Video: Life's origins
PETER MITCHELL was an eccentric figure. For much of his career he worked in his own lab in a restored manor house in Cornwall in the UK, his research funded in part by a herd of dairy cows. His ideas about the most basic process of life - how it gets energy - seemed ridiculous to his fellow biologists.
"I remember thinking to myself that I would bet anything that [it] didn't work that way," biochemist Leslie Orgel wrote of his meeting with Mitchell half a century ago. "Not since Darwin and Wallace has biology come up with an idea as counter-intuitive as those of, say, Einstein, Heisenberg and Schrödinger."
Over the following decades, however, it became clear that Mitchell was right. His vindication was complete when he won a Nobel prize in 1978. Even today, though, most biologists have yet to grasp the full implications of his revolutionary ideas - especially for the origin of life.
"Mitchell's ideas were about how cells are organised in space, and cellular energy generation is a feature of that," says geochemist Mike Russell of NASA's Jet Propulsion Laboratory in Pasadena, California. "The problem is that most ideas on the origin of life lack both spatial organisation and a supply of energy to drive replication or growth."
A few researchers, including Russell, have been rethinking the origin of life in the light of Mitchell's ideas. They think the most counter-intuitive trait of life is one of the best clues to its origin. As a result, they have come up with a radically different picture of what the earliest life was like and where it evolved. It's a picture for which there is growing evidence.
The most counter-intuitive trait of life could be one of the best clues to its origin
Before Mitchell, everyone assumed that cells got their energy using straightforward chemistry. The universal energy currency of life is a molecule called ATP. Split it and energy is released. ATP powers most of the energy-demanding processes in cells, from building proteins to making muscles move. ATP, in turn, was thought to be generated from food by a series of standard chemical reactions. Mitchell thought otherwise. Life, he argued, is powered not by the kind of chemistry that goes on in a test tube but by a kind of electricity.
The energy from food, he said, is used to pump positively charged hydrogen ions, or protons, through a membrane. As protons accumulate on one side, an electrochemical gradient builds up across the membrane. Given the chance, the protons will flow back across, releasing energy that can be harnessed to assemble ATP molecules. In energy terms, the process is analogous to filling a raised tank with buckets of water, then using the water to drive a waterwheel.
Mitchell dubbed his theory chemiosmosis, and it is not surprising that biologists found it hard to accept. Why would life generate energy in such a complicated and roundabout way, when simple chemical reactions would suffice? It just didn't make sense.
It might be counter-intuitive, but chemiosmosis has turned out to be ubiquitous in the living world. Proton power drives not only cell respiration, but photosynthesis too: energy from the sun is converted into a proton gradient in essentially the same way as the energy of food.
And proton gradients are often harnessed directly, rather than being used to make ATP. They drive the rotation of the bacterial flagellum, as well as the active transport of numerous substances in and out of cells. So proton power is central to energy generation, movement and maintaining the internal environment - some of the most basic features of life.
This suggests that proton power is no late innovation but evolved early in the history of life, an idea supported by the tree of life. The first branch in the tree is between the two great groups of simple cells, bacteria and archaea. Both of these groups have proton pumps and both generate ATP from proton currents, using a similar protein. The obvious explanation is that both inherited this machinery from a common ancestor - the progenitor of all life on Earth.
Think about the properties of that common ancestor, however, says Bill Martin of the University of Düsseldorf in Germany, and you come up with a very strange beast indeed. He starts from the assumption that traits found in both the archaea and bacteria are most likely inherited from the common ancestor of all life - though a few have clearly been acquired later by gene exchange. Traits that are distinct presumably evolved independently.
There is no doubt that the common ancestor possessed DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. The detailed mechanisms for reading off DNA and converting genes into proteins were also in place. In short, then, the last common ancestor of all life looks pretty much like a modern cell.
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Have your say
Absolutely brilliant theory.
I must confess had never heard of Peter Mitchell or his work before.
And I am not really into molecular biology.
But this explanation is much better than the 'primordial soup' and 'extraterrestrial influence' rubbish they fed us at school.
Agreed, the best New Scientist article I've read this year. Well written, unbiased, incredibly informative and backed by well supported evidence.
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Nice Article!
Would like to conjecture:
1. The transition from innanimate materials to living cells was a continuoum of many incremental changes.
2. The first step to cells was not dna or proteins but the ability to maintain an outside and an inside (cell membranes)
3. Once primordial conditions had created puddles of organic compounds and oils, water was also mixed in. When this was constantly agitated (like from waves or wind), these formed an emulsion of oil and water.
4. Through natural selection, those bubbles of water covered in oil that remained were those that were increasingly able to hold their integrity. This was due to better incorporation of phosphates, proteins etc that made cell membrane more adaptable. Example perhaps some phosphates made the membrane better able to hold its layer form, and perhaps proteins made it possible to poke holes in other neighboring cells to reduce competition, or perhaps even share material.
5. Other molecules such as dna / rna and stuff were roaming in the water and doing some evolution of their own - but they didnt get far because they were exposed to the environment. They then found their way into some "cells" and symbiosis developed - first as enzymes, then as information carriers.
6. And on and on.. multicellular, animal (eating others), terrestrial, warm blooded, intelligence, etc...
7. Then evolved culture over form just as life had evolved over inanimate matter. Culture was to long lived and wide spread to be effectively natural selected. It had to "learn" and adapt to changes that way.
After reading page 2, the cell membrane first conjecture is probably wrong and I take it back.
I also agree. This is the best article I've seen anywhere in a long time in terms of interest, honest presentation & references.
Yes, for a change real science that is explained in a pretty simple way. I am not a life science fan, I am more into physics, but this article was written in a way that most people can understand. Good job NS
This is the kind of article that got me reading NS in the first place. Too bad this kind of quality piece is now so rare for NS to produce.
+1
+2
please someone from NS, notice this! pleeeeease!!!
Yep Yep this article is truly well written. As soon as i looked at this page and found that it was 4 pages long i thought, its gonna be a long read or should i skip but when i started reading i just found it was so well written that i read all of it.
NewScientist has a great article writer on their team.
Kudos to the writer.
The only gripe with this idea is that life was created and did not evolve.
The model does not go far enough.
The organization of living molecules arose because of the regularity of crystalline structures within the rock substrate, and radioactivity played a key role - perhaps innate in the rocks themselves or from radon.
So one can see the order in life and time itself and ageing arising at once from the earth.
oNe must admit that the key characteristic of life is not the proton pump itself but creation.
That only holds true if you take creation as fact. I personally, along with a great deal of other people, do not hold this view. erego my key characteristic of life is whatever is the currently held scientific standard, a self-replicating, self-sustaining process, organic or not, with the capacity for growth, functional activity and continual change preceding death. The 'Organisms' proposed by the proton pump theory fall well within this category.
Another way of putting it rather than,'creation'. might be 'catalysis'. iN other words conditions arose in which the inherent order of crystalline rock, micro-porous geometry, chemistry, energy fluxes, thermal electrical , radiation etc. gave rise to a complex dynamic feedback reaction. But prior to this catalytic reaction - there was no life. So at one point in time - life arose from none-life. i.e.was created. This living entity - as you describe and identify - had a 'self' - as distinct from none living material - which did not have a 'self'.
oR at what point in your evolutionary model does 'self' appear?
I'm not a chemist or biologist,but it seems obvious to me that for there to be life there has to be consciouness.
This articule doesn't mention this
Define 'consciousness', because at the moment it's sounding worryingly like you mean "God must have made us".
Or are you suggesting that bacteria and archaea possess a rudimentary form of 'consciousness' that this rocky predecessor lacked? Are plants 'conscious' within your meaning of the word? Certainly all of these organisms react to the outside world, but I'm not sure that I'd describe them as conscious organisms.
If you aren't a Chemist or a Biologist, you can't possibly hope to understand the fundamental inner workings of what this research is based on. New Scientist may give the majority of us a good overview, and for the few of us who are particularly well informed, an excellent insight.
What may be obvious to you may easily be your innocent ignorance of what is truly happening, and to those of us without said ignorance, it may be painfully obvious (oh yes, it is painful) that your suggestion is entirely untrue.
"it seems obvious to me that for there to be life there has to be consciouness"
I have no idea if bacteria are conscious, but it's possible that water itself is sentient. We have no idea even what sentience is, or what causes it.
"We have no idea even what sentience is, or what causes it."
By popular usage sentience and consciousness is simply a word invented to describe what human brains do, and to a lesser extent what human-like brains do.
We would likely be rather weary of ascribing sentience to very sophisticated artificial intelligences or alien brains unless they happen to be structured to solve the same problems our own brain do and present the same social interactions outwards.
I can't even begin to imagine what led to this conclusion given that cells are obviously not conscious in any meaning of the word that I am familiar with.
Unless you embrace some kind of crazy dualism there isn't any such thing as real consciousness, not even in a human brain. Consciousness is simply a reification of what lots of human-like braincells do when you structure them like a human brain. Since a dog-brain is somewhat similar but less sophisticated than ours and since dogs are social creatures, we treat them like they have a consciousness of a lesser quality, like a toddler or someone in the early stages of dementia. Insects are almost universally regarded as mere mechanisms; they're 'brains' certainly do a lot of calculation and the exhibit fairly complex behaviour but we ascribe no more consciousness to it than we ascribe to a pentium.
Claiming there is "real" consciousness is like claiming there is real "marketness" to a market, some ethereal property that doesn't arise from the myriad actions and ambitions of its participants, or like claiming there is real "foodiness", an illdefined property of food that makes it more than just a collection of atoms juxtaposed in a very intricate way that for evolutionary and cultural reasons are appealing to our monkey brains.
"or like claiming there is real "foodiness", an illdefined property of food that makes it more than just a collection of atoms juxtaposed in a very intricate way that for evolutionary and cultural reasons are appealing to our monkey brains."
aahahahahhahahaha awesome
Excellent comment.
Is it too self-referential to say that "-ness" is a categorical judgment devised by "consciousness" to aid in organizing the world? Otherwise, some of the discussion on consciousness is sounding pretty Platonic.
And is it a leap to say "I am conscious, therefore the quality of consciousness exists"? Without getting too philosophical about this, the idea of consciousness may be the only thing (other than faith) which allows us a path out of solipsism.
Frank Boase, I'm not a chemist or biologist, either, but I am a scientist, and it seems obvious to me that you're not.
You're welcome to play here with the pros, but please remember that you're relatively unknowledgeable about the topics you're discussing. Asking questions would be more useful than trying to assert your beliefs.
Consciousness
Tue Oct 20 20:11:59 BST 2009 by Cyrus
http://thephilosopherstone.ca
Frank,
Pay no attention these commentary detractors. I AM an organic research chemist with 20 years of experience and several pharmaceutical patents. You are absolutely correct, although the research presented here is a definite advancement in understanding the origin of life, IT WOULD NOT HAPPEN WITHOUT CONSCIOUSNESS!
It is convenient that they have failed to mention the astronomical odds against all the required chemicals making their way into the little pores to start the process. Furthermore, these chemcials include DNA, which does NOT naturally occur.
If life did start this way, then it could only have happened with a conscious impetous.
"I AM an organic research chemist"
That may be so, but not only do you seem to be strictly religious, you are also a philosopher. Which in the eyes of many here, is no different from a pseudo "scientist".
I'm an organic research chemist with 40 years of experience and countless pharmaceutical patents. I've also got 10 PhD's and a black belt, so don't make me go kung fu on you.
When you're done pretending to be something you're not (presumably for the entertainment value of annoying people like me), you might want to go back and read what the article has to say about DNA formation. And I've never gotten something as big, complex, and patently alive as a redwood tree to repeat, "I think, therefore I am", so I have no idea what consciousness has to do with anything.
I suggest you take a look at another recent NS article about what happens when people like yourself wind up on juries and send innocent people to jail because of their own failure to understand basic Bayesian probability.
Unless you can produce a priori odds that the pre-existing consciousness you allege caused life to form existed, then your claim that the odds were too low for life to have come about spontaneously is complete rubbish.
'consciousness' means different things to different people. However if you simplify it to 'choice' - i.e. the idea that anything capable of making a choice must be conscious, then we can take that back with us to an essential characteristic of all lfe.
"ATP powers most of the energy-demanding processes in cells, from building proteins to making muscles move"
"...In short, then, the last common ancestor of all life looks pretty much like a modern cell."
So the common ancestor has already got everything a "modern cell" needs. I am wondering where did that ancestor got all that and why those features didn't evolve in such a long time?
Another point I have to make is this: the fact that a scientist understood how a process really works in nature does not automatically mean that he also found the origin of all that. We are striving to dissect nature to learn and be amazed. Every step in this quest brings about more interesting things that we could imagine. More efficient built than we could ever dream. And yet we could not wait for the end of the book. We prefer to guess the ending and we make that guess our truth. Further more we feel the need to convince everybody around us of the truth we think we have.
Be open minded as you say you are, wait for the secrets to be revealed. Stop forcing your guesses (evolution) on everybody
In an oft-used example. I can only truly 'guess' Napoleon existed since he died before anyone i have ever met was born, however the evidence of his existence is overwhelming, so this changes my 'guess' into knowledge based on evidence (evolution).
You call this a good example?
Your example does not match my arguments. In case of Napoleon you have a lot of evidence documented by people(pictures/docs/statues etc). In case of science we only have what we can manage to find out with current technology. So the newest finding is never documented anywhere, thus making it such an "amazing" discovery. Evolution is like fictional stories telling you there must be intelligent life on Mars. And until we were able to go there we could take that as the truth. But now we know it's not.
Back to your uninspired example: you could try replacing Napoleon with Jesus for an exercise.
"the fact that a scientist understood how a process really works in nature does not automatically mean that he also found the origin of all that"
Oddly, you are correct there. That is exactly what the article says.
"We prefer to guess the ending and we make that guess our truth"
Oh, shame. Wrong again. We make hypotheses ("guesses") and test them to see which are nearest the truth. We don't cling blindly to an idea simply because someone told us to.
"Further more we feel the need to convince everybody around us of the truth we think we have."
Yes you do. Please stop doing that.
Be open minded. Go out and look at the evidence. Stop forcing your religion on everybody.
I am not forcing religion on anybody. I just want scientists to do their research unbiased by religion or darwinism. I don't need to be converted. But evolutionists always think they got all the answers and therefore they have to make everybody accept what they think. Just stop that and people like me will not object anymore
"We make hypotheses ("guesses") and test them to see which are nearest the truth"
And how can anybody test all the ficti.. err "hypotheses" presented in this article? Not even the author can test it
Actually, you are no better. In your original statement you are only "guessing" that consciousness is needed. You have absolutely no proof of that either, but eh, it's obvious to you for some reason.
> I am wondering where did that ancestor got all that ...
Have you heard of "evolution"?
I suggest you actually read the article instead of ignoring the bits that contradict your worldview
Have you understood my point before commenting?
"I am wondering where did that ancestor got all that .."
* I am wondering, where did the ancestor get all that ?*
Read the article he describes very well how the ancestor came by it's traits.
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