Nova Interview With Andy Knoll on the Origins of Life

I was surprised by the 4 billion years ago number. Basically that's right after the Earth came out of the oven (so to speak).

I often wonder about the statement, " from a single ancestor?" Pondering the concept myself I prefer to think that the first molecules acted in a completely erratic manner, so when looking for clues one might expect to find an array of different chemical mixtures, and natural selection playing its part due to a number of different factors, producing a whole host of possibilities? So at the end of the day evolution would eventually produce a stable cell or cells that we have come to think of as life. I know this is only speculation, but I prefer to think that in the beginning a whole range of different interacting organisms evolved, giving rise to the present day world? Just some thoughts.

Regards JD.

One thing we know for sure, there is genetic material in common to every living thing on this earth (barring a few very limited exceptions in archaebacteria afaik). We are all kin.

Apparently nothing becomes alive, unless it receives living genetic material from another living being. Turns out there is dead DNA lying around all over the place. True, some bacteria make interesting use of stray DNA/RNA. But they have to be alive, first, to do so. Stray DNA doesn't bring non-living things to life. The basic blueprints are passed on from a living ancestor.

There seems no room for doubt that Knoll's "newcomers" = plants and animals, whole new kindoms of organisms, at some point emerged from a fairly radical reorganization of the existing genetic material of life. Otherwise, we wouldn't share the genetic material of the earlier kindoms.

With respect to the "single ancestor", this is an interesting question. At the point where life was undergoing the "emergence" of completely new and different forms of life, would the conditions have been such as to cause multiple emergences of organisms similar enough to be capable of reproduction?? Or of numerous members of a new "kindom" which are distinct species or families?

It's a bit easier to fathom if you think about new species within families of animals, already constrained by complexity and sexual reproduction. Could radical changes such as chromosome number occur in more than one individual in exactly the same way? It doesn't seem entirely impossible, at least where more than one individual of the same species has been affected by exactly the same circumstances: in other words, it might be most likely to be a localized phenomenon, happening within a defined population and geographical area. This would also provide the new beings, if they are of a type depending on sexual reproduction, with genetically compatible and locally available new mates....

The absence of mates is a real glitch in the "single ancestor" format for complex organisms, when you think about the emergence of, say, human beings from existing simian DNA. The idea that a single mutant could go on to produce viable offspring and found a new species, without a mate, is problematic, even absurd. Therefore there must be a more reasonable explanation. A localized "multiple ancestors within a species population" paradigm is more realistic IMO.

I also vote "egg" to "chicken or the egg" question. Feel free to ridicule me if an extra leg starts growing from my head or wings sprout from my back... I will take it in good part...

I personally think of life as one big superorganism of which we are all a part. I find it a very useful perspective... I'm never lonely!

I agree with your speculation, it seems a more logical progression than a magic moment and a single ancestor.

Some further thoughts on the subject. Over the years different things sticks in ones mind, such as the following. Life could not have evolved because too much energy is involved putting things together? And if you look at the DNA there is no record of its evolution. And the other statement I have a little problem with is, that evolution is a process of natural selection, a statement that one would not normally question.

When the earth was a cooling molten mass, one often see's reference to the heat, when one thinks about its probable origins, mass generated within some sun or other? Then I think of possibly radiation being part of the story, after all lead was once radioactive uranium. So I think part of the chemistry involves radiation of some kind? As for DNA carrying evolutionary information, though not specific to the origin of life, I read an interesting article on the Y chromosome, where a small mutation in the DNA chain can be attributed to all males, but where this is the only mutation in a group of males (race), it acts as a pointer to where modern humans originated?

Natural selection? This suggests gradual development, some dominant feature, like eye colour etc, playing a survival role when passed on to future generations, but as these I believe have not changed for generations, some dominant feature would have to mutate? What I have in mind is the extinction of the dinosaurs and the emergence of new life forms. An unnatural set of conditions where most life forms have become extinct, and the opportunity for the survivors, having no competitors and limited predators (maybe, at first)? This does not suggest selection but rather abundance, the development of different genetic pools, without competition at first until the pressures of over population or natural forces brings natural selection into play, but evolution would have occurred before this. One could therefore equate abundance with the evolution of life?

I think I have put enough down to get me into deep water.

Regards JD.

Thanks, it's an interesting read.

I will check it at cannot access it at work

but according the introduction it sound intriguing

An interesting topic that no doubt fills our minds regularly as we try to understand this life..A pop tune from my youth "What's it All About Alfie" sums up much of this sentiment..From a sentimental point of view the breath of God and other cultural creation stories are adequate...From a scientific point of view resonance somehow is important to life..By that i mean a sustained resonance involving chemistry in motion.....reflecting perhaps the music of the big bangs continuing echo...Its as if life is captured in a bag(cell) and is continually trying to get out but is contained for a lifetime till that organism stops containing the "life force"..at last giving that resonance back to the general milieu..WE know this as death..Really interesting,removed from the cares of the day thread..Thanks...MArty Wolf

So if we are using the dinosaurs to fuel our auto's, after there total extinction.

The next earth inhabitants will use us to fuel there ?

So we would like to know, where and thus when is that asteroid or planet that is pre-programmed to collide with earth and continue this mass of evolution ?

Having watched a TV program last nite about changing the atmosphere of Mars to make it habitable by humans, because they believe earth will be made uninhabitable by atmospheric pollution from human activity, it makes sense to make a plan to modify the atmosphere of earth to improve the chemistry of the atmosphere.

Hi,

in the interview:

"Knoll: Yes. There are multiple doors that enter the maze, but there's really only one historical path that life took"

I do not believe this. Mitochondria (the energy factories inside our cells) have a totally different genetic code (compared to the everywhere else existing code, everywhere else also not true but nearly) and these organelles have a double cell wall around. So these mitochondria are thought to be remnants of early predating: one cell swallowing others, killing, digesting and ...

This evolved into surviving swallowed cells in the predator. This evolved may be into illness of the swallowing cell, chronical illness finally and then cooperation and symbiosis. (The first steps of this evolution may be observed today: tuberculosis bacteria are surviving dormant inside immune cells.)

Other processes similar to this early event happened later after the establishment of "the" genetic code, so other organelles have the same genetic code as the host: chloroblasts and cell nucleus...

Considering this extremely unlikely event, in the results surviving until now, I think a scenario of many different genetic codes competing against each other to be much more likely.

Knoll:

How do you go from some warm, little pond on a primordial Earth that has amino acids, sugars, fatty acids just sort of floating around in the environment to something in which nucleic acids are actually directing proteins to make the membranes of the cell?

This too is not likely: The warm little pond was the ocean, many different temperatures, concentrations, products of early forms of may be life or not life.

Cell walls are likely to have formed from simple concentration gradients (and pH and...) in this soup of nutrients.

Last steps of non-life: autocatalytic chemistry of using the ingredients of the surrounding soup to synthesise more of this type of molecule that acts catalytically. May be this was the advent of RNA or simpler precursors.

First steps of life: identical to last step of non-life: producing more of the same species provided the environment has anything that is needed.

Next step of evolution: many these reactions competing against each other and using the ingredients of the surrounding soup and changing the ingredients!

Next step: hold together inside a walled compartment the necessary tools: early enzymes. Make the wall stronger for protection.

Now let nearly 3 billion years pass with single cell organisms until everything changed a lot.

During this time: total change of atmosphere by photosynthetic algae. Oxidation of early sulfidic minerals. (Not at all complete). Thereby change of color of sediments from green (anaerobic) to red (oxidised). Change of metals in solution: early enzymes only surviving by conservation and reinvention of synthetic pathways (vitamin B12). Invention and use of many new enzymes using elements that are soluble only in the changed ocean - not in the early ocean.

Totally new cycles of energy usage: oxygen is a nasty poison for bacteria that live in anaerobic environment. Oxygen use is requiring a totally different metabolism. Because of frequent changing environment from oxygen poor to oxygen rich conservation of old energy pathways in new organisms with the ability (until now) to switch back and forth.

I hope that we will find carbon-hydrogen based life (or the remnants) in decent time on Mars, and maybe later on the planets (hopefully) of nearby stars.

I have no doubt that life will start if water, ammonia, hydrogen, dissolved minerals, abundant lightnings in the atmosphere and considerable time exist.

This is not explaining the remaining mystery of matter and our universe. Where did this come from.

RHABE

(creationists are a momentary fall-back into medieval times, they cannot live with new ideas, sticking to the old-fashioned is simple, using new concepts is like Adam and Eva in the biblical myth, they were not content with the old-fashioned, tried the new possibilities and unlocked all the fascinating and often cruel real world.)

The business of the mitochondria is an important example: this is the transition from the bacterial kindom to what is called the eukaryotic or "true" cell. This type of cell is found in all of the more complex life forms and kindoms on earth.

Some very interesting work has been written about the mutualism implicit in this arrangement between mitochondria and the cell. Think about it Rhabe. There's the mitochondrion with its double wall, inside another double walled cell. There are single-walled organelles too, inside there, all doing specialized functions for the big cell.

If the paradigm of "predation" killing, digesting... or chronic "illness" or parisitism was really the true model, the cell would be in a state of internal chaos, one organelle fighting the other. NEVER can this happen unless the cell is about to die! Seriously. So it is a crappy model for evolution.

There's only one life on this earth, and everything alive is part of it. Just like your organs are parts that cooperate for the whole, there is a necessary mutualism underlying the relationship amongst living things, between the kindoms and between species, as there is amongst the organelles of the cell or the tissues, cells and organs in your body.

Another point is that diversification is a major feature of life. Life diversifies, and mechanisms of diversification are generally part of reproduction for most life forms; life generates variation and difference and specialization and opportunities to do things a bit differently, open new niches for life, and to bring different skills to the table. That adaptibility and capacity to change would be wasted if the driving force is to "crush the other guys" and survive. The successful, adaptive mutualist which is tolerant of others and performs very well the function that it has vis a vis the whole of life, is the fittest, IMO.

"with its double wall, inside another double walled cell"

Hi,

this is important because double walled is equivalent to a complete cell.

But still more important is the fact of a different genetic code in the mitochondria: encoding for the same natural amino-acids with different sequences of the bases in the DNA.

This is an indication that there have been different codes relying on RNA or DNA in early cell development: in prokaryotes.

And only after some coexistence originated there was the possibility to combine good and positive possibilities to start with eucariots.

And then after additional 3 billion years with higher multicellular organisms - may be by a similar action of symbiotic combination.

The genes for "eyes": light, sensitive and optical imaging devices are the same throughout all higher organisms: crabs to mammals!!!, the genes for thorax is the same in insects as in vertebrates!

Explain this with different possibilities

I am convinced that this started as symbiosis, and symbiosis started as predation, swallowing, incomplete or blocked digestion, long-term survival and co-evolution until one new organism was existing.

RHABE

The genes for "eyes": light, sensitive and optical imaging devices are the same... ya! Squid eyes are amazing, for example. So like our own, but quite far from us on the genetic tree.

Symbiosis and swallowing... I can agree with that, where 'predation' is more like bumping into one another or groping along, swallowing 'whatever' without too much of a plan. A slight difference of ideas based on different words.

The "swallowing" action is not actually digestion: in bacteria, taking in foreign material is not only a way to get nourishment but, of course, is also a means of exchanging information : genetic code. It is routine for bacteria to exchange plasmids containing DNA. They "swallow" the plasmids, as in, take them in through the "wall", but in fact this isn't a digestive type swallowing.

Since they don't have the kind of specialized organ systems that we animals have, it's easy to imagine how the simplest life forms could evolve into eukaryotes, just by some lucky or advantageous accidents.. lady luck rules, maybe...?

Thanks Roger, this sounds pretty intriguing. When I have time I'll make sure I read it.