This is something that frequently comes up in the CvE debates -- that evolution necessarily increases diversity (creationist) versus diversity is a result of evolution and can fluctuate (evolutionist).
The first problem is how to define (biological) "diversity" ...
Fairly obviously we would use the second definition.
If we take it to it's extreme it would mean each individual organism differs from all others, so the sum total of all organisms would be the total diversity at any one time. The problem here is that there is ongoing death and ongoing birth, and the total numbers do not change significantly except in times of major extinctions.
If we limit it to species (per example in the definition), then diversity would be measured by the sum total of all species at any one time. Again, the problem is that species are born and die, and the total numbers do not change significantly except in times of major extinctions.
Either way the concept can be quantified (although actual measurement could be extremely difficult), so the increase or decrease over time could be measured and compared.
That an individual organism or a species can die at any time shows that diversity does not always increase due to evolution (mutation and natural selection processes).
Evolution is the change in hereditary traits in populations from generation to generation, and this results in added diversity, when new species are "born," or in loss of diversity, when old species "die." The diversity we see is the result of evolution, but it is not a necessary result, just what happens.
What this data can tell us is whether more or less species are being developed vs going extinct. This in term may inform debates on whether global warming or the impact on man on the environment is having an effect on biological life and the diversity of life as we know it.
But I don't see it as being a critical factor in the study of biology or evolution.
I guess the questions are: am I missing something? Do creationists see this differently? Is there some tie-in to "macro"evolution?
This came up in debate with MurkyWaters regarding the definition of the theory of evolution, and it seemed a puzzle to me why he was so intent on it (other than to try and make the definition as impossible as possible).
I guess the questions are: am I missing something? Do creationists see this differently? Is there some tie-in to "macro"evolution?
Someone reading Darwin's "Origin" one can encompass his notion of diversity via the angles here (only diagram in the book):
Yes, and in that diagram you can see that diversity can increase but that it doesn't have to: there are several extinctions shown and places where a horizontal line would have more species than at the end.
I think we can agree that the observation that there are more species now than at the (presumed microbial) start would be an increase in diversity that is explained by this process, but not that an increase in diversity need occur at any generation time.
I suspect however that a creationist position against macroevolution would looke pricipally to showing that Darwin's spatial restriction of diverification can not exist on our actual Earth ...
... Temporally it matters how much time is supposed to be represented from the top to the bottom. The Earth is near spherical after all.
Yes it would come down to a matter of the limitations of time and space. One thing to point out is that the number of species known to exist and have existed could of it's own mean that a minimum time is needed no matter how you cut the timelines.
This would be a matter of possible biodiversity and ecological support.
By the change in hereditary traits in populations from generation to generation. See Definition of Evolution to discuss further, as this is off-topic here.
How would “survival of the fittest” explain the origin of the fittest?
It doesn't need to. The ecology is constantly changing in many little to major ways, and "fittest" just means best able to take advantage of the ecology available. Any organism has some "fitness" to any ecology, and some will be better than others. Perhaps you can start a new thread to discuss this further, as it is off-topic here.
But then lots of scientific theories don’t sound very credible to me. See my web site, Questions about Materialism at
This forum is not about advertising your websites or your ignorance. And they are off-topic here (as is your second paragraph -- see the [forum=-10] forum topics).
So, do you have anything to say about diversity?
Enjoy.
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Welcome again 42 on your 43rd post (was the previous one the answer to the big question of life, the universe, and everything?)
do creationists believe evolution necessarily increases diversity?
It's more that they believe (or have been told by creationists) that the theory of evolution says that there must always be an increase in diversity, which (of course) is wrong.
Since the Permian extinction there appears to have been a 'punctuated" increase of diversity at a rate of about 3 families per Myr.
Why isn't this evidence of a naural increase in biodiversity?
Even ignoring the mass extinction events like the Permian we see a constant flux up and down in the number of species, and this alone shows that increased diversity is not a mandatory result of evolution, that if anything it is a "two steps forward, one step back" kind of process.
It is a likely event over the long term because of the way random events work, and the fact that natural selection plays a role in surviving random environmental challenges so that the next occurrence is less threatening to those species that survive one.
Evolution explains the diversity we see, but this is just the record of life on earth, an ad hoc result. It just happens to show increased diversity over most periods, just as it does show massive loss of diversity during some periods. The balance between diversity growth and diversity loss is not due to evolution, per se, but to the record of environmental change, sometimes ferocious sometimes benign.
A more or less hospitable planet would have different results, and all evolution can do is adapt life to the planet such that over time the planet (if things remain the same ... ) would be more hospitable for the kind of life that exists than before.
I'll be very interested in seeing any other ad hoc results of biological evolution. Do you know of any?
Any species you care to name is an ad hoc result -- it is what happened, it is not what needed to happen.
Wings on birds, bats, butterflies and bees are ad hoc results.
Natural selection of beaks in Galapagos finches is NOT an ad hoc result, because it directly involves selection for the result, but whether the finches end up with large or small beaks after multiple generations of selection back and forth is an ad hoc result of whatever the final environmental factor was. capice?
Don't know what you are saying here. If we look at marine families there an unmistakable trend toward evolvolving diversity, unless you know of another way diversity happens.
But you can't become less diversified than extinct. Start with a single species, and toss a coin: heads you have a new species, tails the one you had goes extinct. Keep running this experiment and you will have a number of cases where everything dies out. You will also end up with some that have a lot of species.
What is there about the TOE that supports your assertion that a macroscopic trend toward greater diversity would not happen on another habitable planet?
The factor under consideration was the level of hospitality of of that other planet: if it had a lot of extinction events due to meteors and the like it could wipe out life.
Preamble: Life, through the evolutionary process "explores" all accessable niches in the biosphere. Thus the degree of diversity is shaped by what the environment allows, what is reachable and what is selected for.
Here is my statement of the law: Biodiversity increases to the maximum that the current environment allows and that the evolutionary processes working with the results of historic contingencies make possible.
Corollary: The spread of biodiversity into new ecologies is limited by the existing biodiversity's ability to reach those new ecologies.
Life couldn't diversify on land until it could live on land. We won't be able to diversify on Mars until we reach Mars.
Since all living things themselves are part of the environment we ave a corollary: After a contingent mass extinction the rate of increase in biodiversity will be high.
For replacing organisms extinct due to catastrophic but relatively rare events. If the catastrophic events are relatively common it will be difficult to move in to fill the ecologies between the extinction events.
Especially when you have competition for dwindling resources, or when one species overruns an ecology making it difficult for other species to survive in the same area. Like say, caused by human overpopulation ...
quote:adj. 1. Formed for or concerned with one specific purpose: an ad hoc compensation committee. 2. Improvised and often impromptu: "On an ad hoc basis, Congress has . . . placed . . . ceilings on military aid to specific countries" (New York Times).
adjective 1. often improvised or impromptu; "an ad hoc committee meeting" 2. for or concerned with one specific purpose; "a coordinated policy instead of ad hoc decisions"
A phrase describing something created especially for a particular occasion: “We need an ad hoc committee to handle this new problem immediately.” From Latin, meaning “toward this (matter).”
Contrived purely for the purpose in hand rather than planned carefully in advance. E.g. "We didn't know what to do about the sausage rolls, so we set up an ad-hoc committee".
To me ad hoc means arbitrarily developed to deal with something after it has occurred.
Basically in this case I mean it is an arbitrary, improvised or impromptu result, and not a necessary result. This is similar to the post hoc ergo propter hoc logical fallacy.
My point is that we have empirical evidence of life diversifying on a macroscopic scale, and doing so irrepressibly, even after mass extinctions.
But this is only what has happened (so far) on earth, it isn't necessary that this happened. It has not happened on Mars.
But what still bothers me is that interesting increase of marine families since the Permian Extinction, shown in Sepkoski's graph in Message 56.
Think of it this way: it happened because back then the ecology and the habitability of the planet was such that it could happen, and because it could happen there was a 50-50 chance that it would, meanwhile life muddled along evolving as it went.
2. And you are saying that because macro-biodiversity "could happen there was a 50-50 change that it would." Here's where I start having trouble. What enables you to assume that macro-biodiversity has a "50-50 chance" of happening?
It's a question of speciation versus extinction, and what I was thinking was that it could go either way at any time. One species may become very successful and edge others out (ie humans?) in an otherwise optimum environment for speciation so you could either have a + or a - change at any time.
Even with a 50-50 chance at any time to increase vs decrease there is likely to be a long term trend to an overall + result due to the skewed, necessarily skewed graph of organism number vs diversity. Diversity cannot be less than zero, but has no absolute upper limit.
Does this automatically mean then that biological evolution could not muddle in the direction of macro-diversification?
Of course it could - in your graph it has - but it isn't a direct cause and effect relationship.
Cope's rule states that the size of a species will increase over time - is that a necessary result of evolution (it's called a "rule" after all eh)? Nope, but it is more common than not.
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