diablodelmar said:
ahhh well, you see I have a real problem with Evolution. It was a theory created by Darwin mainly to have a good reason why we don't need a god.
sorry to bust your bubble, but this is imply - false!
(I should know, I just attended a two-semester seminary on Darwin's books). Darwin himself tried for a very long time to gete his evidence to fit the bible and the then-current thoughts on creation. He failed, whcih caused him quite some pain, but in the end simply gave up when the evidence AGAINST direct creation became overwhelming.
Why do you think did he hide his manuscript? Why did he apologize over and over throughout the book 'Origin of species', advocating any conceivable way to show him wrong (and, in the process, showing how, sadly, these way wouldn't work)?
because he was a devout Christian AND a scientist (naturalist is the term used back then), who suffered loads when he found that Christian dogma was wrong.
Besides, evolution should not be talked about in the terms of Darwin anymore - our knowledge has increased immensely. Today, the term you should use, and the theory you should investigate, would be the 'Integrated Theory of Evolution', which e.g. incorporates the evidence from genetics and molecular biology that Darwin couldn't have a clue about. Anything new that was found out about reproduction, adaptation, genetics, etc. after Darwin published his book has been found to CORROBORATE his theory (the main lines, he was off in a few details). Why would you ignore that plethora of data?
Also, I am currently watching some dvds about evolution, so hopefully I shall have some scientific arguements.
Good.
Better: read! Read good and new(!) biology and paleontology textbooks, then switch to recent scientific publications! Remember, good textbooks are about 10 years outdated at the very least!
But please, please, please disprove for me the theory of "bidirectional lungs" because it isn't only birds that are affected. I find it funny because all I could find in my school's many textbooks to explain it was "its one of lifes many mysteries!"
Can you guess how 'old' a book is when you get to read it in school?
It has to be researched (sadly, many authors copy large sections of older books without checking whether they are correct, or whether knowledge has increased and the current paradigm is different), written, printed, checked by authorities, printed in mass, bought by the schools.......
In my experience, nothing moe recent than stuff 15 years old makes it into school science books. Nothing. And that is assuming the original text as written by the author is correct.
OK, on the lungs:
First, please forget the term 'reptiles' in the meaning of 'iguanas, corcodiles, snakes'. it has long been proven that this supposed clade doesn't exist. it is not a monophletic group (monphletic means one ancestor and ALL descendants, which means that all members once shared the same genes and then evolved on from there). What people still teach in schools in this case is utterly WRONG!
properly, we should talk about a different classification, which incorportes the fact that crocodiles are NOT closely related to all the other animals usually grouped as 'reptiles'. For our purpose, here, we should use
'Archosaurs' = last common ancestor of crocodiles and birds (which means the clade includes dinosaurs, pterosaurs, and a bunch of others extince groups)
and
'Squamates' = snakes etc.
Both groups are supported by a plethora of special autapomophies (things one animal has which close relatives lack and which all descendants will have - e.g. a lengthwise string of 'gristle' is shared by all chordates (intervertebral discs in humans), feathers are shared by all birds, possession of an enlarged nasal trunk is common to all elephants). 'reptiles' as used by laypeople is NOT supported by any good set of autapomorphies.
Now, crocodile lungs differ significantly from snake lungs. The latter are elatively simple sacks, with the air going in and out the same was as in our lungs. The former, though basically similar, show a differentiation: some parts of the lung are sack-like, others are massively subdiveded and are far more active in gas exchange than the rest (this is based on work by aforementioned Steve Perry). This allows a crocodile to gain more oxygen then a snake from the same inhaled volume.
If we compare the ancestral state, as snakes still have, to that of crocodiles, then imagine this process of differentiation goes one step further, then we have the sacks and lung as in birds. Now we only lack small valves (no worries, the Bauplan for those is already in the genome, you just need to repostition them) and a few openings connecting the sacks-lung-sacks in a circular fashion (this means leaving out a tiny piece of lung tissue, no big deal) and the breathing can go partly bird-style. A tiny hole would give a slight improvement, allowing a part of the air to be expelled without passing the exchange tissue a second time (the second time the exchange goes the 'wrong' way, as by then the air is low on O2 and high on CO2) but only once, while the air is full of O2. And then, the bigger the hole is, the more air goes that way. Until, in the fnal stage, ALL goes in unidirectional flow.
All through these changes, the lung remains functional! There need NOT be a time where it is closed due to construction. It just improves in tiny steps.
Sadly, public perception is based an false assertions, introduced into science about 150 years ago. Back then, researchers lacked both the knowledge we gained from fossils (most hadn't been found yet) and the techniques we can employ today to study lung structure. but still people think that a snake lung and a croc lung are the same. They aren't!
Did you just say that gene duplication is a loss of information? And what do the other genes have to do with it?
