How did life emerge on Earth?

[Jupiter60]

Many people have claimed that evolution started life. I'd say it did not. Life started evolution. Before there is evolution, there must be life. Am I right?

 

[DaveC426913]

Who has claimed evolution started life?
They are ignorant.

 

[berkeman]

Interesting discussion -- the Mentors are watching this thread...

 

[Evo]

Let's not confuse abiogenesis (the start of life) and evolution. They are not the same.

ABIOGENESIS
22 Sep , 2009 by Jean Tate

How did life on Earth arise? Scientific efforts to answer that question are called abiogenesis. More formally, abiogenesis is a theory, or set of theories, concerning how life on Earth began (but excluding panspermia).

Note that while abiogenesis and evolution are related, they are distinct (evolution says nothing about how life began; abiogenesis says nothing about how life evolves).

http://www.universetoday.com/41024/abiogenesis/

To keep this within known, accurate science, if you post, you will need to post your source which is acceptable accordng to our guidelines..

 

[Laroxe]

It all depends on how you define evolution, if you think of it as the way things might change or develop it could mean lots of things. Its often better to talk about biological evolution which is far more specific and everyone knows what being, discussed. Most dictionaries provide reasonable sources for this.

 

[jackmell]

Many people have claimed that evolution started life. I'd say it did not. Life started evolution. Before there is evolution, there must be life. Am I right?

Is that not correct in the sense that (chemical) survival and reproductive success were relevant, crucial, and necessary for the origin of life on Earth even during pre-biotic evolution, even before any signs of life existed on earth, and therefore the fundamental tenant of evolution, survival and reproductive success, was necessary for life to emerge on earth, and in this regards, one could suggest, "evolution started life?"

 

[rootone]

This begs the question of how to define what is life and what is not.
From our one example of life on Earth we might say it's life if it's a contained self replicating system driven by DNA, (a cell).
But we don't know if other kinds of self replication can exist, and even taking the DNA/cell basis as a definition there are viruses, which are not cells and can in some cases consist only of a (relatively) simple package of RNA + proteins.

 

[Kilo Vectors]

I have another question for you OP. Only intelligent life can create information, what created DNA in the first place? the conventional theory of it arising out of a melting pot of ideal conditions... Even the most basic of DNA, are we really to believe the conventional explanation?

 

[Drakkith]

Only intelligent life can create information

This is incorrect. Information: At its most fundamental, information is any propagation of cause and effect within a system.
Clearly this is occurs in non-living systems all the time.

I cannot believe that the mentor on this thread posted such flawed information!

No flawed information has been posted. Biogenesis is not a theory on the origin of life and never has been (as the wiki article you posted yourself explains).

 

[litup]

Creationists are the ones insisting the intimate coupling of life origin with evolution. They say, you can't know evolution if you don't know beginnings, then they inevitably start the 'let there be light' bit...

 

[Silicon Waffle]

... Abiogenesis is a theory on the origin of life here on Earth.

OK I agree, it's a hypothesis that says life can be created from non-living materials.

Biogenesis is not.

Why do you say so ?

The term biogenesis was coined by Henry Charlton Bastian to mean the generation of a life form from nonliving materials, however, Thomas Henry Huxley chose the term abiogenesis and redefined biogenesis for life arising from preexisting life.[3] The generation of life from non-living material is called abiogenesis, and occurred at least once in the history of the Earth,[4][5] or in the history of the Universe (see panspermia), when life first arose.[6][7][8]
The term biogenesis may also refer to biochemical processes of production in living organisms (see biosynthesis).

Louis Pasteur's experiment supports the hypothesis of biogenesis. So I don't see the point as to why you turn it down as a "hypothesis" of life origin.

 

[rootone]

Essentially the term 'biogenesis' in it's modern context, (as defined by Huxley, referenced above), is more or less a synonym for 'evolution' - lifeforms arise from ancestor lifeforms.
Except that it doesn't infer 'natural selection', which usually is the implication nowdays when when we speak of 'evolution' of life.
Abiogenesis is a proposal (actually there are a few different ones) for the origin of all life, 'biogenesis' (not a frequently used term anyway), does not propose an origin.

 

[MindWalk]

I understand why someone might see a connection between Pasteur's experiment and a disproof of abiogenesis, but this misconception arises from a failure to understand what it was that Pasteur's experiment was designed to attempt to disprove and what it was not designed to attempt to disprove. The nineteenth-century hypothesis of spontaneous generation and the modern hypothesis of abiogenesis might seem very similar, but they are distinct and should not be confused.
From https://en.wikipedia.org/wiki/Spontaneous_generation: "Spontaneous generation refers both to the supposed processes in which different types of life might repeatedly emerge from specific sources other than seeds, eggs or parents, and also to the theoretical principles which were presented in support of any such phenomena. Crucial to this doctrine is the idea that life comes from non-life, with the conditions, and that no causal agent is needed (i.e. Parent). Such hypothetical processes sometimes are referred to as abiogenesis, in which life routinely emerges from non-living matter on a time scale of anything from minutes to weeks, or perhaps a season or so. An example would be the supposed seasonal generation of mice and other animals from the mud of the Nile.[7] Such ideas have no operative principles in common with the modern hypothesis of abiogenesis, in which life emerged in the early ages of the planet, over a time span of at least millions of years, and subsequently diversified without evidence that there ever has been any subsequent repetition of the event."

 

[Drakkith]

Louis Pasteur's experiment supports the hypothesis of biogenesis. So I don't see the point as to why you turn it down as a "hypothesis" of life origin.

Mindwalk explained it better than I ever could. The theory of biogenesis, as tested by Louis Pasteur, was developed as a competing theory to spontaneous generation, not as an explanation of where all life originally came from, which is what has been proposed in this thread.

 

[Kilo Vectors]

this thread is clearly very confusing.. anyone who thinks evolution started life is WRONG. Evolution came after life! So that would be very ignorant. Also it is difficult to actually know when evolution is occurring, say, is it just a mutation/change in gene/allele (forgot which term)..I would say its much easier to judge from context and effect. Evolution can take thousands of years or decades..I only studied a level biology but its not that hard to realize its a bit relative.

secondly, of course only life can create other life, BUT we want to know what and how created the first ever life form and that is something no one has been able to prove convincingly. There are certain 7 characteristics of life forms from what I remember in A level biology (I don't remember everything well):

1. respiration
2. Movement
3. growth (an increase in dry mass?) (?)
3. Excretion
4. ability to sense environment/changes in environment.
5. Most important ability to reproduce

Now there is also a debate on how to define this basic criteria itself..some say a virus is non living but others say it isn't as it is just a collection of RNA. So there are many problems, as to my point of intelligent life only being able to create the hyper detailed instructions known as DNA, well... The funny thing is, we don't even know what came first! the DNA or the organism/structure that produces it (ribosomes).

So what would be the first ever, "life" form? no doubt one general consensus would say some ancient micro organism.. But HOW did that come into existence? No one has been able to conclusively tell and anyone who claims otherwise is simply wrong.

Why is it important to know? because the answer could very well tell us the purpose of "life" or of our perceived existence as well. Some say living organisms are just vessels for DNA's survival.. the reason they exist is so DNA CAN has been proposed.

What are the theories? ( I am listing all I have come across) NOTE: I AM LISTING NOT SUPPORTING ANY, these are all including out of the realm of mainstram science..but it is important to know!

1. God (most popular amongst the human population)

2. Natural processes leading to a perfect ideal conditions, causing the building blocks of life to form..which led to life (most popular in scientific community) (very logical theory, and I also believe this but need to see more evidence)

3. Otherworldy beings created us (even as a simulation can fit in here) and left easter eggs in the form of pyramids/stonehenge/easter island...(Popular amongst crackpots like myself, but is number one different from 3?) (a theory discussed by some physicists, really not mainstream science)

so all in all, any discussion on the origins of life has very deep significant meaning for all of us, but evolution did not start life, evolution is the result of life processes.

 

[jackmell]

The dynamics necessary for the origin and evolution of life existed before life and are independent of life. The inconsequential trappings of biology and chemistry instantiating life on Earth are just happenstance and convenient for our particular planet. Consider a concrete example: termite mounds. Camazine and others have formulated a coupled system of PDEs modeling the dynamics between termite, mud, and pheromone. The marvelous clay cathedral "emerges" not because of some termite blue-print a master termite is following, but rather entirely because of non-linear dynamics. Then on a more fundamental level, the mud, pheromone, even the termite becomes irrelevant; we could just as well replace them with marbles, pencils, and paperclips behaving in the same dynamic way and a mound (pencil perhaps) would still emerge! The same could be argued with many other biological systems on Earth according to Camazine's book "Self-Organization in Biological Systems," and therefore I do not believe it is an unreasonable stretch of logic to suggest the same may or could be said about the origin of life itself: the dynamics needed for the origin of life to occur existed before life (is timeless) and in this way I argue the "dynamics" of evolution started life on earth.

Citation: http://press.princeton.edu/titles/7104.html

Note: In an effort to be rigorous, I should note the PDEs modeling termite behavior cited above where not just "conveniently" constructed to achieve a desired effect but rather, to the best available experimental data, constructed according to the actual physical interactions between termite, mud and pheromone.

 

[rootone]

The simplest self replicating molecule we know of seems to be RNA, as viruses.
Yet RNA only can do that by taking over the reproductive machinery of more complex cellular organisms.
It's a puzzle.

 

[Drakkith]

The simplest self replicating molecule we know of seems to be RNA, as viruses.

I don't think that's true, but I'll have to look around to see if I can find the information on it.

 

[Drakkith]

The simplest self replicating molecule we know of seems to be RNA, as viruses.

I looked around a bit and found some information primarily on autocatalysis. I'm not sure if this is quite what you meant by your statement, but I would say there are plenty of examples of self-replicating molecules out there.

Here's a slideshow on a few, most of which are biological molecules: http://www.slideshare.net/bfrezza/selfreplicating-molecules-an-introduction

Some info from the journal of the american chemical society (behind a paywall unfortunately): http://pubs.acs.org/doi/abs/10.1021/ja00099a003?journalCode=jacsat

More info on self-replication: http://www.astroscu.unam.mx/~angel/tsb/Rebek.htm

 

[Silicon Waffle]

The simplest self replicating molecule we know of seems to be RNA, as viruses.
Yet RNA only can do that by taking over the reproductive machinery of more complex cellular organisms.
It's a puzzle.

That is one of the difficulties for people to also consider a pre-RNA (PNA) world. This is an interesting summary about chemicals and pre-life.
What about experiments to generate or create amino acid sequences from simple chemical elements and compounds e.g NH3, H2, O2, C, etc. in nature ?
Self-replicating molecules must receive an energy input enough to perform their reactions and replication and at the same time release an amount of energy. Where does the input energy come from ? and what is the output for ?

 

[jackmell]

The simplest self replicating molecule we know of seems to be RNA, as viruses.

I do not believe that's true.

I don't think that's true, but I'll have to look around to see if I can find the information on it.

Look no further than “At Home in the Universe,” by Stuart Kauffman:

At its heart, a living organism is a system of chemicals that has the capacity to catalyze its own reproduction . . . a collectively autocatalytic system is one in which the molecules speed up the very reactions by which they themselves are formed: A makes B, B makes C, C makes A again. Now imagine a whole network of these self-propelling loops. Given a supply of food molecules, the network will be able to constantly re-create itself. Like the metabolic networks that inhabit every living cell, it will be alive.

“How likely is it that such a self-sustaining web of reactions would arise naturally? . . . The answer is heartening: The emergence of autocatalytic sets is almost inevitable. As the diversity of molecules in the (pre-biotic) Earth increased, the ratio of reactions to chemicals increase. As the ratio of chemicals to reactions increases, the number of reactions that are catalyzed by the molecules in the system increases. When the number of catalyzed reactions is about equal to the number of chemicals, a giant catalyzed reaction web forms, and a collective autocatalytic system snaps into existence. A living metabolism crystallizes. Life emerges as a phase transition.”

And if I may be allowed to make a comment in the interest that some reading this may be stimulated to pursue this further, Kauffman mentions "phase-transition." That phenomenon is very common in our Universe and is one defining property of non-linear dynamics: non-linear systems often exhibit "critical-points" in their behavior in which the dynamics is no longer smooth, but at some point, the critical point, the dynamics abruptly and qualitatively changes as the systems trajects through a phase-transition -- think water abruptly freezing to ice as the temperature is lowered to the freezing point. And since the Universe is so massively non-linear, it should not be such a stretch of logic to suggest that living systems might emerge naturally and perhaps commonly, as a consequence of natural phenomena occurring in a non-linear world such as ours. :)

Citation: https://www.amazon.com/dp/0195111303/?tag=pfamazon01-20