Evolution question - how did complex biological systems develop?

Question

Simple example:

There is a species of frog that shoots poison darts. In order for this to happen, the frog needs 1) poison glands, 2) darts, 3) muscles and nerves that can shoot the dart, 4) brain physiology that can target prey and trigger the attack, and 5) probably a bunch more stuff too. None of these attributes seems to have any evolutionary advantage without the others so how does the theory of evolution/selective generation explain that something like the poison dart shooting mechanism developed slowly from generation to generation?

I'm generally a scientific guy and not overly religious, but the "theory of evolution" never passed my common sense test. I can believe that species adapt to their environment, but I can believe that complex biological mechanisms like the one listed above can gradually develop over many generations.

Thoughts? ( no religious rants or long Bible quotes please)

Another simple example: vision. It requires dozens of unrelated parts to work together. Brain physiology, cornea, retina, jelly stuff inside the eye (ewe!), muscles to shift and focus, etc. What evolutionary advantage did any individual component offer until they all worked together to create "vision"?

Answer 1

Your question is just one example of the argument from incredulity this short article taken directly from www.talkorigens.org, responds directly to your over all question and further examples are avalible at the website this came from, like the bombadeir beetle. I do not believe that the frog you are reffering to is covered but the concept is well covered. If you are talking about the many species reffered to as poison dart frogs (I am not sure that you are) they are called poison dart frogs not because they shoot poison darts but because the secrete a poison that local people would cover the darts they had made in, in order to make them more effective hunters.

Claim CB301:
The eye is too complex to have evolved.
Source:
Brown, Walt, 1995. In the Beginning: Compelling evidence for creation and the Flood. Phoenix, AZ: Center for Scientific Creation, p. 7.
Hitching, Francis, 1982. The Neck of the Giraffe, New York: Meridian, pp. 66-68.
Response:

1. This is the quintessential example of the argument from incredulity. The source making the claim usually quotes Darwin saying that the evolution of the eye seems "absurd in the highest degree". However, Darwin follows that statement with a three-and-a-half-page proposal of intermediate stages through which eyes might have evolved via gradual steps (Darwin 1872).

* photosensitive cell
* aggregates of pigment cells without a nerve
* an optic nerve surrounded by pigment cells and covered by translucent skin
* pigment cells forming a small depression
* pigment cells forming a deeper depression
* the skin over the depression taking a lens shape
* muscles allowing the lens to adjust

All of these steps are known to be viable because all exist in animals living today. The increments between these steps are slight and may be broken down into even smaller increments. Natural selection should, under many circumstances, favor the increments. Since eyes do not fossilize well, we do not know that the development of the eye followed exactly that path, but we certainly cannot claim that no path exists.

Evidence for one step in the evolution of the vertebrate eye comes from comparative anatomy and genetics. The vertebrate βγ-crystallin genes, which code for several proteins crucial for the lens, are very similar to the Ciona βγ-crystallin gene. Ciona is an urochordate, a distant relative of vertebrates. Ciona's single βγ-crystallin gene is expressed in its otolith, a pigmented sister cell of the light-sensing ocellus. The origin of the lens appears to be based on co-optation of previously existing elements in a lensless system.

Nilsson and Pelger (1994) calculated that if each step were a 1 percent change, the evolution of the eye would take 1,829 steps, which could happen in 364,000 generations.

Links:
Lindsay, Don, 1998. How long would the fish eye take to evolve? http://www.don-lindsay-archive.org/creation/eye_time.html
References:

1. Darwin, C., 1872. The Origin of Species, 1st Edition. Senate, London, chpt. 6, http://www.talkorigins.org/faqs/origin/chapter6.html
2. Nilsson, D.-E. and S. Pelger, 1994. A pessimistic estimate of the time required for an eye to evolve. Proceedings of the Royal Society of London, Biological Sciences, 256: 53-58.

3. Shimeld, Sebastian M. et al. 2005. Urochordate βγ-crystallin and the evolutionary origin of the vertebrate eye lens. Current Biology 15: 1684-1689.

Further Reading:
Dawkins, Richard, 1996. Climbing Mount Improbable, New York: W.W. Norton, chpt. 5.

Land, M. F. and D.-E. Nilsson, 2002. Animal Eyes. Oxford University Press.

Answer 2

Even though I know Im wasting my time I'll give you some short answers: 1.Something from nothing? Who says the singularity comes from nothing. There are theories like M-theory etc that attempt to answer it, but the short answer is that we just don't know yet. And the Big Bang isn't a bloody explosion, its an expansion. 2.Physical laws an accident? Thats just the laws the universe has, why is it so important that they were specifically put in place? Another universe may have laws that are completely different and therefore work completely differently. It just so happens our universe supports life. 3.Life from dead chemicals? Scientists have recreated the events in a lab. 4.Complex DNA and RNA by chance? I'm not a biologist, ask this in the biology section. 5.Reproduction without reproduction? Huh? Life started out with the ability to reproduce. Sexual reproduction is more effective in keeping species diverse and healthy. 6.Plants without photosynthesis? The ability evolved over time/ 7.Explain metamorphosis! What has this even got to do with evolution? Ask the biology section! 8.It should be easy to show evolution. Firstly evolution refers only to biological life, not the origins of the universe. Secondly, there is one hell of a lot of evidence for evolution. It can be proven to you in a matter of hours if you just research it. 9.Complex things require intelligent design folks! No. Natural selection is a great way to create something complex that works without a designer.

Answer 3

It is hard to think about things like eyes evolving -- because any land animals that had the intermediate stages would be wiped out by those with eyes -- so they aren't around to observe. I know that there are sea creatures with eyelike structures that can't see they way we do -- but don't know much about them.

But I was thinking about this exact same topic a month or so ago. I recently moved to Boston and live near the harbor. There are a lot of seagulls here -- and they are just so aerodynamic. I started to wonder how wings could evolve -- because, like eyes, it seemed like a big jump to make to go from having arms to having wings. At first the intermediate steps didn't seem like they would be useful. Then two things happened. One is that I realized that flying squirrels -- which are really gliding squirrels -- are an intermediary step. They don't have wings -- but have loose skin that they can stretch out & use to flide. The other was an article I read on experiments with certain ants in Brazil. They, too, couldn't fly -- but could glide.

So -- I think the answer to your question as to how these complex systems developed is -- slowly.

Answer 4

There are 3 mechanisms of evolution that allow complex useful traits to develop. They are:

1. complex useful traits building upon simpler useful traits
2. opportunistic use of a part for an unrelated purpose
3. accumulated random traits, due to such traits not being burdensome enough to be selected out

Answer 5

Many evolutionary aspects developed as a means of survival. As the species encounters new surroundings and situations, it changes accordingly to cope with the surrounding.

Your question about the frog is interesting. I read about a certain frog species that has a tremendous amount of poison in it. The reason for the poison was to keep a snake that feeds on it away. This particular snake has developed immunity to the poison. As the strength of the poison the frog generates increased the anti-poison of the snake increases too. Both are doing it as a measure of survival.

Poison is nothing but purified saliva. All saliva, of every species, has some poison which is mainly due to the bacteria that thrives in it. The frog you mentioned may have started to eat certain kinds of prey which developed methods to evade the frog. The frog in turn had to develop methods to catch the prey from a certain distance. We can see it in ourselves. Athletes develop certain parts of their body in relation to the sport they are playing. This is to ensure they can perform at their best.

Answer 6

What you're actually asking is "what is evolution". Go back to school.

Answer 7

I think it does pass the common-sense test. As a non-scientist I have to a very non-science approach to attempting to describe how I think it happened:

If you think of how sugar and starches work when we ingest them, you recall how sugar stays sugar. Starch gets turned into sugar. Digestion has to convert one. Two different principles can be seen here: 1) that biology may respond to different things with different degrees of complexity of response, and 2) that Nature has a way of having at its roots some very, very simple principles.

Rather than to just assume something like the frog in question adapted to its environment I would think there's also the possibility there was some genetic mutation that essentially turned the frog into a frog with a "birth defect" but that the frog then made use of that "defect". Not long ago there was a young man on television who had no legs. He used not having the weight of legs to his advantage by propelling his light body around far more quickly and adeptly than, say, a walking person would. So sometimes what may start out as a defect can actually have its advantages; but that isn't even my main idea when it comes to the evolution thing....

Some of the most very basic ingredients in animal life are things like that there is some degree of aggression involved in reproduction, there is the propelling of a substance that starts to new life, and there is the substance itself. If you imagine life starting as simple cells and then mutating into a number of different "foundations" for future species, and if you accept that from many of these simpler branchings out from the original simpler life came additional branchings out and varying degrees of complexity and at different places in the history of evolution; then you can picture how somewhere along the way there was a blueprint for a basic frog, and from that blueprint would come any number of different types of frogs.

Suppose that at the point in the evolutionary history of frogs when there was susceptability to alterations in the blueprint something could have, say, gone awry with the design of the reproductive system to the point where, perhaps, something happened like the a mutation that affected the development of glands occurred. From that some "freak thing" could have gone on and caused "a version of an extra reproductive system" to develop in the frog. Of course, because it was coming from a different set of glands it would not operate the way the normal frog reproductive system does; so maybe this system works as follows: Just as with the reproductive system in many animals the frog spots its subject. The aggression normally associated with reproduction in most animals may not have as its aim mating but because the frog has no mating instinct toward its prey it the aggression is instead just aggression. Suppose the substance that is given off is not a fertilizing, life-creating one but just a poison because poisons can be created in biology as described by another answerer. Suppose to, that at the root of this mutation may have even been the mixing of what should have been the blueprint for a female reproductive system or at least or at least for a blend of male and female reproductive actions. Suppose, for example, at the blueprint stage and at the mutation stage, some element of whatever it is that causes newly fertilized cells to begin to divide and multiply and form tissue could have been introduced into the previous design of this frog, and so the substance that it gives off has some properties similar to tissue (if I'm using the right word) and is a "dart" rather than liquid. Suppose, too, something was in play with this frog when it came to a general blend of sexual response - it had the male aggression but it may also have had the general aversion to mating that female animals tend to have. If it something like this was going on then the frog's response to other creatures could be based in either the aggressiveness associated with male reproduction or even with an attempt to fend off any mating that the other animal could be presumed to have in mind (as could be linked to the female mating behavior).

I know nothing about glands or any of the other "intricacies" of biology for the most part, and I'm not saying that my poorly described scenario above is how the frog thing happened. I'm saying, though, that it could be a common sense explanation for how such a thing could develop in a species.

With regard to eyes, I'd assume that with single-celled life that had no vision there was a connection to the environment by some boundary and some forces that were going on in the living cell. You can see the beginning of the eyes being formed in an embryo, and you know that the brain is forming at the same time as well. I'd think that whatever process (the blueprint) designs that we have feet at the end of our legs is the same process that may have designed eyes essentially hanging off the brain the way legs hang off a torso. When you think of the complexity of the brain it isn't hard to imagine how the less complex eye could have been formed through evolutionary blueprinting and genetic mutation. (I know the eyeball doesn't "hang off" the brain. I mean in terms of its being linked to the brain in its function.)

If you picture that there is a very simple process at the root of mutations and blueprints, and if you picture that with every feature that every species has there is a long history of blueprinting and mutations, it is easy to imagine how it could have occurred.

If you watch a speeded up film of a human embryo growing into a fetus and a baby, and then a stocky toddler with a large-ish head and then a slimmer, more refined appearing school-aged child and eventually, say, the taller but slim teenager and eventually the taller and more filled out and well defined musculatur of an adult; it looks to me like watching the whole story of evolution played out in a very, very condensed time frame.

It is possible to believe in God and still believe in evolution. If you can see how miraculous the evolution thing can be, and if you can imagine how there could have just been some time and some space and a very simple concept - and God could have "flipped a switch" on all of life and started it all in progress.....

You could then believe that all of life continues to be God's work in progress and that He didn't just build a one-shot-deal masterpiece with the first humans and animals. If you could believe that life continues to be God's work in progress you could see why a perfect God may not yet have the perfect world and perfect creatures.

Answer 8

Neccesity, survival....Isn't Mother nature awesome

Answer 9

hmm-maybe we are underestimating the abilities of the small cells and atoms that we are made of.