Umbran said:
Actually, Tonguez's definition ("It Consumes fuel, requires oxygen, can grow, can reproduce and eventually dies") does not constitute an accurate representation of the "standard definition" of life.
For one thing, the usual definition does not include "eventually dies". While it does seem that all multicellular life on Earth does eventually die, things get a little sticky for singe-celled organisms. You may claim that an amoeba "dies" when it reproduces. I challenge you to show me the corpse, and prove that it is dead
For another, the "consumes fuel, requires oxygen" is inaccurate. This is usually phrased as "has a metabolism". While this includes burning fuel, it is not limited to that. Nor do the standard definitions really rquire oxygen. There's usually an assumption that life requires the chemical process of oxidation, but other elements may be used. Technically, you can even postulate a metabolism based upon nuclear energy, rather than chemical.
Most importantly, you leave something major out . A living thing responds to the environment to maintain homeostasis and it's own existance. Fire most assuredly does not do this, and so is not alive.
Well, for one thing, I wasn't defending Tonquez' definition specifically. I was pointing out that WizarDru was attacking Tonquez' position based on two debatable points. Fire DOES grow and reproduce, using the dictionary definitions of those terms, and defining your units. And increasing complexity is NOT a required benchmark of life. Furthermore, I am well aware that not everything has a definitive death and of the nature of single-celled organisms. And, until very recently, oxygen was a metabolic poison to all life on earth. It started off as a waste chemical.
Furthermore, not all living things actively maintain homeostasis. Some are entirely passive about it. Some don't need to because of the nature of their environment. This includes some of the critters that use a non-oxygen metabolism.
And that's without bringing in sticky questions like viruses. And don't give me the "viruses aren't alive because they don't reproduce themselves" argument. They reproduce themselves just fine given the proper environment. But then, the same could be said for us, couldn't it?
But wait... "viruses aren't alive because they don't have a metabolism."
Neither do many spores, yet they are alive. And a great many bacteria can go to a completely quiescent state for obscenely long periods of time (again, including some of your non-oxygen metabolisms)
"But that's only for a brief part of their life cycle. Viruses NEVER have a metabolism."
Untrue. There's a case to be made that a virus has a VERY active metabolism when inside a host cell. They've simply got a life cycle that keeps them quiescent for more of the time. Very efficient solution, actually. Too bad we didn't think of it.
You give me the standard 7-point defintion of life (or is it 8-point nowadays?) that they provide to high school kids and most college freshmen, and I'll be happy to knock it down all day.
