The case for Evolution.

I'd like to discuss the case for Evolution, and why I accept that it has been scientifically validated at every level. Evolution is often (erroneously) accused of having no evidence to support it. Clearly, it is a reactionary statement by creationists - who hear it time and time again, and feel that they can parrot it willy-nilly.

Firstly, before we delve into the evidence for evolution - I think we should state from the get go what evolution is NOT.

Evolution does not discuss the origins of life. If your argument against evolution is based on whether or not we have sufficient evidence for how life originated, then you're not arguing against Evolution I'm afraid - but against abiogenesis. (Which in itself is a fascinating topic, but not pertinent to the current topic)

Evolution is not where a dog turns into a cat, or where a crocodile turns into a duck. That is magic, and we don't believe in magic. We believe in gradual changes over long periods of time, which can eventually result in speciation.

So with evolution, over time you should find something like this:



And not something like this:



Fossil Record

When people think of Evolution, they think of fossils. While the fossil record at present is remarkable, it is not the most compelling evidence for Evolution. Or at least, not the only evidence for evolution.

We can look at the fossil record in two ways. One - is as an overall glance at how life advanced over 100's of millions of years. We see in the rock layers, the most simple forms of life in earlier rock, progressing on to fish, early amphibians, reptiles, mammals and birds and so forth..



We will never find humans before dinosaurs in the fossil record. Homo habilis will always pre-date homo sapiens in the rock timeline. And this is exactly what we would expect in a world with evolution by natural selection.

There are so many species that are well documented in the fossil record. The horse, fish to tetrapods, whale and humans are amongst these. The evidence for these transitions is clearly visible for anyone who wants to see them.

In human evolution, we see an increase in intelligence, brain-size, tool competency, and language over the course of a very long period of time all the way back to Australopithecus right up to modern day Homo Sapiens and less recently, Neanderthal. Creationists never really agree on which member of the Homo genus is man, and which is ape. What we do see however is a genus becoming less ape-like in it's traditional sense, and more human-like as time progresses. Homo erectus for example had an average brain size about 3 quarters the size of a human. So while these guys were not Einstein, they were clearly much more remarkable than the earlier Homo Habilis, who in turn was more intelligent than the even earlier Australopithecus Afarensis.

Typical arguments against the fossil record, always refer to the 'missing link'. There will always be missing links between any set of species. We are very lucky to have the record that we have. But that doesn't mean that we can't get a very solid picture with the fossil record that we have. We have a number of intermediary species, which give us more than ample information on the evolution of humans.

In the fish to tetrapod transition, we see weight bearing limbs gradually form over time along with a more tetrapod shaped head.



In the evolution of the horse, we see the animal grow in size, become more sturdier, turn from a multi-toed mammal, into a single-toed mammal, eventually into a hooved mammal.




Old traits that remain in modern species.

The idea of a flightless bird seems almost ironic. Why would a God create a bird if it could not fly? Would it not seem much more appropriate to give them the ability to fly, or to make them a mammal if they are going to spend all of their time on the ground? The real answer is that wings on flightless birds are vestiges of a time, when they could once fly. We know this based on fossil evidence and DNA analysis.

Some, like the Kiwi have wings so small that they are virtually useless. But we can see through natural selection why their wings would lose purpose. Having spent a large period of time in an area with little to no dangers on the ground - they had no need for flight. This can be of benefit to the Kiwi who can mobilise on the ground a lot easier than it's flying cousins.

A potential drawback of this however - anywhere where predators have been introduced to the areas of similar flightless birds like Kakapo, they have been hunted to almost extinction or indeed, total extinction. The problem is that evolution by natural selection doesn't happen overnight, and evolution by natural selection cannot occur quick enough to deal with a rapid threat, such as the instant introduction of a non-native predator like a cat. Once again, this is exactly what you would expect from Evolution.

Some other flightless birds, who may have lost their ability to fly - have not completely lost use in their wings. In Ostriches, we see that they have adapted their wings to serve a new purpose - balance whilst running at high speeds, for matural rituals, and for shading their young from the African heat. The penguin has obviously adapted their wings to allow them to swim.

So being able to fly is advantageous, but being more mobile on land, where there are no native predators or swimming swiftly in fish-filled waters can be even more advantageous where the habitat permits it.

We also see day's of an older time visible in other species. The whale is a great example. It curiously has a pelvis, and hind limb. If you go back slightly further to one of it's predecessor, Durudon - you see even larger limbs at 2 feet long - but yet surely spent all of it's time in the water. Even more curious is the atavisms that exist in Whales. 1 in every 500 whales is born with the remnants of it's old legs. Dormant genes which contain these features can be re-activated in an array of different species. Dormant genes from a time gone by where the Whale's ancestor had functional legs, and walked on land.



So it's clear - the evidence for evolution is compelling. Opponents of it either do not understand what the theory of Evolution states, or expect impossible evidence such as a step-by-step, fossil-by-fossil sequence of every animal that has ever existed from single-celled creatures to modern day humans. That is simply not feasible, given that fossil occurances are very rare. But it doesn't stop us from being able to build a picture - a picture that shows the important transitions.. The arrrival of early fish, the transition from lobe-finned fish to tetrapods, the evolution to reptiles, then to mammal-like reptiles, on to mammals.. The arrival of the primates is well documented, and their evolution right up to modern day homo sapiens.

So anyone who says there is no evidence for Evolution is either lying, or has not bothered to look at the evidence in an honest and rational manner. Some opponents even accept evolution within a species which they label 'micro-evolution', but 'macro-evolution' is simply micro-evolution over a much longer period of time, which results is a much greater and noticeable change.

Feel free to add any particulars to support evolution in this thread.