If there is an expert in the study of evolution, can you please explain it to me? When I say expert I mean someone that has a bachelor, masters, PhD in biology and works in the field today as a scientist. I am just looking for the evidence and data that convinces so many people in the scientific community that they are correct. It seems like evolution is the one thing they state as fact, when it has always been my experience that scientists always speak of everything as a theory. Please enlighten me.
I have a PhD in paleontology and cover evolution (briefly) in my lectures so I'd be happy to answer questions. It's a very broad and complicated topic so I can't really type out everything (and the website Mike gave is a good introduction). But if you have questions about particular things you find there or elsewhere I can definitely try to answer them. Evolution is a very non-intuitive thing, for several reasons I think. First, speciation typically takes too long so a single person can't observe it in a lifetime. We live in the "middle world" where we really just don't get things that are very big or very small, or take a very long or very short time. Second, nearly every complex item that we deal with on a daily basis was designed (cars, computers, etc.) so it's natural to make the leap that everything complex was designed. Living things are obviously very complex so it's easy to view them as designed as well. But interestingly, languages are also very complex constructs (think of all the words and rules) but they evolved in exactly the same way as species evolve. Less frequently used words (smaller population size) change more frequently, just as smaller populations of organisms are more likely to change. During speciation of languages, they undergo a burst of evolution in a process called "punctuated equilibrium." Languages most often diverge by allopatric speciation, where a new language evolves when it is physically separated by a barrier from its parent - reducing meme flow. Barriers reduce gene flow in living populations and promote speciation. Languages borrow words from other languages, just like bacteria can take genes from other bacterial species (lateral gene transfer). And languages are only known from incomplete snapshots preserved in writing, just as the fossil record is incomplete snapshots of biological evolution. We don't know how every word changed at all times, yet it is still clear how the languages evolved. We also have no record of languages first began, as the oldest written record is of a fully formed language - just like we don't know how life originated as the first fossils are of fully formed bacteria. The similarities are really striking, and I'm actually researching language evolution more to retool my evolution lecture to talk mostly about them (as language is more accessible and familiar to non-scientists). Yet despite having the same types of incomplete information and operating by the same principles, biological evolution is controversial among the general public while language evolution is accepted (or perhaps just ignored). -MEC
I am glad you mentioned languages because that is something I follow. I think you are correct when you say ignored because most people have no idea where most words come from. Ok here is my first question. I understand the change in species which plants and dogs are usually given as the example. Why haven't humans observed a new species emerge that did not exist before? I understand that evolution talks about a process that exists over millions of years, but does that mean all life evolves at the same time? Second question. I understand changes within a species where certain traits become more dominate than others. What I don't understand is where all the different species come from and how they got there? I don't see how we got from [FONT=Arial]primordial ooze to the different life forms that have inhabited the Earth. How did we go from ooze to dinosaurs, birds, cats, dogs, reptiles and you and I? [/FONT]
I've been saying this for years, but Darwin was misunderstood, and someone at The Church is finally owning up to that. http://www.usatoday.com/tech/science/2008-09-15-anglican-darwin_N.htm
But interestingly enough, the fact that we don't know the origin of a word doesn't mean that we can't study language evolution. Who knows why the number 2 is called "two" - but the same basic word is used in all Indo-European languages. We actually understand a lot about how today's languages have evolved, just as we understand a lot about how life has evolved, even though we don't know how exactly either began in the first place. Evolution is a process that takes a long time, but not everything evolves at the same rate. Some species can stay the same for tens of millions of years while others may last for only a few hundred thousand years or less. There are two main reasons why we don't observe new species evolving. The first is that speciation (the splitting of a species or evolution of a new species) among animals typically takes longer than a human lifetime. The second is that it usually occurs by the accumulation of many small changes, such that each change is basically imperceptible but over time they add up to something that can look quite different. Think of changes in the length of daytime during the year - when you compare December to July the difference is quite obvious, but do you actually notice the change on a day-to-day basis? The difference between September 15th and September 16th is really tiny so the big change ends up sneaking up on you through all the tiny changes you don't notice. As a result, there is probably no moment in time that you could put your finger on and identify as the exact moment something became a new species. Well, it's similar to what I described above, with the gradual accumulation of lots of little changes. Generally if a species is separated into two populations by some barrier (a river, ocean, highway, anything) they can start evolving separately because they no longer breed (much) and exchange genetic information with the other population. That means that just through random chance they may evolve in different directions. They key is that those changes have accumulated over more than 3.5 billion years for life itself and nearly 600 million years for animal life. Those are just mind-bogglingly large lengths of time, and that's part of the reason why it is such a non-intuitive concept. Even though I deal on a daily basis with times like 250 million years, I still don't actually have an understanding of how long that is - I don't think it's actually possible for anyone to really get it. We consider 50 years a long time so just can't intuitively grasp 500 million years; we consider 100 miles a long distance so really can't visualize how far 100 million light years actually is, and so forth. -MEC
Recent studies appear to have found a use for the appendix after all. It serves as a storehouse for the good bacteria that lives in our digestive tract. Should something like dysentery flush the system, so to speak, there would be some bacteria left in the appendix to help restore a normal balance of the good bugs.
It can happen much quicker. In 1971, ten Italian wall lizards were transported to a small island. In just 30 generations, there are now over 5,000 descendants that have evolved an entirely new digestive tract, larger head, and a harder bite.
Maybe it is the length of time. I don't understand how fossils and other evidence leads so many to be so sure about the theory. If it is something we truly can't grasp and something we will never be able to verify, why are we so certain we are right? I see many people speak with more certainty about evolution than they do about current sciences. The evidence just does not seem to be there to support the theory to my non scientific mind. I have heard this said before. Not sure how I would go with that
Not to put words in PlixTixiplik's mouth, but no one said we couldn't grasp it. Just that it's unintuitive because of the long time scales involved and thus difficult to grasp. That doesn't mean we can't understand it.
My idea of evolution concerns cross the board of life evolving simultaneously. Yes super bacteria were going to kill us off but I have a feeling we all evolved just the same yet in our own directions. The formula I had developed to explain this was that evolutions is measured by the integration or, making a wholeness to, the change in time as time become closer and closer to now from the point of birth to the actual death of life. This is a personal theory of mine that I have attempted to prove on several occasions.
We have verified that evolution occurs. Short-lived insect species make a great testbed for that, among other things. Given that evolution exists, and evidence from the fossil record, evolution on a larger scale than just what we can observe directly is an entirely believable phenomenon. What I suspect we don't have complete certainty of is our exact family tree. But there are clues we can use to get a pretty good idea what happened when.
Actually, we have observed new species evolving, but only with very simple microorganisms with life cycles that only last a few seconds or minutes. Evolution takes time. You might as well ask "why can't i watch the wind sculpting new rocks?" Well, you can, but its not going to look like anything in your own life span. Maybe I should stay out of this since I'm just an aspie whose read a lot of books, but the simple answer to that question is entropy. Genetic coding is not perfect. Things fall apart and break down. 99.9 percent of the time a mutation is not beneficial and the organism that has it dies or fails to reproduce or at least suffers increased stress over it. But every now and then, a mutation occurs which is beneficial and then over time, that mutation spreads to larger populations. Whats hard to wrap ones mind around is how a bazillion tiny changes can lead to such large apparent changes. The important thing to remember is that essentially all evolution over the very short term is a minor change in a species. Tiny tiny tiny little baby steps, which add up over geological time to increasingly larger differences. Well, we can grasp it, its a matter of removing yourself from human scales and human time frame. Just imagine living for a billion years. Yes, thats hard to picture, but thats the perspective that we are looking for. The evidence is there and it is overwhelming. However, what that evidence shows is that evolution does happen, but not any kind of track record for the exact particulars of how it happened. There are new theories emerging all the time to explain the evidence we have, and new evidence is being found constantly. For instance, some scientists now think that there is not just one evolutionary tree, but several, and that many different forms of simple life arose randomly from the same conditions. Its also now being shown that normal evolution creeps along very slowly, because species evolve to fill ecological niches. But if an ecology is shocked and there are mass die offs, evolutionary forces speed up to thousands of times faster than the normal rate. (Which is one reason why human stupidity regarding ecology is such a bad idea- we are creating a situation ripe to breed the critters which will destroy us, IE we have become the new ecological niche and we have shocked the ecosystem as bad as a meteor hit.)
Ooze -> bacteria -> plants -> worms -> animals with bones The keyword is "phylogenetic tree". http://images.google.com/images?um=1&hl=en&safe=off&q=phylogenetic+tree Example:
The problem with the phylogenic tree itself, or, any given version of it, is that its conjectural. We know for a fact evolution happens. We don't know the exact paths it took, except for in a few cases.