Evolution in a nutshell.
Posted: Thu Dec 02, 2010 11:46 pm
Evolution....the ups and downs.
Firstly, for you creationists out there, I would like to say that many believe believing in evolution is compatible with a belief in God. For example, Pope John Paul II and the current pope Benedict XIII stated that we evolved. Many leading figures in churches all over the world also acknowledge that the evidence for evolution is overwhelming.
The main argument against evolution for me is: How do we know to evolve? And how did some organism decide to reproduce, and what could have possibly driven it to do so? Not its own survival, certainly. It must have had some ‘intelligence’ to ascertain that in order for the species to survive, it must reproduce.
Basic Evolution as I understand it is thus: species have many more offspring than can survive. Therefore only the strongest survive, leaving the best suited genes. There’s a lot more too it, though, such as how selective breeding (in nature or by man) can increase or even create traits in future generations.
It can most easily be demonstrated with "variation in domestication", the first chapter in Darwin’s "The Origin of Species" which points out that animals do indeed differ within a few generations, e.g. cows with more muscle mass or milk production have these qualities increased with selective breeding, or how we have arrived at the modern pig from its boar-like predecessor several hundred years ago. Modern domesticated cows would most certainly not be “the fittest” in the wild. For a start the hugely oversized udders stop them from running fast. This is a clear example of “artificial selection” as opposed to “natural selection” where the genes we want as opposed to those which benefit the animal are deliberately bred. We have muscular chickens and cows with higher meat content. He shows that within a generation we can change aspects of creatures of the same family. The most useful features for us are kept, whilst the useless ones are ignored.
For example many breeds of domestic animals, including dogs, have floppy ears. they can’t make their ears go rigid, because for many generations their ancestors have not been often presented with danger, and therefore haven't had the need to erect their ears properly to listen for it. The offspring are born with ear muscles a small amount weaker than the parent. This was shown in the Belyaev experiment mentioned below with the domesticated foxes.
Another example is the modern common banana. Some creationist will tell you that the banana was clearly created by God, because of how easily it fit’s the human hand, it’s easy to open and is nutritional and tasty. We arrived at the modern banana through selective breeding, and natural bananas look very different indeed.
What makes the genes in the offspring differ? How do they know? It is held that the differences take place before the young develop, in the embryo. And if they differ gradually enough for the effects to take millennia to be noticed, they why do they start to change in the first place, and how do the individuals carrying the changing genes survive when their saviour genes haven’t evolved to the point of being useful?
For example, Darwin observed the different breeds of finches. Some had narrow long beaks designed for insects, others hard short wide beaks for cracking nuts.
Supposing they started off with the same beak as the theory suggests. One bird spends its life catching insects, the other cracking nuts.
Firstly,
How do the genes suddenly decide to change to make the offspring very gradually start to change shape? Why so gradually? If the genes have just learnt that a bigger, heavier beak is needed in order to survive, why change it only a miniscule bit?
Well, the truth is, it doesn’t always take millennia for differences to be noticed.
Here are a few modern examples:
Elephants have been observed to have a (noticeably) increasingly low average tusk weight in the past 100 years
There was an experiment done with lizards called “Podarcis Sicula” in 1971. There are two small islets off the coast of Croatia called Pod Kopiste and Pod Mcaru, the former was home to the lizard, and the latter had none at all. In 1971, on Pod Kopiste the lizards diet was vastly made up of insects, and a little plant matter. Then several pairs of “Podarcis Sicula” were transported to Pod Mcaru and allowed to breed. Then in 2007, 37 years later, there is a noticeable difference in the size and shape of the lizards head, which adds up to a much stronger bite. This is because a much stronger bite is needed for its new diet, which is now mainly plant matter- much the same way that a heavier beak was needed by the finches who wanted to crack the nuts. The lizards on the original island have stayed the same, whilst the lizards on the new island have adapted in just 37 years. Other adaptations were also observed, such as developed stomach valves, increased population density and a reduction in territorial behaviour.
A man called Dr John Endler set up an elaborate experiment involving guppy fish. I will shorten it somewhat to the main points. There were 10 ponds in a greenhouse with different types of gravel at the bottom, and different levels of predation, and all containing guppies from different types of streams. The fish were allowed to breed for 6 months without predators, and then they were introduced to all ponds spare two. From this point the mean number of colourful spots on the guppies plummeted, and by 14 months the change was astounding. The ones with predators grew spots to match whatever size pebbles were at the bottom of their pond, and grew less colourful. In those without predators, the spot size continued to grow in size and colourfully to differ from the pebbles and so to attract females.
A Russian scientist named Belyaev bred foxes to tame them. They all started out wild and hostile to humans. Within 6 generations of selective breeding for tameness (choosing only class 1 out of 3 for tameness) the foxes had changed so much that some were named the “domesticated elite” and acting like domesticated dogs. After 10 generations, 18% were elite; after 20 generations, 35% were elite., after 30-35 generations, 70-80% were elite. The Side-effects: The tame foxes began to look like domestic dogs. They lost their foxy pelage and became piebald black and white like welsh collies. Their ears went floppy, and their tails turned up at the end like dog’s rather than down like a foxes brush. The females came on heat every 6 months like a bitch, instead of a vixen. According to Belyaev, they even sounded like dogs.
Another issue for many is the eye. I can’t see coherently how an eye develops naturally. It’s far too convenient. If we had complex organs such as this just happening randomly all life on Earth would be covered in bits of useless stuff. Right? No.
If random mutations led to useless organs, surely the useless trait wouldn’t be passed on in the wild.
On a program regarding evolution I heard the development of an eye explained something like this:
“Supposing an organism developed a dip, which detected light + dark to help it evade predators. This dip, being useful, then widened, became a hole and rounded, developing into a complex system which could absorb and differentiate light”
Why would it do this? Like I said, it wouldn’t just happen because of the reason above, so creation is the only logical solution! Right? No.
The part about photosensitive light cells sounds plausible, but surely there must have been something unthinking which could accidentally detect light, and probably tell the difference between light and dark and, in order for it to develop, reap some benefit from this.
The closest I can get to envisioning this is some simple, primordial marine creature which is so simple its outer body (or at least a part of it) is somewhat translucent, and perhaps the genes notice that it always gets attacked from the side of it’s body which has the most light on it, and it then in turn exploits this light. After all, if you are visible, you are more likely to become prey.
Here's the pickle.
And it must surely take some degree of intelligence to do this, but how could intelligence have came about in the first place? If evolution is correct then intelligence could have evolved, but then that points to us, as we are evolving intelligence. I’m not saying that we created ourselves, but the only way I can see the creation of intelligence is if evolution works, then intelligence comes about through the product of evolution (us) when we start to think.
Otherwise could intelligence possibly have evolved separate from a body? Perhaps in a similar way that matter reacted with other matter to form bacteria or amoebas, neural, electrical or some other energy could have reacted, interacted and stuck together to form a system which eventually thought.
Could in some incomprehensible way this entity expanded and evolved to a point where it could interact with solid matter, to an extraordinary, possibly sub-space level. This seems significantly less likely than the theory of evolution. Saying that intelligent, complex matter existed at the beginning of the universe is certainly less logical than saying matter existed at the beginning of the universe which over billions of years formed intelligence.
Another possible explanation is that the intelligence progressed in creatures like us, to a point where it could ‘ascend’, i.e. the consciousness became so powerful it could support itself indefinitely. But that still points to evolution and not a deity.
Before I go onto the hard evidence for evolution, I would just like to logically disprove the literal story of Noah’s ark, as I believe this backs up evolution in itself. Firstly, how did the small quantities of prey animals manage to survive without being eaten by the predator animals? And how did the predators manage to survive without eating all of the prey animals? If there were either 2 or 7 of each species as claimed in the Bible, then this is purely impossible unless the predators changed diet for a brief period of procreation, which we know is simply silly. If within the last few thousand years, all the animals in the world came from Mount Sinai where the Ark landed, how on earth are they so well distributed today? There are hundreds of examples of how animals are found almost exclusively in one part of the world. Take Australia for example, where nearly all of the mammals there are marsupials. Why would all the marsupials get decide to head in one direction, not stopping at any of the other lovely hospitable places on the way, somehow manage to cross a large body of turbulent water when they can’t all swim, and then never go back?
And the polar animals. Why would all the penguins go only south, and all the polar bears go only north?
And don’t forget that the measurements given in the Bible for the size of the Ark simply wouldn’t fit 7 of nearly every species in the world in it, and 2 of the “unclean” species.
Some of the hard evidence.
I think it quite necessary to explain some more of the evidence for evolution, not least for the benefit of the hardcore-creationists out there.
Firstly, I will start with the stereo-typical example of fossils.
Here I would like to point out and thoroughly emphasise that without fossils, we would still know about evolution, and that fossils are only convenient evidence to those of us who aren’t plagued with a compulsion to be contrary. In Darwin’s day there was not a clear chain of fossils demonstrating evolution.
We know that as we dig down into the earth, different layers come from different ages, as one must be put down before the one on top of it. This have been proven by various methods of quite accurate dating. Remember these methods have been tried and collaborated all over the world and they all agree on the ages of the various layers. We know that fossils in Cambrian sediment are older than Ordovician fossils, which are older than Silurian, then Devonian, then Carboniferous, then Permian, then Triassic, then Jurassic, Cretaceous and so on.
How do we know the ages of the layers? Here are a few methods of quite accurate dating.
I will start with Dendrochronology, which is the practice of determining the age of ancient pieces of wood using other pieces of wood in a daisy-chain effect, counting their rings. As everybody knows, the amount of rings in a cut tree trunk is a very reliable indicator of exactly how many years old the tree is, or was when it was cut down.
Tree rings vary from year to year depending on the growing conditions, and any given adjacent set of rings will have a very specific, unique ‘fingerprint’ defined by what the exact growing conditions were in that period of time.
This can be compared with the identical fingerprint in other trees of different ages.
For example, fingerprint X is clear at the end of one trees life, X may also be clear near the beginning of another trees life. The same fingerprint in both trees has to have happened at the same time, to have had the exact same growing conditions. Said younger tree grows older to produce Y fingerprint, which we then see in another young tree. We then have a timeline of trees and can say that tree A lived X many years before tree B, which was X many years older than tree C.
This can theoretically be accurate for millions of years but we don’t have enough petrified forests and so Dendrochronology is only useful for around 11,500 years
Similar methods can used in varves- layers of sediment laid down in glacial lakes which vary seasonally and annually. Similar methods can also be used in determining the ages of coral reefs, which have been used to determine the dates of ancient earthquakes.
Secondly, I will briefly explain radioactive dating. To start off, I will explain a few simple facts about atomic structure. You can skip this paragraph if you are confident with your knowledge of atoms and Isotopes.
Atoms consist of a nucleus and electrons, which orbit it. Around a billion atoms fit in a straight single-file line across the head of a pin. To get an idea of the scale of things, imagine that we swell the nucleus up to the size of a marble. The electrons would be the width of a hair, and 2 miles away, with the space in between empty of matter.
The nucleus is made up of Protons and Neutrons. The Protons have a positive electromagnetic charge, and the Neutrons have a negative electromagnetic charge, The number of Protons in an atom determines which element of the periodic table it is, regardless of how many Neutrons there are. The combined number of Protons and Neutrons give us the atomic number.
The states in which an element can exist with varying Neutrons (but the same number of Protons) are called Isotopes, and they have different atomic numbers. Some elements, such as Fluorine, have only 1 Isotope, whereas others may have more, such as Lead which has 5.
There are altogether 308 different Isotopes amongst the elements, 150 stable, and 158 unstable.
Now we go onto the part about radioactive decay and dating.
Some Isotopes are stable, but some are unstable, meaning they decay.
Two of the types of radioactive decay are when a Proton is replaced by a Neutron, (changing the element but not the atomic number) or vice-versa. For example the Isotope Potassium-40 (40 being the atomic number, determining the Isotope but not the element) is one step above Argon-40 in the periodic table, having one more Proton. If a Potassium-40 atom loses a Proton and gains a Neutron, it becomes Argon-40.
All unstable Isotopes have a half-life which we know. A half-life is the time it takes for half of any given amount of the unstable Isotope to decay. That is to say, if you have either a kilogram or a tonne of potassium, it’s half-life will remain the same. For potassium, its half-life is 1.26 billion years.
When volcanic rock solidifies, it contains potassium, but no argon at all. We know this as a fact. At this point of suddenly solidifying into igneous rock it begins to decay, very slowly.
Therefore, the ratio of argon : potassium is a very clear indicator of how long ago the rock solidified.
For example, if the ratio or argon : potassium is 1:3, that must mean that the rock solidified 630 million years ago (being decayed at half the rate of the ratio when its at 1:1 and therefore half of the time).
We can use this method as far back as 49 billion years with rubidium-87,
This is irrefutable science, and arguing with the logic behind it is simply either ignorant or perversely stubborn.
So now you have at least a vague idea of how we know for fact that certain layers of the earth have certain dates.
On to fossils.
Each layer has its given dates, and each layer’s fossils only show up in the dates that their evolutionary tree would suggest, and never before.
For example nothing remotely resembling a mammal has ever been found in Devonian rock. Never.
We also know, from the radioactive dating of igneous rocks found in association with the Devonian strata all around the world, that the Devonian ended around 360 million years ago.
Regarding human evolution, very much evidence has been found along the timeline that we evolved gradually. Aside from the fossils which show the stages of developing man, whilst being proven to come from certain dates, there is also much other evidence which shows our development into the people we are today. The following timeline was compiled from evidence gathered by many dozens of people all over the world, and the various methods of dating all agreed enough to place them at these dates.
2.5 million years ago- simple stone tools found
1.6 million - More complex stone tools, such as a skilfully shaped, symmetrical hand-knives
400,000- Earliest strong evidence of cooking and spears.
160,000- Fire is used to treat stone tools
120,000- signs of pigment use- emergence of symbolism in culture.
100,000- Shell beads give evidence of jewellery.
50,000- Cultural revolution- ritualistic burials, clothes-making and advanced hunting techniques.
35,000- An explosion of cave art in Europe first surviving statue of a woman.
10,000- Agriculture begins.
7,300- Horses are domesticated in Kazakhstan.
6,000- God created the world…???
5,000- Oldest known writing. Bronze age allows development of swords.
4,500- Great Pyramid build at Giza
420- Shakespeare’s plays first performed in London.
1 year ago- The Large Hadron Collider was turned on.
2010- Scientists succeed in trapping anti-matter.
Firstly, for you creationists out there, I would like to say that many believe believing in evolution is compatible with a belief in God. For example, Pope John Paul II and the current pope Benedict XIII stated that we evolved. Many leading figures in churches all over the world also acknowledge that the evidence for evolution is overwhelming.
The main argument against evolution for me is: How do we know to evolve? And how did some organism decide to reproduce, and what could have possibly driven it to do so? Not its own survival, certainly. It must have had some ‘intelligence’ to ascertain that in order for the species to survive, it must reproduce.
Basic Evolution as I understand it is thus: species have many more offspring than can survive. Therefore only the strongest survive, leaving the best suited genes. There’s a lot more too it, though, such as how selective breeding (in nature or by man) can increase or even create traits in future generations.
It can most easily be demonstrated with "variation in domestication", the first chapter in Darwin’s "The Origin of Species" which points out that animals do indeed differ within a few generations, e.g. cows with more muscle mass or milk production have these qualities increased with selective breeding, or how we have arrived at the modern pig from its boar-like predecessor several hundred years ago. Modern domesticated cows would most certainly not be “the fittest” in the wild. For a start the hugely oversized udders stop them from running fast. This is a clear example of “artificial selection” as opposed to “natural selection” where the genes we want as opposed to those which benefit the animal are deliberately bred. We have muscular chickens and cows with higher meat content. He shows that within a generation we can change aspects of creatures of the same family. The most useful features for us are kept, whilst the useless ones are ignored.
For example many breeds of domestic animals, including dogs, have floppy ears. they can’t make their ears go rigid, because for many generations their ancestors have not been often presented with danger, and therefore haven't had the need to erect their ears properly to listen for it. The offspring are born with ear muscles a small amount weaker than the parent. This was shown in the Belyaev experiment mentioned below with the domesticated foxes.
Another example is the modern common banana. Some creationist will tell you that the banana was clearly created by God, because of how easily it fit’s the human hand, it’s easy to open and is nutritional and tasty. We arrived at the modern banana through selective breeding, and natural bananas look very different indeed.
What makes the genes in the offspring differ? How do they know? It is held that the differences take place before the young develop, in the embryo. And if they differ gradually enough for the effects to take millennia to be noticed, they why do they start to change in the first place, and how do the individuals carrying the changing genes survive when their saviour genes haven’t evolved to the point of being useful?
For example, Darwin observed the different breeds of finches. Some had narrow long beaks designed for insects, others hard short wide beaks for cracking nuts.
Supposing they started off with the same beak as the theory suggests. One bird spends its life catching insects, the other cracking nuts.
Firstly,
How do the genes suddenly decide to change to make the offspring very gradually start to change shape? Why so gradually? If the genes have just learnt that a bigger, heavier beak is needed in order to survive, why change it only a miniscule bit?
Well, the truth is, it doesn’t always take millennia for differences to be noticed.
Here are a few modern examples:
Elephants have been observed to have a (noticeably) increasingly low average tusk weight in the past 100 years
There was an experiment done with lizards called “Podarcis Sicula” in 1971. There are two small islets off the coast of Croatia called Pod Kopiste and Pod Mcaru, the former was home to the lizard, and the latter had none at all. In 1971, on Pod Kopiste the lizards diet was vastly made up of insects, and a little plant matter. Then several pairs of “Podarcis Sicula” were transported to Pod Mcaru and allowed to breed. Then in 2007, 37 years later, there is a noticeable difference in the size and shape of the lizards head, which adds up to a much stronger bite. This is because a much stronger bite is needed for its new diet, which is now mainly plant matter- much the same way that a heavier beak was needed by the finches who wanted to crack the nuts. The lizards on the original island have stayed the same, whilst the lizards on the new island have adapted in just 37 years. Other adaptations were also observed, such as developed stomach valves, increased population density and a reduction in territorial behaviour.
A man called Dr John Endler set up an elaborate experiment involving guppy fish. I will shorten it somewhat to the main points. There were 10 ponds in a greenhouse with different types of gravel at the bottom, and different levels of predation, and all containing guppies from different types of streams. The fish were allowed to breed for 6 months without predators, and then they were introduced to all ponds spare two. From this point the mean number of colourful spots on the guppies plummeted, and by 14 months the change was astounding. The ones with predators grew spots to match whatever size pebbles were at the bottom of their pond, and grew less colourful. In those without predators, the spot size continued to grow in size and colourfully to differ from the pebbles and so to attract females.
A Russian scientist named Belyaev bred foxes to tame them. They all started out wild and hostile to humans. Within 6 generations of selective breeding for tameness (choosing only class 1 out of 3 for tameness) the foxes had changed so much that some were named the “domesticated elite” and acting like domesticated dogs. After 10 generations, 18% were elite; after 20 generations, 35% were elite., after 30-35 generations, 70-80% were elite. The Side-effects: The tame foxes began to look like domestic dogs. They lost their foxy pelage and became piebald black and white like welsh collies. Their ears went floppy, and their tails turned up at the end like dog’s rather than down like a foxes brush. The females came on heat every 6 months like a bitch, instead of a vixen. According to Belyaev, they even sounded like dogs.
Another issue for many is the eye. I can’t see coherently how an eye develops naturally. It’s far too convenient. If we had complex organs such as this just happening randomly all life on Earth would be covered in bits of useless stuff. Right? No.
If random mutations led to useless organs, surely the useless trait wouldn’t be passed on in the wild.
On a program regarding evolution I heard the development of an eye explained something like this:
“Supposing an organism developed a dip, which detected light + dark to help it evade predators. This dip, being useful, then widened, became a hole and rounded, developing into a complex system which could absorb and differentiate light”
Why would it do this? Like I said, it wouldn’t just happen because of the reason above, so creation is the only logical solution! Right? No.
The part about photosensitive light cells sounds plausible, but surely there must have been something unthinking which could accidentally detect light, and probably tell the difference between light and dark and, in order for it to develop, reap some benefit from this.
The closest I can get to envisioning this is some simple, primordial marine creature which is so simple its outer body (or at least a part of it) is somewhat translucent, and perhaps the genes notice that it always gets attacked from the side of it’s body which has the most light on it, and it then in turn exploits this light. After all, if you are visible, you are more likely to become prey.
Here's the pickle.
And it must surely take some degree of intelligence to do this, but how could intelligence have came about in the first place? If evolution is correct then intelligence could have evolved, but then that points to us, as we are evolving intelligence. I’m not saying that we created ourselves, but the only way I can see the creation of intelligence is if evolution works, then intelligence comes about through the product of evolution (us) when we start to think.
Otherwise could intelligence possibly have evolved separate from a body? Perhaps in a similar way that matter reacted with other matter to form bacteria or amoebas, neural, electrical or some other energy could have reacted, interacted and stuck together to form a system which eventually thought.
Could in some incomprehensible way this entity expanded and evolved to a point where it could interact with solid matter, to an extraordinary, possibly sub-space level. This seems significantly less likely than the theory of evolution. Saying that intelligent, complex matter existed at the beginning of the universe is certainly less logical than saying matter existed at the beginning of the universe which over billions of years formed intelligence.
Another possible explanation is that the intelligence progressed in creatures like us, to a point where it could ‘ascend’, i.e. the consciousness became so powerful it could support itself indefinitely. But that still points to evolution and not a deity.
Before I go onto the hard evidence for evolution, I would just like to logically disprove the literal story of Noah’s ark, as I believe this backs up evolution in itself. Firstly, how did the small quantities of prey animals manage to survive without being eaten by the predator animals? And how did the predators manage to survive without eating all of the prey animals? If there were either 2 or 7 of each species as claimed in the Bible, then this is purely impossible unless the predators changed diet for a brief period of procreation, which we know is simply silly. If within the last few thousand years, all the animals in the world came from Mount Sinai where the Ark landed, how on earth are they so well distributed today? There are hundreds of examples of how animals are found almost exclusively in one part of the world. Take Australia for example, where nearly all of the mammals there are marsupials. Why would all the marsupials get decide to head in one direction, not stopping at any of the other lovely hospitable places on the way, somehow manage to cross a large body of turbulent water when they can’t all swim, and then never go back?
And the polar animals. Why would all the penguins go only south, and all the polar bears go only north?
And don’t forget that the measurements given in the Bible for the size of the Ark simply wouldn’t fit 7 of nearly every species in the world in it, and 2 of the “unclean” species.
Some of the hard evidence.
I think it quite necessary to explain some more of the evidence for evolution, not least for the benefit of the hardcore-creationists out there.
Firstly, I will start with the stereo-typical example of fossils.
Here I would like to point out and thoroughly emphasise that without fossils, we would still know about evolution, and that fossils are only convenient evidence to those of us who aren’t plagued with a compulsion to be contrary. In Darwin’s day there was not a clear chain of fossils demonstrating evolution.
We know that as we dig down into the earth, different layers come from different ages, as one must be put down before the one on top of it. This have been proven by various methods of quite accurate dating. Remember these methods have been tried and collaborated all over the world and they all agree on the ages of the various layers. We know that fossils in Cambrian sediment are older than Ordovician fossils, which are older than Silurian, then Devonian, then Carboniferous, then Permian, then Triassic, then Jurassic, Cretaceous and so on.
How do we know the ages of the layers? Here are a few methods of quite accurate dating.
I will start with Dendrochronology, which is the practice of determining the age of ancient pieces of wood using other pieces of wood in a daisy-chain effect, counting their rings. As everybody knows, the amount of rings in a cut tree trunk is a very reliable indicator of exactly how many years old the tree is, or was when it was cut down.
Tree rings vary from year to year depending on the growing conditions, and any given adjacent set of rings will have a very specific, unique ‘fingerprint’ defined by what the exact growing conditions were in that period of time.
This can be compared with the identical fingerprint in other trees of different ages.
For example, fingerprint X is clear at the end of one trees life, X may also be clear near the beginning of another trees life. The same fingerprint in both trees has to have happened at the same time, to have had the exact same growing conditions. Said younger tree grows older to produce Y fingerprint, which we then see in another young tree. We then have a timeline of trees and can say that tree A lived X many years before tree B, which was X many years older than tree C.
This can theoretically be accurate for millions of years but we don’t have enough petrified forests and so Dendrochronology is only useful for around 11,500 years
Similar methods can used in varves- layers of sediment laid down in glacial lakes which vary seasonally and annually. Similar methods can also be used in determining the ages of coral reefs, which have been used to determine the dates of ancient earthquakes.
Secondly, I will briefly explain radioactive dating. To start off, I will explain a few simple facts about atomic structure. You can skip this paragraph if you are confident with your knowledge of atoms and Isotopes.
Atoms consist of a nucleus and electrons, which orbit it. Around a billion atoms fit in a straight single-file line across the head of a pin. To get an idea of the scale of things, imagine that we swell the nucleus up to the size of a marble. The electrons would be the width of a hair, and 2 miles away, with the space in between empty of matter.
The nucleus is made up of Protons and Neutrons. The Protons have a positive electromagnetic charge, and the Neutrons have a negative electromagnetic charge, The number of Protons in an atom determines which element of the periodic table it is, regardless of how many Neutrons there are. The combined number of Protons and Neutrons give us the atomic number.
The states in which an element can exist with varying Neutrons (but the same number of Protons) are called Isotopes, and they have different atomic numbers. Some elements, such as Fluorine, have only 1 Isotope, whereas others may have more, such as Lead which has 5.
There are altogether 308 different Isotopes amongst the elements, 150 stable, and 158 unstable.
Now we go onto the part about radioactive decay and dating.
Some Isotopes are stable, but some are unstable, meaning they decay.
Two of the types of radioactive decay are when a Proton is replaced by a Neutron, (changing the element but not the atomic number) or vice-versa. For example the Isotope Potassium-40 (40 being the atomic number, determining the Isotope but not the element) is one step above Argon-40 in the periodic table, having one more Proton. If a Potassium-40 atom loses a Proton and gains a Neutron, it becomes Argon-40.
All unstable Isotopes have a half-life which we know. A half-life is the time it takes for half of any given amount of the unstable Isotope to decay. That is to say, if you have either a kilogram or a tonne of potassium, it’s half-life will remain the same. For potassium, its half-life is 1.26 billion years.
When volcanic rock solidifies, it contains potassium, but no argon at all. We know this as a fact. At this point of suddenly solidifying into igneous rock it begins to decay, very slowly.
Therefore, the ratio of argon : potassium is a very clear indicator of how long ago the rock solidified.
For example, if the ratio or argon : potassium is 1:3, that must mean that the rock solidified 630 million years ago (being decayed at half the rate of the ratio when its at 1:1 and therefore half of the time).
We can use this method as far back as 49 billion years with rubidium-87,
This is irrefutable science, and arguing with the logic behind it is simply either ignorant or perversely stubborn.
So now you have at least a vague idea of how we know for fact that certain layers of the earth have certain dates.
On to fossils.
Each layer has its given dates, and each layer’s fossils only show up in the dates that their evolutionary tree would suggest, and never before.
For example nothing remotely resembling a mammal has ever been found in Devonian rock. Never.
We also know, from the radioactive dating of igneous rocks found in association with the Devonian strata all around the world, that the Devonian ended around 360 million years ago.
Regarding human evolution, very much evidence has been found along the timeline that we evolved gradually. Aside from the fossils which show the stages of developing man, whilst being proven to come from certain dates, there is also much other evidence which shows our development into the people we are today. The following timeline was compiled from evidence gathered by many dozens of people all over the world, and the various methods of dating all agreed enough to place them at these dates.
2.5 million years ago- simple stone tools found
1.6 million - More complex stone tools, such as a skilfully shaped, symmetrical hand-knives
400,000- Earliest strong evidence of cooking and spears.
160,000- Fire is used to treat stone tools
120,000- signs of pigment use- emergence of symbolism in culture.
100,000- Shell beads give evidence of jewellery.
50,000- Cultural revolution- ritualistic burials, clothes-making and advanced hunting techniques.
35,000- An explosion of cave art in Europe first surviving statue of a woman.
10,000- Agriculture begins.
7,300- Horses are domesticated in Kazakhstan.
6,000- God created the world…???
5,000- Oldest known writing. Bronze age allows development of swords.
4,500- Great Pyramid build at Giza
420- Shakespeare’s plays first performed in London.
1 year ago- The Large Hadron Collider was turned on.
2010- Scientists succeed in trapping anti-matter.