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The energy expansions of evolution
Nature ^
| April 28, 2017
| Olivia P. Judson
Posted on 05/20/2017 10:29:40 PM PDT by LibWhacker
AbstractAbstract
The history of the lifeEarth system can be divided into five energetic epochs, each featuring the evolution of life forms that can exploit a new source of energy. These sources are: geochemical energy, sunlight, oxygen, flesh and fire. The first two were present at the start, but oxygen, flesh and fire are all consequences of evolutionary events. Since no category of energy source has disappeared, this has, over time, resulted in an expanding realm of the sources of energy available to living organisms and a concomitant increase in the diversity and complexity of ecosystems. These energy expansions have also mediated the transformation of key aspects of the planetary environment, which have in turn mediated the future course of evolutionary change. Using energy as a lens thus illuminates patterns in the entwined histories of life and Earth, and may also provide a framework for considering the potential trajectories of lifeplanet systems elsewhere.
Free energy is a universal requirement for life. It drives mechanical motion and chemical reactionswhich in biology can change a cell or an organism1,2. Over the course of Earth history, the harnessing of free energy by organisms has had a dramatic impact on the planetary environment3,4,5,6,7. Yet the variety of free-energy sources available to living organisms has expanded over time. These expansions are consequences of events in the evolution of life, and they have mediated the transformation of the planet from an anoxic world that could support only microbial life, to one that boasts the rich geology and diversity of life present today. Here, I review these energy expansions, discuss how they map onto the biological and geological development of Earth, and consider what this could mean for the trajectories of lifeplanet systems elsewhere.
In the beginningIn the beginning
From the time Earth formed, around 4.56 billion years ago (Ga), two sources of energy were potentially available to living organisms: geochemical energy and sunlight. Sunlight is a consequence of the planet's position in the Solar System, whereas geochemical energy is an intrinsic property of the Earth. Geochemical energy arises when water reacts with basalts and other rocks8,9,10. These waterrock reactionswhich continue today11generate reduced compounds such as hydrogen, hydrogen sulfide, and methane8,9,10. Oxidation of these compounds releases energy, which organisms can capture and store in the form of chemical bonds. Although sources of geochemical energy can be at or near Earth's surface, they need not be: many are deep within the planet, out of reach of sunlight.
Assuming that life did not parachute in, fully formed, from elsewhere, a number of authors12,13,14,15 have argued that the transition from non-life to life took place in the context of geochemical energy, with the ability to harness sunlight evolving later (Fig. 1). Consistent with this, both phylogenetic16 and biochemical13,17 evidence suggest that the earliest life forms were chemoautotrophs, perhaps living by reacting hydrogen with carbon dioxide and giving off acetate, methane and water13,16. Mounting evidence18,19,20,21,22 suggests that the transition from non-life to life may have taken place before 3.7 Gaa time from which few rocks remain23.
Figure 1: Key events during the energy expansions of evolution.
(i) Life emerges; epoch of geochemistry begins. (ii) Anoxygenic photosynthesis: start of energy epoch 2, sunlight. (iii) Emergence of cyanobacteria. (iv) Great Oxidation Event: energy epoch 3, oxygen. (v) Probable eukaryotic fossils appear. (vi) Fossils of red algae appear. (vii) Start of energy epoch 4, flesh. (viii) Vascular plants colonize land; fire appears on Earth. Finally, the burning logs indicate the start of energy epoch 5, fire. The dates of (i)(iii) are highly uncertain. For (i) I have taken the earliest date for which there is evidence consistent with life20. For (ii) I have taken the earliest date for which there is evidence consistent with photosynthesis18,19,21. For (iii), I have marked the date currently supported by fossil evidence for the presence of cyanobacteria (see main text, Cyanobacteria and the oxygenation of the air). Tick marks represent intervals of 25 million years. Figure drawn by F. Zsolnai.
TOPICS: Science
KEYWORDS: energy; evolution; expansion; life
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To: PeterPrinciple
from the article:
"have argued that the transition from non-life to life"PeterPrinciple: "Spontaneous generation has continually been proven wrong.
Accepted scientific principle.
Life begats life."
Nobody today talks about the old "spontaneous generation", but complex chemistry is seen to evolve naturally and that has lead to much new research.
Beyond Pasteur in 1862 and Miller-Urey 1950s experiments, much more has been learned in recent decades.
So there are any number of new books on this subject and ones I've read include:
21
posted on
05/21/2017 10:06:33 AM PDT
by
BroJoeK
(a little historical perspective...)
To: BroJoeK
Thanks for posting, Joe.
One question...
Since the Earth and meteorites all formed from microscopic dust particles and gas, wouldn’t the rate of radioactive decay measure when the dust and gas was created by a supernova, and NOT the date when the dust and gas coalesced into planets and meteoroids?
Thanks for explaining this.
To: grey_whiskers
Re: No living organism directly utilizes fire as a primary biological energy source.
Yes, you make a good point.
On the other hand, I felt the author was saying that land animals could not have evolved into their current size without the after effects of fire.
To: zeestephen
On the other hand, I felt the author was saying that land animals could not have evolved into their current size without the after effects of fire. Like the wooly mammoth, during the ice ages.
Or the African and Indian Elephants, or the giraffe and hippopotamus.
All dependent on cooking for their size...?
Now, if you were talking about the average feminist American land whale...
24
posted on
05/21/2017 11:10:33 AM PDT
by
grey_whiskers
(The opinions are solely those of the author and are subject to change without notice.)
To: BroJoeK
Hmm Bro. I’m going to have to buy those books.
25
posted on
05/21/2017 11:34:55 AM PDT
by
ckilmer
(q e)
To: BroJoeK
oh yeah, the all ‘agree’...especially when you start with unprovable assumptions about the starting quantities of argon, etc, et al...and then you throw out the wildly off ages...dismiss them with a wave of your hand...you know, accuracy...etc...
nice try...
now, back to the altar of darwin with you...
To: zeestephen
zeestephen:
"One question..." Great question.
If I ever see an answer, will pass it along to you. ;-)
27
posted on
05/21/2017 1:03:32 PM PDT
by
BroJoeK
(a little historical perspective...)
To: raygunfan
raygunfan:
"oh yeah, the all agree...especially when you start with unprovable assumptions about the starting quantities of argon, etc, et al...and then you throw out the wildly off ages...dismiss them with a wave of your hand...you know, accuracy...etc..."
nice try...
now, back to the altar of Darwin with you... Radiometric dating merely measures the time elapsed since the material's clock was last "reset", whenever that happened or however it came about.
For example, Carbon-14 with a half-life around 6,000 years is useful to measure back about 60,000 years ago.
Other radiometric materials with half-lives in the millions & billions of years can measure back much further.
Naturally, if you reject, as you say, "unprovable assumptions", then you won't accept their conclusions.
However, those assumptions are reasonable and their conclusions consistent across dozens of measuring methodologies.
That's why from a scientific perspective they are pretty convincing.
But your taunting with "the altar of darwin" is uncalled for, since science strictly defined is the opposite of any religion.
The only thing you need to overthrow even the most "settled" scientific idea is confirmed data or better ideas which falsify it.
Insults carry no scientific weight, FRiend.
28
posted on
05/21/2017 1:26:11 PM PDT
by
BroJoeK
(a little historical perspective...)
To: BroJoeK
sorry, fake science carries no scientific weight either my friend. now, back to your Humanist Altar.
To: raygunfan
raygunfan:
"sorry, fake science carries no scientific weight either my friend.
now, back to your Humanist Altar." What you call "fake science" is just normal science whose assumptions, data & conclusions you don't like, for reasons which have nothing to do with science itself.
But here now in your second post you again seem obsessed with a fake "alter", so I'm guessing there's something about alters which make you just a little bit crazy?
Do you need help with that?
Maybe some counseling, FRiend?
30
posted on
05/21/2017 1:56:24 PM PDT
by
BroJoeK
(a little historical perspective...)
To: BroJoeK
Nobody today talks about the old “spontaneous generation”, but complex chemistry is seen to evolve naturally and that has lead to much new research.
Exactly, it was just renamed. It is still trying to prove spontaneous generation.
And yes, new research than continues to prove life begets life. Your so called chemistry is under highly controlled lab conditions that don’t exist in nature. and your chemical reactions independent of multiple systems goes no where.
So tell me why it is so offensive to live with scientific results that life begets life?
Once you accept this result then you can be a real scientist like George Washington Carver:
When I was young, I said to God, ‘God, tell me the mystery of the universe.’ But God answered, ‘That knowledge is for me alone.’ So I said, ‘God, tell me the mystery of the peanut.’ Then God said, ‘Well George, that’s more nearly your size.’ And he told me.
31
posted on
05/21/2017 3:53:48 PM PDT
by
PeterPrinciple
(Thinking Caps are no longer being issued but there must be a warehouse full of them somewhere.)
To: PeterPrinciple
PeterPrinciple:
"Exactly, it was just renamed.
It is still trying to prove spontaneous generation." In your first sentence here you may have inadvertently recognized the power of word definitions.
In this case the question: what exactly is life?
Is a virus alive? I think not in any ordinary sense.
What about the prions which cause Mad Cow disease?
Certainly not, yes, it's complex organic chemistry to be sure, but not alive in our ordinary sense of that term.
So the question is, can complex organic chemistry evolve enough life-like features for us to classify it as living?
Of course, if you reject the very idea of evolution then necessarily your answer will be "no".
But much of today's speculations revolve around how that might have happened.
Yes, it's all speculation -- hypotheses, not theories, much less observed facts.
But it's pretty interesting stuff, I think, and we learn much from it.
The two books I posted are just two among many others you'll find in my link to Amazon.com.
PeterPrinciple: "And yes, new research than continues to prove life begets life.
Your so called chemistry is under highly controlled lab conditions that dont exist in nature.
and your chemical reactions independent of multiple systems goes no where."
What recent experiments show is that under certain natural conditions, such as those expected in early Earth, organic chemistry will "complexify" (I hate that word, but what other is there?), meaning grow larger and more feature rich.
Yes, many, many "complexifications" are needed for mere chemistry to become life-like, but that's the path they study.
PeterPrinciple: "So tell me why it is so offensive to live with scientific results that life begets life?"
Not in the least "offensive", but the question is how, exactly, do we define the word "life".
At the molecular levels of prions and viruses, "life" can be pretty hard to define, subject to interpretations and changeable with new understanding.
So let me ask you: why do you find it so "offensive" to consider certain complex organic molecules as "pre-life"?
PeterPrinciple: "When I was young, I said to God, God, tell me the mystery of the universe.
But God answered, That knowledge is for me alone.
So I said, God, tell me the mystery of the peanut.
Then God said, Well George, thats more nearly your size.
And he told me."
Great story! That's exactly how science works, thanks.
32
posted on
05/22/2017 3:05:11 AM PDT
by
BroJoeK
(a little historical perspective...)
To: LibWhacker
I am not saying I have the answers but this is gobbledygook. I know BS when I see it.
Assuming that life did not parachute in, fully formed, from elsewhere, a number of authors12,13,14,15 have argued that the transition from non-life to life took place in the context of geochemical energy, with the ability to harness sunlight evolving later (Fig. 1). Consistent with this, both phylogenetic16 and biochemical13,17 evidence suggest that the earliest life forms were chemoautotrophs, perhaps living by reacting hydrogen with carbon dioxide and giving off acetate, methane and water13,16. Mounting evidence18,19,20,21,22 suggests that the transition from non-life to life may have taken place before 3.7 Gaa time from which few rocks remain23.
33
posted on
05/22/2017 3:32:08 AM PDT
by
central_va
(I won't be reconstructed and I do not give a damn.)
To: central_va; LibWhacker
central_va quoting article:
"Mounting evidence18,19,20,21,22 suggests that the transition from non-life to life may have taken place before 3.7 Gaa time from which few rocks remain23." central_va: "I am not saying I have the answers but this is gobbledygook.
I know BS when I see it."
Not total BS, but admittedly speculation, hypotheses based on very detailed observations and some experiments.
So when might natural organic chemistry have "complexified" into biology -- was it 3.7 billion years ago?
Maybe, but that all depends on your definition of "life".
34
posted on
05/22/2017 12:44:11 PM PDT
by
BroJoeK
(a little historical perspective...)
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