In a new study Life Before Earth, Alexei A. Sharov and, Richard Gordon argue that the complexity of life grows exponentially over time in a manner similar to Moore’s Law. They “measure genetic complexity by the length of functional and non-redundant DNA sequence rather than by total DNA length.” When they plot this measure on a graph with representative types of organisms they find the greatest complexity found in life on Earth at any point in time doubles every 376 million years. If the line on the graph is extended backward, the beginning point of the line, the hypothetical beginning of life, is about 9.7 billion years ago. This is before Earth existed. From that, they conclude that life must not have originated not on Earth.
While I am not totally convinced of their argument, the authors certainly raise some provocative questions.
The most important is what predated the most primitive organisms on Earth. The accepted theory is that the earliest forms of life on Earth were prokaryotes. These are organisms without a nucleus and include among them bacteria. Part of the problem is that these organisms are already fairly complex so it is almost impossible that one of these assembled randomly. So the authors argue that life may have begun with something as simple as one nucleotide and evolved greater complexity via an evolutionary process over 5 billion years to reach the level of complexity of the prokaryotes. This evolution took place probably in some special environment unlike Earth.
Another conclusion is that intelligence and consciousness are related to genetic complexity. The complexity found in humans required almost 10 billion years to evolve. Therefore, intelligent life in the universe is only now emerging. Intelligent beings could not have seeded the earliest life to Earth because there was insufficient time for them to have evolved. The earliest prokaryotes arrived on Earth from spores carried by comets and asteroids. This suggests that we will likely find life much like that on Earth on other planets in our solar system and probably throughout the galaxy.
The authors finally try to draw some conclusions about the future. Genetic complexity may only be a good measure of intelligence on the lower end of the spectrum and now genetic complexity may be lagging behind growth in intelligence. They make a distinction between the growth rates of human technologies, such as computer speed, and the functional complexity of human civilization which might better measured by such things as number of scientific papers or number of patents. They find functional complexity doubles approximately every generation. “In summary, the functional complexity of human civilization grows exponentially with a doubling time ca. 20 years, but we do not see any signs of an approaching ‘technological singularity’ when humans would be replaced by intelligent machines. Instead, we expect a stronger integration of human mind with technology that would result in augmented intelligence.”
Although this study is fascinating, I think the question of whether the first organisms developed solely by evolutionary forces is still open. There may have been supplemental forces of some type at work. Evolutionary theory suggests that organisms evolve by random mutation. Therefore, a mutation could create a more genetically complex species, one equally complex, or a simpler one, although probably the odds of doing each are not equal. It would seem that prokaryotes in natural or laboratory settings ought to mutate occasionally into simpler organisms. If this were observed, this could provide a clue to what preceded the prokaryotes and whether evolutionary forces created the first organisms or some additional mechanism was at work. If it were some other mechanism, the development of the prokaryotes that required 5 billion years in this study may have taken place more quickly.
It would not make sense that a small part of the Universe, Earth, would be the originator of life.
There is whole galaxies out there that are not even like our life on Earth. Life in all its many forms and intelligence in all its many forms are not centered around us. It would be a huge mistake to presume such….the ego does not know it all, in fact, the ego limits our thinking in ways we cannot even imagine. Ego is stuck on itself, there is so much more……
Thanks for the post, interesting thoughts and ideas.
Thanks for commenting.
The alternative is that given the right conditions matter has an ability to organize itself into living organisms. Life could arise spontaneously in many different places in the universe.
Both views lead us to conclude that life is prevalent throughout the universe.
Only the view that life is rare and an amazing series of accidents or divine design created it in only one place would lead us to the opposite conclusion.
This is fascinating and lends credence to the theory of Panspermia and a plausible resolution to Fermi’s paradox.
However, a fundamental question remains.
1. Is the application of Moore’s law justifiable over these time-frames?
– Evolution is known to proceed in fits & bursts (the Cambrian explosion for example)
Good point. Actually they try to address this:
“Although we fully agree that evolutionary rates fluctuate in time and that catastrophic changes of the environment followed by mass extinction provide a boost of novel adaptations to survived lineages, we strongly disagree that the concept of punctuated equilibrium is applicable to the general trend of the increase of functional complexity of organisms (Fig. 1). First, adaptive radiation of lineages observed during periods of rapid evolutionary change has nothing to do with the increase of functional complexity. Multicellular organisms have enough functional plasticity to produce a large variety of morphologies based on already existing molecular and cellular mechanisms. Second, many rapid changes in the composition of animal and plant communities resulted from migration and propagation of already existing species (Dawkins, 1986), a mechanism that does not require an increase in functional complexity. Third, there is no reason to expect that functional complexity of organisms did not increase during long “equilibrium” periods with no dramatic change in the morphology of organisms. Morphology is the tip of the evolutionary iceberg as the greatest changes occur at the molecular level.”
One other note.
A reviewer of an earlier paper by one of the authors pointed out that the Moore’s Law calculation seemed to be based on just a few data points so extrapolation from them is unwarranted.
To me a bigger issue is how do evolutionary forces come into play before we have the viable organisms. Best estimates are that the simplest organisms would need at least several hundred genes. So evolution would need to be working on combinations of nucleotides and proteins that might not have been totally viable organisms for billions of years to arrive at the complexity of what we see today as the most primitive organisms. It is hard to imagine how that could happen in nature since it would seem that would require some very unique, protected, and stable environment for that entire time.
On the other hand explaining how several hundred genes could assemble themselves might be even more difficult.
Obviously we are missing some key piece of information in all of this. I have occasionally thought that there might be a sort of assembler molecule that acts like a boot program on a computer. If this molecule were placed in a soup of organic material, it would spontaneously seize components it needed to create a simple organism.
A lot of trigger words in what is written here.
I was going to comment on punctuated equilibrium. Then I read where they ruled it out, and gave their reasons. I think they are being overly hasty, perhaps even what Dennett calls “greedy reductionism.”
The first thing I would note with this concept is that, being so new it is easy for them to try to explain too much with the idea. At the same time, I know that to come up with a really new idea, the old ideas have so many tentacles of research in so many directions – all of which eventually will have to be compared and debated before any rel progress can be made. I ppoint to the Younger Dryas Impact Hypothesis as an example of that. It is impossible to address all the tentacles, and skepticism can use any one or many of them to attack the new idea. So people proposing new ideas will, naturally, try to head off as many of those right off the bat if they can. This can lead to possible greedy reductionism, but it can also simply be them covering as many angles as possible.
At the same time, on any of those tentacles/angles they may turn out to be wrong or partially wrong – and still have a viable hypothesis.
I agree with Avi Raj about Moore’s Law or a biological equivalent in asking if it is even a valid approach. I also agree with the previous reviewer you mention who objects to the extrapolation on so few data points. I would argue that even with sufficient data points the “half-life” they came up with may be wrong by as much as a magnitude or more. Even half a magnitude would put the beginning of life back into “normal” time and space, as it were.
Where you then say, “To me a bigger issue is how do evolutionary forces come into play before we have the viable organisms.” – This I agree with, too. For some reason I find myself objecting a bit to the use of the term “evolution” in this context. I kind of think “development” is more appropriate.
I’d also like to throw a curve ball in here, in mentioning the work of radical thinker Rupert Sheldrake from Cambridge University. His morphic resonance may not be mainstream, but he asks some questions that may apply here. Morphic resonance does explain some things which DNA cannot yet explain, even if it sounds half-baked and pseudo-scientific. If anything the work of Sharov and Gordon may bolster Sheldrake’s work in some small way.
I need to read the paper first to comment intelligently, but my own first question is to ask why they assume any linearity to the “half-life”. Such a simplification in science always gets me squirming at the presumption attached to the assumption. This early in the game to draw more than basic conclusions is certainly bordering on greedy reductionism.
But now, having said all that and probably put my foot in it, I need to read the paper…
A bit more…
Where they write, “Morphology is the tip of the evolutionary iceberg as the greatest changes occur at the molecular level” – this is more or less exactly the point of Sheldrake’s morphic resonsance – that the form of organs and appendages and bones and sinew are not inherent in DNA, but that some field – his morphic field – determines the shape and internal structures in toto. This is NOT mumbo jumbo, though it may be characterized by some as that. It is simply another direction of inquiry. Sheldrake points out that a upper arm has the same DNA as a wrist or ankle or kidney and yet the types of cells are put together in completley different gestalts. He argues that DNA only deals with proteins, and that nothing in that process suggests the forms that result.
As such, Sheldrake would argue strenuously that morphology is NOT the end of the developmental trail but the mold withni whcich the development is organized. Something, he argues, is organizing these organs and tissues, and it is not DNA. I personally object to anyone talking about “self-organization,” as that implies a level of intelligence even down to the cellular level (and below?) that may exceed our own modern minds.
Oh, one pertinent point may be the fact that not all biologists and paleontologists are in favor of Gould’s punctuated equilibrium. The fact that these two write against it here may be simply their own bias.
Thanks for your comments on this.
I was hoping to have another post up soon on something closely related to this topic but I think I need to do a little more thinking on it.
Your reference to Sheldrake is interesting. Have you heard of Stuart Newman. He has a theory about the origin of the animal forms at the time of Cambrian explosion. For some reason not clear to me, both he and some of his critics want to pick a fight somewhat along the lines of the Darwinism vs. the Intelligent Design, but his argument as I understand it (still reading by the way) is the morphological structures of animals are based on similar structures at the single cell level and make use of some of the same genes.
Maybe we could probably go farther back on this.
Working down the level of complexity.
Multicellular organisms arose from clumping of single organisms which begin to fold into a hollow body and develop specialized cells and tissues. See here https://en.wikipedia.org/wiki/Multicellular_organism#The_colonial_theory.
A single cell organism is a body enclosed in a cell membrane. Hence, there may be some unit less than a cell that clumped together and folded in a similar morphological manner to single cells forming multicellular organisms in order to create the initial cells. Interestingly protein folding is itself a key part of proteins forming their three dimensional shapes for them to work properly. Prions, in fact, are misfolded proteins. Nucleic acids also rely on a folding and coiling process. If we had something like a protein(s) folded around a nucleotide, we might have something like a pre-cellular unit of life. If it clumped together and formed a hollow body, eventually the nucleotide part might separate to form the initial genetic material while the protein part forms a cell membrane. We would have the first cells.
Life might have arisen through some basic folding mechanism that began to work through electromagnetic properties of individual molecules . This folding may be the key to the capture of genetic information. This might be something that would be the molecular basis of Sheldrake’s morphic resonance field.
Anyway, this is quite a bit of speculation, I know.
I hope you come back to see my full post whenever I get it up.
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James, I wrote a response to your question here.
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Fascinating. As is so often the case when talking time spans of billions of years the extrapolations are rife with uncertainty. To show their analysis is robust would require, I think, them to adjust their definition of complexity somewhat and repeat the analysis. If a fair amount of variation in the starting conditions produced much the same conclusions, the robustness of this speculation would be significantly improved.
Still, this is fascinating; thanks for the link!
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Their scale based on Moore’s Law could be questioned certainly. Intuitively it seems like the most complex organisms existing at any point in time trends to increased complexity. How fast the trend is could be questioned along with proposed measures for complexity.