Typhon

Well, that's a decidedly odd way to start a thread (shrug). I suppose if you're just looking for facts, then sure, we'll be happy to help.

Actually, that's an extremely easy question. Many mammals (as well as other species, both living and extinct) have evolved the ability to fly, or at least, glide.

It does not take much imagination to see the progression of an early glider, towards the true flying mammals, namely Chiroptera.

As for "incomplete, flightless wings" being "quite detrimental to the mammal's survival" I do not concur at all. Gliding is an excellent if imperfect form of locomotion for arboreal dwellers, both to cover territory as well as for feeding and/or escaping predators. The loose skin folds which form the webbing may even be of some use for clinging onto the rough bark of trees, and there is little reason to think that the early stages of bats, where little different.

This one seems far less puzzling that bats, and I'm not even puzzled by bats at all. Many types of birds use their beaks to hunt for insects on plants and on fallen or dead trees. Finches are an excellent example of specialization of beak for feeding on certain types of food. That a species evolved to take advantage of their particular combination of traits, i.e. a hard head and a long, sharp beak, allowed the species to feed on insects not accessible to other competing birds who lacked this advantageous combination.

I disagree regarding your so-called "fact." This is to the best of my knowledge, a misunderstanding.

Besides, even if this urban myth had some element of truth in it, and some of the areas of our brain were not always "being used," what of it? Many things exist in species which may or may not be entirely useful. Whales have pelvic bones. Boas have hip bones. Some cave-dwelling salamanders have eyes, even though the species is entirely blind and exist in a lightless environment. Furthermore, who is to say you need entirely all of your liver at any one time? You can even lose half of it, and still live a full life. Our bodies do generally, like many living organisms, allow for a certain amount of redundancy, which helps no doubt, our survival margins, or once did. Still, I do not ascribe that any portion of the brain has been scientifically shown to be "superfluous" and again, this is not supported by current medical knowledge.

As an aside however, if for some reason a portion of the brain was to be found to be completely unused and of no value, this would not make a good case for arguing for a perfect, planned creation, unless the designer happened to be asleep on the job that day.

I love it when creationists mistakenly try to argue that a perfect world supports the existence of a perfect creator. The world and the organisms in it, have been well and repeatedly found to be imperfect, inefficient, flawed, and not always of the most logical design.

Life has never been concerned with evolving perfection, just something that works well enough. It's a big hole in the fabric of creationist theory, for those who mostly out of ignorance of biological facts, point to the "perfect" world as proof of their leaking superstitions.

Hope this helps,

.T.

[ May 30, 2002: Message edited by: Typhon ]</p>

parkdalian

There is some evidence for a rather large amount of brain tissue redundancy.

This linked article is from
SCIENCE. VOL. 210. 12 DECEMBER 1980

<a href="http://www.enidreed.com/serv01.htm" target="_blank">Is Your Brain Really Necessary</a>

Quetzal

It's a slow day at the office, so I'm going to pretend these are legitimate questions and not some hovind-esque stump-the-evilutionist silliness.

I'll just take one:
Bats are fascinating. Although there are alot of gaps in our understanding of bat evolution, it appears from the available evidence that bats in general may have evolved from Cretaceous insectivores. The similarity in dentition patterns between the eutherian Cimolestes (75 mya) for example and the first true Microchiropteran fossils Icaronycteris index (55 mya) is striking. The origin of the Megachiropterans, whose first fossil species Archaeopteropus transiens appears 35 mya, is a bit more cloudy. Scientists are still arguing the intraordinal relationship here. However, there's little question that the earliest Micros evolved from a eutherian.

About bat wings. Your statement about "incomplete, flightless wings" being a negative attribute is correct, as far as it goes. No one argues otherwise. No organism ever made a living as a "transitional form". You're making one of the classic creationist blunders - the fallacious assumption of linearity, or "purpose" in nature. Living organisms are observed to be, in general, sufficiently functional in their current environment to reproduce their species. They are not evolving toward any specific end result. Partial bats' wings, therefore, must have been fully functional for some purpose other than flight, for their possessor.

My personal favorite evolutionary pathway for bat wings is based on observations of living, non-flying species: gliders. There are a number of different animals that have gliding adaptations, including a frog (Rhacophorus nigropalmatus), a gecko (Ptychozoon kuhli), two species of snake (Chrysophelea paradisi and C. ornata), a squirrel (Glaucomys volans), and my favorite - the world record holder at 136 m - a lemur (Cynocephalus variegatus). The latter two are particularly interesting because they are fully functional, four-footed mammals who ALSO have the capability of using a simple spare membrane to glide long distances. Since we have numerous modern organisms with membranous "wings" used for gliding, there is absolutely no reason why the ancestors of bats couldn't have developed their true wings from a gradual extension of the same kind of gliding membrane.

Answer your question?

[Edited to add: and the previous posts are proof that typing a response in Word and then pasting into a thread without checking means that the sharper posters will beat you to the same information every time. Sigh. Sorry about the cross post everyone. Note to self: type faster next time. ]

[ May 30, 2002: Message edited by: Morpho ]</p>

Duvenoy

Hmm. Bats.

Now there, from the big flying foxes to the tiny pipestrell are some fascinating animals.

The support structure of a bat’s wing roughly conforms to our hand and wrist, a feature that gliders such as flying squirrels lack. It is not difficult to imagine a small, arboreal insectivore evolving to catch insects on the fly. I say ‘imagine’ because bat fossils are even harder to come by than those of snakes.

Once on the wing, bats began to fill a myriad of ecological niches and some parts of their world adapted to them. Some species of cactus in the southwestern US could not survive without nectar-drinking bats to pollinate them. There is a bat that fishes, skimming minnows from the surface of the waters. There is another that feeds only on blood from living animals.

This last is especially interesting in it’s social structure. If a vampire bat has been unable to feed, it will go to a ‘friend’ who will regurgitate a portion of it’s meal for it.

Some moths too, have adapted to bats. They are able to pick up the sounds of a bat’s echo location system and take evasive action.

Bats are evolution in high gear!

With woodpeckers, it’s not so much the hardness of the beak as it is the structure of it’s head that keeps it from bashing it’s brains out. It has a network of muscle and tendon that acts as a shock absorber. Again it is not difficult to see where the bird with the best shock absorber gets the most grubs to eat because it can dig deeper for them without getting a migraine. Therefore, it developed this system along with a beak adapted to the job. It also adapted it’s tail feathers to act as a short, stiff support while it clings to a vertical tree trunk.

Evolution! All of this wasn’t done in an instant, but over eons of trial and error. A flying squirrel or a sugar glider will never fly like a bat due to the structure of their feet, but that doesn’t mean that they could not evolve a different kind of wing, given time and ecological pressure.

Dunno anything about brains. Seems like some folks use more of theirs than others.

luck,

d

DieToDeath

I gotta answer this one too. We don't have superfluous brain matter. It's just that the majority of our brains are devoted to ordinary bodily functions (such as making your heart keep beating) and instincts (such as breathing). We simply cannot perform the chemical process known as "thinking" with this brain matter, since it's already in use.

...and what parkdalian said.

Someone7

<a href="http://www.tafkac.org/science/10_percent_of_brain.html" target="_blank">http://www.tafkac.org/science/10_percent_of_brain.html</a>
<a href="http://www.snopes2.com/science/stats/10percnt.htm" target="_blank">http://www.snopes2.com/science/stats/10percnt.htm</a>

[ May 30, 2002: Message edited by: Someone7 ]</p>

pseudobug

Jeebus, RvFvS. Havn't you figured it out yet?

The great Sky Daddy does these type of things for reasons we as mere mortals can't understand.

Clutch

Of course we only use 10% of our brains.

That's why 90% of the people who get shot in the head suffer no problems to their health. In most cases, the bullet hits nothing important, passes straight through, and just leaves the victim with a sore neck and a headache.

Mageth

Clutch:

Where did you get those statistics? I have serious doubts about them.

For one, there's a difference between being shot in the head and being shot in the brain.

For another, "no problems to their health"? A headache and a sore neck? I doubt if a 911 operator would tell someone to give their head-shot friend two tylenol and see your doctor in the morning.

Godless Dave

Clutch, I think you forget your sarcasm tags.