This has been a huge debate recently, so I thought I'd start a topic on the matter...

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Evolution is a fact!

I am sure this forum will put forth the many sides of the argument, but on a personal level, evaluating everything I have ever experienced or read or learnt, I haven't found any argument other than evolution for a couple of reasons

So many of the predictions that evolutionary theory have predicted have been confirmed - not just by theorists but by different areas of science

Absolutely zero evidence of any other process has been found - and we all need evidence to confirm beliefs

Major opposing theories are untestable. I realise this is why Creationism requires 'faith', but in terms of explaining the world we find ourselves in why must I prove some areas of science are correct by observation and experiment (Physics, Chemistry etc) yet drop those testing values when considering the descent of man?

For the record, I do not think accepting evolutionary theory is incompatible with faith in God, whichever religion it is that is practiced. But that may be a different thread altogether

Grow leeks. They rock.

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Evolution as far as I understand it is fact. The absolute specifics of how it works in all cases are not fully established, there are certainly some tantalizing mysteries, but this is true of all theories. Maths for example holds many unsolved mysteries, however they certainly in no way cast doubt on the theory of Maths!

I think the "confusion" that has arisen in recent years comes from two primary sources; firstly I believe that there is a genuine attempt to discredit evolution by some parts of the conservative religious community (more on this in a bit). Partly this has been fueled by point two; a simple misunderstand of the correct use of the English language.

"Evolutionary Theory", a simple term at first glance that actually causes confusion. It needs to be understood that the scientific community uses the word "theory" (in this context) is a different way to the general public.

A theory is two things. Firstly, (and more commonly used by the layman) it is a proposed proposition to explain the mechanics for a possible outcome or phenomena, nothing more that a hypothesis. For example: "Theoretically if I had four legs I could run faster for longer".

Secondly (and more commonly used by the scientific community) it is a well substantiated explanation of some aspect of the natural world. For example: "Theoretically the sum of two numbers is the total of their respective individual values".

Which is Evolutionary Theory? Is it a hypothesis or a well substantiated explanation?

Well, in scientific terms it is certainly a well substantiated explanation, but to doubters it is nothing more than a hypothesis. Arguments about Evolution often boil down to this. A new word perhaps is needed? This thread should perhaps be more correctly titled "Evolution - Theory or Theory?".

So that covers my second point, the first point is a little more complex.

Some parts of the religious right (the Intelligent Design supporters) are not happy about the prevelance of evolutionary theory because it appears to rule out the role of a creator or God. For the record I for one believe this is in fact true.

However putting that aside, lets address the issues.

They claim that evolution is impossible on two grounds; "Irreducible Complexity" (or "Irreversible Complexity") and "Mathematical Probability".

Evolution of life occurs through changes by means of random genetic mutations and Natural Selection (Survival of the Fittest); random mutations affect many many tiny changes, and Natural Selection ensures that the "best" most effective mutations go on to breed and reproduce. One outcome of this is that by looking at any organism you must be able to reverse the process and sustain a viable lifeform. So, if you could take away the previous mutation the lifeform must still function. In fact you must be able to continue "removing" mutations all the way back to the most primitive primordial cellular life forms. Darwin actually cited this in The Origin Of Species, as a well respected scientist he understood that it was necessary to highlight possible flaws in his theories in order that if it were to be disproved it would happen quickly. He wrote: "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.".

Take a watch for example, you may be able to remove certain "design" elements, certain evolutionary changes to the style and design of watches added over time. But fundamentally you cannot remove the essential components that make it a watch, to do so would not allow it to function and so why would such a thing exist? It wouldn't, it couldn't. This presents a "gap" in the evolutionary chain, the only way to fill this gap, as with a watch is with a designer! Case proven! Or is it...?

What is needed is some hard evidence, Darwin the worlds most foremost biologist could not find such a case, but he certainly did not have access to todays microscopic technology.

The eye is a famous example of an "irreducibly complex" structure, due to its many elaborate and interlocking parts, seemingly all dependent upon one another. It is frequently cited by Intelligent Design advocates as an example of irreducible complexity. What use is an eye in a "reduced state"? How could an eye function with one component missing? How could all the components know to evolve in the "knowledge" that when they had "finished" they would fit perfectly with other simultaneously evolving components?

However, while difficult to imagine, (even Darwin stated that the eye proposed particular difficulties: "to suppose that the eye... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree") there are plenty of plausible explainations for eye evolution.

The Flagella is another favourite piece of evidence for the Intelligent Design proponents. The flagella is a long, whip like projection composed by microtubes. They help propel cells and organisms in a whip like motion. Requiring the interaction of about 40 complex protein parts, and the absence of any one of these proteins causes the flagella to fail to function. How could the 40 components all evolve together with the same "pre-planned" goal? Well again, it seems that there are plenty of theories.

Put together is becomes obvious that the evidence for Intelligent Design, isn't evidence for anything at all, it is in fact just evidence of tiny less well explained components of Evolution. Most of which Darwin pointed out himself 150 years ago.

The second component of the Intelligent Design argument "Mathematical Probability" is not an argument for Intelligent Design at all but a badly constructed criticism of Evolution based on Mathematical Probability.

It goes something like this; the chances of complex life evolving are so remote that it should be considered impossible. If you try to calculate each step in reverse then the probability of this occurring is pretty much zero.

This argument however is flawed for this reason: If you enter a lottery, say you need to pick 6 correct numbers from a possible pool of 50 (as is the UK lottery) then your chances of getting it right are somewhere in the region of 14 million to 1. But at the end of the day you will always pull out 6 balls. You always end up with a set of 6 numbers. If you look at the draw in isolation you can say the odds are amazing, yet you always end up with a result.

Now if we were to draw all the balls, all 50, the odds of any particular order are staggering, but once you start, you indeed will end up with all the balls in a particular order. The odds of that order maybe 1 billion to 1 but the chance of you successfully drawing all the balls is pretty much a certainty.

Once you pull the first ball, you start the draw, once life starts, you have to end up somewhere, whatever the odds.

So, having dealt with the minuscule amount of "evidence", "against" evolution lets take a quick look at the basic evidence for evolution:

1) Survival of the fittest or more correctly "Natural Selection". The process by which individual organisms with favorable traits are more likely to survive and reproduce than those with unfavorable traits. Proven without doubt, millions of documented pieces of evidence, constantly peer-reviewed and accepted. Sometimes refereed to as a tautology - that is, it is so obvious that it does not need explanation, something along the lines of: "Out of the two options the best option is the best one". The strong survive the weaker do not. The strong pass on their genes the weaker do not. Lions catch and kill the weaker Wilderbeast, only the Peacocks with the finest plumes get to breed, only the strongest sperm reaches the egg.

2) Random Mutation or more correctly "Variation" is the process by which change happens. The AIDS virus is extremely difficult to kill because of its ability to mutate randomly and quickly. If you introduce and anti-viral AIDS drug into a patient it may kill off 99% of the virus but the 1% of the virus that contains mutations that make it less vulnerable to the drug will survive and multiply, again taking over the victim.

3) Replication or Reproduction. Replication occurs this isn't up for debate.

When thes three componets all work together: Selection, Variation, Replication you end up with evolution, its rather hard to draw any other conculsion!

All in all, I believe that "Evolutionary Theory" explains an awful lot of what we see. Not only that, but it is also elegant, succinct, beautiful and quite brilliant. A "Theory" perfectly fitting to describe the wonder of life.

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I found out an interesting thing about evolution the other day. Boobies (the birds after which booby traps are named, due to the ease in which they can be caught) mostly die due to blindness!

They catch fish by dive bombing them from above, the constant pressure on their eyes slowly causes blindness to a point where they are no longer able to feed themselves. Now evolution clearly can explain this, because of course this behaviour in the early years of their life enables them to eat plenty of fish and so they remain fit, strong and healthy.

They reach breeding age without apparent problem and so the genes for this behaviour are passed on to the next generation. The blindness comes later - and so it will for their offspring - as the genes for this apparent suicide have also been passed on.

The thing I find interesting about this is - how do you suppose that proponents of Intelligent Design might be able to explain this? Where exactly is the intelligence in this design? There are plenty of other diving birds that don't suffer the same fate?

Cooksta - just curious as to how you equate these two opposing viewpoints in the same post?

Yes its a very good question atomic - then again I guess they would say that you shouldn't try to second guess God and his "mysterious ways"!

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james - with regard to your points about irreducible complexity, I have a couple of additional comments.

Firstly, humans have "fairly reasonable" eyes in evolutionary terms, but remember that they are poor compared to say a Sparrow Hawk. A Sparrow Hawk may think that you or I only have 50% of an eye as their vision is that much better. So potentially our eyes are "reduced" versions of better eyes.

Likewise, many animals have less of an eye that humans, squid I believe have eyes very similar to ours but without a lens - their eyes are actually full of water! So in this example they have eyes that are "reduced" versions of our own.

So talk of eyes being in anyway irreducible is kind of nonsense because their are many eyes of many level of sophistication and complexity. Eyes can be reduced in complexity or indeed increased in complexity and still serve their owners perfectly well.

Which brings me onto my second point which is how eyes - or anything else with any level of dependent complexity - got that way. If you see, for example, a biological system with 3 components (A, B and C) that all appear to be part of a complex system - each part "relying" on the other, you may well wonder how it got that way. But remember this:

Part A in a more primitive state may serve a function of some sort - lets take a primitive tail for example - it wags weakly and with limited range but helps to propel our imaginary creature along. It manages to feed and reproduce well. Now a later natural variation causes a new component to appear, let’s say a larger socket for the tail. The creature with the larger tail socket has a larger range of motion in its tail, it swims faster than its rivals (with small sockets) and gets to food quicker, it is stronger and therefore healthier. It also gets to females first and as such it is highly successful in the evolutionary game.

Quite soon all these creatures have larger sockets in their tails, the decedents of our first “large socket” version have become the norm. Now a further variation may introduce a new variation to the socket - let’s say a muscle that attaches to the socket and the tail – it directly provides much more force to the tail. In this way A (the tail) may now appear reliant on B (the socket) and C (the muscle), it’s a well designed system for driving our creature through its habitat. A-B-C one without the other is useless.

Component A does a job, component B helps A do this job, but later A becomes reliant on B because this configuration is better than then previous non reliant setup. Component C then comes along and helps both A and B do their jobs better, A & B evolve to become reliant on C.*

The system as we now see it appears to be "irreducibly complex", and in a way it is - take away A or B or C and the whole system stops working. But that’s not to say that it was always that way!

(In this example for ease of explanation I "introduce" new components but remember that they evolve over many thousands or millions of years. The socket very slowly become more rounded each step aiding the tail further, only after many, many years the tail relies 100% on its socket.)

Irreducible complexity is NOT unexplainable complexity.

* In fact you can probably explain it in more simple terms that even that: A does a job, B helps A; but later, A becomes reliant on B.

Again, some very good points atomic, I found an interesting article about the evolution of upright walking on the BBC.

"They suggest the shift made by our ancestors to a terrestrial lifestyle came about as climate change thinned out their forest habitat.
In response, these ancient ape-like creatures, or hominids, may have abandoned the high canopy for the forest floor. Here, they remained bipedal and began eating food from the ground or from smaller trees. "

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