What is life?

Discussions on general biology and biological evolution, genetics, zoology, ecology, botany, etc.

What is life?

Postby Alan McDougall on May 12th, 2017, 8:02 pm 

What is life?

Give your best short definition of what life really is below.
Alan McDougall
Banned User
 
Posts: 137
Joined: 07 Dec 2010
Location: Johannsburg South Africa


Re: What is life?

Postby Braininvat on May 12th, 2017, 8:18 pm 

viewtopic.php?nomobile=1&f=37&t=6722

A fairly extensive SCF discussion on this question. I haven't reread it, so can't totally vouch for its usefulness, but perhaps worth a look?
User avatar
Braininvat
Forum Administrator
 
Posts: 5251
Joined: 21 Jan 2014
Location: Black Hills
BioWizard liked this post


Re: What is life?

Postby Alan McDougall on May 13th, 2017, 4:04 pm 

Braininvat » May 13th, 2017, 2:18 am wrote:http://www.sciencechatforum.com/viewtopic.php?nomobile=1&f=37&t=6722

A fairly extensive SCF discussion on this question. I haven't reread it, so can't totally vouch for its usefulness, but perhaps worth a look?


The "Cambrian Explosion" refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains.

It may represent the most important evolutionary event in the history of life on Earth.

The Cambrian explosion makes one suggest that the theory of evolution is not 100% correct?
Alan McDougall
Banned User
 
Posts: 137
Joined: 07 Dec 2010
Location: Johannsburg South Africa


Re: What is life?

Postby DragonFly on May 13th, 2017, 4:06 pm 

Life is of metabolism in a system not in equilibrium.
User avatar
DragonFly
Resident Member
 
Posts: 2114
Joined: 04 Aug 2012
BioWizardvivian maxine liked this post


Re: What is life?

Postby Alan McDougall on May 14th, 2017, 3:52 am 

DragonFly » May 13th, 2017, 10:06 pm wrote:Life is of metabolism in a system not in equilibrium.


We exist as living beings on a knife edge of conditions and if just one of them goes out of wack we die.
Alan McDougall
Banned User
 
Posts: 137
Joined: 07 Dec 2010
Location: Johannsburg South Africa


Re: What is life?

Postby BioWizard on May 14th, 2017, 6:28 am 

Alan McDougall » 14 May 2017 02:52 am wrote:
DragonFly » May 13th, 2017, 10:06 pm wrote:Life is of metabolism in a system not in equilibrium.


We exist as living beings on a knife edge of conditions and if just one of them goes out of wack we die.


I don't know if I can agree with this. Our bodies will adapt in all sorts of ways and will try to keep us alive under extreme environmental and health conditions. People survive all sorts of crazy stuff all the time. Biology is quite robust and not the fickle balance on a knife's edge you seem to think it is.
User avatar
BioWizard
Forum Administrator
 
Posts: 12401
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)


Re: What is life?

Postby Alan McDougall on May 14th, 2017, 12:38 pm 

A candle or even a crystal could be taken as a form of life?
Alan McDougall
Banned User
 
Posts: 137
Joined: 07 Dec 2010
Location: Johannsburg South Africa


Re: What is life?

Postby BioWizard on May 14th, 2017, 12:53 pm 

Alan McDougall » 14 May 2017 11:38 am wrote:A candle or even a crystal could be taken as a form of life?


Not really.
User avatar
BioWizard
Forum Administrator
 
Posts: 12401
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)


Re: What is life?

Postby doogles on May 14th, 2017, 4:44 pm 

Life is a coordinated series of electron shifts mediated by enzymes under gene control.
doogles
Member
 
Posts: 794
Joined: 11 Apr 2009


Re: What is life?

Postby Eclogite on May 19th, 2017, 10:50 am 

Alan McDougall » Sat May 13, 2017 8:04 pm wrote:The "Cambrian Explosion" refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains.

It may represent the most important evolutionary event in the history of life on Earth.

The Cambrian explosion makes one suggest that the theory of evolution is not 100% correct?
I thought I would use my 'please select your preferred answer on this one', so here goes.

Please select your preferred answer from the following responses:

1.The Cambrian explosion appears sudden, but in many respects it is not. The Eocardian fauna predate it, for example. Other examples exist. Further examples are likely to be found in future.

2. Some used to say that the Cambrian explosion represented the first appearance of life. We modified that to the present statement of complex animals with minerliased skeletons. Then we had to change it to macro fossils of complex animals, since Precambrian microfossils of complex animals were discovered. And so it goes. Nothing to see here. Move along.

3. One may say this questions the theory of evolution, but tens of thousands would say it is wholly consistent with it. The "sudden appearance" after a Snowball Earth episode is probably not a coincidence.

4. No theory is ever 100% correct. This is science, not religion.
Eclogite
Forum Moderator
 
Posts: 1320
Joined: 07 Feb 2007
Location: Around and about
BioWizard liked this post


Re: What is life?

Postby hyksos on May 19th, 2017, 3:45 pm 

Alan McDougall » May 13th, 2017, 4:02 am wrote:What is life?

Give your best short definition of what life really is below.

In universities they tell the biology students a kind of non-committal definition of life. That if a thing X reproduces progeny and transmits traits to them by DNA, that thing X is alive. In informal settings you can get it smaller, "If it copies DNA, it is alive". So doogle's answer is really close to what you hear on campus.

I'm not a personal fan of the DNA=life motto. I'm much more excited about the metabolic non-equlibrium theories. But they are still (unfortunately) still fringe science as of today.

I think we have a resident biologist here. (maybe he already posted in this thread). I think he can vouch for these things.
User avatar
hyksos
Member
 
Posts: 917
Joined: 28 Nov 2014


Re: What is life?

Postby mitchellmckain on May 26th, 2017, 11:59 pm 

I would say that...

Life is a dynamic self-organizing process (in a universe with many such processes) which has attained the capacity for adaptation so that it can maintain its own internal organization apart from the environment through a range of environmental changes. This means the system has something like an awareness of environment and self for it is sensitive to changes in them and responds to these changes. As such, life is a is a highly quantitative characteristic for the degree of this adaptation, sensitivity, and responsiveness varies greatly.

I would argue that the attributes growth and reproduction often used in the definition of life are actually particular strategies of maintenance and adaptation rather than definitive of life itself. For I would argue that organisms do not cease to be alive when they cease to grow or reproduce. But once an organism ceases to maintain its own organization apart from the environment then it has indeed entered into the process we call death. In other words, we call something alive because it does things for in own reasons in response to the environment but when this breaks down so that everything is simply a direct effect of changes in the environment then it is no longer alive.

You can say this means there is a layer of complexity involved between the environmental changes and the internal adaptations. But it is not just complexity because there are reasons for them. For example, an organism typically generates heat in response to a drop in environmental temperature in order to keep the chemical process going which are needed for its own organization and maintenance.
User avatar
mitchellmckain
Member
 
Posts: 389
Joined: 27 Oct 2016



Return to Biology

Who is online

Users browsing this forum: No registered users and 8 guests