When does life begin?

Perhaps it's as simple as reclassifying the inanimate, even if only temporarily. To borrow from Vonnegut......mud that gets up and looks around. Does that mean to be alive an organism must sense its environment?

I posed this question once: if a baby is born lacking all the senses, is it alive? Assuming it survives I think we'd look at it as being alive. Realistically , would it be any different than an inanimate.object, totally unaware like a grain of sand and if the brain is dead or not turned on (functioning ) can it sense? Can the cells be alive and the organism brain dead at the same time? Seems so but for the cell, individually speaking, it is alive. There seems to be something missing.

(Sep 26, 2018 10:30 AM)Zinjanthropos Wrote: Perhaps it's as simple as reclassifying the inanimate, even if only temporarily. To borrow from Vonnegut......mud that gets up and looks around. Does that mean to be alive an organism must sense its environment?

Introductory biology classes usually begin with some definition of life, if only to define the subject matter of the class. Unfortunately, despite a couple of thousand years of biology, extending all the way back to Aristotle if not before, there still isn't any universally accepted definition of "life".

Wikipedia tried this:

"The definition of life is controversial. The current definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve. However, several other biological definitions have been proposed, and there are some borderline cases of life, such as viruses or viroids."

https://en.wikipedia.org/wiki/Life

My feeling is that if totally alien "life" is ever discovered in outer space, 'life' with a a totally different origin, then our definition of 'life' will probably undergo a dramatic revision. My expectation is that it will move away from a descriptive approach based on what we see with Earth life, towards a functional approach based on the functions that anything worthy of the name 'life' would have to perform. Metabolism (which may differ dramatically from ours), homeostasis (more or less, life can't be totally static and unchanging), ability to make more of itself (growth and/or reproduction) and the ability to evolve. The 'borderline cases' will almost certainly multiply, which will necessitate more flexible definitions.

Quote:I posed this question once: if a baby is born lacking all the senses, is it alive?

Certainly 'yes' in the biological sense. Each of its cells would be every bit as alive as a bacterial cell, the entire baby would have a metabolism and presumably still need to be fed. Its heart will be beating, its liver metabolizing, etc.

But would it ever be able to develop a human personality? Probably not.

(Sep 26, 2018 06:23 AM)Magical Realist Wrote:

Quote:Something that was dead suddenly coming to life.

Patients do it all the time--dying and coming back to life.

No, they actually don't. You can only defibrillate a fibrillating (arrhythmically beating) heart...not a completely stopped one.

Myth: Shocking someone who has flat-lined can get their heart started again.

It never fails. You’re watching television and someone is circling the drain, in the toilet that is their life. The noise from the heart monitor affirms they’re still alive, with its consistent, rhythmic beeps. All of the sudden, alarms start going off. On the monitor- the dreaded “flat-line”.
...
The problem is that, in real life, you’ll be accomplishing nothing by shocking a “flat-line”. Unless you like your meat well done that is.

Medically, a “flat-line” is known as asystole, meaning no (heart) contraction. It might seem common sense that if there is no contraction you might want to contract it with a shock. The truth about why this will never “restart” the heart lies in how the heart creates its life giving beat. In the end, it all comes down to electrolytes.
- https://gizmodo.com/why-shocking-a-flat-...1376053985

Arrhythmia is a heart beat that is too chaotic to circulate blood, which is why people do chest compressions to maintain some blood flow/oxygen to vital organs. Shocking it can restore a regular rhythm and circulation.

Quote:FYI the brain of the fetus isn't dead. It's alive and growing. It's just not functioning yet. That's what is meant by brain dead.

brain death
irreversible brain damage causing the end of independent respiration, regarded as indicative of death.

A developing brain is not damaged, nor has there been any activity to cease. Again:

death
the end of the life of a person or organism.
the permanent ending of vital processes in a cell or tissue.

So brain death presumes a vital brain process existed then ended, and permanently.

Quote:All the cells in your body die and get replaced by new  generations of cells.Did you know your tissues start dying the moment you are conceived? Death is just a stage in the process of life. It's called regeneration.

And? Living cells divide into more living cells, to replace themselves, before they die (just like humans can't reproduce after death). A dead cell doesn't magically come to life or produce a living cell. Again, you're conflating widely disparate things. Aging is not actually dying, and cellular regeneration is not organism death.

I'm having a hard time believing that anyone can actually be this ignorant of basic science.

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(Sep 26, 2018 03:22 PM)Yazata Wrote: Introductory biology classes usually begin with some definition of life, if only to define the subject matter of the class. Unfortunately, despite a couple of thousand years of biology, extending all the way back to Aristotle if not before, there still isn't any universally accepted definition of "life".

Wikipedia tried this:

"The definition of life is controversial. The current definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve. However, several other biological definitions have been proposed, and there are some borderline cases of life, such as viruses or viroids."

https://en.wikipedia.org/wiki/Life

Maybe try a better source than Wikipedia:

Life
(1) A distinctive characteristic of a living organism from dead organism or non-living thing, as specifically distinguished by the capacity to grow, metabolize, respond (to stimuli), adapt, and reproduce
- https://www.biology-online.org/dictionary/Life

Sounds pretty definite and universally accepted to me. Like many things, life is defined by both what it is and what it is not.

Quote:My feeling is that if totally alien "life" is ever discovered in outer space, 'life' with a a totally different origin, then our definition of 'life' will probably undergo a dramatic revision. My expectation is that it will move away from a descriptive approach based on what we see with Earth life, towards a functional approach based on the functions that anything worthy of the name 'life' would have to perform. Metabolism (which may differ dramatically from ours), homeostasis (more or less, life can't be totally static and unchanging), abillity to make more of itself (growth and/or reproduction) and the ability to evolve. The 'borderline cases' will almost certainly multiply, which will necessitate more flexible definitions.

So..the same definition as the one I've given.
Differing or not, if a thing does not take in energy (metabolize) it either cannot be alive or it is violating the second law of thermodynamics.

Quote:So brain death presumes a vital brain process existed then ended, and permanently.

No it doesn't. It only assumes the brain is non-functioning. Being brain dead is the state that defines that. There is no requirement that that state be preceded by being alive. It is the same state for the early fetus and for an expired human.

As far as life coming from dead matter, we know that happens at the molecular level all the time. When you digest food, you are breaking down dead matter and reassembling it into living tissues. Life has nowhere to come from BUT from dead matter. Animate matter is just a chemically activated version of inanimate matter. That's just a fact of nature.

(Sep 26, 2018 07:25 PM)Magical Realist Wrote:

Quote:So brain death presumes a vital brain process existed then ended, and permanently.

No it doesn't. It only assumes the brain is non-functioning. Being brain dead is the state that defines that. There is no requirement that that state be preceded by being alive. It is the same state for the early fetus and for an expired human.

As far as life coming from dead matter, we know that happens at the molecular level all the time. When you digest food, you are breaking down dead matter and reassembling it into living tissues. Life has nowhere to come from BUT from dead matter. That's just a fact of nature.

No, you're just repeating your bare assertion without any actual reasoning, citations, or justifications.
I've given you the definition of "death" several times now, and you've yet to provide any contrary sources or definitions.
You're, again, conflating words...here "non-functioning" with "dead". They are not synonyms, especially in the sense of a brain. It's not like your electronics, where we colloquially call a nonfunctional piece of tech "dead".

No, life doesn't "come from" molecules, otherwise we would have proof of abiogenesis (and you'd likely win a Nobel prize if you could...so there's no lack of motivation). Food is converted to chemical energy for a living organism to do the work of growing tissue; food doesn't become living tissue.

You're scientific illiteracy is appalling.
But then, this is coming from a guy who believes in toilet ghosts: https://www.scivillage.com/thread-6186.html

Quote:You're, again, conflating words...here "non-functioning" with "dead". They are not synonyms, especially in the sense of a brain. It's not like your electronics, where we colloquially call a nonfunctional piece of tech "dead".

That's how science defines death--the non-functioning flatline of the brain. Being brain dead. It's the same for early fetuses. There is no difference in these states.

Quote:No, life doesn't "come from" molecules, otherwise we would have proof of abiogenesis (and you'd likely win a Nobel prize if you could...so there's no lack of motivation). Food is converted to chemical energy for a living organism to do the work of growing tissue; food doesn't become living tissue.

Yeah..food comes from dead tissue and non-alive molecules. It is the way life continues, by using the non-alive molecules of dead tissue and building itself out of those. The living matter doesn't just appear out of nowhere. Matter that is dead turns into matter that is alive. This is basic science. I'm surprised you didn't know this.

If a brain was functioning at one time, then irreversibly ceases functioning, it must have previously been alive. (A brain can't function unless its many neurons are living cells.)

(Sep 26, 2018 07:58 PM)Yazata Wrote: If a brain was functioning at one time, then irreversibly ceases functioning, it must have previously been alive. (A brain can't function unless its many neurons are living cells.)

And a brain that is not functioning previous to being alive, as in prior to the 25th week, is the same as a brain that not functioning after being alive. Non-functioning is non-functioning. A turned off tv is turned off whether it was previously turned on or just bought from the store.

Quote:That's how science defines death--the non-functioning flatline of the brain. Being brain dead.

Bacteria are alive, and they don't even have brains. The same thing is true of plants.

The 'brain death' criterion is a legal standard, not a biological or scientific one. It's about when hospitals can legally 'pull the plug' on patients.

Quote:It's the same for early fetuses. There is no difference in these states.

I'm not convinced that's true. As I understand it, there's quite a bit of neural activity in developing fetal brains. It's just that it doesn't look like wakeful awareness after birth. It's probably associated with guiding how the developing brain wires itself.

https://www.nibib.nih.gov/news-events/ne...n-activity

http://citeseerx.ist.psu.edu/viewdoc/dow...1&type=pdf

Quote:Bacteria are alive, and they don't even have brains.

We're talking ofcourse about human life. That was the assumption of the OP.

From article:

Quote:"The team first tested their method on adults by telling them to purposely move their head in the scanner. After showing they could successfully quantify brain activity in moving subjects, they then scanned eight fetuses between 32 and 37 weeks of pregnancy,"

The brain activity was measured in fetuses after 25 weeks. That's after the brain starts functioning.