Does evolution ever go backward?

[rangerrebew]

Does evolution ever go backward?
By Michael Dhar published January 15, 2023
In regressive evolution, organisms lose complex features and can appear to evolve "in reverse." But evolution doesn't retrace its steps, experts said.

 
Evolution has produced stunningly complex features, from neuron-studded octopus arms to the mammalian ear. Can evolution ever go "backward," though, reverting complex creatures to previous, simpler forms?

In so-called regressive evolution, organisms can lose complex features and thus appear to have evolved "back" into simpler forms. But evolution doesn't really go backward in the sense of retracing evolutionary steps, experts say.

"The chances that the same tape [of evolutionary changes] would be … reversed in the same way is highly improbable," William R. Jeffery(opens in new tab), a biologist at the University of Maryland, told Live Science.

https://www.livescience.com/regressive-backward-evolution

[rangerrebew]

But of course it does!!  Just look at all the lunatics this country has bred since people used to kind to each other!!

[roamer_1]

Evolution is an absurdity that flies directly in the face of entropy.

You can have one or the other, but not both.

[rustynail]

LBJ proved it can.

[Gefn]

Reality TV proved this too.


 

[DefiantMassRINO]

Evolution moves in whatever direction it needs to.

Competition leads to more evolution.

Lack of competition leads devolution.  The Dodo Bird is a prime example of this.

[Free Vulcan]

Can't say for certain, but Ron Perlman comes close.

[catfish1957]

[roamer_1]

Evolution moves in whatever direction it needs to.

Competition leads to more evolution.

Lack of competition leads devolution.  The Dodo Bird is a prime example of this.

Actually, the opposite would have to be true... Competition leads to stasis.
Lack of competition leads to new exploitation.

[Kamaji]

Actually, the opposite would have to be true... Competition leads to stasis.
Lack of competition leads to new exploitation.

No.  Competition puts the pressure on a population that allows minor genetic differences to spread if the difference, relative to the base population, provides a net benefit under pressure.  Without competitive pressure, there is no selection pressure, and genetic differences just wander around without either taking over the population or fading away (othe than those mutations that are clearly deleterious).

[catfish1957]

No.  Competition puts the pressure on a population that allows minor genetic differences to spread if the difference, relative to the base population, provides a net benefit under pressure.  Without competitive pressure, there is no selection pressure, and genetic differences just wander around without either taking over the population or fading away (othe than those mutations that are clearly deleterious).

 

I think this was all covered in detail in 1980.  Whip it boys!!!!!!

[roamer_1]

No.  Competition puts the pressure on a population that allows minor genetic differences to spread if the difference, relative to the base population, provides a net benefit under pressure.  Without competitive pressure, there is no selection pressure, and genetic differences just wander around without either taking over the population or fading away (othe than those mutations that are clearly deleterious).

No. Think about it... Adaptation requires time. And it must be profitable.

If a resource is already being exploited by multiples already adapted, the new adaptation would have no profit.

Hence Darwin's finches, arriving on an island with many exploitable paths adapted severally to fill the gaps - something that is rare, since most places resources are already multiply exploited, leading to stasis, unless an already better interloper arrives.

Certainly with several species in competition, already suited to exploit a resource, new adaptations will be inherently rare.

[DefiantMassRINO]

Why didn't dodo birds fly?  Because they didn't need to; they had no natural land predators.  When they first arrived on Mauritius, they were pigeon-like birds that could fly.  Without a natural land predator, they no longer needed to fly, and devolved to become flightless.  That's why dodo birds were such easing pickings for humans.

Why don't pengiuns fly?  They don't need to.  They had no land predators in Antarctica, but, they needed to evolve into aquatic birds to survive - to find food in the ocean.

Why did the native populations of the Americas almost become extinct?  They did not have immunity to European diseases.  They lacked immunity because they were never exposed to those pathogens before Europeans arrived.

Why did American elm and chestnut trees nearly become extinct?  Because they lacked immunity to European blights which decimated their population in the 20th Century.

Competition for survival drives the need to evolve competitive advantages to survive, perpetuate, and possibly dominate.

[Kamaji]

No. Think about it... Adaptation requires time. And it must be profitable.

If a resource is already being exploited by multiples already adapted, the new adaptation would have no profit.

Hence Darwin's finches, arriving on an island with many exploitable paths adapted severally to fill the gaps - something that is rare, since most places resources are already multiply exploited, leading to stasis, unless an already better interloper arrives.

Certainly with several species in competition, already suited to exploit a resource, new adaptations will be inherently rare.

No, if there is no pressure, then there is no selection for one trait over another, and the genetic pool just undergoes genetic drift - a mutation that could potentially provide a survival benefit under competitive conditions never gets the opportunity, so it never affects the breeding outcomes (i.e., its bearers do not outbreed non-bearers), and therefore it just stays where it is.  Competition is the key to natural selection, not the lack thereof.

[andy58-in-nh]

Does evolution ever go backward?

Have you been to Baltimore or Philadelphia lately?

[roamer_1]

No, if there is no pressure, then there is no selection for one trait over another, and the genetic pool just undergoes genetic drift - a mutation that could potentially provide a survival benefit under competitive conditions never gets the opportunity, so it never affects the breeding outcomes (i.e., its bearers do not outbreed non-bearers), and therefore it just stays where it is.  Competition is the key to natural selection, not the lack thereof.

Then there should be continual new adaptation ongoing and observable... But there is not -  By and large, the world is at stasis.

And the reason for that is because of inter-species (as opposed to intra-species as you are limited to) competition for the same limited resources. A species does not adapt because it must. It dies. A species adapts because IT CAN. That requires time (some generations) and a resource worth adapting for - one that offers a wide abundance with relatively little competition to allow the time for the adaptation to carry forward.

Thus adaptation being most likely in catastrophe, where the normal food chain has been disrupted. and where catastrophe is not, stasis reigns.

[roamer_1]

Why didn't dodo birds fly?  Because they didn't need to; they had no natural land predators.  When they first arrived on Mauritius, they were pigeon-like birds that could fly.  Without a natural land predator, they no longer needed to fly, and devolved to become flightless.  That's why dodo birds were such easing pickings for humans.

'Devolve' is nonsensical. It adapted. And became HUGE because it could. And it had reached a stasis. Its demise was at the hand of an interloper (Man), newly introduced.

Why don't pengiuns fly?  They don't need to.  They had no land predators in Antarctica, but, they needed to evolve into aquatic birds to survive - to find food in the ocean.

Again, it did not devolve. Its DNA did not lose data. It adapted. Very successfully. One need not consider 'flightless' to be a devolution.

Why did the native populations of the Americas almost become extinct?  They did not have immunity to European diseases.  They lacked immunity because they were never exposed to those pathogens before Europeans arrived.

Why did American elm and chestnut trees nearly become extinct?  Because they lacked immunity to European blights which decimated their population in the 20th Century.

In both cases, an interloper. Stasis was obtained and maintained until the interloper.

[Kamaji]

Then there should be continual new adaptation ongoing and observable... But there is not -  By and large, the world is at stasis.

And the reason for that is because of inter-species (as opposed to intra-species as you are limited to) competition for the same limited resources. A species does not adapt because it must. It dies. A species adapts because IT CAN. That requires time (some generations) and a resource worth adapting for - one that offers a wide abundance with relatively little competition to allow the time for the adaptation to carry forward.

Thus adaptation being most likely in catastrophe, where the normal food chain has been disrupted. and where catastrophe is not, stasis reigns.

No, because most changes are either deleterious, or confer no survival advantage, so they just result in genetic drift that creates a degree of variety - different colors of fur in household pets - without a difference in survival fitness.

It is only when competition puts pressure on that elicits different responses based on a genetic difference, and one variant results in improved survivability does evolution come into play. 

[roamer_1]

No, because most changes are either deleterious, or confer no survival advantage, so they just result in genetic drift that creates a degree of variety - different colors of fur in household pets - without a difference in survival fitness.

It is only when competition puts pressure on that elicits different responses based on a genetic difference, and one variant results in improved survivability does evolution come into play.

Competition = must change ==DIE. Every time.
Once stasis has been obtained in an environment, losing a share of the pie just means another species, equally adapted, will take a bigger share.

Stasis confounds adaptation. each species has found a niche, and it is terribly hard for them to re-specialize, as something else is already using the resource. Always.

Unless catastrophe. Or interloper. Otherwise stasis.

[Kamaji]

Competition = must change ==DIE. Every time.
Once stasis has been obtained in an environment, losing a share of the pie just means another species, equally adapted, will take a bigger share.

Stasis confounds adaptation. each species has found a niche, and it is terribly hard for them to re-specialize, as something else is already using the resource. Always.

Unless catastrophe. Or interloper. Otherwise stasis.

No, it doesn't.

[roamer_1]

No, it doesn't.

Yes, It does. Adaptation does not happen because it must. Ever. Death.
Adaptation happens because it can.
That means resources are wide open.
Which means that competitor species are gone.

It is the breaking of environmental stasis that allows adaptation.

[The_Reader_David]

Evolution is an absurdity that flies directly in the face of entropy.

You can have one or the other, but not both.

Entropy applies to closed systems.  So long as energy is entering a system (e.g. from the sun), entropy can be overcome.  Evolution as an account of the origin of all biological diversity may well be wrong, but if so, it is not because it "flies directly in the face of entropy".  Entropy is no more a problem for evolution as an account of biological dynamics than it is for engineering as an account of bridges and airplanes.

[Fishrrman]

Darnit, Andy, you beat me to it with reply 14 above...

[roamer_1]

Entropy applies to closed systems.  So long as energy is entering a system (e.g. from the sun), entropy can be overcome.  Evolution as an account of the origin of all biological diversity may well be wrong, but if so, it is not because it "flies directly in the face of entropy".  Entropy is no more a problem for evolution as an account of biological dynamics than it is for engineering as an account of bridges and airplanes.

Biological systems ARE closed systems, and subject to decay.
DNA is code, and is subject to decay as well - There is no new DNA getting written into animals - just preferences in the code already built in. If anything there is loss - A chihuahua cannot become a wolf again - too much of its original code has been lost. A husky might... but not a chihuahua.

So yes - Entropy effects everything. New energy does not write new code.

[The_Reader_David]

We have ourselves made systems in which computer code writes new computer code, some of which are even modeled on the Darwinian paradigm.  They do not violate the law of entropy because we provide them with energy.

If you want to argue against abiogenesis on the basis of entropy, your case is stronger, but against evolution it doesn't wash because, were it valid, most modern AI systems would also "fly directly in the face of entropy" and would not work.