Evolution is a Fact #11 - Tiktaalik
Lovely set of facts. If it don't convince a creationist it should sure make him uncomfortable.
So he figured because he couldn't live outside of that thar water the way his body was designed-and-all that he would have to re-design his body... - EQV
This is a common misunderstanding about how evolution works. Average Joe made very similar point last week.
No creature ever adapted to it's environment or made a decision to change it's own phenotype.
Evolution is something that happens to populations of similar creatures. It is about changes in the frequency of alleles in a gene pool.
Early fish had fins that were supported by rays of fine bones. The genes that code for the proteins that build those bones are controlled by other genes that switch them on and off. A random mutation in one of those switches could result in a bone growing differently resulting in a longer or thicker bone. An individual with stronger fins would enjoy a slight advantage in swimming ability, catching prey, escaping predators or moving through shallows to deeper pools.
Future generations of descendants of this individual may experience further mutations building on the strength of their fins and gaining further advantage. These then leave more copies of these genes in the gene pool and so on. Each small change accumulates over millions of generations.
Notice both the earlier fine fin-ray bones and the beginnings of larger bones can be seen in the skeleton of Tiktaalik. These eventually became the pattern of large and smaller bones we see in all tetrapods today. This hybrid form of fins along with a combination of gills and lungs makes it a fantastic example of a transitional form between fish and amphibian.
In fact the whole succession of changes from ray-fin fish through lobe-finned fish to early amphibians can be seen in the fossil record. I will describe some of the details in a future post.
This principle applies everywhere in evolution. Gradual random changes that offer a slight advantage are favoured by natural selection and result in larger changes in the phenotype.
Hope that helps.
EQV I enjoyed your “ Just so” story about Tiktaalik, however except for the sarcasm, you make a good case of how illiterates must have interpreted things they found and had their ideas written down as holy truth.
For a more convincing illustration of evolution’s reality, might I recommend the philosopher Daniel Dennett in his book Darwin’s Dangerous Idea. He likens the process of evolution to a heartless tennis tournament where the losers are shot and the only winners go forward together to breed (Djokovic breeds with Williams!) The aberrant lizard types were the only ones physically equipped to survive the specific conditions in the lagunal backwaters where Tiktaalic was found, the fishy types all died in that environment. Amphibians rule!
The point being that no organism adapts itself... it's simply death before breeding if you can't cope with the environment. Life on Earth is a biological death and destruction derby whether you like it or not.
I LOVE reading anything and everything I can about evolution, so thank you for these posts Cofty! Can't wait for number 12!
I am very grateful and thankful for all these posts on Evolution.
Thanks cofty. Substantial food for thought and reason.
Next thing you are going to tell us that Alligators and Crocodiles are actually real. Ha
These sound like insurmountable problems, but if evolution is true there must have been creatures that made the leap successfully. In 2004 Neil Shubin and his team set themselves the challenge of finding exactly this transitional fossil. What they discovered was astonishing.
Their success was not entirely down to good luck. The critical time period was already known. Fossils from rocks 385 million years old all look like fish, younger rocks dated at 365 million years old reveal fossils that are all recognisably amphibian or reptile. To find a relative of the transitional species between fish and land-dwelling animals Shubin knew he had to concentrate on rocks that were 375 million years old, preferably laid down in an ancient river or stream and which were now exposed on the surface.
And along comes Tiktaalik. Proof of transition from water dweller to land dweller. Amazing. So much information from one fossil.
A picture is brought into a court room. A snap shot of a man. We'll call him Joe. Three lawyers are going to give their argument to the court based on one picture. Each will use the picture to prove something completely different.
Lawyer 1 will prove that Joe was walking forward when the picture was taken.
Lawyer 2 will prove that Joe was walking backward when the picture was taken.
Lawyer 3 will prove that Joe was neither walking forwards or backwards when the picture was taken. He was motionless.
The judge dismisses them all. None have proven their case. No matter what colourful language and illustrations they used they do not have sufficient evidence. After all, it is only a picture.
Why would anyone jump to the conclusion that transition from water dweller to land dweller is taking place, from one fossil? Why could not a similar case be given for this fossil proving transition from land dweller to water dweller? Why not a strong case for an animal, complete and able to function just fine the way it is?
Why would anyone jump to the conclusion that transition from water dweller to land dweller is taking place, from one fossil? - EQV
Nobody does that.
We have a whole line of gradual evolution from fish to fish-like amphibian to amphibian to amphibian-like reptile to reptile. These display a line of step by step change from fins to limbs, the development of a neck, the evolution of the inner ear that can hear sounds in air and the change from gills to lungs.
Have you heard about Eusthenopteron, Panderichthys, Acanthostega, Ichthyostega, Tulerpeton Ceratodus, Chinlea, Dipnorhynchus, Dipterus, Gooloogongia, Griphognathus, Gyroptychius, Holoptychius, Hyneria, Macropoma, Mandageria, Osteolepis, Rhizodus or Strunius? Some of these are known from thousands of specimens.
Would you like me to describe the amazing transitions that these display?
Why could not a similar case be given for this fossil proving transition from land dweller to water dweller?
So are you suggesting that a species can evolve that way but not the other?
Why not a strong case for an animal, complete and able to function just fine the way it is?
Every one was a exactly that. Every animal that has ever lived is a transitional form.
This is a really important point. Nothing is ever on a mission to become something else, every creature has evolved to prosper in its own environment.
How about doing some research, would you like some suggestions for further reading?
Cofty, as your reply to EQV shows, to understand the concept of evolution you have to get down to the nitty gritty of the details. This means knowing about the actual species involved and their characteristics and dates of arrival in the geological column. The analogies and illustrations used by creationists do not dare to recognise the simple logic of the 'connectedness' of all living things.
Religious belief however eclipses reason...............