sleepy,
Evolutionary science works by explaining the evolution of organisms and their traits by proposing "darwinian histories" and testing these against known facts: the fossil record, dating, the evidence from the genes, geologicial history, etc, etc. For some things, it is natural that our evidence is lacking. For example, we know relatively little about how the first multicelled organisms developed. It is a billion years ago or so, so it should not surprise us.
To really say whether a particular darwinian history is convincing, we will have to evaluate it on a case-by-case basis. You'd then have to read through the research results published in scientific journals and evaluate the specific evidence put forth, and propose or conduct further studies to confirm or rebut it. This is essentially what scientists do for a living.
There have been millions of different organisms on this planet, 99.9% of which are today extinct. We are totally ignorant about many of them, as we have found no fossil evidence for them. This is the sad reality of things, and scientists have to work with what we have.
I know there are lots of research material available on how exactly the brain developed. I have read very, very little of it. I don't think it is realistic to expect convincing darwinian histories for every feature of our brains to exist now. There should be work for countless generations of scientists to put the nuts and bolts together. The picture we have, however, is very consistent with what we know about how brain capacity evolved from the (more or less) chimp-like brain of the early australopithecene to our much more advanced brain.
I don't really see a problem if creating a convincing darwinian history for how increased brain capacity gave a specific survival advantage over more "primitive" individuals. We know all humans living today came from a very small stock of ancestors living some hundred thousand years ago. This population was under intense evolutionary pressure. The capacity for tool-making and complex social interaction was obviously necessary for survival, and both require advanced brains.
It is also feasible that our brain size has developed partially through sexual selection. If at one time e.g. certain females were attracted to the most intelligent males, then two characteristics would be likely to develop from their offspring: 1) tendency to be intelligent; and 2) tendency to be attracted to intelliegence. This starts a self-reinforcing, runaway feedback process which may very well explain intelligence way beyond what the environment demands. I don't know to what degree sexual selection gave us intelligence, but it is pretty obvious that it gave our women larger breasts than are necessary for breastfeeding. It certainly gave male peacocks a ridiculously large and beautiful tail, one that is no advantage for it apart from attracting females.
IW,
Why is it there are no interspecies? Why are there today no chimpanzees that are in various stages of evolving into humans? Why are there no sea creatures with rudimentary legs and lungs, attempting to venture onto land?
Rudimentary, as in non-functional, organs can only exist
after it has been useful for a species, not before. The appendix we have, and that causes us so many problems, is a rudiment of an organ that was useful and necessary for some of our ancestors. Likewise, we still have a rudimentary tail, because a real tail provided our ancestors with a survival advantage.
Evolution is extremely near-sighted and cannot make any organ that is not immediately useful for the organism. So the answer is that all species are at least potentially intermediate forms for something. But all species are also species in themselves, fit for the environment where they evolved.
If evolution were true it seems to me we should have partial humans still evolving, pre-humans who have evolved enough to stand erect, speak and have the ability to make rudimentary tools but are less human than the rest of mankind.
Evolution states the exact opposite: ancestor species went extinct because they were outcompeted by the later forms.
Why have the transitory species disappeared? Natural selection does not answer the question because every change was due to some advantage yet the previous species which really should have been wiped out because of some weakness was not wiped out, but the newly changed transitory creature which supposedly changed to adapt WAS wiped out!
Natural selection is the answer. The ancestor species was outcompeted and went extinct. But species have evolved in different directions, each taking advantage of different niches (or geographical locations).
E.g. if a sub-species gradually leaves forested areas and start living in the open land, we should expect "rapid" evolution. Limbs for climbing are no longer useful, while running fast is very essential. The ancestor species of the new, specialised fast-running species will still remain in the forest and be fit in that enviroment. If the forest-dweller came out in the open, he would be unable to compete with the new species. Likewise, if the savannah-dweller tried to move back into the forest, he would likely fail.
IW, you seem to be very interested in evolutionary theory. There are lots of good web sites explaining evolution very well, e.g. http://www.talkorigins.org , and many very good books. As always, I strongly recommend Richard Dawkins' books The Selfish Gene and The Blind Watchmaker. This will give you a much more detailed explanation than you can expect on a message board.
ThiChi,
Copy and paste is the order of the day, eh? The "abiogenesis law" is simply a general statement based on observations in the 19th century. Life has been around and evolved for billions of years, and it's a safe bet that nothing we'd recognize as life could originate from non-living material in this environment.
Yet, Miller et al's experiment, much maligned by creationists, demonstarted that in the environment of ancient earth, amino acids -- which are organic -- developed continuously. These molecules form very complex structures without any interaction from living things. Once self-replicating molecules exist, we have what is by defintion life. And there is no stopping such replicators from developing into far more advanced forms, due to natural selection.
[edited to add:] If Pasteur's statement was universally correct, then life could not exist (or it always existed). Logically, life must have originated somehow, thus demonstrating Pastaur's law is not universal. If you want to argue that God created life, then I would say that 1) since god does not procreate, he is not life as understood by biologists; 2) if it is true that Pasteur's lacking observation of life originating from non-life "proves" that abiogenesis is impossible, then our non-observation of God or gods creating life is an even stronger argument that no god ever created any life. You can't have your cake and eat it, too.
Your second posted article is simply ignorant. Some organisms (e.g. flies, but also many fish) procreate by giving birth to an enormous amount of offspring, in the hope that one or two will survive into adulthood. When it has "chosen" this strategy, it cannot put any resources into caring for or protecting its offspring. Numbers alone will have to do the job. The alternative strategy is to put all the resources into some very few, maybe one, child. It is then free to protect, feed and care for these children, thus hoping to increase its success. As nature demonstrates very well, both strategies can work (and of course there is a continuoum between them).
Your assertion that creating an enormous amount of offspring is the only viable road to success is simply wrong, as anyone with a rudimentary knowledge of the world around us can tell you. Don't creationists ever actually study nature to find out how it works? You shouldn't be too busy misquoting evolutionists and copying each other's ignorance to actually do some real research of your own.
- Jan
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- "How do you write women so well?" - "I think of a man and I take away reason and accountability." (Jack Nicholson in "As Good as it Gets")
