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Kandy's avatar

What does it mean to be alive?

Asked by Kandy (363points) November 27th, 2011

People would argue that plants,single-cell organisms, viruses,etc. are alive. I understand that plants and fire “breathe” air and can be killed. How/why is something considered ‘alive’ if it has no brain or heart?
Am I just being dogmatic because if something doesn’t have a brain or heart, it isn’t actually alive?

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13 Answers

Blackberry's avatar

Who the heck said fire was alive lol?

Some people like to believe things without much evidence, so they speculate and attribute characteristics to things. This is where spirits come in. If there is no brain or heart, it has a spirit instead.

Kandy's avatar

Ha, yes. It seems crazy that one would say fire was alive. They argued that because it depended on oxygen, it was alive.

TheIntern55's avatar

My understanding, correct me if I’m wrong, is that only living things are made up of cells and that’s what determines whether something is living or not?
I’m not sure that’s right, but all those things except fire are made of of cells. That’s how it is scientifically, but to most, only animals and plants are considered alive.

Dutchess_III's avatar

Something that can reproduce is considered to be alive. It has nothing to do with having brains and hearts, unless you’re specifically dealing with animals, like dogs and humans and fish.

YARNLADY's avatar

There is actually some disagreement at the microscopic level about whether some single cell entities are alive, but in the macro world, the ability to grow and reproduce is considered alive. There are many science sites that contain a full discussion of the definition.

Blondesjon's avatar

@YARNLADY . . . careful, you’re dangerously close to sparking an abortion debate.

Kayak8's avatar

@Dutchess_III nailed it—the ability to reproduce independently (e.g., why viruses are not considered to be alive as they need the reproductive capacity of the host cell).

Kandy's avatar

Thank you for all your imput. Greatly appreciated. These kinds of questions litter my brain every day.

gondwanalon's avatar

DNA is life.

If it has functioning DNA then it is alive. If it has functioning RNA and or proteins that utilize a host DNA then it is probably alive.

ucme's avatar

If any living thing is aware of it’s own existence, then it is truly alive.
Probably said by some crazy old chinese hermit living in the mountains….or was it Jerry Springer?

marinelife's avatar

It is alive without a brain or heart although most living things have those things.

wundayatta's avatar

Here’s a little outline of the scientific issues involved in determining what life is.

The succinct definition in that article:

Life (cf. biota) is a characteristic that distinguishes objects that have signaling and self-sustaining processes (i.e., living organisms) from those that do not, either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate.

One of the key questions is whether viruses are alive or not. Wikipedia says:

Viruses are most often considered replicators rather than forms of life. They have been described as “organisms at the edge of life,” since they possess genes, evolve by natural selection, and replicate by creating multiple copies of themselves through self-assembly. However, viruses do not metabolize and require a host cell to make new products. Virus self-assembly within host cells has implications for the study of the origin of life, as it may support the hypothesis that life could have started as self-assembling organic molecules.

Dutchess_III's avatar

@marinelife I’m pretty sure plants outnumber animals by a mile..and they don’t have a brain or a heart. @ucme I don’t think plants are aware of their own existence. At least, I hope not or I’ll never be able to clear some of the junk trees and underbrush on my land. The guilt would consume me!

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