How Random is Evolution?

Man is the product of causes which had no prevision of the end they were achieving . . . his origin, his growth, his hopes and fears, his loves and his beliefs, are but the outcome of accidental collocations of atoms. . . .” – Bertrand Russell

In high school or college, you were probably taught that human life evolved from lower life forms, and that evolution was a process in which random mutations in DNA, the genetic code, led to the development of new life forms. Most mutations are harmful to an organism, but some mutations confer an advantage to an organism, and that organism is able to flourish and pass down its genes to subsequent generations –hence, “survival of the fittest.”

Many people reject the theory of evolution because it seemingly removes the role of God in the creation of life and of human beings and suggests that the universe is highly disordered. But all available evidence suggests that life did evolve, that the world and all of its life was not created in six days, as the Bible asserted. Does this mean that human life is an accident, that there is no larger intelligence or purpose to the universe?

I will argue that although evolution does indeed suggest that the traditional Biblical view of life’s origins are incorrect, people have the wrong impression of (1) what randomness in evolution means and (2) how large the role of randomness is in evolution. While it is true that individual micro-events in evolution can be random, these events are part of a larger system, and this system can be highly ordered even if particular micro-events are random. Moreover, recent research in evolution indicates that in addition to random mutation, organisms can respond to environmental factors by changing in a manner that is purposive, not random, in a direction that increases their ability to thrive.

____________________

So what does it mean to say that something is “random”? According to the Merriam-Webster dictionary, “random” means “a haphazard course,” “lacking a definite plan, purpose, or pattern.” Synonyms for “random” include the words “aimless,” “arbitrary,” and “slapdash.” It is easy to see why when people are told that evolutionary change is a random process, that many reject the idea outright. This is not necessarily a matter of unthinking religious prejudice. Anyone who has examined nature and the biology of animals and human beings can’t help but be impressed by how enormously complex and precisely ordered these systems are. The fact of the matter is that it is extraordinarily difficult to build and maintain life; death and nonexistence is relatively easy. But what does it mean to lack “a definite plan, purpose, or pattern”? I contend that this definition, insofar as it applies to evolution, only refers to the particular micro-events of evolution when considered in isolation and not the broader outcome or the sum of the events.

Let me illustrate what I mean by presenting an ordinary and well-known case of randomness: rolling a single die. A die is a cube with six sides and a number, 1-6, on each side. The outcome of any roll of the die is random and unpredictable; if you roll a die once, the outcome will be unpredictable. If you roll a die multiple times, each outcome, as well as the particular sequence of outcomes, will be unpredictable. But if you look at the broader, long-term outcome after 1000 rolls, you will see this pattern: an approximately equal number of ones, twos, threes, fours, fives, and sixes will come up, and the average value of all events will be 3.5.

Why is this? Because the die itself is a highly-precise ordered system. Each die must have equally sided lengths on all sides and an equal distribution of density/weight throughout in order to make the outcome truly unpredictable, otherwise a gambler who knows the design of the die may have an edge. One die manufacturer brags, “With tolerances less than one-third the thickness of a human hair, nothing is left to chance.” [!] In fact, a common method of cheating with dice is to shave one or more sides or insert a weight into one end of the die. This results in a system that is also precisely ordered, but in a way that makes certain outcomes more likely. After a thousand rolls of the die, one or more outcomes will come up more frequently, and this pattern will stand out suspiciously. But the person who cheated by tilting the odds in one direction may have already escaped with his or her winnings.

If you look at how casinos make money, it is precisely by structuring the rules of each game to give the edge to the casino that allows them to make a profit in the long run. The precise outcome of each particular game is not known with certainty, the particular sequence of outcomes is not known, and the balance sheet of the casino at the end of the night cannot be predicted. But there is definitely a pattern: in the long run, the sum of events results in the casino winning and making a profit, while the players as a group will lose money. When casinos go out of business, it is generally because they can’t attract enough customers, not because they lose too many games.

The ability to calculate the sum of a sequence of random events is the basis of the so-called “Monte Carlo” method in mathematics. Basically, the Monte Carlo method involves setting certain parameters, selecting random inputs until the number of inputs is quite large, and then calculating the final result. It’s like throwing darts at a dartboard repeatedly and examining the pattern of holes. One can use this method with 30,000 randomly plotted points to calculate the value of pi to within 0.07 percent.

So if randomness can exist within a highly precise order, what is the larger order within which the random mutations of evolution operate? One aspect of this order is the bonding preferences of atoms, which are responsible not only for shaping how organisms arise, but how organisms eventually develop into astonishingly complex and wondrous forms. Without atomic bonds, structures would fall apart as quickly as they came together, preventing any evolutionary advances. The bonding preferences of atoms shape the parameters of development and result in molecular structures (DNA, RNA, and proteins) that retain a memory or blueprint, so that evolutionary change is incremental. The incremental development of organisms allows for the growth of biological forms that are eventually capable of running at great speeds, flying long distances, swimming underwater, forming societies, using tools, and, in the case of humans, building technical devices of enormous sophistication.

The fact of incremental change that builds upon previous advances is a feature of evolution that makes it more than a random process. This is illustrated by biologist Richard Dawkins’ “weasel program,” a computer simulation of how evolution works by combining random micro-events with the retaining of previous structures so that over time a highly sophisticated order can develop. The weasel program is based on the “infinite monkey theorem,” the fanciful proposal that an infinite number of monkeys with an infinite number of typewriters would eventually produce the works of Shakespeare. This theorem has been used to illustrate how order could conceivably emerge from random and mindless processes. What Dawkins did, however, was write a computer program to write just one sentence from Shakespeare’s Hamlet: “Methinks it is like a weasel.” Dawkins structured the computer program to begin with a single random sentence, reproduce this sentence repeatedly, but add random errors (“mutations”) in each “generation.” If the new sentence was at least somewhat closer to the target phrase “Methinks it is like a weasel,” that sentence became the new parent sentence. In this way, subsequent generations would gradually assume the form of the correct sentence. For example:

Generation 01: WDLTMNLT DTJBKWIRZREZLMQCO P
Generation 02: WDLTMNLT DTJBSWIRZREZLMQCO P
Generation 10: MDLDMNLS ITJISWHRZREZ MECS P
Generation 20: MELDINLS IT ISWPRKE Z WECSEL
Generation 30: METHINGS IT ISWLIKE B WECSEL
Generation 40: METHINKS IT IS LIKE I WEASEL
Generation 43: METHINKS IT IS LIKE A WEASEL

The Weasel program is a great example of how random change can produce order over time, BUT only under highly structured conditions, with a defined goal and a retaining of those steps toward that goal. Without these conditions, a computer program randomly selecting letters would be unlikely to produce the phrase “Methinks it is like a weasel” in the lifetime of the universe, according to Dawkins!

It is the retaining of most evolutionary advances, while allowing a small degree of randomness, that allows evolution to produce increasingly complex life forms. Reproduction has some random elements in it, but is actually remarkably precise and effective in producing offspring at least roughly similar to their parents. It is not the case that a female human is equally as likely to give birth to a dog, a pig, or a chicken as to give birth to a human. It would be very strange indeed if evolution was that random!

But there is even more to the story of evolution.

Recent research in biology has indicated that there are factors in nature that tend to push development in certain directions favorable to an organism’s flourishing. Even if you imagine evolution in nature as a huge casino, with a lot of random events, scientists have discovered that the players are strategizing: they are increasing or decreasing their level of gambling in response to environmental conditions, shaving the dice to obtain more favorable outcomes, and cooperating with each other to cheat the casino!

For example, it is now recognized among biologists that a number of microorganisms are capable to some extent of controlling their rate of mutation, increasing the rate of mutation during times of environmental challenge and stress, and suppressing the rate of mutation during times of peace and abundance. As a result of accelerated mutations, certain bacteria can acquire the ability to utilize new sources of nutrition, overcoming the threat of extinction arising from the depletion of its original food source. In other words, in response to feedback from the environment, organisms can decide to try to preserve as much of their genome as they can or experiment wildly in the hope of finding a solution to new environmental challenges.

The organism known as the octopus (a cephalopod) has a different strategy: it actively suppresses mutation in DNA and prefers to recode its RNA in response to environmental challenges. For example, octopi in the icy waters of the Antarctic recode their RNA in order to keep their nerves firing in cold water. This response is not random but directly adaptive. RNA recoding in octopi and other cephalopods is particularly prevalent in proteins responsible for the nervous system, and it is believed by scientists that this may explain why octopi are among the most intelligent creatures on Earth.

The cephalopods are somewhat unusual creatures, but there is evidence that other organisms can also adapt in a nonrandom fashion to their environment by employing molecular factors that suppress or activate the expression of certain genes — the study of these molecular factors is known as “epigenetics.” For example, every cell in a human fetus has the same DNA, but this DNA can develop into heart tissue, brain tissue, skin, liver, etc., depending on which genes are expressed and which genes are suppressed. The molecular factors responsible for gene expression are largely proteins, and these epigenetic factors can result in heritable changes in response to environmental conditions that are definitely not random.

The water flea, for example, can come in different variations, despite the same DNA, in response to the environmental conditions of the mother flea. If the mother flea experienced a large predator threat, the children of that flea would develop a spiny helmet for protection; otherwise the children would develop normal helmet-less heads. Studies have found that in other creatures, a particular diet can turn certain genes on or off, modifying offspring without changing DNA. In one study, mice that exercised not only enhanced their brain function, their children had enhanced brain function as well, though the effect only lasted one generation if exercise stopped. The Mexican cave fish once had eyes, but in its new dark environment, epigenetics has been responsible for turning off the genes responsible for eye development; its original DNA has been unchanged. (The hypothesized reason for this is that organisms tend to discard traits that are not needed in order to conserve energy.)

Recent studies of human beings have uncovered epigenetic adaptations that have allowed humans to flourish in such varied environments as deserts, jungles, and polar ice. The Oromo people of Ethiopia, recent settlers to the highlands of that country, have had epigenetic changes to their immune system to cope with new microbiological threats. Other populations in Africa have genetic mutations that have the twin effect of protecting against malaria but causing sickle cell anemia — recently it has been found that these mutations are being silenced in the face of declining malarial threats.  Increasingly, scientists are recognizing the large role of epigenetics in the evolution of human beings:

By encouraging the variations and adaptability of our species, epigenetic mechanisms for controlling gene expression have ensured that humanity could survive and thrive in any number of environments. Epigenetics is a significant part of the reason our species has become so adaptable, a trait that is often thought to distinguish us from what we often think of as lesser-evolved and developed animals that we inhabit this earth with. Indeed, it can be argued that epigenetics is responsible for, and provided our species with, the tools that truly made us unique in our ability to conquer any habitat and adapt to almost any climate. (Bioscience Horizons, 1 January 2017)

In fact, despite the hopes of scientists everywhere that the DNA sequencing of the human genome would provide a comprehensive biological explanation of human traits, it has been found that epigenetics may play a larger role in the complexity of human beings than the number of genes. According to one researcher, “[W]e found out that the human genome is probably not as complex and doesn’t have as many genes as plants do. So that, then, made us really question, ‘Well, if the genome has less genes in this species versus this species, and we’re more complex potentially, what’s going on here?'”

One additional nonrandom factor in evolution should be noted: the role of cooperation between organisms, which may even lead to biological mergers that create a new organism. Traditionally, evolution has been thought of primarily as random changes in organisms followed by a struggle for existence between competing organisms. It is a dark view of life. But increasingly, biologists have discovered that cooperation between organisms, known as symbiosis, also plays a role in the evolution of life, including the evolution of human beings.

Why was the role of cooperation in evolution overlooked until relatively recently? A number of biologists have argued that the society and culture of Darwin’s time played a significant role in shaping his theory — in particular, Adam Smith’s book The Wealth of Nations. In Smith’s view, the basic unit of economics was the self-interested individual on the marketplace, who bought and sold goods without any central planner overseeing his activities. Darwin essentially adopted this view and applied it to biological organisms: as businesses competed on the marketplace and flourished or died depending on how efficient they were, so too did organisms struggle against each other, with only the fittest surviving.

However, even in the late nineteenth century, a number of biologists noted cases in nature in which cooperation played a prominent role in evolution. In the 1880s, the Scottish biologist Patrick Geddes proposed that the reason the giant green anemone contained algal (algae) cells as well as animal cells was because of the evolution of a cooperative relationship between the two types of cells that resulted in a merger in which the alagal cells were merged into the animal flesh of the anemone. In the latter part of the twentieth century, biologist Lynn Margulis carried this concept further. Margulis argued that the most fundamental building block of advanced organisms, the cell, was the result of a merger between more primitive bacteria billions of years ago. By merging, each bacterium lent a particular biological advantage to the other, and created a more advanced life form. This theory was regarded with much skepticism at the time it was proposed, but over time it became widely accepted. The traditional picture of evolution as one in which new species diverge from older species and compete for survival has had to be supplemented with the picture of cooperative behavior and mergers. As one researcher has argued, “The classic image of evolution, the tree of life, almost always exclusively shows diverging branches; however, a banyan tree, with diverging and converging branches is best.”

More recent studies have demonstrated the remarkable level of cooperation between organisms that is the basis for human life. One study from a biologist at the University of Cambridge has proposed that human beings have as many as 145 genes that have been borrowed from bacteria, other single-celled organisms, and viruses. In addition, only about half of the human body is made up of human cells — the other half consists of trillions of microbes and quadrillions of viruses that largely live in harmony with human cells. Contrary to the popular view that microbes and viruses are threats to human beings, most of these microbes and viruses are harmless or even beneficial to humans. Microbes are essential in digesting food and synthesizing vitamins, and even the human immune system is partly built and partly operated by microbes! If, as one biologist has argued, each human being is a “society of cells,” it would be equally valid to describe a human being as a “society of cells and microbes.”

Is there randomness in evolution? Certainly. But the randomness is limited in scope, it takes place within a larger order which preserves incremental gains, and it provides the experimentation and diversity organisms need to meet new challenges and new environments. Alongside this randomness are epigenetic adaptations that turn genes on or off in response to environmental influences and the cooperative relations of symbiosis, which can build larger and more complex organisms. These additional facts do not prove the existence of a creator-God that oversees all of creation down to the most minute detail; but they do suggest a purposive order within which an astonishing variety of life forms can emerge and grow.

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s