The Meerkat of Science!: Dating
Right, I should mention that this post has nothing to do with the science of romance! Nor I am not the best person to ask for dating advice! I’ve not been too sure how to classify this post, since it is also a response of sorts, and it might look at the problem of creationist pseudo-science as well.
What I instead refer to is how people date the past. Archaeologists – good ones at least – have a variety of tools at their disposal, and will use them to get a reasonable idea as to how old any given set of remains is. It does not give one hundred percent answers, but that doesn’t mean those answers should be rejected. Science is rarely about absolutes. In most fields, be it biology, chemistry or physics, we are constantly learning. New experiments lead conclusions both expected and unexpected, which in turn lead to new tests, which lead to new conclusions, and so on.
The same is true with studying the past. We learn stuff that we might expect, and also that we don’t expect, but what we don’t do is throw the baby out with the bath water if an experiment yields something we didn’t expect, or for whatever reason, don’t like.
Creationists tend to do the latter. They start with a conclusion – basically working entirely against sensible scientific methods – and try to force the facts to fit their conclusion. With more and more evidence leading away from creationism – be it studies of earth and fossils, or the cosmos at large – creationists are becoming more desperate and dogmatic, but this does not make their arguments any more logical or fact-driven.
Instead, they resort to dishonest attacks on scientific processes. There are a number of dating methods that good archaeologists use to learn about the past. To quote this post, written by one Tracy V. Wilson:
The most widely known form of radiometric dating is carbon-14 dating. This is what archaeologists use to determine the age of human-made artifacts. But carbon-14 dating won’t work on dinosaur bones. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old. Dinosaur bones, on the other hand, are millions of years old — some fossils are billions of years old. To determine the ages of these specimens, scientists need an isotope with a very long half-life. Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.
Unfortunately, these elements don’t exist in dinosaur fossils themselves. Each of them typically exists in igneous rock, or rock made from cooled magma. Fossils, however, form in sedimentary rock — sediment quickly covers a dinosaur’s body, and the sediment and the bones gradually turn into rock. But this sediment doesn’t typically include the necessary isotopes in measurable amounts. Fossils can’t form in the igneous rock that usually does contain the isotopes. The extreme temperatures of the magma would just destroy the bones.
So to determine the age of sedimentary rock layers, researchers first have to find neighboring layers of Earth that include igneous rock, such as volcanic ash. These layers are like bookends — they give a beginning and an end to the period of time when the sedimentary rock formed. By using radiometric dating to determine the age of igneous brackets, researchers can accurately determine the age of the sedimentary layers between them.
Using the basic ideas of bracketing and radiometric dating, researchers have determined the age of rock layers all over the world. This information has also helped determine the age of the Earth itself. While the oldest known rocks on Earth are about 3.5 billion years old, researchers have found zircon crystals that are 4.3 billion years old [source: USGS]. Based on the analysis of these samples, scientists estimate that the Earth itself is about 4.5 billion years old. In addition, the oldest known moon rocks are 4.5 billion years old. Since the moon and the Earth probably formed at the same time, this supports the current idea of the Earth’s age.
To put it in other terms, scientists know the ages of the rocky material that dinosaur remains have been found in, thanks to the behaviour – and known quantity – of radioactive isotopes. This technique may not be able to draw conclusions like ‘this dinosaur is precisely 97,874,321 years old’, but it can tell us that any given species would have lived between say, 99 and 96 millions of years ago. This same geological record is the reason we know of different epoches, and the method for learning about it is a proven one.
The bottom line is, we know dinosaurs existed. We know, from advanced methods of study, when they existed. We know how they died out, and we know when they died out. These conclusions are driven from a neutral observation of the world around us, as opposed to being driven by a biased desire to force evidence to fit a pre-determined conclusion (or worse, ignoring evidence completely).
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