Is change in biology--any change--variable in timing or quick and constant??

[Tiberius]

I think that it is not only the type of biological phenomenon under observation, but just as you indicate, the scale in which the observations are being made as well.

The bottom line is that no matter how many times someone claims it, all change in all living things is not always sudden. Sudden being commonly understood to be rather rapid depending on the scale on which the claim is made. That distinction of timescale was not and has not been made regarding the claim I have seen. It was made as if all change happens at the same, nearly instantaneous rate regardless of the change or the scale of observation.

Here's something that should put it in perspective.

The Cambrian explosion took place over a period of about 30 million years. Evolution: Library: The Cambrian Explosion

 

[Subduction Zone]

Here's something that should put it in perspective.

The Cambrian explosion took place over a period of about 30 million years. Evolution: Library: The Cambrian Explosion

Something that most people do not realize is that the fossil record is measured in geologic time. Sudden in geologic time is one to ten million years usually. Sudden in biological evolution would be 100 years or 1,000 years at the most. The two time are orders of magnitude in difference.

 

[TagliatelliMonster]

I have heard claims that all change in biology is sudden, but I do not know fully what is meant by that. There are events in biological systems that happen rapidly. Biochemical reactions, nerve impulses, conception, receptor binding all could be classified as sudden to a degree. Nerve impulses are still much slower than electricity travelling along a wire though.

But there are numerous examples of slower processes in biology. Starvation does not happen suddenly, though quickly in some cases. Depending on the species and the locations, migration could take a little or a lot of time. Plenty of species migrate over great distances within the frame of a season or a year. Much slower than nerve impulses.

Change in species over time is not sudden, though we do have evidence that it varies and in some instances, the evidence supports it can be very rapid geologically followed by extensive periods of stasis (little significant change).

I can think of many examples of biological events that occur at different rates from sudden to slow.

I think you would all agree that sudden needs to be defined. That is imprecise at best to claim sudden as the rate of change without even knowing what that means.

I am not arguing that some changes in living things are not relatively quick, but how can all biological change be sudden?

I propose that sudden be viewed as relative to the conditions and the time scale under discussion. Sudden in reference to evolution, for instance, is commonly on a geological time scale or over 100's, 1000's, tens or hundreds of thousands of generations. That any claim of sudden change be explained in that relation. Caution would be against making sudden, suddenly cover all time frames rendering its application useless as a descriptor of the time of change.

If anyone has evidence or different ideas about change in living things and the rate, I would be interested in seeing that explained.

Sensu strictu... I'ld say that change (mutation) is pretty constant, although it varies among species. Expressed in the "mutation rate".

What isn't constant is the amount of changes that get selected by natural selection.
The rate there tends to depend on the state of the environment.
Periods of stability will specialize species in their niche so much that it will become increasingly harder for genetics to stumble upon mutations that "improve" the species one way or the other. At some point, they reach what is called "local optimum". This is a place where there are no more "easy" genetic pathways to further improve. Things that can be accomplished with few mutations and which immediately yield enough impact to get selected.

When the environment then changes, local optimums will shift. Now the potential amount of mutations that can improve the organism, goes up again.

The mutation rate stays the same. It's just about what potential portion of it is actually helpful enough to the organism in order to make it through the filter of natural selection.

 

[Jayhawker Soule]

Well, changes in the fossil record often seem to be sudden. The idea seems to be that species seem to be fairly stable and constant over time, with speciation events rather quick and sudden.

Punctuated equilibrium - Wikipedia

Yes. It isn't true that everything in biology is sudden or gradual. There are examples of both.

Precisely. Parenthetically, the books by Stephen Jay Gould are an absolute joy to read - even if you're not a baseball geek.

 

[YoursTrue]

I have heard claims that all change in biology is sudden, but I do not know fully what is meant by that. There are events in biological systems that happen rapidly. Biochemical reactions, nerve impulses, conception, receptor binding all could be classified as sudden to a degree. Nerve impulses are still much slower than electricity travelling along a wire though.

But there are numerous examples of slower processes in biology. Starvation does not happen suddenly, though quickly in some cases. Depending on the species and the locations, migration could take a little or a lot of time. Plenty of species migrate over great distances within the frame of a season or a year. Much slower than nerve impulses.

Change in species over time is not sudden, though we do have evidence that it varies and in some instances, the evidence supports it can be very rapid geologically followed by extensive periods of stasis (little significant change).

I can think of many examples of biological events that occur at different rates from sudden to slow.

I think you would all agree that sudden needs to be defined. That is imprecise at best to claim sudden as the rate of change without even knowing what that means.

I am not arguing that some changes in living things are not relatively quick, but how can all biological change be sudden?

I propose that sudden be viewed as relative to the conditions and the time scale under discussion. Sudden in reference to evolution, for instance, is commonly on a geological time scale or over 100's, 1000's, tens or hundreds of thousands of generations. That any claim of sudden change be explained in that relation. Caution would be against making sudden, suddenly cover all time frames rendering its application useless as a descriptor of the time of change.

If anyone has evidence or different ideas about change in living things and the rate, I would be interested in seeing that explained.

Yo boy, you ask some big questions here.