, should the various prophecies concerning “singularities” and the like come true, and we cease to be or do any of the above things, then for good or ill we will no longer be human.

Pay heed, all you gurus, lest in your eagerness for innovation you push us completely off the rails.