Speed of Evolution

[Senator Cheese]

One thing I don't quite understand yet - why does the speed of evolution accelerate as time progresses? Why did it take much, much, much longer for prokaryotes to develop into eukaryotes than it took for humans to develop out of a mammal protoancestor?

I would have intuitively imagined the speed of evolution to slow down as the complexity of organisms (and thus the complexity of genomes) increases, seeing as how the probability of a mutation causing disease instead of being an evolutionary advantage decreasing with the complexity of the genome.

Possible explanations I could come up with:
- homeobox (as in, conserved genetic code being moved/altered/copied to fit newer functions)
- higher selection pressure

What's the reason though?

 

[Elendur]

This needs to be said:
We get relatively few good questions about evolution here, but this definitely is one of those few.

I can't answer it without speculating though. I hope you will get some good answers

 

[BL2KTN]

Good question. Here is the likely answer:

According to Kurzweil, since the beginning of evolution, more complex life forms have been evolving exponentially faster, with shorter and shorter intervals between the emergence of radically new life forms, such as human beings, who have the capacity to engineer (intentionally to design with efficiency) a new trait which replaces relatively blind evolutionary mechanisms of selection for efficiency. By extension, the rate of technical progress amongst humans has also been exponentially increasing, as we discover more effective ways to do things, we also discover more effective ways to learn, i.e. language, numbers, written language, philosophy, scientific method, instruments of observation, tallying devices, mechanical calculators, computers, each of these major advances in our ability to account for information occur increasingly close together. Already within the past sixty years, life in the industrialized world has changed almost beyond recognition except for living memories from the first half of the 20th century. -- Accelerating change - Wikipedia, the free encyclopedia

 

[Senator Cheese]

This needs to be said:
We get relatively few good questions about evolution here, but this definitely is one of those few.

I can't answer it without speculating though. I hope you will get some good answers

Thank you.

Good question. Here is the likely answer:

According to Kurzweil, since the beginning of evolution, more complex life forms have been evolving exponentially faster, with shorter and shorter intervals between the emergence of radically new life forms, such as human beings, who have the capacity to engineer (intentionally to design with efficiency) a new trait which replaces relatively blind evolutionary mechanisms of selection for efficiency. By extension, the rate of technical progress amongst humans has also been exponentially increasing, as we discover more effective ways to do things, we also discover more effective ways to learn, i.e. language, numbers, written language, philosophy, scientific method, instruments of observation, tallying devices, mechanical calculators, computers, each of these major advances in our ability to account for information occur increasingly close together. Already within the past sixty years, life in the industrialized world has changed almost beyond recognition except for living memories from the first half of the 20th century. -- Accelerating change - Wikipedia, the free encyclopedia

Accelerating change in the sense of technological advancement is something that I find intuitively easy to understand. I don't see how the analogy grasps in regards to genetic mutation, though.

The fact remains that the more complex a genetic system is, the more likely a mutation will trigger disease instead of an advantage. Or maybe I understood your post wrong - I understood that you were pointing at genetic engineering (which cannot account for the quick evolution and biodiversity experienced in the more recent past). Could you maybe try to phrase it differently so I can understand what you are trying to say? Thanks!

 

[BL2KTN]

Accelerating change in the sense of technological advancement is something that I find intuitively easy to understand. I don't see how the analogy grasps in regards to genetic mutation, though.

K, let's take a look at what you said and I'll see if I can help.

The fact remains that the more complex a genetic system is, the more likely a mutation will trigger disease instead of an advantage.

What you miss is that the more complex a biological system, the less likely a negative mutation will be deadly. A single cell has much less room for error since it has far fewer parts that can differentiate without severely negative impact. This limits the speed of change in highly simple systems existing in an inhospitable environment.

Or maybe I understood your post wrong - I understood that you were pointing at genetic engineering (which cannot account for the quick evolution and biodiversity experienced in the more recent past). Could you maybe try to phrase it differently so I can understand what you are trying to say? Thanks!

Let me know if I answered your question sufficiently.

 

[sfs]

One thing I don't quite understand yet - why does the speed of evolution accelerate as time progresses? Why did it take much, much, much longer for prokaryotes to develop into eukaryotes than it took for humans to develop out of a mammal protoancestor?

I would have intuitively imagined the speed of evolution to slow down as the complexity of organisms (and thus the complexity of genomes) increases, seeing as how the probability of a mutation causing disease instead of being an evolutionary advantage decreasing with the complexity of the genome.

Possible explanations I could come up with:
- homeobox (as in, conserved genetic code being moved/altered/copied to fit newer functions)
- higher selection pressure

What's the reason though?

How are you measuring the speed of evolution? Biologically, prokaryotes are vastly different from eukaryotes, while humans are only slightly different from ape relatives. So just what are you measuring?

 

[Strathos]

Don't trust Ray Kurzweil, he's a hack who has been predicting a technological singularity for decades now with no results.

 

[[serious]]

There are two key factors:

1. Creatures with sexual reproduction can respond faster as good genes can get shuffled around and combined

2. You aren't comparing apples to apples. Prokaryotes into eukaryotes is a much more profound change than something like a tetrapod becoming a tetrapod with warm blood and mammary glands.

 

[[serious]]

There are two key factors:

1. Creatures with sexual reproduction can respond faster as good genes can get shuffled around and combined

2. You aren't comparing apples to apples. Prokaryotes into eukaryotes is a much more profound change than something like a tetrapod becoming a tetrapod with warm blood and mammary glands.

 

[BL2KTN]

Don't trust Ray Kurzweil, he's a hack who has been predicting a technological singularity for decades now with no results.

Kurzweil has always predicted the singularity at 2045 and his results are impressive (even if you disagree with some of his long-term thoughts). Since the 1980's his predictions have been around 87% accurate. That's pretty amazing given the number of predictions, but he does it using... science. All he does is have a team of individuals measure the speed of technological increase using hard data, then extrapolate where technology will be at any point in the future given that same improvement trajectory.
Predictions made by Ray Kurzweil - Wikipedia, the free encyclopedia

I disagree with Kurzweil on some things. That said, the head of engineering at Google is probably not a "hack".

 

[selfinflikted]

Don't trust Ray Kurzweil, he's a hack who has been predicting a technological singularity for decades now with no results.

I don't know much about that, but the man designed and built some KILLER synthesizers and samplers. I own a Kurzweil synth, and it's amazing.

 

[Split Rock]

One thing I don't quite understand yet - why does the speed of evolution accelerate as time progresses? Why did it take much, much, much longer for prokaryotes to develop into eukaryotes than it took for humans to develop out of a mammal protoancestor?

I believe the current theory is that eukaryotes and prokaryotes evolved along different lines, therefore prokaryotes are not ancestral to eukaryotes.

I would have intuitively imagined the speed of evolution to slow down as the complexity of organisms (and thus the complexity of genomes) increases, seeing as how the probability of a mutation causing disease instead of being an evolutionary advantage decreasing with the complexity of the genome.

Possible explanations I could come up with:
- homeobox (as in, conserved genetic code being moved/altered/copied to fit newer functions)
- higher selection pressure

What's the reason though?

Once multicellular organisms evolved, I believe this opened up many more avenues for evolutionary changes to produce new adaptations. I am not sure I agree that since then there has been an ever increasing acceleration in evolution, however.

 

[BL2KTN]

 

[Mystman]

One thing I don't quite understand yet - why does the speed of evolution accelerate as time progresses? Why did it take much, much, much longer for prokaryotes to develop into eukaryotes than it took for humans to develop out of a mammal protoancestor?

A mouse and a human are basically the same creature. A bit more expression of protein X, a bit less of protein Y, protein Z is shaped a bit differently, maybe there is a protein ZY that is a copy of parts of Z and parts of Y, and the end result is an organism that looks very different to our eyes but that operates very similar on the cellular scale.

Then consider the number of evolutionary "steps" it takes to go from a cell without any recognizable precursors of the photosynthetic machinery, to a cell that can photosynthesize. The changes are immense, it wouldn't surprise me if it has involved billions of generations, untold trillions of individuals. And the end result is a cell that may look very similar to our eyes ("still just bacteria", a creationist might say..), but that is profoundly different on a level that most people are not really aware of.

And photosynthesis isn't the only system. Most single celled organisms and "simple" multicellular organisms have thousands of proteins, all doing stuff. And a lot of that stuff is so important/advantageous that the basic idea hasn't changed between the early multicellular blobs and modern humans.

But the earliest single-celled organisms didn't blink into existence with thousands of proteins and pieces of cellular machinery most people have never heard of. All those "basic" things that are now common to humans and cows and worms first had to be evolved. And compared to that, the task of changing some proto-mammal into a modern human is almost trivial.

 

[BL2KTN]

Wow that's a terrific answer.

 

[Mystman]

Wow that's a terrific answer.

Thanks.

I just hope it's accurate

 

[DogmaHunter]

One thing I don't quite understand yet - why does the speed of evolution accelerate as time progresses? Why did it take much, much, much longer for prokaryotes to develop into eukaryotes than it took for humans to develop out of a mammal protoancestor?

I would expect that the relative difference between a prokaryote and an eukaryote is much greater then the relative difference between any 2 mammals or their mammalian ancestors.

Possible explanations I could come up with:
- homeobox (as in, conserved genetic code being moved/altered/copied to fit newer functions)
- higher selection pressure

What's the reason though?

Generally, we see that evolution speeds up right after big changes to certain habitats. This can be causes by many many things. Like some epidemic of a virus that kills loads of creatures, volcano eruptions, floods, asteroids, severe draughts, ice ages, etc. Even by a certain species being introduced to a new habitat one way or the other. Like migration for example.

Usually such things go hand in hand with massive extinction waves etc, which opens up new niches for life to fill. It reshapes the natural environment and makes big changes to selection pressures. At which point it becomes an "evolve or go extinct" kind of scenario.

When populations remain in the same habitat for a long time and selection pressure stay relatively unchanged, at some point the species living there will reach a "local optimum", which basically means that evolution for those species would slow down.

 

[sfs]

Generally, we see that evolution speeds up right after big changes to certain habitats. This can be causes by many many things. Like some epidemic of a virus that kills loads of creatures, volcano eruptions, floods, asteroids, severe draughts, ice ages, etc. Even by a certain species being introduced to a new habitat one way or the other. Like migration for example.

The biggest change in habitats throughout the planet was the increase in atmospheric (and oceanic) oxygen. Not coincidentally, it was followed not long after by the development of complex animal and plant life.