Undeniable by Bill Nye Page A

way, is DNA, or something much like it, an essential feature of life? The only way to find out is—to find out.
    But for certain people who hold a creationist point of view, life’s common chemistry paints a completely different picture. They claim it indicates that we are all the product of a designer who made everything according to the same plan, all at once.
    That line of reasoning also leads to questions—but they’re the exasperating kind. If there was a designer, why did he or she or it create all those fossils of things that aren’t living anymore? Why did the designer put all these chemical substitutions of radioactive elements in with nonradioactive elements? Why did a designer program in this continual change that we observe in the fossil record, if he or she assembled the whole system at once? In short, why mess around with all this messiness? If you’re a creationist reading this, and you want to remark something like, “Well, that’s the way he did it,” I’ll tell you right back, that is just not reasonable, nor is it satisfactory. If we were playing on a team right now, I’d say, “Get your head in the game.”
    Another thing: If there were a designer, I’d expect some better results. I’d expect no common cold viruses, for example. Or, if viruses are an unavoidable or accidental consequence of a designer designing with DNA molecules, I would hope that we’d be immune to those accidental viruses. If the argument is, “Well, that was all part of the plan,” then I have to ask: How can you take the lack of evidence of a plan as evidence of a plan? That makes no sense.
    Rather than ascending a tree, I like to think instead of a life moving along a time line, akin to my walk through time across the United States. This “Tree of Life” grows sideways, with time going from the distant past on the left to the present day on the right. Whatever we do to understand the branching pattern of a tree of life, we are working backward. We examine fossils and do our best to assess the age of the rocks in which the fossils are preserved. How else can we do it? We are constrained by the nature of time to start with where we are today and work our way farther and farther into the past, noting branches on a Tree of Life as we come upon them.
    The way to peer into life’s past is to examine fossils and to determine when a branch was first created by assessing the age of rocks when a certain fossil was formed. The oldest known fossils are of bacteria that apparently lived in ponds or a shallow sea located in what is now western Australia. They are fossil mats of bacteria, called stromatolites, whose metabolism led them to excrete calcium carbonate, chalk, the stuff of seashells and limestone. The ancient ponds dried up for some climatological reason, and these bacterial mats turned to stone. They’re 3.5 billion years old.
    As we examine rocks that are provably somewhat younger, we find evidence of more complex organisms. When we sample the floor of the ocean down just a few meters, we find a great many deposits of tiny sea creatures. These microfossils are beautiful, complex, cone- and mesh-shaped disks and spirals, which were the homes and bodies of ancient sea creatures. These tiny fossils are often the size of the head of a pin. If you know where to look, you can find hundreds of them in just a cubic centimeter of seafloor sediment. (A cubic centimeter is a milliliter in beer can and baby medicine measurement; it’s the same as a cc in old-school medical terminology.)
    The farther back in time we carry out an accounting of the number of different living things on Earth, the fewer different kinds we find. The implication is that evolution naturally leads to an increasing number of different kinds of living things. In this way, it is much like a tree. The higher a tree grows, the more branches will grow and bifurcate; each bifurcation leads