[Poppa Oomowmow (OP)]

Humans have consciousness and animals have a level of intelligence as well. But how do trees exist? They are alive but how are they alive? What happens in their existence? Can anyone know? Thanks for any feedback anyone may have.

[another_someone]

Existence and living and consciousness are all different things.

Rocks exist, but they do not live (by any common definition of living).

To ask 'how are they alive', you must first answer 'what is life?'.

It is a highly ambiguous question, although it is the kind of question we need to be able to answer with far greater precision than we have if we are to start really looking for extraterrestrial life (whether or not it exists, we must at least have some definition by which we can judge if we have found it or not).

The common definition for life, as I see it, seems to be vaguely around the ability to reproduce in an inexact but inheritable way (i.e. each generation is subtly different from the previous, but the changes that occur from one generation to the next is then passed on to subsequent generation).  Trees, in common with all vegetable matter (in broad terms there is nothing exceptional about a tree) does satisfy this criteria (with the caveat that it does get a bit more ambiguous when an organism, and this can be true of animals as well as vegetable, reproduce vegetatively).

Consciousness is just one possible function (assuming it is in reality anything more than an illusion) of life, and in that respect it is no different from sight, smell, or any other way in which we understand the world around us.  Each facility gives the organism that has that facility some advantage (although not without some cost), but no organism has every facility to the same extent (humans cannot hear as well as dogs, and we have almost no sensation of electrical voltage, although sharks have this in good measure - but we do have conscious thought in much larger amounts than any other species we are aware of).

It would be wrong to say that trees cannot process information - they clearly can do that, but as far as we are able to ascertain they have nothing comparable to conscious thought (although, while we may be able to localise approximately where conscious thought happens in the brain, we are still not able to define it with sufficient precision to prove with certainty that another species, especially one with which we have almost no communication, has or does not have the faculty, excepting that if it does have it, it must manifest itself in a way very different to the way it manifests itself in humans).

[neilep]

I am really pleased that trees exist...me luffs them !

[Gaia]

To ask 'how are they alive', you must first answer 'what is life?'.

The common definition for life, as I see it, seems to be vaguely around the ability to reproduce in an inexact but inheritable way (i.e. each generation is subtly different from the previous, but the changes that occur from one generation to the next is then passed on to subsequent generation). 

Sorry George, gotta problem with 'each generation is subtly different from the previous'. What about Amoebae that reproduce by binary fission? They are most definitely alive. I would suggest that this should be rephrased to 'the ability to reproduce'. This led me to discussions/arguments with my academic tutor when I was an undergraduate, over whether viruses were 'alive'. He said they weren't because they couldn't reproduce without 'hijacking' another living cell, I said they were because that meant they reproduced!

[another_someone]

To ask 'how are they alive', you must first answer 'what is life?'.

The common definition for life, as I see it, seems to be vaguely around the ability to reproduce in an inexact but inheritable way (i.e. each generation is subtly different from the previous, but the changes that occur from one generation to the next is then passed on to subsequent generation). 

Sorry George, gotta problem with 'each generation is subtly different from the previous'. What about Amoebae that reproduce by binary fission? They are most definitely alive. I would suggest that this should be rephrased to 'the ability to reproduce'. This led me to discussions/arguments with my academic tutor when I was an undergraduate, over whether viruses were 'alive'. He said they weren't because they couldn't reproduce without 'hijacking' another living cell, I said they were because that meant they reproduced!

If you had read to the end, I did make the caveat that this creates ambiguities with things that reproduce vegetatively (which infers that anything that reproduces asexually, including amoeba).

The trouble with allowing reproduction alone to be a criteria is that it then becomes very broad, including (as has been mentioned by others on here) fire, as well as stellar reproduction (i.e. the death throws of a star as it goes super nova then creates the conditions for the birth of the next generation of stars).  It also includes prions.

Ofcourse, one could regard all of these things as living (and in the past, fire would probably have been regarded as being alive, though maybe for other reasons - as life was more associated with movement, hence the use of the word quick to refer to both movement and life).

The point about the need for variation in genetic (in the broad sense - not necessarily through DNA) materials, together with inheritability of traits, is that both of these are primary requirements for selective evolution.  I cannot say how Amoebae go about evolving, but in order to do so, they must create both genetic variability, and inheritability of that genetic variance.

[daveshorts]

I don't know about amoeba specifically, but a lot of single celled organisms reproduce asexually but can still vary down the generations, either just from pure mutations, or a lot of bacteria swap genetic material by loops of genetic material called plasmids.