Once again I am following a chapter in Jerry Coyne’s Why Evolution is True.
There is a pattern within Life that can be seen on oceanic islands. Species which are present are often endemic – only found in that one location. The species common to continents, on the other hand, are often not present on these islands.
In 1703, Alexander Selkrik was part of a plundering group that sailed to the Juan Fernandez archipelago, a few hundred miles off the coast of Chile (pretentiously pronounced “chill-a” by people not from Chile who like to pretend they’re so full of culture). He was voluntarily marooned on one of the islands (Mas a Tierra). He remained there for over four years. He hunted goats and utilized other species introduced by earlier sailors. Little did Selkrik know, his island (now named Alejandro Selkrik Island) was full of these foreign species.
On the island are five species of birds, 126 species of plants, a fur seal, and various insects which are entirely unique to the location. Equally notably, there’s a lot missing from the island. There are no native amphibians, reptiles, or mammals. Islands throughout the world show this same pattern.
Creationism wholly fails to explain the distribution of species – biogeography. It is only in the light of evolution that any logically tenable solution is found. Species are spread across the globe in patterns which follow the movements of the continents. For instance, plants which have a clear common ancestor are explained by the fact that Earth once was composed of a supercontinent known as Gondwana. It split into several sections. This divided species which had already split from one another, causing more adaptation (or extinction). One must believe in tremendous coincidences to just wave this away. That is, the evidence (the biggest foe of the creationist) says plate tectonics caused the movement of the continents which corresponds perfectly to the distribution of species. There is no other plausible explanation.
When observing the world’s biogeography, it is obvious that Australia needs some explanation. Why is it dominated by marsupial mammals while lacking so much in placenta mammals? Better yet, why is the rest of the world lacking in marsupial animals (except for the Virginia opossum)? The answer is in evolution. The animals on Australia show their common ancestry with animals elsewhere by their Class: they are mammals, just as tamarins are mammals. However, they show their divergence and evolution with key differences. Notably, the birthing process and raising of young differs drastically.
Now here’s a prediction that all this makes. Marsupials are found as early as 80 million years ago. Interestingly, they are not found at this time in Australia, but instead North America. With their evolution, they spread to South America about 40 million years ago. About 10 million years later, they’re in Australia. This means there was a connection of land from South America to Australia. The evidence bears this out. Geologists know South America was connected to Antarctica. That in turn was connected to Australia – actually, it was more like a cobble of connection; these continents were all part of Gondwana, deep in the Southern Hemisphere. So, to get from South America to Australia, marsupials must have passed over what is now Antarctica. Prediction: There should be fossils dating between 30 and 40 million years in Antarctica.
It shouldn’t surprise you to learn that, yes, there are marsupial fossils in Antarctica. And yes, they date from 35 to 40 million years in age. Again, a person has to believe in tremendous coincidence to reject this evidence. Geologists independently concluded that Gondwana existed and how it separated, and at roughly what times this all happened. Biologists then concluded that, if evolution is true, marsupial fossils must be presented in a particular location. They were right. Only in the light of evolution does this make sense.
Coyne goes on to explain islands, which I may address in the future. For now, I will leave the evidence at this point. The tremendously short attention span of people – creationists and rationalists alike – forces my hand.
Filed under: Evidence, Evolution | Tagged: Alejandro Selkrik, Alexander Selkrik, Australia, Biogeography, Chile, Continential drift, Jerry Coyne, Marsupials, Mas a Tierra, Only in the light of evolution, Plate Tectonics, Why Evolution is True | 1 Comment »