Discovering Religion: Episode 7 – Transitional Species
Darwin predicted that if his theory of natural selection is correct, we should find fossils of animals in so called “transitional forms” that link primitive species to more modern, evolved ones. However, the concept of a transitional species appears to be a common source of confusions for many creationists.
To properly understand what is meant by an intermediate or transitional species, we must first realize that almost all animals presently living on the Earth, with a few exceptions, are considered to be modern species. This means, if you were to travel back 65 million years ago just about every animal you recognize today would not yet exist. Theists that know very little about the process of evolution often ask questions like:
“My question. Where are all the monkeys? If mankind is truly descending from monkeys, it would stand to reason that occasionally a man and woman would have recessive ‘monkey genes’ and occasionally you would see a child born that was a monkey. 100% monkey.”
What we classify as monkeys, apes, and human beings, all belong to different species that for millions of years have evolved along their own, individual evolutionary lines. Evolution predicts at one point in time all members of the Hominidae family shared a common ancestor within a population, which became isolated from one another, giving rise to the divergence of many different species as we all continued down separate paths of adaptation and evolution.
Humans and apes shared common ancestors within a population that became isolated from one another, giving rise to the divergence of our two species as we continued down separate paths of adaptation and evolution. For some reason many Creationists cannot seem to get a handle on this concept.
In their flimsy attempts to discredit the Theory of Natural Selection, creationists often select two modern forms of animal species, which have nothing to do with each other’s evolutionary development, and challenge scientists to demonstrate proof of an intermediate form.
“Because of the fact that I was once an atheist, so I know how they feel and how they think. And when you’re confronted with the evidence and you approach it with honesty and sincerity it’s a no-brainer, God exists. And that’s what I’m hoping. People who are confused about the subjects because of guys like Dawkins will watch this and go, ‘You know what? This is so simple a child can understand it.’ Plus! Darwin said in order to prove evolution, which is the number one alternative to God, you’ve got to be able to prove transitional forms. One animal transitioning into another. And all throughout the fossil record and life, we don’t find one of these. A ‘crocoduck’! There’s just nothing like it! There is no one animal transitioning into another.”
Not only does Cameron pull this shtick on the O’reily Factor, he tries it again in a nationally televised debate on evolution.
“Science has never found a genuine transitional form that is one kind of animal crossing over into another kind, either living or in the fossil record, and there is supposed to be billions of them. Now what I am about to show you does not exist. These were actually created by our graphic artists, but I want you to keep your eye out for this because this is what evolutionists have been searching for hundreds of years. Alight? And if you find one of these you could be rich and famous. So here are some transitional forms. This is called the ‘crocoduck’. Do you see this? Oh my God, what a numb nut. A crocodile and a duck. Alight lets try another one. This is the bullfrog. Half bull half frog. Or of course the sheep dog.”
It is clear most creationists do understand even the basic of evolution, nor do they care to know. For if they truly understood what the theory of evolution explains they would be held accountable to refute this evidence with logic, with reason, with contradictory evidence. Therefore, it is much easier for creationists to wall themselves off from logic by making outrageous claims and speculations, without ever attempting to perform an experiment or to even check the facts.
Yet, despite creationists incessant claims that scientists have never produced proof a transitional species, there is a vast array of fossils that are shown to be a link between one form of animal and another. One of the most important milestones in evolution took place 400 million years ago when animals made the exodus from the water onto land.
Until recently, little was understood about the transition of primitive fish into terrestrial tetrapods. Most text books hypothesized fish first came on shore then developed legs; however, Jennifer Clack of Cambridge University suspected the explanations given in many text books were inaccurate.
“You’ll find in many of the old text books, the pictures that you’ll see in books, children’s books, and museum galleries, is a picture of a fish stranded in a drying pool trying to support itself out of water. And it looks really odd if you look at it objectively. “
Through exhaustive digging and total of 4 years of drilling through 4 tons of rock, Clack was rewarded with the most complete early tetrapod skeleton ever found, and it forever changed the textbooks.
It had a fish-like tail and gills for breathing in the water, but at the end of its limb was an unmistakable array of bones, shaped like a peddle; possibly the first hands on Earth. The creature was named acanthostega. Clack’s find was a scientific breakthrough, for it demonstrated that some fish developed limbs in the water before they moved onto land.
The evolution of limbs on aquatic fish-like animals aided their attempts to seek out new sources of food and different habitats to exploit. Therefore, it was only a matter of time before animals moved on to land, and adaptations that allowed them to remain on the surface for longer periods of time were passed on to the following generations, giving rise to many new species of life. For example, the development of a egg shells allowed reptiles to be independent of the water, where their ancestors, such as amphibians, remained tied to the water for reproduction.
Over the following hundreds of millions of years, dinosaurs of all shapes and sizes ruled over the world. Mammals, on the other hand, remained small and mostly nocturnal. However, 65 million years ago a meteor struck the Earth, causing global devastation and the mass extinction of many species. Due to their small size, mammals were able to hide in the ground and survive the blast, destined to become the Earth’s dominant life form once the devastation had cleared.
After the impact the climate had become much hotter and tropical forests covered the entire world. Animal life during this period shared a common feature, their size. Almost every creature over 20 lbs had been whipped out. However, with time mammals became larger and began filling every available niche, including the ancient oceans. Three hundred million years after acanthostega first came ashore, mammals began returning to the water.
Pakicetus was a carnivorous predator that lived and hunted along the shores of the ancient seas. Perhaps this animal found the water as a source of abundant food and a haven from competition. For, eventually this mammal, ambulocetus, would come to dominate the waters in a period known as the Eocene, some 50 million years ago.
This was one of the earliest ancestors of the whale and over the next 10 million years the decadence of ambulocetus evolved into refined water dwellers, their limbs becoming flippers and their tail becoming a fluke. In the late Eocene, some 35 million years ago, there lived several species of whale that still retained their vestigial legs.
Dorudon lived in vast numbers throughout the ancient oceans. This animal perfectly exemplifies an intermediary in the line of whale evolution, not only because its displays vestigial limbs, but also due to the location of it nostrils, found midway on its skull, between its snout and the top of its head. However, dorudon was not the only large whale patrolling the ancient waters.
Basilosaurous, measuring 60 feet and weighing 60 tons, was the top seafaring predator of its day. Despite basilosaurous’s purely whale-like appearance, this animal also had two small hind legs, a vestige of its terrestrial ancestry. Although these appendages were useless for walking or even swimming, it is believed these oversized creatures used their legs to stabilize themselves during the mating process.
As the Eocene period came to an end, a great climate change took place. The poles of the earth began to freeze, producing erratic shifts in weather, changing the ocean currents and causing the death of up to 20% of the Earth’s animal life. Giant predators like dorudon and basilosaurous could no longer be sustained; however, the whale group as a whole survived and have flourished within the oceans until present day.
It is important to note not a single species of modern-day whale displays hind legs. Cleary, the benefits these appendages offered their ancestors were so negligible that the ability to become more streamlined by losing their legs was of a much greater advantage. Although anti-evolutions like to claim these hind legs were vitally necessary structures used in mating, why do we not observe a single species of whale with them today, for modern-day whales are just as big and cumbersome, if not more so, than their ancestors such as durodon and basilosaurous.
Fossils are not the only evidence of whale evolution, their ancestry is also visible in the way they move. Fish swim by flexing their spines from side to side, like this shark. But mammals swim differently. This otter swims by undulating its spine up and down. The same way that whales do. And, as it turns out, the same way that land mammals use their spines when running. Animals took with them in the water their ancestral way of moving. And we can still see it, 50 million years later.