My apologies in advance to anybody who has studied genetics or evolutionary biology here, as I'm really going to bastardise some points for the sake of simplification and brevity.
philinho said:
Just watched the video, superb presentation, glad I watched it with the speakers on because the soundtrack especially was brilliant! It's a decent explanation of one possibility, but I don't think it explains what happened, but not how it happened.
That's the thing that I'm trying to get it, this is what we can absolutely prove DID happen. It is based on evidence, logic and observation. Sometimes, theories are like a jigsaw that need to be fit together, there's an excellent story about how the Big Bang theory went from the random musings of an ancient Ionian scholar to the proven scientific theory that we see today. It involves everything from religious persecution, jealousy, nuclear synthesis, gluttony, several large scoops of genius, solar eclipses, priests and pigeon shit.
One of the most important physicists who ever lived, who was the first to establish the truly scientific idea of the Big Bang was a Catholic Priest called Lemaitre.
I think that you have mistyped the last sentence in the above. If you meant to say that the video shows what happened, but not how, then I do agree. I just needed to show it as that creates the framework of information and we can fill in the rest of the structure with questions so that you at least have the opportunity to examine the evidence yourself. I actually came up with the idea of finding that video again because I wanted to explain planet formation as per your earlier question and didn't want to bore everybody with a crash course on cosmology to explain the early protoplanetry discs.
For example, how did the trilobyte change into the fish. If it happened over billions of years, where are all the inbetween bits? In the section about the fish growing legs, what advantage did the fish get (assuming natural selection) by having stumpy legs, surely that would slow it down in the water making it more easy to catch?
I'm about to explain a big bit of evolution here, so I might miss some stuff out either due to lack of research or lack of knowledge.
I suppose that the first big hurdle to tackle is abiogenesis, or the origin of life on the planet. There are numerous hypothesis on exactly how this occurred, but we don't yet know the absolute answer. When I talk of life, I'm not talking of life as we know it, we can see where that came from using, for example, the Miller-Urey experiment:
[youtube]http://www.youtube.com/watch?v=G4Y9w6fo_zY[/youtube]
This creates the amino acids that start to bind together to create the proteins that creates the first ever RNA, which eventually leads to DNA. Now, I wouldn't really call this evolution, more of a fluke, a chemical reaction - just like turning water into steam isn't evolution so to speak. It's a really deep subject on how exactly that happened, but it is to do with the structure of the proteins, RNA and eventually DNA (think of two things 'hooking together'). It isn't unlike a computer. DNA is programming language, RNA is the machine code and the proteins are the processor's switches. Sort of.
It is currently unknown in which order all of these appeared, and research is still going on.
Eventually, something approaching cells appeared. This is the thing to remember here, reproduction of these things happened ridiculously quickly, their generations are seconds long. It took a billion years to get to anything approaching what we would even recognise as a cell and even then it didn't have a nucleus. That's trillions upon trillions of generations to get to there. We know these things exist even today as nanobacteria
Once these molecules became cells, this is where evolution first started, before that it is more chemical reactions driving the production of 'life'.
For an understanding of the first ever life on the planet (well, undisputed life), there's a PDF available
here, which dates it at around 3.5 billion years ago.
Now we are at a point of having simple, single celled organisms. From here, as you can imagine, natural selection starts to take over for a couple of billion years to form many different species of them; some adapted to hot oceans, some cold, etc. The interesting ones are the ones that started to feed off of nitrogen and output oxygen as a byproduct of this. Some believe that this is how the atmosphere first became oxygenated. It's only a hypothesis for now, but there's some evidence to suggest it.
From single celled, we eventually get multi celled organisms. This is perhaps the most important step ever taken in the story of life. These little bacteria figured out that their job was much easier if they had one cell that focused on reproduction, one cell that focused on food, etc. Just as dual core processors split the workload thus are more efficient, instead of breaking off from each other when using asexual reproduction, they would just 'stick'. This massive paradigm shift needed to happen otherwise all of the other animals to come wouldn't have existed. Single celled life IS successful, as we can see today with the various species still around, but multicellular life was MORE successful.
Somewhere around this time, sexual reproduction started occurring rather than asexual. The reasons why are pretty simple; it is advantageous because new genetic material produces the product of the strongest of the two sets of genes.
I should also mention that some life developed symbiotic relationships with each other, in which they had a mutual gain from living inside of it. Coral, for example, has millions of bacteria living on it, stripping away the unneeded or dead cells allowing energy to be focused on growing newer and healthier cells. Human digestive system is also a good analogy here. You have to remember this as how things like predators appeared later and how plants appeared on land. Competition for energy is absolutely everything, and most used food as a source (whereas plants eventually learnt how to photosynthesise).
Once we have sexual reproduction and multi celled organisms, everything kind of exploded. Think of how many different possible variations that there were for those cells to be arranged in, and how sexual reproduction would produce even newer species with completely different adaptations to it. Thus we end up with hard shelled trilobyte type creations (I'm missing sponges, flatworms and just loads of stuff here)
[Edited thanks to correction by ElanJo]
Bear in mind when I say all of this that "they did XXX" is just a stupid term to describe evolution; it's just shorter than saying "a genetic mutation caused XXX which made them more successful at competing for food, thus their genes were passed down through reproduction and their offspring also had the same physical characteristics".
Your fish legs idea is a good question. Yes, there were animals that had 'stumpy flippers' for legs and were generally pretty shit. However, they were successful because not only could they swim and pick up food in the water, but they were then able to get food off of land, diversifying their food sources. As they evolved, their flippers began to bear more of their weight and eventually turn into the legs that we see today. Here's a picture guide of three seperate species that shows the link:
Water only Panderichthys
Amphibious Acanthostega:
The 'transitional species' that you asked about before, Tiktaalik:
Obviously, these are just pictures, but you can google their names on Google Images and find the actual fossils. The Tiktaalik was the first known animal to have a wrist bone in their flipper, which meant that it could bear some of the weight of it's body when feeling the previously unfelt force of gravity.
I could continue on, but this is getting a bit long. Needless to say, there are transitional species for each major evolutionary effect that we have found in the fossil record. If you have any specific questions, please ask and I'll try my best to find you the evidence.
Again, if it happened over billions of years, there must have been more than one to develop this mutation at the same time and to meet another one that was also developing the same mutation at the same time in order for them to reproduce and the mutation to continue. During this time, they had to find other animals with similar mutations, whilst avoiding being eaten etc...
You are misunderstanding genetics a little there. The easiest (and possibly highly offensive!) way of thinking about genetics is thinking about skin colour in humans. Let us imagine that the only people left alive in the world were white people. Would this mean that humanity would never have a black person as part of the race again?
No. Though it is very, very unlikely, two white people can give birth to a black child. This is because black skin is determined by the status of a particular gene that regulates the production of melanin in the body (again, simplified, but used for purposes of discussion). The gene can be turned on by mutation, hence causing the strange birth. As I say, not likely, but certainly possible.
Speaking of skin colour, more evidence of natural selection is the prevalence of darker skin for people who originate from hotter countries. Hotter = more Sun = more UV = black skin. Darker skin protects the person from the Sun better than light skin does, which is why so many White Australians have skin cancer now; their bodies are not yet evolved enough to live in the climate. In a few thousand years, all Australians will be black.
It just seems that it's highly unlikely, the only argument being that given enough time anything is possible, but I just don't buy it, like I said earlier it seems to me that it requires at least as much faith as a belief in a deity. Apologies if I've missed anything.
It isn't a question of belief, it's a question of what you can prove. It requires no faith at all, because we can see it in front of our eyes, and can date the fossils pretty accurately to understand their age. The argument isn't that given enough time a turtle can become a zebra; the argument is that all life survives by beating the competition for food using whatever means necessary.
I do have some more questions though...
I get what you're saying about the missing link, but I still don't think it covers it. If the start was a series of cells, at some point they had to turn into something, if everything on earth started out the same, and now we have millions of different creatures at some point one creature must have changed into another creature.
If this took billions of years, why can't we see anything that is halfway between one thing and another. If it happened spontaneously, why does it not still happen now?
Hopefully I have answered that above, but I'll try to reiterate a little. Firstly, we do see many transitional species in the historical fossil record as detailed earlier. We still see things today that are halfway between one thing and another.
Here'sa scientific text that explains how sticklebacks are diverging in species from each other. Here's hero of mine Carl Sagan explaining Evolution using crabs in his own special way:
[youtube]http://www.youtube.com/watch?v=SvMoC1M-GYw[/youtube]
Regarding the age of the earth, can you explain what the current thinking is, and how the age of the earth is determined? Is it through the different strata of the earth, carbon dating, red shift etc? because it seems to me they are all based on assumptions which may or may not be true... strata may not always form at the same rate etc, carbon dating assumes the thing was entirely carbon at the beginning, red shift requires the big bang or a single starting point for everything.
Again, there's a bit of a misunderstanding of carbon dating here, and radiometric dating, which is how the Earth age is formed.
All things in existence are made up of certain chemical elements, which all contain protons and neutrons. However, some of these are inherently unstable and decay over time, producing a separate isotope of an element. We know that the rate of which increases exponentially according to its half life, therefore we can use simple maths to determine it's age.
For example, the Sun is powered by Hydrogen fusing together and making Helium. If we know exactly how much Helium there is, and the exact time that it takes to react/turn from H to He, then we can work it backwards to the age of the Sun. This is a simplified example, but explains the basics.
There are around 50 different methods of radiometric dating, each of which has been performed thousands of times on the Earth, each coming up with the same age. The Earth will only become older, as we find older rock samples to test, it won't get younger. This is why we say that the Earth is
at least 4.54 billion years.
What's your opinion on the fish fossils on mountain tops I mentioned earlier?
Without looking into the specific case, it's hard to tell. In particularly, I'd like to know the age of the fish, and the exact location of them. My best 'guess' (and it is only a guess) is that the mountains used to be part of the sea floor but we made to be mountains by tectonic pressures. All mountains were flat at some point, and we commonly find fossils upon them.
What's your opinion on why humans are considerably more developed/intelligent than every other creature on earth?
A combination of things really. Firstly, we were absolutely lucky. The dinosaurs were once the dominant species on this planet which meant that we (mammals) had a natural predator and had to live in the trees or burrow underground to survive. Then, about 65 million years ago, Baptista hit just off the coast of Mexico and created an ELE (Extinction Level Event). In every ELE, the first thing to go are the big animals, who need lots of food and have slow reproduction cycles. We were still eating insects at the time, and somehow got through it.
From there, we developed as primates in trees because we lost the ability to produce Vitamin C thus needed to eat fruit to survive (and obviously as fruit is in trees and all the long necked dinos were dead, we filled our boots, so to speak). It took us about 60 million years to get out of the trees and start walking on land. We learnt that instead of growing new arms, having bigger and more logical brains helped in evolution, thus began to develop rudimentary tools, and everything kind of spirals from there.
You mentioned that there is the idea of an intelligent designer in current scientific thinking, can you go into that in a bit more detail?
I mentioned that it is possible that if the multiverse theory is proven to be correct (and it looks promising). This would mean that every possible event (from the collision of two atoms, to worlds blowing up) will happen in some Universe somewhere, therefore it would be logical to assume that some Universe must have a creator. Unfortunately, this also means that some Universe must be completely filled by Ewoks. It's just a logical consequence of the theory rather than any particular evidence.
ID and Creationism are bad, agenda driven science and are a little frustrating. However, if I had to point to something and say that there is a place for God there, I would point to the very moment of creation itself.
The Big Bang is a silly name, as it wasn't big and wasn't a bang. In reality, it was more like a deflated balloon been blown up, which is why every point of the Universe appears to be moving away from each other (think of drawing dots on a small balloon then inflating it, which one is 'the centre'?). Who blew the air into the balloon is a complete mystery.
My problem with the First Cause problem is that everything in there is faith and not science. You ask me who created the Big Bang, I say nobody did, it just happened. I ask you who created the Big Bang, you say God. I ask who created God, and you say nobody, He just happened. Nobody is right and nobody is wrong, because there is no evidence either way. I'm an evidence based person, I need to see proof of situations or have watertight logic before I can conjure up a better answer than "I don't know".
Isn't it the case that things tend to degrade in quality rather than increase? mutations in people very rarely improve them for example, houses left alone crumble and fall (poor example I know but I've had a long day :-)) so how is this considered in evolution (not so much natural selection), similarly animals (lions for example) that are deformed are generally left by the herd to fight for themselves and therefore have virtually 0 chance of survival in the world.
You are correct in your assertion that mutations rarely help people. However, as I have mentioned in the skin colour examples, sometimes they do. You have to think on a scale of thousands and millions of years. Numerous mutations will occur, but as they will not help in the competition for food or breeding, they are unsuccessful and do not get passed on in greater numbers.
How much of this is proven in labs and on what scale? Obviously, no one was around billions of years ago so how can we be certain of these things?
Whats your opinion on why? Like the video said at the end?
Sorry for all the questions, but thinking about this all weekend :-)
No worries, I hope that I've helped to answer some questions. This is a subject that I have a real passion for and do a lot of reading about, and I like sharing any understanding that I have acquired form it :)
As far as proof goes, nearly everything has been proven. One of the unhelpful things as I mentioned in a previous post is the difference between common and scientific language. Theory of evolution doesn't mean guess, we have more evidence for evolution than you can shake several forests at. This evidence comes from a combination of the fossil record, dated using radiometric dating, and genetics, where you can actually see the mutated genetic differences between differing species and how much DNA that they actually share between them.
On the aspect of why, I really have no idea. This is the realm that I wish religion would fill in, as it would be a useful part of society. Science can tell you what happened and show you the proof, but it can never tell you why.
I'm not even sure that there is a why, perhaps it happened because it just did, I don't see why as a question that needs to be answered. It would be like asking "why were you born in Manchester?" Although there is a reason, it probably isn't a good one apart from 'convenience'.
