The cicada sings its song, the blue whale sprays a shower from its blowhole, the rattlesnake strikes at lightning speed, a dandelion turns toward the sun. These and all the other species just happened to arise. The designs were fortuitous for reproduction, but they were accidental.
Given the contingent nature of the evolutionary process, the theory predicts that what it produces is rather unpredictable. Unlike physics with its laws and predicted trajectories, the evolutionary process is more of a random walk. The biological design space is enormous and evolution traces circuitous veins through it, no more predictable than a the path of a bolt of lightning.
The prediction then is that evolution is unpredictable. We can observe what evolution produces but can hardly predict what it will produce. Theodosius Dobzhansky put it this way: “The evolution of every phyletic line yields a novelty that never existed before and is a unique, unrepeatable, and irreversible proceeding.” Likewise Ernst Mayr wrote that “Laws and experiments are inappropriate techniques” for explaining evolutionary events and processes.
Stephen Jay Gould explained that if evolution were replayed again it would go down a radically different pathway. It is a central tenet of neo Darwinism, explains Simon Conway Morris, that evolution is open-ended and indeterminate in terms of predictable outcomes.
Similarly Ken Miller wrote that chance “plays an undeniable role in history ... The twentieth century could easily have been very different—the next century more different still.”
Perhaps he read Ray Bradbury’s 1952 short story “A Sound of Thunder” which illustrated this evolutionary view. The story takes place in the mid twenty first century when time travel has not only become possible, it is rather mundane. Eckels, a cowardly but curious safari hunter, signs up to go on a safari back in time but doesn’t respect the hazards of time travel.
The safari company has carefully selected dinosaur targets for the hunt. The dinosaur must be one which is about to die from some natural cause such as drowning in a tar pit. They may kill the beast a moment before its death but otherwise they must leave the scene untouched. They use an anti-gravity metal path to walk about without touching the ground and they even recover the bullets after the kill.
But these precautions are lost on Eckels. Travis, the safari guide must explain to him the fragility of the future:
“A Time Machine is finicky business. Not knowing it, we might kill an important animal, a small bird, a roach, a flower even, thus destroying an important link in a growing species.”
“That’s not clear,” said Eckels.
“All right,” Travis continued, “say we accidentally kill one mouse here. That means all the future families of this one particular mouse are destroyed, right?”
“And all the families of the families of the families of that one mouse! With a stamp of your foot, you annihilate first one, then a dozen, then a thousand, a million, a billion possible mice!”
“So they’re dead,” said Eckels. “So what?”
“So what?” Travis snorted quietly. “Well, what about the foxes that’ll need those mice to survive? For want of ten mice, a fox dies. For want of ten foxes a lion starves. For want of a lion, all manner of insects, vultures, infinite billions of life forms are thrown into chaos and destruction. Eventually it all boils down to this: fifty-nine million years later, a caveman, one of a dozen on the entire world, goes hunting wild boar or saber-toothed tiger for food. But you, friend, have stepped on all the tigers in that region. By stepping on one single mouse. So the caveman starves. And the caveman, please note, is not just any expendable man, no! He is an entire future nation. From his loins would have sprung ten sons. From their loins one hundred sons, and thus onward to a civilization. Destroy this one man, and you destroy a race, a people, an entire history of life. It is comparable to slaying some of Adam’s grandchildren. The stomp of your foot, on one mouse, could start an earthquake, the effects of which could shake our earth and destinies down through Time, to their very foundations. With the death of that one caveman, a billion others yet unborn are throttled in the womb. Perhaps Rome never rises on its seven hills. Perhaps Europe is forever a dark forest, and only Asia waxes healthy and teeming. Step on a mouse and you crush the Pyramids. Step on a mouse and you leave your print, like a Grand Canyon, across Eternity. Queen Elizabeth might never be born, Washington might not cross the Delaware, there might never be a United States at all. So be careful. Stay on the Path. Never step off!”
But when Eckels sees the towering dinosaur up close he panics. “It could reach up and grab the moon,” exclaims the overwhelmed Eckels when he first sees the beast. The immense and terrifying dinosaur is too much for him and he must retreat to the safety of the time machine. But in his fright Eckels slips off the path and onto the ground. What has he done to the future?
The safari guides are livid. One wants to leave Eckels there in the past, but of course that would risk even greater changes to the future. They take Eckels back to the 21st century with them, only to discover a dead butterfly in the mud on Eckels's boot and along with it a different world.
Eckels killed the butterfly and altered the future. Bradbury’s tale captures the evolutionary view of natural history as a contingent process. As Miller put it, “The twentieth century could easily have been very different—the next century more different still”
The expectation that evolution is a contingent, unrepeatable, unpredictable, indeterminate process has been falsified by the many examples of repeated designs found in otherwise unrelated branches of life. Such repeated designs are not merely occasional. They are not the anomalous exceptions to the rule. Rather biology presents a seemingly unending stream of such repeated designs. They range from molecules to social systems and cognitive processes.
Such similarity, referred to as homoplasy, reveals not a random walk but consistent trends in life’s designs. As Conway Morris suggests, this prediction that evolution is open-ended and indeterminate is “now open to question.” Here is one example:
Consider, for example, the seemingly arcane area of frog ecomorphs. As befits an evolutionary laboratory, the frogs of Madagascar show a series of adaptive radiations, with the occupation of habitats as diverse as burrowing, as well as dwelling in trees, rocks and torrential streams. These ecomorphs find a series of striking convergences with the frogs of Asia (principally India), and so too in this latter region there are further episodes of parallel evolution (e.g., independent development of fangs). The comparisons between Madagascan and Asian frogs are all the more striking because they extend to the larval forms, but there is one striking omission. Thus, in Asia there is no counterpart to the iconic poisonous mantellids. So, the principle of the repeatability of evolution fails at the first hurdle? Not quite, because the mantellids display a series of striking convergences with the neotropical dendrobatids.
Homoplasy is ubiquitous in biology and Conway Morris has documented many examples in his book Life’s Solution.
While some evolutionists realize that the massive homoplasy observed in biology requires a rethinking of their theory, many simply ascribe homoplasy as a consequence of similar environmental pressures. Unfortunately this simple explanation does not help as it, itself, invokes the non evolutionary concept of environmental pressures inducing biological change. Also, homoplasy is not necessarily correlated with the environment.
To convert the explanation to an evolutionary one we must say that random biological changes just happened to converge to similar designs in distant lineages, over and over and over. Regardless of how evolution’s repeatability is explained, it falsifies a fundamental prediction of evolution.