Bozo Erectus
Master Baker
- Joined
- Jan 22, 2003
- Messages
- 22,389
On the basic level: anything that uses things found in its environment to produce copies of itself.
I like that one.Dumb pothead said:On the basic level: anything that uses things found in its environment to produce copies of itself.
"Reproduce" as in "cell reproduction" rather than species propagation.insurgent said:Mise: That certainly isnt correct. As I said, lots of life forms don't reproduce. Sterile humans, mules, whatever. And as you said, fire.
Excrete as in release waste products from the system.Yom said:Including excrete?
Homeostatis? How do plants do that? I thought this was a characteristic of animals, rather than life in general. Plants exchange gas at different rates depending on the light level, and overproduce CO2 or O2 as a result. That would indicate that they don't care much for keeping their levels of various chemicals constant.Syterion said:OK, I found em.
1. Cell(s).
2. Response to Stimuli
3. Ability to Metabolize.
4. Ability to MAintain Homeostasis.
5. Reproduction
6. Growth and repair
7. Motion
Phasmida said:Mise's definition seems pretty good to me... what living thing doesn't exhibit those traits?
So what. You're gettin examples of specialization... and in the case of butterflies, it's not because it doesn't want to feed anymore that it hasn't feed itself before to grow.... so it's rather pointless.Aphex_Twin said:For instance... An individual worker ant/termite/bee doesn't reproduce. Plants don't move. Not all beings grow throught their life. Certain butterflies never feed after they emerged from the cocoon.
I think it says it all. Who would deny that something which takes energy from its environment and uses it to copy itself is alive? Nobody serious I think.Marla_Singer said:I like that one.![]()
Fire does that tooDumb pothead said:I think it says it all. Who would deny that something which takes energy from its environment and uses it to copy itself is alive? Nobody serious I think.
Dumb pothead said:I think it says it all. Who would deny that something which takes energy from its environment and uses it to copy itself is alive? Nobody serious I think.
What if we only know of a single member (a worker and) of an ant species. The species itself has no chance to reproduce (through usual means). Do we consider that ant living?Marla_Singer said:So what. You're gettin examples of specialization... and in the case of butterflies, it's not because it doesn't want to feed anymore that it hasn't feed itself before to grow.... so it's rather pointless.
Then we can only argue those living cells are alive and not the ant itself. The definition for a species requires a DNA. If we meet something on an alien planet which exhibits certain characteristics (stimumus-response, homeostasis,...) and we don't find a structure symilar to DNA can we conclude we have found life?Mise said:Ant's etc. are made up of living cells which reproduce. Also, it could be argued that the *species* is capable of reproduction, therefore members of the species are living.
Plants move! Their flowers open, their leaves fold at night, etc.
What beings don't grow throughout their lives?
Those butterflies still feed though, whilst in their cocoons. Humans feed, even though they dont do so for most of the day.
betazed said:Not so fast. By that definition, thunderstorms would be alive. They take energy from the environment and make little thunderstorms. And What about waves in the ocean?
Edit: x-post with Mise.
Hmm.., Fascinating... I must think now.Mise said:Fire does that too
Damn fire! It spoils every theory!
But it's one thing to say, "all living things do this," but quite another to say "no non-living things do this which living things do." Man that was a confusing sentence!
Best of luck, sincerely.Aphex_Twin said:I'm trying to find a set of necessary and sufficient criteria for life.
I can try, can't I?betazed said:Best of luck, sincerely.When you do find it do not forget to send it to NASA. They need it too.
Btw, that is a key question in Astrobiology. I mean, how can we test for something if we cannot even define it properly?![]()
No, that's neither true in the case of thunderstorms nor in the case of waves since in both cases they are reproducing smaller entities of themselves... Not copies of themselves. That makes a huge difference.betazed said:Not so fast. By that definition, thunderstorms would be alive. They take energy from the environment and make little thunderstorms. And What about waves in the ocean?
Well, fire releases energy, but in its most familiar form, it is atoms of carbon combining with atoms of oxygen to produce that energy. Fire is not simply energy, it has a rather physical presence that quickly disperses in the process.Marla_Singer said:No, that's neither true in the case of thunderstorms nor in the case of waves since in both cases they are reproducing smaller entities of themselves... Not copies of themselves. That makes a huge difference.
Moreover, I should add that in our instinctive way to apprehend what life is. The fact it's an autonomous being is extremely important. A plant grows in a specific way to reach sunlights. Neither storms nor waves do such a thing. They aren't looking for energy, they don't goes where there are energy. They have absolutely no freedom of movement. Just like the example of the Earth.
When you want to get counter-example, you're forced to distort it.
Edit : Actually, in the case of storms, waves or fire... those phenomenons are simply energy. Life isn't energy, Life uses the energy in its environment to reproduce copy of itself.
So what.Gastric ReFlux said:Well, fire releases energy, but in its most familiar form, it is atoms of carbon combining with atoms of oxygen to produce that energy. Fire is not simply energy, it has a rather physical presence that quickly disperses in the process.
The point that the threadstarter may have wished to raise here is that life is an emergent property of basic physical processes, that life becomes more so as it evolves more complexity.
That idea has been much more aptly expressed in the link I provided above.