Why is Evolution So Successful?

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For evolution to take a single, single-celled organism (I assume that it begun with just one) and then to produce everything we see alive around us today, along with all the various lifeforms that we have evidence for in the past is quite remarkable. On top of that it has taken life from near extinction on several occassions to a robust and thriving global ecology. This would be miraculous if it were a one time event, but if the current theories are only fractionally accurate, there have been many events that have desimated life, and life has bounded back. Given all the evidence of mass die-offs, it is obviously true.

Growing up in the 80’s I have had a healthy dose of warnings about animal endangerment and exstinction. Life seems so fragile when you pay attention to all of the warnings. Climate change says that slight changes in enviroment pose a danger to all life. Yet, life has never ceased since it first began. I’m sure the answer to why life is so successful will be credited to evolution. Because life evolves it is able to adapt to whatever condition arises. But what makes evolution so successful? I’m not sure what answer I am looking for. I am just currious to hear what the answer/s may be.

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No, it doesn’t. The rapid changes humans are producing in the planet’s climate threatens the extinction of many species and the severe disruption of the food chains. That includes humans who are still at the top of those chains. No one expects all life on the planet to go extinct.

That’s like asking what makes gravity so successful. Evolution is a naturally occurring physical process that produces certain outputs based on certain input conditions. If you’re asking why life diversified after each previous mass extinction event it’s because the mass extinctions opened up large ecological niches which the surviving life was free to radiate into.

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Thanks for the answer.

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These are good faith questions that are important to take seriously and answer with empathy,

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I believe Timothy at least answered the questions seriously and correctly. Empathy costs extra.

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Hi Cris, I think this is a really interesting question. @Timothy_Horton is right that your premise (about slight changes endangering all life) is wrong; life on earth has weathered catastrophic change many times in natural history, and then bounced back spectacularly. But I like your question, because it seems to be asking about the robustness of life and how it is related to evolution. (That’s my rephrasing of your question, and I know it might be different from what you intended. Hope that’s okay.) My opinion is that evolution’s success (at generating diversity and adaptation) and life’s success (at surviving and thriving and colonizing) are related. They don’t necessarily have to be related, but I think they are.

Cool question, thanks.

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Thanks for the questions, @Cris_DeLoach. Here is my attempt at an answer. In the words of Michael Crichton so memorably expressed by Jeff Goldblum in Jurassic Park: “Life finds a way.”

Actually, that’s not much of an answer; it is little more than a restatement of the question. But sometimes rephrasing the question makes it easier to find or express the answer. By unpacking that statement, I believe we will find three properties that have a lot do with why evolution is successful.

  • Life is abundant
  • Evolution is extravagant
  • Life is connected

Life is abundant

When we say “Life finds a way” what do we mean by “life”? We don’t mean specific living organisms; it is not a statement about the cleverness of dinosaurs. We mean the more abstract property of being alive. All life as we know it is mediated by atoms and molecules, and so takes the form of a set of self-sustaining and self-propagating chemical reactions. That is not all there is to life, but it is one consistent feature of everything we consider alive.

These self-sustaining, self-propagating chemical reactions are a subset of all chemical reactions. There is lots of chemistry that isn’t alive. At the same time, we can look around and see that there is great diversity in the combinations of chemistry that can be alive. And so the abstract space of all possible chemistry seemingly teems with (equally abstract) life. Thus evolution is successful because there is abundant life to find.

Evolution is extravagant

When we say “life finds a way”, “finds” implies a search. Searching has become a technical topic of study in the realm of computer science and machine learning, and there is some question as to whether evolution, as an algorithm, qualifies as a search in this technical sense. At the same time, it is clearly a process for exploring that abstract space of all possible chemistry. And from what we observe, that exploration is extravagant.

Some approaches to exploration or search focus on efficiency. They seek to find the most direct path to the or a solution, and stop when they reach it. Evolution is not like this, at least not in all cases. It does not stop when it finds a single instance of life; it does not appear to have halting criteria of any kind. It just continues exploring and finding more and more solutions. At the same time, it is not an exhaustive exploration; it is not guaranteed to find every instance of life, or to explore in a systematic fashion. So, neither efficient nor exhaustive, it is extravagant. We attribute its success to this extravagance in the sense that when drastic change occurs, some of the versions of life it has found may still be able to persist in the new context.

Life is connected

If “life finds a way” there must be a way for life to find. Life may very well be abundant in the space of all possibly chemistry, but if there are broad expanses of nonliving chemistry in between, how does evolution get from one life form to another? Evolution may very well be extravagant in its exploration of the space of all possibly chemistry, but it can only occupy the living portions of that space. It must also be the case that the abundance of living chemistry is contiguous in some way, so that evolution can move from life to life. Thus evolution is successful because there is a way to success for it to follow.

Now of course there are other technical considerations. Evolution is successful because the sun is a hot spot against the backdrop of otherwise cold space, allowing the Earth to persist far from thermodynamic equilibrium. Evolution is successful because Jupiter is so large, reducing the number of catastrophic asteroid impacts on Earth and giving life and evolution time to extravagantly expand into the abundance of life that exists in the space of all possible chemistry. Evolution is successful because atoms behave according to consistent patterns such that living chemistry today is living chemistry tomorrow. And so on.

And of course we can probe further. Why is life abundant? Why is evolution extravagant? Why is life connected? We can answer these questions for a while in terms of the periodic table and the properties of subatomic particles and so on. At some point we will reach the limit of such explanations. In parallel, we might say that life is abundant and connected because God intended for physical reality to bring forth a diverse array of life as indicated in the Bible. I think these are complementary explanations and all true.

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This one seems to me one of the largest factors that have made it possible for life to “bounce back” from major extinction events. There is life everywhere on Earth. Everywhere. From high up in the atmosphere in tiny watery aerosols, to deep in the Earth’s crust, life is ubiquitous. It would be very unlikely for a single event to completely sterilize the entire planet. Something truly cataclysmic, like a planetary collision, that would completely transform the atmosphere to an incandescent plasma, vaporize away all the oceans, and molten the entire crust, would have to happen to fully ensure the eradication all life. Nothing like that has happened since the collision thought to have originated the Moon.

But the kinds of extinction events that have happened have all had some degree of constrained locality to them. Asteroid impacts have not been large enough to kill everything on all continents, they have not vaporized away the oceans, or sterilized the atmosphere. They have wiped large parts of certain continents, but that’s “it”.

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If you have spent enough time working in biological research you will have the unfortunate experience of finding out how resilient life is, at least microbiological life. Scientists have to go to extraordinary lengths to sterilize equipment and reagents. If you stripped all of the oxygen out of the atmosphere the anaerobic bacteria would be happy as clams. It is for these reasons that NASA and other space agencies are very careful not to contaminate other planets with bacteria from Earth because once they become established they would be nearly impossible to get rid of. Instead of finding new life on other planets we would find the life we contaminated those planets with.

Ecosystems are often finely balanced and can be easily interrupted, but it is going to be very difficult to rid the Earth of life.

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But just how successful is evolution, really? I’m not sure we know. Certainly evolution is successful enough for life to thrive. I tend to think that evolution is close to some maximum level of success, but actually defining what that means might be difficult. Some think that evolution is not as successful as it appears to be, thus the ID movement.

BUT what if evolution could be more successful than what we observe? We see some evidence of this in the flawed human knee and lower back, where function is limited by historical form. What if there were some turn of mutation and selection that lead to a missed opportunity? Some function that might exist, but never happened simply by chance? I think it is likely there are unexplored pathways of evolution.

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This discussion also makes me recall a SciFi book, which examines a possibility that evolution might not be done with us yet.

PS: I’m pretty sure Bear’s biology is somewhat fanciful, but I still enjoyed it.

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Hey Brother Andy, I’m glad to hear from you again. Thank you for lending yourself to the cause.

So, it woul be fair to say that evolution is successful because the things that makes life (the chemistry, I mean) is abundant, & relentless. I usually try to make the analogy from us (organic life) to electronics, robotics, & AIs. In that scenario energy, that thing that would drive the process on in the absence of someone doing it, is missing. You could have all the parts needed for a circuit board, but there is nothing to move the material, nothing that would drive the assembly process. With organic life though, the material building blocks come with its own energy source.

Do you think that the first life was a single cell/organism/thing that duplicated over and over, and from it all life came; Or do you think that at that right time, right place, right environment, with the right chemistry, that it was more likely that many of first living things began independently?

When I think about this question, I can’t help but think about all the possible ways for life to have never begun, and ways for it to have ended for good. The point of pointing out climate change, and how the coral reefs live or die over a few inches of water and a few degrees of temperature change, was not to suggest that climate change would end all life. I simply meant to point out how fragile it is. If everything that is thought to have happened in the past, all the gradual along with all of the sudden and drastic climate changes, then there has been plenty of opportunity for it to have ended. If you were looking to design & build a better, more robust system that keep producing no matter how hard of a hit it took, I can’t imagine you how you could.

Thanks again.

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I suppose, in the sense you mean it, evolution is successful because it amplifies those that survive.

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It’s not just that life is so abundant that it would be nearly impossible to eliminate. Its that it can go from that simple thing to all the other things. So, if you could wipe out all multicelled organisms across the globe, you really would not have done that at all; because there is a mechanism & a pathway that leads from the single cell organism to the largest multi celled organism. If it is impossible to whipe out all life, but you completely altered the planet, it seems almost certain that the mutation:slection process would lead to a life that is complex and suited to thrive in the new environment. As long as there is enough energy & warmth for the process to continue, it should do what it has already proven it can do. It is a bit awe inspiring.

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Thanks for the response. I didn’t mean that slight changes in global temp would destroy all life in that strict of a one time sense. Everything fits its niche, and when that niche is changed, that life goes extinct. There are far more ways & reasons for it to have ended,Yet, it bounces back. I feel like you understood what I was trying to say. Thanks again.

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But that’s not right either. Adaptation, you know.

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