Something Fishy About Shark Evolution

In practically every book, magazine article and TV program about sharks, you will be told that sharks have remained virtually unchanged for millions of years. The hypothesized evolutionary history of sharks is a bit more complex than that, but there certainly haven’t been any major changes to the shark kinds (go to http://www.answersingenesis.org/get-answers/topic/created-kinds to find the out what a “kind” is) that can’t be explained by simple natural selection.

According to evolutionary interpretations of the fossil record, sharks first appeared in the Ordovician Period (450-420 MYA). Thus, by the evolutionary timescale, they evolved long before the dinosaurs (the order fits with Genesis, as sea creatures were made on day five and land animals on day six, but not the timescale).

A curious thing about the fossil record in regard to sharks: despite some minor differences, sharks appear to have always been… sharks. There isn’t even any fossil evidence of fish evolving from invertebrates – it’s all just speculation. Scientist believe that bony fish and chondrichthyes (cartilaginous fish) evolved from agnatha – the first fish. However, there’s no evidence of this. They simply infer it because of their prior belief in evolution. There is also no evidence of sharks evolving from early species of chondrichthyes. It’s as though for billions of years there are no sharks, then one day they appear, fully-formed (that’s not to say that the “early sharks” were the same as the species we have today. More on this later). The fact is, the simplest interpretation of the fossil record is that sharks are sharks and have always been sharks – they’ve simply changed a bit due to natural selection.

An important thing to note when reading long evolutionary fables about shark history is that many of the extinct sharks are known exclusively from their teeth (which are constantly shed throughout a shark’s lifetime and fossilize better than the rest of the skeleton), as cartilage doesn’t fossilize very well. There is so much variation in shark teeth among closely related species that one simply cannot use teeth as a means of gauging evolutionary development. There are a number of exquisitely preserved shark fossils (no doubt buried in Noah’s Flood – even the evolutionists admit that they would have had to have been rapidly buried), but none of them are significantly different from modern sharks. These scanty fossil remains do not attest to evolution. They don’t “tell” us anything about sharks in the past. This is not to say that useful information can’t be gleaned from studying them, but the fact of the matter is we have to interpret the evidence according to prior knowledge and beliefs. The fossils don’t speak for themselves. That’s why a single tooth might be given a complex evolutionary history – the scientists make an assumption based on their preconceived ideas. So although we can often make reasonable assumptions about these fossils, we will never be able to prove them since the past cannot be repeated, and is not available for observation. In the end, we base our interpretations of the evidence on our worldview.

“Molecular clocks” are an example of these underlying assumptions: scientists have used molecular clocks to measure mutation rates in sharks and trace back their divergence points. You see, mutations (which, by the way, DON’T add new information) are copying mistakes in the DNA, and are passed on from generation to generation. Scientists use these mutations as a kind of clock. For example, a species of fish is somehow split into two geographically isolated populations (meaning they can’t interbreed). Over time, new mutations will be accumulated, and each population will have its own set of unique mutations. To find out how long ago the two populations diverged, scientists would need to determine the average mutation rate. Once they did this, they could see how many different unique mutations there were among the two populations, and trace them back to the approximate time of divergence. Sounds all well and good, right? Well, not exactly, as this method involves several assumptions: first of all, they assume that the mutation rate remains constant. However, certain environmental factors can influence the mutation rate. Second, their method of calibration assumes the earth is millions of years old. For instance, geneticist Andrew Martin calibrated his molecular clock for sharks by comparing the DNA of two geographically separated populations of hammerheads who were supposed to have been separated around 7 million years ago by the rise of Isthmus of Panama. The problem is that the dating of the Isthmus of Panama relies on evolutionary principles. If this date is wrong, then it completely ruins the calibration of Martin’s clock.

So, when one has a biblical worldview, how do we explain the origins of sharks, the changes they’ve undergone, and their fossilization?

Well, the origin of sharks is recorded in Genesis: “And God said, ‘Let the waters swarm with swarms of living creatures[…]’ So God created the great sea creatures and every living creature that moves, with which the waters swarm, according to their kinds[…] And God saw that it was good. And God blessed them, saying, ‘Be fruitful and multiply and fill the waters in the seas[…]’ And there was evening and there was morning, the fifth day.” Genesis 1:20-23.

As strange as it may sound, sharks would originally have been vegetarian. This is because in God’s original perfect creation, there was no death (plant’s don’t “die” in the same was as humans and animals. You could destroy a plant, but it would still be “alive” in the sense that the pieces could take root and grow again). Unfortunately, Adam and Eve sinned, causing the whole of creation to come under judgment from a just and righteous God.

After the world was corrupted, animals began eating each other. Whether they were redesigned during the curse or carnivorous behavior developed as a result of natural selection is still a topic of debate. This brings us to the next question – how come sharks look different now compared to fossil sharks?

There are several reasons. First of all, God didn’t create each individual species when He made sharks. He would have created several “kinds” (the shark family seems too diverse to have originated from a single kind). Over time, natural selection (to find out more about natural selection – which is NOT evolution – go to http://www.answersingenesis.org/articles/nab/is-natural-selection-evolution) caused these original kinds to diversify, and give rise to new species of shark. The sharks we see in the fossil record would most likely have been buried during the Flood of Noah.

Some of these sharks were truly bizarre, such as Helicoprian, which appears to have had a strange spiral tooth arrangement; the megalodon, which grew to a formidable sizw; Stethacanthus, a shark with a strange flat surface on its head and dorsal fin (you have to see pictures of reconstructions to understand just how odd this shark was); Hybodus, which had strange tiny “horns” on its head; and Falcatus, which had a strange backward-facing spine in place of a dorsal fin.

These sharks are often referred to as “evolutionary experiments”. First off, evolution is a supposed to be an unguided natural process, so it can’t “experiment”. However, when trying to explain the incredible design and diversity seen around us, scientists usually end up personifying evolution by talking as if it possesses forethought and purpose. The second problem with this statement is the implications that these sharks were somehow inferior and unsuccessful (a natural assumption for an evolutionist, since they believe that evolution is constantly improving everything). How do we know these creatures were unsuccessful? In a biblical framework, the mostly likely view is that these sharks were the result of natural selection acting on information present in the original kinds, and that these particular types of shark went extinct during or shortly after the Flood. Those sharks that did survive the Flood gave rise to our current shark families (there are a number of still-living shark species represented in the fossil record, such as frilled sharks).

Another important thing to note is that although most current species seem rather boring in comparison to their fossilized relatives, there are still some very weird sharks alive today, such hammerheads, whose name is pretty much self-explanatory; the goblin shark (which was originally known from fossil remains, and believed to have gone extinct 100 million of years ago, until it was caught by Japanese fishermen), which has a long protrusion on the end of its nose; the megamouth, which is the third largest species of shark and whose mouth is out of proportion to the rest of its body; the carpet shark, which is covered in coral-like appendages; the thresher, whose upper caudal fin is very long; the eelike frilled shark; and the enormous whale shark (the largest living fish), a harmless filter feeder covered in white spots and stripes. The shark family is still very diverse – just not as diverse as in the past, which fits with the Creation but not evolution.

When one looks at how well-suited sharks are for their environment, how perfectly designed they are, and how beautiful (in their own, sadly sin-cursed, way) they are, one cannot help but feel awe for their Creator, Who made us as well, and loved us enough to send His only Son to die for us so that we might be redeemed.

Sources:

http://www.elasmodiver.com/elasmobranch_evolution.htm
Sharks and Rays: Fish With No Ancestors by Robert Doolan, Answers in Genesis.com.
http://www.sharks-world.com/shark_evolution.html
http://www.elasmo-research.org/education/evolution/evol_s_predator.htm
Sharks: Denizens of the Deep by Paula Weston, Answers in Genesis.com.

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