19.11.09

Rate of Change

It's been a while since I have blogged about evolution or faith and science. But this article in New Scientist has provoked me again.

The debate between evolutionists and creationists often goes nowhere, in my opinion. The Darwinists' understanding of the science is often much better and the creationists' arguments are often embarrassingly poorly constructed and as such are easily torn to pieces. However it would be a logical fallacy to assume that the more educated opinion is always correct. History has proved this to be wrong within the scientific community countless times. Copernicus's theory of a helio-centric solar system was considered poorly constructed and logically flawed by his scientific peers, and many dismissed his ideas as a result - but he was right.

Rather than get drawn into the details, that both sides are expert at shouting down, lets take a step back, and examine the big picture in simple terms.

The world is full of a diversity of life. The question is how did this diversity arise. Let's take the analogy of a bathtub full of water representing all the biodiversity on the planet. The creationist says, "God filled the tub." The evolutionist says, "The tap is running."

There then ensues an argument about the nature of the tap (which the Darwinist understands far better) and whether any water (biodiversity) is really flowing into the tub (through the process of evolution).

But there is one other important fact, which is beyond dispute by either side. The plug is out on this tub. Extinctions are irreversibly reducing the biodiversity of the planet all the time. A recent newspaper article I read suggested that as many as 11 species disappear each year. With many thousands more on the critically endangered list. (Indeed evolutionary theory relies on extinction to provide the steering hand of evolution - Natural Selection).

So let's side-step all the arguments about whether the tap is running or not, and ask a more fundamental question. Even if the tap is running; is it running sufficiently fast to explain a full tub with the plug out?

This is just a matter of empirical data. If the initial state of the bath-tub was empty, as the Darwinists propose, then the average rate of "speciation" must exceed the average rate of extinction. Or the bath tub would stay empty. The mind-bending periods of time (8.3 billion years) don't help here either, because if the car is not going forwards it doesn't matter how long it drives for, it is never going to get anywhere!

The plain and simple fact is that even taking what scientists propose to be recent speciation events (usually at least several thousand years ago) they don't add up to anywhere near 11 a year. The tub is getting more empty, not more full. Not great news for the initially-empty-bath-tub-theory.

Perhaps the rate of extinction was not so high in the past? Well here the evidence is to the contrary too, with several well documented periods of mass-extinction or elevated extinction rates. According to Berkley's information, of all the life that has ever existed on this planet, over 99% has become extinct.

The only option left for the empty-tubbers is that the tap must have been running faster in the past than it is now. In other words it relies on conditions and processes that cannot be tested and verified in the laboratory today. Hardly the irrefutable proof, that no-one could seriously disbelieve.

People often criticise creation(ism) as being unscientific. Yes, it is. It doesn't (or shouldn't) pretend to be otherwise. But unless you are an atheist, and disbelieve that anything miraculous can happen, this doesn't automatically make it untrue.

Equally, hard evidence for mutations, genetic drift, microevolutionary changes within a species, and the process of natural selection do not mean that Darwin's theory on the origin of the species is correct.

The tub is full, yet it is draining faster than it is filling (if it is filling at all). Does this suggest that the tub was initially full or empty?

17 comments:

Ricky Carvel said...

Interesting analogy.

Having sat in on a couple of debates on this issue recently, I am fairly frustrated by the 'evolution vs creationism' issue. The main problem I see is that the two 'sides' are not actually two sides in the same arguement.

Creationism is an opinion/belief about how the whole thing got started, while evolution is a theory about how things changed in the time after then.

Evolution offers no theory on the origin of life, only on the origin of (different) species. In fact, origin is probably a bad word choice here. 'Diversification' of species would probably have been better.

Creationism, on the other hand, generally assumes (for no particularly good reason) that once something has been created, it doesn't change. Could something not have been created to change?

These two theories are not really rivals and the debate is only perpetuated by people who have agendas other than finding out how the universe actually works.

R.

Chris HH said...

Important distinction. Thanks, Ricky.

Personally I wouldn't have a problem accepting that two closely related species had originally been one species that has separated due to changes in isolated gene-pools.

As you say this has to do with diversification not origin.

It's the Origin of the Species that I object to, and the assumption that proof of one implies proof of the other.

As you point out, whenever Science talks about origins it is straying from it's home turf.

PS I do believe we were created to be changed :-)

DH Strother said...

Neither the rate of extiction nor the rate speciation is a constant. So, looking at the rate of extinction today tells you very little about whether or not an empty bath tub can be filled, especially when one considers that today's extinction rates are unusually high. Your suggestion that an empty tub can not be filled by speciation relies on untestable and unverifiable assumptions. Unless you actually know the rates of both speciation and extinction for every moment of the history of life on Earth, your bath tub analogy is of little value.

Chris HH said...

Hi DH. Thanks for your comments.

I agree that both extinction and speciation are not constant. However, I disagree that the analogy is without merit. The point of the tub analogy is it demonstrates that you cannot just rely on tiny undetectable increases in biodiversity and then multiply by 8.3 billion years to explain the current state of life on earth.

On average, the rate of speciation must have been greater than the rate of extinction for the theory to hold, and the rate of extinction, both now and at every other measurable point in history, is neither tiny nor undetectable.

According to this site:
http://www.whole-systems.org/extinctions.html
It is the *baseline* extinction rate that is around 10 per year (1 per million species per year, taken from fossil records) With the effect of human interaction making today's rate much higher as you rightly state.

But even this baseline rate of extinction is much, much higher than the highest rate of speciation that could legitimately be proposed from observations today.

So this does beg the question. If the speciation rates for the current levels of species on the planet are not sufficient to maintain the current levels of species on the planet (even without human interaction), how did they reach these levels in the first place?

This is not a question that requires us to examine every moment over the last 8.3 billion years, but only the most recent speciation vs extinction events. Unless of course one assumes that the mechanisms in the past were considerably more rapid (and thus different) from anything that can be observed today. In which case, one has to ask if there aren't untestable and unverifiable assumptions on both sides!

DH Strother said...

Is the baseline rate of extinction is much, much higher than the highest rate of speciation that could legitimately be proposed from observations today? How do you know?

How did you determine the current rate of speciation? How do you know what the speciation rates were in the past? As an example, the hominid fossil record suggests that in the period from about 5 million to 2 million years ago, the speciation rate exceeded the extinction rate.

The following research suggests that both speciation and extinction rates have varied wildly in the past. This is based on analysis of the fossil record and not just on untestable and unverifiable speculation. Given the fossil evidence, it is reasonable to conclude that speciation rates could have been much more rapid in the past.

http://www.lbl.gov/Science-Articles/Archive/Phys-fossil-biodiversity.html


Yes, there are many things that are difficult to test, but the point is that this particular challenge seems poorly supported by the available data.

Chris HH said...

Thanks for the link.
This article is addressing precisely the issue I am raising:

"Biodiversity appears to rise and fall in mysterious cycles of 62 million years for which science has no satisfactory explanation."

"nothing in present evolutionary theory accounts for it"

"no clear explanation emerged."

To paraphrase: To account for current, and fossil levels of biodiversity, the tap has to explode with water every 62 million years in a way that evolutionary theory cannot explain.

DH Strother said...

I believe that the word "mystery" refers primarily to the cause of the mass extinctions. It's not clear that they would regard rapid speciation as mysterious. And I believe that the authors then go on to propose explanations for the "inexplicable", at least, they propose causes for the mass extinctions.

I don't think that most biologists would find it all that "mysterious" that events that lead to mass extinction would also open up many habitats and/or create new habitats by geological change. It's pretty much standard stuff to predict rapid speciation under conditions in which there are a large number of new and/or open ecological niches. Not a mystery at all. In fact, it's conventional wisdom that the extinction of the dinosaurs created opportunities for diversification among mammal species. Diversification of cichlids in African lakes is another example.

I honestly don't understand why these researchers see this as something "unaccounted" for in evolutionary theory, but then again, they're physicists, not biologists, and I think that they were primarily referring to the extinction rates, not speciation rates. Beside, it's common for scientists to say that something is a big mystery when they think that they have a new answer for something. No one is immune from the temptation to self-promotion.

Can we at least agree that there have been several periods in the past in which the rate at which new species appeared was much higher than today? So, I guess that the alternative explanation would be that God creates lots of species every 60 million years or so? Seriously, I curious about what the alternatives might be.

Also, you never explained how you calculated current speciation rates? It's a rather important rate of your analogy.

Chris HH said...

You're right that the fossil record is really a record of mass-mortality events, and doesn't tell us anything concrete about rates of speciation. These have to be inferred (in ways that often turn out to be incorrect in the light of latter evidence) from absences in previous fossil strata.

Also speciation itself tends to be a rather woolly concept. The standard definition of a species: a set of organisms that are able to mate and produce fertile offspring, allows for "speciation" events where geographic separation and subsequent genetic drift causes two groups of what are essentially the same species, in terms of their genetic structure, to be classified as two separate species because when recombined they are no longer able (or willing) to interbreed.

These kind of speciation events are rare but do occur, and are well documented. I have tried to find a ballpark figure, but been unable to do so. Since most documented cases in the wild are referring to evens several thousands of years ago, my finger in the air guess would be around 2 per century, being generous.

However, to my mind, a true speciation event would be one where a organism is produced that differs in genetic structure from its parents in either the number or sequence of genes in its genome. A true emergence of a new species never seen before. This kind of event is at odds with standard Darwinian evolutionary theory, in that it cannot happen gradually over time. You either have a new gene or you don't, but ironically it is absolutely necessary if evolutionary theory is to explain the origin of the species.

I do have an exact figure in mind for this second kind of speciation event: zero.

I believe God created all the biodiversity in one go, and that what the fossil record shows is selective mass mortality and extinction events, gradually reducing this biodiversity over time.

DH said...

"My finger in the air guess would be around 2 per century, being generous."

There are an estimated 5 to 10 million species on Earth. Each species has the capacity to undergo or be involved in speciation events. Obviously, it’s essentially impossible to monitor 5 to 10 million species for even a few minutes, let alone, for a century. So, in fact, there is simply no way to know how many new species have emerged in the last century from a starting point of 5 to 10 million species. Your guess has no basis in biology; it’s just a number pulled from the air.

"However, to my mind, a true speciation event would be one where a organism is produced that differs in genetic structure from its parents in either the number or sequence of genes in its genome. A true emergence of a new species never seen before. This kind of event is at odds with standard Darwinian evolutionary theory, in that it cannot happen gradually over time. You either have a new gene or you don't, but ironically it is absolutely necessary if evolutionary theory is to explain the origin of the species. I do have an exact figure in mind for this second kind of speciation event: zero."

This is not correct. There are numerous answers to this, but I'd suggest that you start by googling: +speciation +polyploidy

"I believe God created all the biodiversity in one go, and that what the fossil record shows is selective mass mortality and extinction events, gradually reducing this biodiversity over time."

Again, there are an estimated 5 to 10 million species on Earth. And yet there is not an single example of a modern plant or animal species in the Cambrian rocks. If all of the "biodiversity" is present at the start, where are the fossils of these five to ten million species? Do you think that it's possible that all of these species somehow "escaped" fossilization?

If there are no mammals, birds, reptiles, amphibians and angiosperm plants at the start, how do you support the conclusion that “biodiversity” has been reduced over time? The angiosperms, in particular, are a puzzle, because they account for 90% of modern plant species, and yet, they are completely absent from the fossil record until the Mesozoic.

In other words, how do you account for the appearance of new genera, families, orders, classes and divisions long after the start of life on Earth?

Chris HH said...

polyploidy is an interesting phenomenon that can explain how chromosome number can change (by multiples of two) but not how new gene sequences can be inserted into existing chromosome chains.

There is a big leap between duplicating an existing genome and forming a new unique one. But this leap would have to be made several times in the transition from one genetically distinct species and another.

DH said...

"Polyploidy is an interesting phenomenon that can explain how chromosome number can change (by multiples of two) but not how new gene sequences can be inserted into existing chromosome chains."

Once polyploidy produces reproductive isolation, independent genetic events in the separate lineages increases the number of genetic differences. And yes, mutation can produce new genes.

Now, how about tackling my questions about Cambrian fossils and biodiversity?

Chris HH said...

> And yes, mutation can produce new genes.

Is that a statement of fact or faith? Do you have any links you can point me to on that one?

I did start out by saying I didn't want to get drawn into arguing over the "nature of the tap." As I've already failed on that front, I don't want to get drawn any further down this route. But I have appreciated our dialogue thus far. Thank you.

DH said...

Can't say I blame you for wanting to avoid the biodiversity issue.

"Is that a statement of fact or faith?"

Start here:

http://www.talkorigins.org/indexcc/CB/CB102.html

SLW said...

Hello Chris,
A thought and a question.

First the thought: how is it possible to say this is a period of high extinction (as does DH) when paleontologists interpret the fossil record as revealing mass extinction after mass extinction. I would think this is more par for the course, if so, your point is stronger yet.

Then the question: how did you arrive at the 8.3 billion number for the age of life. I've not come across a number larger than 4.567 billion years for the entire solar system, and about .2 billion less for the start of life?

Chris HH said...

Thanks, SLW. It's a typo... it should have been 3.8 billion years. Not the figure I beleive, but the one quoted here:

http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_48

SLW said...

Here's something interesting on the entropic principle.

Josh W said...

Interesting!

It irritates my slightly that as I get older it takes longer and longer to get proper answers to my questions, or even to find out who knows something about them! This is an example of one of those times:

My impression has been that evolutionary theory needs to get it's act together, there's far too much of people assuming that someone else has solved that problem without talking to them about it, then raving at people who complain as being anti-science.

Now that could be totally wrong, but I just keep finding stuff like this in strange islands unconnected from each other; someone can probably build an evolutionary theory that explains this, but does their theory contradict other sub-theories that are required to explain other events?

Now in fairness to the people working in this area, it's conceivable that I'm just not working hard enough at it, thanks to growing older and having more demands on my time, and not seeing the webs of mutually consistent theories within that whole mess, but it seems so unfinished!

I'd like to see the research that has been done in "viable populations" and gene pool health getting mixed in, so we can see what effect mass extinctions can have on robustness and diversity in a way beyond counting breeding incompatabilities.

I'd also like to see some of the stuff on horizontal gene transfer, mutations to encoding proteins etc, to see if those can provide the gene shuffling mechanisms people refer to.

But, well, as you say; extrapolating back constant processes (or even random processes with constant distributions) is a pretty unfinished way to do it; there are just to many variables that haven't been justified as constant.

Our origins on this earth need serious work, both on a mechanical and ethical front. What does it say about our world that God allows such struggle and frustration to be a part of how life develops?

In the face of that, I have only partial heuristics, but if I had time I'd dearly like to get into sorting it out.