In theory.. couldn't bacteria have evolved to other forms of life.. eventually to humans (again.. all in theory)?
The one trait "sensitivity and reactivity" is not the same as awareness. Also, that characteristic alone cannot qualify a potential organism as living; all seven traits must be exhibited. Simple chemical reactions, like fire's rapid oxidization, are not necessarily alive.
Just to be a crackpot: I think that there is a force that I call "the life-force" that is the motivator behind life. In other words, there seems to me to be a force that makes things come to life under certain conditions. Fire is not a resultant of this force. As such, it is not alive.
Well, actually, I've never seen this movie. It just seems strange that we classify utterly countless different objects as alive, and it seems so obvious to me that certain objects are not alive. But, then again, I don't even know how to tell if another human is dead or alive. There are comas and such that seem very death-like to me, but, mysteriously, sometimes people will wake right out of them. Do the dead come back to life so readily? I doubt it, but maybe. The virus is the most contraversial fence-sitter, IMO, but, I thought fire would be a nice simple testing ground for the definition of life. I've asked people this question for years, but they would give me an unsatisfyingly terse response (invariably "no"), and then, they would get agitated when I tried to discuss it with them (or simply disinterested). The responses I've seen so far are EXACTLY the kind of rhetoric and discussion that I was looking for. Y'ALL are all great. Thanks a million.
I'm not sure I know what you mean, but there is some sort of evolution on an extremely accelerated scale when it comes to germs. When the doctor gives you antibiotic ("bio" refers to life, if that's not a gimme), you had better follow the instructions, or else, the germ could mutate (evolve) into a form that is resistant to the medication.
I think the issue might be that our "definition" of life isn't really a definition, but an attempt to condense a shit load of info into a few sentences. I think we start by saying that <i>we</i> are alive. Then, we get a touchy-feely idea of what is life, and we attribute it to certain animals. Then, plants, we say, are also alive, stretching the idea of life to encompass other objects and making ourselves feel less alone. At this point, we should stop and ask, not, "what is life," but, "what is a plant." Which is the stronger definition? "All plants are alive," or, "it is NOT a plant, if it is not alive."
Who said it was a 'move-ee'? It's a television show Please Register or Log in to view the hidden image! Plants aren't alive: they have no choice of movement (a will that is free) Thus fire is not alive because it has no choice of movement.
Plants aren't 'aware' of their environment in any sort of conscious way, but they react to their environment and the vast majority of people would consider them to be alive. All of the 'seven characteristics of life,' with the exception of the cellular structure requirement, are merely traits of ongoing chemical reactions. Both your own body and fire are conglomerations of chemical reactions that are playing themselves out. The only difference is that the reactions which allow you to live are far more complex than the reactions involved in fire.
Mucker, you would say wrong. By common convention, plants are alive. Ask anyone. Go on! Ask the nearest person, see what they say. Start a poll if you like.
Imagine if what we think of as ourselves is really just one single cell that recieves all the sensory input. A king cell that controls all the others. Maybe it's even the original zygote.
If there is a such "Life Force," how can you conclude that it does not result in fire? You only said it makes things come to life, and because the life force is not affecting fire, fire is not alive. What about spontaneous combustion? Maybe a person received too much life force? Please Register or Log in to view the hidden image!
Yeah, it could have, but IT DIDN'T. For example, blue algae is theorized to be the first life form on this planet and it still exists today in the same form as fossils from 10mya or 600mya. Since life is composed of and consumes inorganic materials and the fact that life sprung up from inorganic materials would mean that life and nonlife would carry very common traits. Every particle in the universe is on a mission to duplicate itself, every reaction, every chemical, every thing duplicates. Every process uses energy and produces waste. If you can't follow the criteria, the seven traits, then the term life is baseless and I am as alive as this keyboard. Life is defined by the cellular and anything else is a semantical question. I have pondered the virus question too, and there is a possibility that there are beings composed of completely different forms of energy (like Silicon or pure radiation or something as absurd). For now the definition sits under the seven traits.
as a generality i would conclude as such because fire is not born of seed or womb. Well, that and that fire itself is not of substance, but the label of a common chemical reaction. things that i generally consider "alive" are the result of a chemical reaction rather than the reaction itself.
There's a couple of comments I want to make here. First, reproduction doesn't have to be a trait of life. Ie, the last suriviving member of a species that reproduces via sex is still alive even though it no longer can reproduce (needing a nonexistent partner). But for life that does reproduce, it appears to be ultimately self-propagating information. Eg, the human body ultimately is a vehicle to transport 30,000 or so genes and maybe those genes in turn are present in order to propagate a bunch of symbiotic (but perhaps occasionally parasitic since they may be able to morph into viruses) DNA snippets. The key to self-reproducing information, is that the information must have a way to alter its environment in a way that can improve its chances of propagation. In terms of genes, the gene must be able to "express". From the analogy with genes, if information can't express itself, then it will disappear: overwhelmed by environmental processes, get consumed by information that can express, or collect errors until it is no longer recognizable. Thus, in this sense, computer viruses and worms are alive. They just happen to live in an artificial environment where information can express very easily. Prions are another example of reproducing life in this sense. They are certain proteins that encode a deviant structure which can propagate itself in the presence of appropriate unaltered proteins. Finally, memes (in the incorrect, weaker Internet sense of self-propagating ideas) can be alive since they are information which propagates itself in the minds of human beings.
In this sense, the term reproduction indicates the procreative capability of the entire species. The traits I provided are to be used in the judgment of a fully represented species, not an individual. In a sexually reproductive species, if there were to be only one member of one gender remaining, the species would be, for all practical purposes, extinct. Without the ability to reporduce, the group is already dead.
One of the scenarios I was thinking of when I wrote my article, is what happens if you had for example an intelligent machine built for a single purpose (as a space probe) or perhaps explicit designed so that it wouldn't reproduce nor even change much in its overall design (ie, to further prevent the chance of a von neuman self-reproducing machine). These machines would likely be considered alive by most people. Further, we might discover or build reproducing life that has no obvious speciation. My point is that we have significant trouble even in determining what is alive on Earth within our limited sphere of understanding. As an aside, there's another interesting point. Namely, if for some reason, self-replicating information became the standard for life or just merely valuable in its own right, then how important is it to prevent extinction of self-replicating information and perhaps even aid the propagation and evolution of this? For example, virtually all life contains variations of genetic information that dates back perhaps more than a billion years collectively. Further, even with human interference, we are seeing evolution of organisms in action (human interference is increasing greatly the rate of evolutionary change due to our mass alteration of ecologies, but that's a different story). And a lot of organisms seem to be at some degree of presentience though not necessarily close to humanity. For example, primates, Cetaceans, octopi, other large mammals, and social insects. Finally, these organisms apparently evolved from scratch. Ie, we have a billion years of evolution, very elaborate creatures, all coming from relatively simple organic compounds. I would assign this an extremely high value. On the other extreme, a computer virus may have some inherent value as a crude life form. A sophisticated one would probably be able to achieve most of your criteria for life (obviously not the physical characteristics like having cellular structure or consuming energy though they do consume analogous resources, eg, CPU time, memory, and connectivity access). However, it wouldn't have the same value as say bacteria, because it's the product of a few days or weeks of work, has a collective life span (ie, it and all its progeny) measured in months or perhaps a few years, and finally has no potential since the systems it infects are likely to become obselete in a few years, and of course, it's invariably costly to society to manage. Archiving them in a inert digital form seems a reasonable thing to do though. So there seems to be a host of considerations for what to do with a lifeform (even using a liberal definition of "life"). How long has it and its ancestors lived? What environment is it adapted to? Does it cause harm? What potential does it have? These seem a good start to determining how valuable a particular lifeform is.
