How does this work? "Reproduction + competition leads to pressure to reproduce"

[Simon PayntonParticipant]

It is the dawn of time, the beginning of life on Earth.

Creatures with genome A, and creatures with genome B, living in the same niche, compete for resources.

How does the pressure to acquire resources translate into a pressure to reproduce?

The DNA molecule reproduces itself, but this isn’t the same as a “pressure to reproduce”.  It’s just reproduction.

In other words, why is there a pressure to acquire more resources than the other creature?  I think Hamilton’s Rule comes into it: the Selfish Gene and inclusive fitness.

[Simon PayntonParticipant]

I think that the pressure to compete for resources in a finite environment is axiomatic.  This is because, organisms that don’t compete for resources don’t pass on their genes.

This passing down of genes is something of an arms race between individuals.  Why?  Because genome A and genome B are like competing armies, each competing for finite resources.

This arms race is itself the pressure to survive and reproduce.

[PopeBeanieModerator]

It sounds like a good question, but without researching this (and not having read enough of the right books, I’m embarrassed to admit): I don’t think “pressure” is an enlightening concept, or at least not until sophistication of nerve systems or brains that exhibit “agency” has been reached. Ditto for the word “selfish” for genes. I think I remember Dawkins himself saying it’s a term used metaphorically. Such concepts themselves didn’t exist until increasingly complex biological systems evolved to the current level of sophistication.

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It’s not that reproduction started out being driven by any kind of force in itself. It is that random changes to organic material brought accidental changes, as possible in self-enclosement, reproduction, duplication and the RNA world.

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That link jumps into the middle of a detailed wikipedia article (that’s worth one’s time to skim) on abiogenesis, where a whole lot of other precursor parts and processes had to have happened long before self-replicating “life” could have had its own start.

One characteristic in particular that’s common to all life is a phospholipid bilayer, from their simplest forms (e.g. vesicles) that enclose materials, to cell membranes that only exist in lifeforms. (See the graphic below that shows how these structures can work together. The big question here is how did they evolve.) When a vesicle is incoming, the process is called endocytosis, and when a vesicle is outgoing, it’s called exocytosis:

There are a bajillion kinds of proteins, and the content of a vesicle doesn’t even have to be protein.

As a side-note (which I’m pathologically bound to interject), some viruses have a membrane too… for the sole purpose of making it easier to enter a cell… i.e. by first merging it’s own membrane (called an “envelope”) with the host cell’s membrane, just discarding it when it’s inside. After it replicates while inside, it then robs a piece of the host’s membrane on it’s way out. On it’s way in (endocytosis), just replace the word “food” with “enveloped virus” in the graphic, and realize that it’s not necessarily in a vesicle/vacuole once inside, like the food is:

A non-enveloped virus doesn’t merge and demerge with the host’s membrane, but otherwise injects it’s way in through the host’s cell membrane using other mechanics. I’ll bet they evolved long after enveloped viruses, but alas I haven’t read/researched enough to be more certain. Check out these non-enveloped viruses.

And then for another diversion, there’s the perennial question is a virus a form of “life”? I say no, because it can’t self-replicate all by itself. It needs the machinery inside another living cell in order to reproduce. (Side note to the side note, I wonder if primordial viruses evolved alongside primordial cells, just because they each may have existed, enclosed within their own, at-that-time-common type of phospholipid bilayer.) The real problem here is the need for us to define that word “life” in some kind of eternally precise way, while many people can only perceive such a nasty agent as “living”, just like people assign agency to many complex objects.

The most primitive kinds of vesicles likely came to exist naturally, with random contents, even before there was life. See micelle.

There’s very little of any of that evidence left for science to conclude exactly how it happened, because whatever was there to start the ball rolling ended up being energy and material resource to be consumed by whatever processes that had accidentally become self-sustaining, and accidentally able to able to hold on to any accidental mutations that were more efficient than previous design versions.

Haha, it’s also an accident that millions of years of brain evolution begat human constructs/motivations like spiritual art and ceremony, philosophy, reading and writing, mythologies, God, sacred scriptures, religion, socio-political pressures of belief and conformance, and so on. Most of such accidental constructs can be said to be “intentional”, too.

It’s a whole lot easier to just assume Goditit all intentionally, and not even bother trying to figure out how it could have happened and then solidified accidentally. Another non-intuitive scientific principle to fathom here is entropy, which impedes the self-organization that’s required by abiogenesis and subsequent biological evolution. All those accidents do indeed use up both material and energy resources that are in limited supply.

In the big picture, solar energy and abundance of physical materials made life possible. And then came humans and science, making empirical studies alongside new medicine and other characteristics of modern civilization possible.

I just want to point out for any religionists reading this, even if Godidit, He obviously left it up to us to discover much of how Hedidit.

Simon, I hope my habitual attempt at big-picturing some questions and answers isn’t too much of a distraction from the very interesting question you’ve posed, nor its possible answers. Any perceived “pressure” to reproduce is itself an accidental construct, even if inevitable.

• This reply was modified 4 years, 2 months ago by  PopeBeanie. Reason: minor clarification. Umm, I realize this post could use a few more of them

[Simon PayntonParticipant]

I don’t think “pressure” is an enlightening concept, or at least not until sophistication of nerve systems or brains that exhibit “agency” has been reached.

Any time there’s competition, there’s a pressure to win, as a corollory.

[PopeBeanieModerator]

Simon Paynton wrote:

Any time there’s competition, there’s a pressure to win, as a corollory.

Perhaps. Meanwhile…

How does the pressure to acquire resources translate into a pressure to reproduce?

Isn’t “pressure” to reproduce always there, regardless of resources? And wouldn’t faster reproduction eventually reduce the resources, regardless of competition?

Problem could be I don’t know enough about Hamilton’s Rule and inclusive fitness theory.

[Simon PayntonParticipant]

Isn’t “pressure” to reproduce always there, regardless of resources?

Not only that, but the pressure to survive and thrive are also always there regardless of resources.

wouldn’t faster reproduction eventually reduce the resources, regardless of competition?

It would, but evolutionarily, organisms don’t “know” this, so they keep on reproducing until resources run short, and the individuals begin dying out.  See: Malthus.

“Fitness advantage” results in “reproductive advantage”.  “Fitness” comes from “having more resources”.  It is advantageous for genome A to out-reproduce genome B, because then, genome A has a greater share of the finite resources.

[Simon PayntonParticipant]

Here’s a quote from nature.com :

Natural selection occurs when individuals with certain genotypes are more likely than individuals with other genotypes to survive and reproduce, and thus to pass on their alleles to the next generation.

So, maybe it’s the other way round.  Natural selection is going to lead to a pressure to reproduce, as those that experience a pressure to reproduce will leave more babies behind.  A pressure to reproduce leads to a pressure to survive (at least long enough to reproduce), which leads to a pressure to thrive, and a pressure to consume finite resources.

 

[UnseenParticipant]

Simon Paynton wrote:

How does the pressure to acquire resources translate into a pressure to reproduce?

There’s no “pressure to reproduce.” What gives you that idea? Natural selection doesn’t operate under pressure. It is about as passive a process as could be.

[Simon PayntonParticipant]

There is a pressure on the individual to reproduce.  Is sex the best thing ever?

[PopeBeanieModerator]

Simon Paynton wrote:

Is sex the best thing ever?

I think I know what bonobos would say. But it doesn’t necessarily lead to offspring. Instinctive pleasure of sex here has been hijacked by evolution to promote social bonds, because enhanced social bonds (in this species and ours, at least) increases fitness. (And there I go, implying that Mother Nature planned the hijack. But I don’t mean that.)

I don’t claim to know the answer to your question, but I’m also not sure yet what a meaningful answer might be. Bacteria that have survived over epochs manage to keep dividing until resources are used up, then die, but still manage to shed enough offspring to survive in nearby environments. Where does the notion of “pressure” apply here, except perhaps metaphorically?

As for making more sense out of how evolution works, and explaining it to people learning about it (along with your idea of a “pressure to thrive”), I wonder if an ability to control more resources might be more germane in competitive environments than a pressure to acquire and use resources? This may be nitpicking, but I’m still not comfortable with that word “pressure”, except perhaps wrt a pressure to compete when it’s willful, like when a brain is calculating what behavior to perform.

[PopeBeanieModerator]

Take, for example, c. diff vs beneficial bacteria in the human gut. It’s well known now that the use of antibiotics can kill many of our beneficial gut bacteria. As a consequence, damaging bacteria such as c. diff can reproduce and take over, even causing death in the human host, unless and until beneficial bacteria can return and reproduce enough to out-compete for intestinal real estate against the c. diff.

Note also that when too much oxygen is present, c. diff stops reproducing and protects itself:

C. diff is classified as an anaerobic bacterium because it thrives in the absence of oxygen. Like its cousins, the Clostridia that cause tetanus, botulism, and gas gangrene, C. diff passes through a life cycle in which the actively dividing form transforms itself into the spore stage. Spores are inert and metabolically inactive, so they don’t cause disease. At the same time, though, spores are very tough and sturdy; they are hard to kill with disinfectants, and they shrug off even the most powerful antibiotics.

(Btw I believe that anthrax is also one of those anaerobic cousins.)

If the phrase “pressure to reproduce” sufficiently describes these competitive and sporulating scenarios, then go for it. This might just be no more than a semantic nitpick stuck in my brain.

[Simon PayntonParticipant]

I think I know what bonobos would say. But it doesn’t necessarily lead to offspring.

Like Freud said, we’re obsessed with sex.

Where does the notion of “pressure” apply here, except perhaps metaphorically?

It’s an emergent property, a natural consequence of evolution.  I just can’t quite put my finger on the mechanics of how it happens.

[Simon PayntonParticipant]

It’s related to Richard Dawkins’ “Selfish Gene”.  According to him, there is a pressure for genomes to take care of (even partial) copies of themselves.  But why?

[Simon PayntonParticipant]

I think the answer is simple.  Those genomes that experience a pressure to reproduce, reproduce more than those that don’t, thereby replacing them within a finite population (because the resources are finite).  In The Extended Phenotype, Richard Dawkins says:

One of my purposes in this book is to question the central ‘theorem’ that it is useful to expect individual organisms to behave in such a way as to maximise their own inclusive fitness, or in other words to maximise the survival of copies of the genes inside them.

[PopeBeanieModerator]

I can only think of “pressure” and “inclusive fitness” as purely accidental, possibly emergent outcomes that just happen to increase fitness. The evolutionary sequence of exactly how that happens and is then reinforced by evolving genes is what we’re trying to understand here, right? All other inherited behavior must be cultural in nature, and is worth considering on its own terms. Genetic and cultural types of evolution can now affect each other, with culturally evolved behaviors a decreasingly relevant factor the further back we go into animal brain evolution.

One (especially like myself) must also consider cultural evolution as a kind of artificial evolution, since we now willfully control much of it for better and for worse. This kind of evolution includes it’s own set of arbitrarily invented and implemented philosophies, socio-political-economic affectors, and other cognitive abstractions spiced with metaphysical fantasies. When using a word like “pressure”, there’s a chicken and egg question: Which came first, the pressure or the fitness? Perhaps the accidental fitness came first, and it only looks like pressure now, or at least there seems to be no better way atm to explain the increasing fitness. (And any said kind of “fitness” could also become a liability, under changing environmental circumstances.)

Long story short, any genetically-incorporated “pressure” in a species phenotype was at first accidental. E.g. how about fear of death? What if sexual bonding is more likely between pairs who share similar feelings wrt their fear of death? This might affect offspring genetics, right? And it, alongside an increasing prominent trait that enhances group-wide empathy could increasingly translate into a species-wide “pressure to thrive” trait. Especially when coupled with cultural reinforcement.

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