Undeniable (4 page)

The modern mechanical world runs on heat, and it's also bounded by the Second Law. Car engines, jet airplane turbines, and coal-fired power plants all use heat produced by burning to make something spin. The heat comes from chemical reactions. The same is true for us animals. Instead of fire in our bellies, produced by combining carbon fuel with oxygen, we have enzymes that enable chemicals in our food to combine with oxygen to produce chemical energy. But whether it's a turboprop or a cricket, we all must produce a bit more energy than we are able to use. We lose some fraction of our energy to the universe; the Second Law constrains us.

From time to time, people pursue this bit of logic: If heat is always spreading out, won't the entire cosmos cool down to some fantastically cold state, with nothing moving at all, anywhere? Will there be a heat death of the universe (sometimes known as the “Big Freeze”)? If such a state is destined to be, it will occur unimaginably far into the future. The universe is 13.8 billion years old, and from our vantage point, it seems to be just getting under way.

Now back to those creationists who go all crazy insisting that since disorder always increases, and heat spreads out, Earth and everything on it must be getting more and more disordered. They are completely wrong that the Second Law puts a lid on complexity, because of their confusion (or deception?) about closed versus open systems. But it turns out that the analysis of the flow of energy, especially with the Second Law in mind, is a wonderful way to approach evolution. It provides a useful way to understand the way that living things use the energy that's available. I hope you read every word of my book, but there's more on this particular idea in the next chapter as well as in chapters 29 and 35. Read on.

Evolution is also not random; it's the opposite of random. One of Darwin's most important insights is that natural selection is a means by which small changes can add complexity to an organism. With each generation of offspring, the beneficial modifications can be retained. Each mutation that doesn't work as well in nature either dies off with the organism directly, or gets outcompeted by others of its kind in succeeding generations of offspring. It's by the process of evolution that beneficial changes are added up and up and up.

The fundamental energy needed for these beneficial mutations to evolve comes primarily from the Sun and the molten insides of Earth. Decaying organic matter consumed by living beings provides the chemical energy for each beneficial mutation. And each successive generation can carry all of the beneficial mutations. The mechanism for adding complexity is in having offspring. Each generation leading up to any given organism's existence used energy from the Sun to provide its nutrition and warmth.

Far from violating the Second Law of Thermodynamics, evolution is a powerful validation of the law. Embracing the idea that life adheres to the Second Law is akin to saying that evolution is not random; living things are directed and selected by competition. Life runs on energy, and likewise evolution runs on energy. A system that makes use of energy almost serves as a definition of life. There's an intriguing new twist on thermodynamic energy and life; we mention it again in chapter 35. Earth's whole ecosystem comprises organisms expending energy collectively, competing, and developing new forms. That is what makes life so marvelous: It channels energy into butterflies and
Arabidopsis
(first plant to have its genome sequenced) and sea jellies and people.

That's what makes the creationist viewpoint not just staggeringly wrong, but sadly impoverished. In twisting around the Second Law of Thermodynamics, they take a powerful tool for understanding the world and try to make it into a barrier to understanding instead. But there is a silver lining here. By inspiring people to learn the fundamental features of nature described by the Second Law of Thermodynamics, creationists can actually inspire a richer appreciation of the mechanism of evolution.

 

4

BOTTOM-UP DESIGN

When I was a senior in college, earning a degree in mechanical engineering, I was recruited by the Boeing Commercial Airplane Company to work on the 747. Rest assured that I was very well supervised. Like most human organizations, Boeing is organized from the top down. The company was started by Bill Boeing himself; he hired the people he wanted and assigned them to desks and drawing boards, organizing his business in top-down fashion. To this day, Boeing has a top-down structure headed by a CEO, a president, a board of directors, and a chairman of the board. It's an arrangement familiar to anyone who has worked for, or with, a large corporation. It's also a big reason for a lot of popular misconceptions about the process of evolution.

In top-down organizations, everything follows a chain of command. At work you might have an organization chart (an “org” chart) that shows this chain: the boss at the top, a layer of managers beneath her or him, a layer below those middle managers, including shop foremen, team leaders, and entry-level employees. The same pattern plays out in all other kinds of hierarchical groups. If you're a student, you can pretty much count on there being a principal or president and a vice or assistant principal at the school. Universities are loaded with presidents, deans, department chairs, ombudsmen, professors, and teaching assistants.

Nature follows an organizational scheme, too, but one that's stunningly different from ours—and that's where the confusion can creep in. Humans like to organize things from the top down; many of us reasonably assume everything is organized that way. But nature works the other way around. In the natural scheme of things, changes made in the past are the only things that determine whether or not any feature of the organization is retained in the future. There's no planning. If there were a day-to-day manager of nature, he or she would have a cushy gig, because he or she wouldn't have to do anything. Nature is self-organizing. That's another way of defining evolution: Nature builds ecosystems, in all of their complex glory, from the bottom up.

Looking at nature with a human's top-down perspective can create a mistaken sense of intentional design. I'll show you what I mean. Let's say you've started a business, and your organization is successful enough that you are able to hire a few people. Your business grows, and as it does, it gets more complicated and requires more energy. More computers are needed. More phones are needed. You need more equipment and more energy to supply everything from copy machines to farm irrigators. All this equipment and all these people have to be organized. The more complicated it gets, the more organizing it needs. The energy enabling this organization and this growth comes from outside of the company. If you sell things or services, your business growth comes from your environment: in this case, from the money spent by your customers.

In nature, living things depend on their environment, as well. We get energy stored in chemical bonds in our food; plants generally get their energy from sunlight; a few ecosystems run on geothermal or volcanic heat. When we view our systems and nature's systems from the standpoint of energy, our organizations and nature have a lot in common. However, there is a big difference between the two. Any decisions you make to shape and direct your business are based on what resources are available, but they are your decisions. You directed your organization to make certain purchases, hire certain people, and fill out certain paperwork, or whatever documentation you might require. Your company or business gets more complex, because you chose to make it so.

In nature, living things also have the ability to use the resources in their environments to become more complex, not by their conscious choices, but by outcompeting other living things. This is one of the fundamental mechanisms of Darwinian evolution: natural selection. The chemicals along a strand of DNA are arranged so that the molecule can make a copy of itself. Things being the way they are out there (or way down in there), these copies are not perfect. In the same way, you can tell the difference between an original document and a copy of the document made with a copy machine, it's very difficult in nature to make a perfect copy. Those small changes in DNA that occur during an organism's developmental stage result in the organism being just slightly different from its parents or parent organism. They introduce variation within a population. These changes can help an organism live and eventually reproduce, hinder the organism's reproduction, or produce no noticeable difference. You can see why people might think these changes result from conscious or willful acts, but they don't.

The changes that help an organism reproduce stay with the organism's offspring; beneficial changes get passed on in the DNA. When the offspring, in turn, reproduce, they have that beneficial characteristic, and that helps them produce offspring themselves later on. The changes that hinder an organism keep some fraction of that organism's population from reproducing. So hindering changes don't get passed on; they disappear from future versions of that organism's DNA. The changes that don't make any difference—don't make any difference. They get passed on as well.

In general, when energy becomes available to an organism, that energy helps an organism survive and reproduce. Incoming energy (from food or sunlight) can drive and create a beneficial change, which can lead to increased complexity in the offspring of those living things. Once Charles Darwin saw this connection, he realized what a powerful idea it is.

You can contrast the system in nature with a system in a human-built organization like a corporation. Hardly anything happens to benefit an organization unless someone somewhere makes a choice. Very few changes happen organically, that is, from the organization being affected automatically. Someone has to step in and hire or fire, invest or divest, buy or sell, or else nothing happens. Certainly nothing happens automatically to make a system more complex in a good way. You might say that human organizations depend on an intelligent designer.

As a corporation grows, different divisions add systems, paperwork, forms to fill out, hoops to jump through, and so on, to help their division get things done. At some point a manager might come in and analyze that the organization is top-heavy, too many middle managers managing too few people below them. He or she might determine that there is too much paperwork, too much redundant storage of transactions or records, and so on. Then that manager starts cutting pieces off or trying to streamline things.

It doesn't work that way in evolution. If you have a system that holds an organism back and keeps it from reproducing with success, that organism will not pass its genes to the next generation. Nobody has to decide anything. Although a change in a gene usually happens at random, the next generation of that gene is subject to forces that are anything but random. You've got the right combination of genes or you don't. You're still in the game, or you're not. We call it selection pressure; it determines which genes get through.

Many creationists and science deniers, especially in the United States, cite randomness as part of the process of evolution and go on to insist that since evolution is random it cannot explain the rich complexity of life. This is essentially another form of the thermodynamics argument I talked about in the previous chapter. Creationists often use the example of a hypothetical tornado swirling its way through a hypothetical junkyard whose contents include all the pieces to build one of my beloved old 747s. (This is sometimes called the junkyard tornado argument.) What are the chances, they ask, that you'd end up with a perfectly assembled, operable airplane? Obviously, zero, because it would be random.

The problem with this argument is that the premise is wrong. Evolution, and the selection of reproduction-worthy genes that drives it, is the opposite of random. It is a sieve that living things have to pass through successfully, or we never see them again. At Boeing—well, at any company—there are selection pressures that work quite a bit like natural selection. There is competition between airplane companies. Customers and airline corporations that buy billions of dollars' worth of planes want their equipment to be efficient. They want their planes to use less fuel, to be easy to maintain, and to be cheaper overall, because those things are expensive. So, managers, engineers, machinists, interior designers, ergonomic experts—everybody works to make the planes faster, better, and cheaper.

When I was in engineering school, my aeronautics professor showed us that winglets were gimmicks, a waste of time and energy. (You've seen them. Winglets are the little vertical pieces on the tips of modern airliner wings.) Airplanes and birds are able to fly because the air pressure under the wing is higher than the air pressure above it. It's a result generally of tipping the wing up in the front a little, giving it what's called an angle of attack. It works for 787s and barn owls. The higher pressure under the wing induces air to squirt around the wing tip. As the plane or owl moves through the air, it leaves a continuous whirlpool behind it. Spinning up the atmosphere in this fashion takes energy. It robs the plane or bird of a little efficiency. Winglets block a great deal of the tip spinning, and so improve energy efficiency, but they also add weight. My old professor had us do this analysis assuming aluminum wings and aluminum winglets. What we didn't account for, at least the first time through, was the invention of lighter weight, strong plastic composite materials.

Today, planes have composite plastic winglets. It's a form of evolutionary selection pressure. It's a result of market forces, but it's still human-caused decision-making. A company that did not embrace that technology might end up selling fewer planes and going out of business. Winglets are a result of countless hours of research and development. They result from management decisions, engineering analysis, and fabricators' skill.

Here's the amazing thing: Barn owls have a style of winglets, too. There is no evidence that they were deliberately designed that way. Instead, owl winglets are the product of generation after generation of owls reproducing and occasionally producing babies (owlets) with feathers that suppressed wing tip vortices just a little better than others of their species. That trait got passed on and on and on, without any org chart.