The Tasmanian Wolf
This incredible example of convergent evolution has been extinct since around 1936. Despite its name, the Tasmanian wolf isn’t a dog at all. It is actually a marsupial! That’s right; It has a pouch, and is closely “related” to the kangaroo. Some people say it hopped like one on occasion, but this is un-confirmed. So how in the world did a dog get a pouch? Or otherwise, how did a kangaroo evolve into a perfect dog impersonator? Scientists are still puzzled. They claim that the similarity is the result of marsupials filling in the vacant position of dogs (who weren’t around yet) in the Australian eco-system.
Problem
Unfortunately, there are any number of designs for animals that I’m sure could have roughly the same effect as a canine on an eco-system. Not only that, every eco-system is different, making it even less possible that natural selection could have fine-tuned a perfect dog look-alike. So really we have to rely on blind chance to magically create two extremely similar species with different DNA and internal anatomy. I don’t think so. Another case of convergent evolution, and another stike against to the entire hypothesis of evolution.
Problem
Unfortunately, there are any number of designs for animals that I’m sure could have roughly the same effect as a canine on an eco-system. Not only that, every eco-system is different, making it even less possible that natural selection could have fine-tuned a perfect dog look-alike. So really we have to rely on blind chance to magically create two extremely similar species with different DNA and internal anatomy. I don’t think so. Another case of convergent evolution, and another stike against to the entire hypothesis of evolution.
6 comments:
No animal has evolved from the kangaroo, and in fact there are any number of marsupials living in the southeast hemisphere of the world including koalas, kangaroos, pandas, and tasmanian wolves. The theory of evolution specifically states that you cannot get a new species from a species that is still living. So you are absolutely right when you think it impossible that these tasmanian wolves evolved from kangaroos. What evolution tells us is that all of these marsupials who live in approximately the same corner of the world evolved from a common ancestor. Evolution does not even stay that each species fits the niche of its eco-system perfectly. There are no "fine-tuned" species anywhere in the world as that would imply an endpoint in a species development and it has been shown that stagnation in adaptation leads to extinction. What we have in the case of marsupials is a number of isolated populations who through generations of breeding have created the created recognizably different species at this point in time. As far as calling the Tasmanian marsupial a wolf, you are correct that it is not a canine but you cannot then say, "how in the world did a dog get a pouch?" because a dog didn't get a pouch as you pointed out earlier in the blog. In conclusion, evolution states that these isolated populations of marsupials have developed through different combinations of ancestral DNA (even though Darwin had no concept of DNA, he called it inheritence) to create the current forms of animals inhabiting these regions.
Right, but no matter who the Tasmanian Wolf's ancestors were, to assume that evolution randomly generated such similar outer features from two different animals is ridiculous.
If you are having trouble discovering what evolution tells us about HOW life came about you are looking in the wrong place and are misunderstanding the purpose of Darwin's theory. Darwin's theory of natural selection no more tells HOW natural selection works than Isaac Netwon's theory of gravity explain HOW gravity functions. To discover the particulars of how natural selection works you need to look at the other disciplines of science; namely genetics, biology, and paleontology. Darwin's theory of natural selection has held up as the correct view of the world because findings in the other areas of science have corroborated what one would expect to find under Darwin's theory. Much like proofs of Einstein's theory of relativity showed how gravity worked and that Newton's view was correct. If other areas of science had not corroborated Darwin's theory it would have been dismissed out of hand. But each of these other areas of science have proven that we have inheritable traits that magnify themselves through successive generations. If you think that it is ridiculous that a certain form came about, you can't ask evolution to explain. You have to look at the other avenues of science for the answer to the how.
No, I’m not confused about natural selection. Darwin’s theory of natural selection is totally viable, and we see it working all around us, even if we don’t know exactly how it works. Maybe you misunderstood what I’m trying to communicate. It is not impossible that natural selection could have produced the Tasmanian wolf. However, it is extremely improbable. This, combined with other examples of convergent evolution set odds, that no random mutations could achieve. It would be like a tornado blowing through a junkyard, and assembling not one, but two or more similar 747 jumbo jets. And since we know the odds of just one jumbo jet being assembled, (or the odds of one creature evolving into a different creature through a gain of information), are impossible, the odds of two jets (or the odds of two separate ancestors producing very similar creatures through a gain of information) cannot be possible, and are in fact, even more impossible.
I would just like to point out the glaring problem with the tornado-plane analogy. A junkyard is not a living system and mixing random junk together via tornado does not create the evolutionary advantages that mutations in creatures can create over the course of years. The idea that mutations cause advantages is an essential component to natural selection, one that is entirely missing from the tornado-plane analogy.
The idea of odds are a very tricky subject because of the susceptibility of numbers to interpretation. Honestly, the chances that we would see any particular form of a species in the present day is a billion to one (estimate) no matter what form is here. However, given enough pathways SOMETHING has to happen. There are a nearly infinite number of ways in which a species MAY evolve, so which path it chooses becomes irrelevant. Take the example of dice. The odd that you roll a two on any turn is 1/6. However after you have rolled the odds that you have a number 1-6 is 100%.
Hey Sean,
the reason that the idea “mutations cause advantages” is not incorporated into my analogy is because science has never observed a beneficial mutation. Evolution depends on beneficial mutations and natural selection causing increasing complexity in creatures (Junk to Jet). The problem is, mutations are not guided by the living creature’s DNA as in micro-evolution, and instead work against natural selection. Mutations that we observe today always cause a lack of information, and sometimes, (very rarely) cause a destructive gain in information. Evolution depends on infinite odds, and so you could dismiss this, and say that given enough time, beneficial mutations would happen, and stack up enough to derive all the species we see today. The problem with this is that our planet could not have sustained life for even 250,000 years, in fact, thirty million years ago our sun would have been so big, it’s surface would be touching the earth! In fact over 80 % of the ways scientists measure the age of the earth show that the earth could not be over 10,000 years old.
Regarding what you said about odds, you are right in saying that given enough pathways, virtually anything can happen. You will excuse me, but this is what evolution seems to depend on. However, you are assuming ON FAITH that there are thousands of pathways. Life perhaps could be in an entirely different form and still survive, but you cannot prove that. Certain things like gravity, oxygen to nitrogen ratio, atmosphere, and many other things effect what type of life can evolve on a planet, and the form of life that was created on our planet may be the only form suited for the earth’s environment. But, if your assumption is correct, the odds that life evolved could be cut down to a thousandth of the original number. You said the chance of any life hear on earth are “a billion to one” but did you know that the chances of the simplest protein essential to life being randomly formed are 1 in 10 with 152 zeros following after? And there are hundreds of different proteins needed to form even the “simplest” form of life. Cutting this number down to a thousanth of the original number hardly puts a dent in the odds. It is still considered imposible by mathmaticians.
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