On my last post, there were a number of comments, but I wanted to highlight one thing Cliff wrote. I thought that this part of a comment he left was worth a full response. Quoted directly: “We can pound Gov Perry for pandering to those of his supporters who don’t believe in evolution. But, in fact, if God created the whole shebang six thousand years ago, how would we know? I don’t think that is the way it came to be, but I would not dismiss someone who did.”
Before I get into how we know the creation hypothesis is incorrect, I would like to address a more philosophical point. We live in a culture that encourages us to have strong opinions, be it about whether politician X should be president or whether Jersey Shore can be considered “culture.” Is this a good thing? Maybe, maybe not. It is good to disagree; it keeps life interesting and ensures that we are exposed to many different viewpoints. Currently in our culture, there are several disciplines of science that are subjected to this type of handling. I would argue that this does a great disservice to our society.
Unlike opinions on politicians or TV shows, scientific arguments are fundamentally data driven. This is not to say that there are not philosophical arguments; there are and they are vitally important, such as the paradigm shift from thinking that natural selection acts on the individual to thinking that it acts on genes. But ideas such as these represent new ways of interpreting existing data. For opinions to be formed, you must first examine the data and then decide whether you accept it or reject it. This is difficult enough for scientists, never mind a layperson. The explanations that make their way to pop science books, even the best of them, are too broad and too lacking in nuance. It takes a lifetime of dedicated study to truly understand even one sub-discipline. And yet we as a society are not humble when we debate scientific ideas. Everyone has an opinion, often formed on the basis of what the pundtocracy says. This is a problem for both the left and the right, whether it be about vaccines, climate change, or evolution. In science, opinions require evidence. We ignore that in our public discussions; rhetoric is far more persuasive. I cannot speak for anyone else, but I approach any new idea in science in two ways. The first is to remind myself that I am not an expert and the person who wrote the paper generally is. The second, which is how science is taught in college, is to assume that there are problems with the paper and to look for them. No ideas are perfect; reality is complicated. Even papers that are published in premiere journals have flaws. With that being said, these papers are (usually) mostly correct. It is from this approach to data that opinions about scientific ideas should be drawn.
With that introduction, I would like to directly address the comment. In particular the question “how would we know” because, while the answers are well established, they are not well known in our society and are often not taught to our children in school. Rather than deal with my own field of evolution, I would like to address the other aspect of creationism: the idea that the Earth is the product of special creation and is relatively young (say, less than 10,000 years old). This is an opinion that is common in our society; depending on what poll you look at, up to 40% of our country agrees with that sentiment. But it is an opinion not founded on data. Below I will explore three of the entirely independent lines of evidence available to all of us.
I will begin with the cosmological evidence. When we look through our telescopes, we are looking back in time. When you gaze upward at the Sun you are seeing light that is a little more than 8 minutes old. This is because of one of the laws of nature: the speed of light is finite. We know it to be roughly 186,000 miles per second. The distance light travels in one year is termed a light year. Combine this with the knowledge that space is expanding and we can form a testable hypothesis: if the universe was specially created in the past 10,000 years, we should not be able to see objects that are more than 10,000 light years away. This is, of course, not what we see when we look through telescopes. The nearest galaxy to our own, Andromeda, is 2.5 million light years away. We can infer from our observational data that the universe is roughly 13.75 billion years old. I would like to stress that this is a well established idea among scientists and there has been no evidence presented that suggests it is false.
A separate line of evidence is based on the idea of radioactive decay and the use of radiometric dating. Certain elements are unstable and thus experience what is known as radioactive decay until an atom reaches a stable state. For example, carbon-14 decays into nitrogen-14. Another example is the decay of uranium-238 through 13 other states before becoming lead-206. The reason radioactive decay is significant is that each unstable isotope has what is known as a half-life: the amount of time for half of the element in a given sample of matter to decay. Each half-life is measurable and is distinct for each element. In the case of uranium-238, its half-life is 4.5 billion years, whereas lead-210, an intermediary between uranium-238 and lead-206, has a half-life of 160 microseconds. Because there is such a wide range of radioactive clocks available, we can not only date objects found, but we can also use several independent measures to date the objects. Based on meteorites found on Earth, meteorites found on Earth that originated on Mars, and rocks found on the Moon, scientists have determined that the Earth is 4.54 billion years old. However, there is another way of corroborating this. Our Sun is what is known as a G-series star. We can observe other G-series stars with our telescopes and these stars are at varying stages of their life spans. (Over time, the size and luminosity of stars change). Because of this, we know that the Sun is 4.57 billion years into its life cycle. Soon we will be able to observe planets forming around other stars and provide a similar corroborating check on the age of the Earth.
The final line of evidence I will highlight is biological, meaning that I am far more comfortable talking about this. All life that we have discovered on Earth encodes its genetic information in DNA (with the exception of most viruses, which use RNA, but for our purposes there is no real difference). Let’s start with a simple example before we delve too far into this. Let’s assume you have one brother and one cousin. All three of you look fairly alike, but you are closer to your brother than you are to your cousin. Or put another way, you all have nearly identical DNA, but your brother’s DNA is closer to yours than your cousin’s is. Now let’s change the time scale to hundreds of millions of years. We know that all species share a common ancestry from at least 3.8 billion years ago. Obviously over time we have diverged; you do not look or behave like your pet dog, never mind the trillions of bacteria in and on your body. This is because DNA mutates over time. One particular type of mutation is relevant here: silent, also known as neutral, mutations. DNA is made up of pairings of four nucleic acids. These pairings form groups of three known as codons, which encode for particular amino acids, which in turn form proteins, which perform functions in your cells. There are twenty amino acids. If you do the math, you realize that several different codons code for the same amino acid. A neutral mutation is one in which the codon changes, but the amino acid stays the same, meaning that there will be no selection for or against the mutation because there is no change in the effect of the codon. This means that neutral mutations will accumulate in genomes at a particular rate. This concept is known as the molecular clock and is used to determine how long ago two (or more) species diverged. This is compared to fossil evidence, which is radiometrically dated, to confirm the accuracy of the molecular clock. I will leave it at one example. Our closest living relatives are chimps. We know from both molecular and radiometric clocks that we shared a last common ancestor with chimps 5 to 6 million years ago. That is a bit more than 10,000 years.
I know this has been a long post, but thank you if you are still with me. I would like to end with explaining why all of this matters to you. There are two sets of reasons. The first is the rather mundane and practical. Much of modern medicine is based on concepts that are true because evolution occurred and continues to occur. And all electronics and nuclear physics are based on the same concepts that tell us how old the universe is. In other words, our society is completely dependent on these ideas, yet many of us reject them. It matters if voters do or do not understand why overuse of antibiotics in livestock is a dangerous practice. It matters if voters do or do not understand that the next deadly virus will probably arise in poverty-stricken bushmeat hunters in Africa. And while it does not really matter if you understand how your computer works or not, society would not be able to function unless a few people did.
For the second reason, I must defer to Carl Sagan and quote him at length. In an essay published in 1995, Sagan wrote, “The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what’s true.” However, this is not meant to be a negative message. In his 1994 book Pale Blue Dot Sagan wrote, “…if our objective is deep knowledge rather than shallow reassurance, the gains from this new perspective [science] far outweigh the losses. Once we overcome our fear of being tiny, we find ourselves on the threshold of a vast and awesome Universe that utterly dwarfs – in time, in space, and in potential – the tidy anthropocentric [universe] of our ancestors.” Truth matters and, as we have found in every discipline of science, truth is far more inspiring than anything our ancestors imagined.
But why does our sense of awe and wonder matter? Pale Blue Dot gives an answer: “The visions we offer our children shape the future. If matters what those visions are. Often they become self-fulfilling prophecies.” To ensure the future vitality of our society we must provide our children with something to dream about. One tiny subdiscipline of one branch of science can provide any child with more than a lifetime’s worth of dreams. In his comment, Cliff wrote that he would not dismiss someone who did believe creationism. I think dismiss is the wrong word; pity perhaps. But any given individual’s beliefs matter less than society’s as a whole and a society that does not embrace the knowledge discovered by its scientists is consigning itself to decay and decline. The golden ages in history centered on science and invention. So let us inspire our children with the truth. It is the surest guide to the future success and prosperity of our country.