Revolutionary Worker #1215, October 12, 2003, posted at rwor.org
Readers who had a chance to read the previous installments of this series1 will have seen that there is a tremendous amount of very concrete scientific evidence which actually proves that all life on this planet has evolved over time (billions of years) and that all living species of plants and animals continue to evolve to this very day. Evolution is so well supported by the evidence that it is no exaggeration to say that there is no theory that is better proven or better corroborated (supported by different kinds of evidence) in all of science. The overwhelming majority of working scientists in all fields of science (biology, geology, astronomy, etc.) will tell you that the theory of evolution has been subjected to extremely rigorous scientific testing for nearly a century and a half, and that they are therefore absolutely confident in saying that the basic facts and mechanisms of evolution have been proven well beyond the shadow of a doubt. The theory of evolution is not somebody's unverified "guess" about how life came to be the way it is--it is not a bunch of untested (and untestable) "beliefs"--and this comprehensive scientific theory is neither "in doubt" nor "in crisis." The basic scientific facts of evolution are by now as well established as the fact that the earth goes around the sun and not the other way around (as explained by the Copernican theory) and the fact that the force of gravity causes objects to fall towards the ground and not away from it (as explained by the theory of gravitation).
Despite all the evidence, many people who hold religious beliefs of one sort or another still find it difficult to accept the scientific facts of evolution, because these scientific facts clearly contradict what is said in the Bible and other religious Scriptures. The science of evolution has demonstrated that all life is constantly changing (evolving) and that all currently living species of plants and animals (including people) have evolved out of different pre-existing ancestor species , through purely natural processes (such as natural selection) which were spread out over millions and billions of years. By contrast, the Creation story in the Bible (written more than 2,000 years ago, long before people knew anything about evolution or even the true age of the earth) says that a divine higher power (a super-natural God) created all the different kinds of life-forms all at once (in just six days) and only a few thousand years ago, and that every single one of the different life-forms was created completely separately .
If this Bible story were actually true, it would mean that all the modern scientific evidence is wrong, and that our planet is not really some 4 1/2 billion years old, that the first simple life-forms didn't really appear some 3 1/2 billion years ago, that none of the life-forms ever underwent any really big changes or spun off any new species, and that none of the living species we see around us today could possibly be related in any way to any other species, past or present. If the Bible Creation story were literally true, every different kind of life-form we see today (wolves, humans, catfish, chimpanzees, whales, bacteria, oak trees, turtles, corn plants, spiders, you name it) would look today just like they looked when supposedly God created them out of nothing and as separate and forever unrelated entities. Well, with all due respect to people's personal religious beliefs, I'm afraid all modern science has shown that the Biblical Creation story is just that--a story, a myth. There is just too much concrete evidence that the earth is actually billions (not thousands) of years old; that all the different life-forms on earth did not appear all at once but spread out over billions of years; that every single species came into being as an evolutionary spin-off of a somewhat different species that existed at an earlier time; and that all the different species on earth today are actually related to each other (to varying degrees) through long lines of descent from a series of shared ancestors.
It all started with some simple one-cell bacteria-like creatures some 3 1/2 billion years ago, but from that point on life evolved and diversified over and over again, following many different evolutionary pathways. That history is etched into every single one of our bodies. On the "branching bush" of life, every human is, one way or another, and to varying degrees, related to (and has at least a few features in common with) every other living species on earth, going all the way back to some of the simplest bacteria-like creatures which emerged out of the "chemical soup" some 3 1/2 billion years ago and from which all life-forms on earth were ultimately derived. Of course, you don't have to have a science degree to realize that human beings are obviously more closely related to (and have many more features in common with) chimpanzees (who are our very closest non-human relatives) or even to wolves, whales (or any other milk-producing mammals) than to songbirds, or catfish, or corn plants or bacteria, just to take a few examples. But even with these much more distant relatives we have at least a few features in common, which are carry-overs from more distant shared ancestors of long ago (for instance, we have skeletons and backbones, but so do catfish and songbirds; and every cell in our bodies contains DNA, but DNA is also present in the cells of all other living things, including corn plants and bacteria).
So, although many people have been taught to believe the Biblical Creation story since early childhood, the evidence from the real world shows it just isn't true. Evidence , concrete scientific evidence : this is what allows us to be so sure evolution is a fact--that it is how all life forms on earth have developed and how all life continues to change in an ongoing way.
As we will discuss later on, many modern-day religious believers have figured out ways to hold on to their basic religious beliefs and values while at the same time accepting the scientific evidence that life has, in fact, evolved. Among modern-day scientists, there are many who are atheists (don't believe in God or any other super-natural powers) and also secular humanists (seek to meet the needs of humanity through secular, or non-religious, means). But among scientists there are still quite a few people who choose to hold on to at least some of the religious traditions of Judaism, Christianity or Islam, for instance, and who may even continue to believe that there could be some higher power supernatural force out there that human beings just can't detect. But even among scientists with these kinds of beliefs, there are literally only a tiny handful who have any doubts that life on this planet has in fact evolved and that the basic facts and mechanisms of biological evolution have long been proven to be true. This is especially true in the life- sciences, of course, since evolution is the cornerstone explanatory theory which lies at the very foundation of all their work and without which further scientific advance would become impossible. And this is true for molecular geneticists, cell biologists, physiologists, paleontologists, animal behaviorists, plant and animal population biologists, community ecologists, conservationists, and so on.
Can't scientists sometimes be wrong? Of course they can. But, as has been explained in greater detail in earlier installments of this series, the reason there is now such tremendous agreement and consensus about evolution in the modern scientific community--the reason that scientists from all the many different fields of science are overwhelmingly confident that the theory of evolution is true--basically boils down to two things:
While an understanding of basic evolutionary principles is relevant to all sciences (such as astronomy, for instance, where there are increasing attempts to apply these principles to an understanding of the evolution of the cosmos) it is especially essential in all the life sciences . If you really want to truly understand what happens in living cells , in whole individual organisms , in larger populations of organisms, or even in broader communities made up of many different but interacting species, you absolutely have to take evolutionary history into account.
It's a simple fact: Nobody working in biology today could even pose the right questions, let alone find the right answers, without having at least a basic understanding of evolutionary principles and mechanisms. And the basic principles and mechanisms of evolution are so fundamental, lie so much at the core of all modern science (including in fields like geology, archaeology, astronomy, etc.) that it really is no exaggeration to say that, "in today's world, without the science of evolution there would be no science."Evolution has shaped and molded all the living things into what they are today. Any scientist working in the life-sciences who in this day and age failed to accept the evidence of evolution and failed to have at least a basic understanding of the historical evolutionary processes through which all the different living species came into being (and which also shaped the ways in which different species interact with each other) couldn't possibly make any truly new and significant contributions to advancing and developing any of the life sciences because they would be trying to work with a highly distorted picture of the features and dynamic processes which characterize living organisms and entire living systems.
Let's look at just a couple of examples, taken from today's headlines, which might help illustrate this point:
It is simply the case that no one can come to understand anything essential about the SARS virus and epidemic (and how best to deal with it) without factoring in some basic facts about biological evolution. The basic principles of biological evolution are, first of all, helping to identify the genetic structure of this particular virus, and to uncover what other viruses the SARS virus is related to (the evolutionary family of closely related "corona viruses"). This evolutionary knowledge in turn is important for trying to figure out which medications and/or vaccines might or might not have an effect on the SARS virus (for instance, if it's in the evolutionary family of corona viruses, it makes sense to look first at what we already know does or doesn't work against other closely related viruses in the same corona family). Then there's the question of trying to figure out where this particular SARS virus came from: understanding evolutionary principles has helped us to understand that viruses can sometimes "jump" from one biological species to another (often, it seems, through predation, when one species eats another species). Understanding how evolution works also helps us to realize that members of a species which have eaten virus-infected members of a different species are much less likely to get sick themselves if the two species in question are only distantly related than if they are more closely related. (Among other things, this is one of the reasons it's really not a very good idea for human beings, who are primates, to eat other primates, such as monkeys and apes; there continues to be speculation, for instance, that the rapidly mutating strains of the HIV virus that causes AIDS in humans originally evolved out of some closely related viruses which have been found to cause an AIDS-like disease in some African primates. A number of biologists suspect some of these viruses may at some point have "jumped" to human hosts through the consumption of "bush meat"--including various species of monkeys as well as apes, such as chimpanzees-- which is an ongoing practice in the region.)
Disease organisms themselves evolve over time and often in conjunction with (together with or in relation to the evolution of) their hosts. The more recently two species shared a common ancestor in the evolutionary past (and the more bodily features they still have in common) the more likely it is that some of the factors that can sicken one (such as a particular virus) can also sicken the other. The theory of evolution allows us to understand such things, and this understanding in turn can give us clues about where to look next to try to figure something out. People who reject evolution, and who believe that all living species of plants and animals are completely unrelated to each other, can't make any real significant breakthroughs in the modern-day struggle to manage or cure infectious diseases. Only people solidly grounded in evolution science can do that. For instance, it is only because they understood and were taking into account some of the basic principles of biological evolution that epidemiologists (biologists who study infectious diseases and their spread and containment) even knew to go looking for the possible source and reservoirs of the SARS virus in non-human species which shared common evolutionary ancestors with humans in the not too distant evolutionary past.Humans are mammals, and researchers have therefore paid particular attention to some of the other mammals that humans come into contact with in areas with a high original incidence of SARS (both domestic mammals, such as pigs, which sometimes live with humans at close quarters, or wild mammals which are hunted and consumed by humans). They have been looking for SARS viruses in areas of rural China where there has been some thinking that the virus could have "jumped" from pig to human. And, as I write this, the latest news is that a species of wild civet (a cat-like mammal which is apparently occasionally hunted and consumed by people in the region) may harbor the SARS virus and represent the pathway through which humans initially contracted the disease. It is too early to tell for sure. But whether or not this particular source turns out to be the right one, the point is that trying to figure out where this virus came from is an important part of trying to figure out how to treat it and contain it in human populations--but scientists wouldn't even know where to look for it if they didn't understand some basic facts about evolution, including why it is that disease-causing factors can sometimes jump between prey and predator species and sicken the predators, especially if they still share many evolutionary features in common with their prey.
The SARS virus, human susceptibility to the brain-wasting "mad-cow disease,"2 the rapidly evolving AIDS virus, the increasingly problematic evolution of bacteria resistant to all known antibiotics, discussed earlier in this series--all these are serious public health problems, and they cannot be fully understood and correctly addressed unless one takes into account the past and present evolution of these disease-causing agents.
Do the Creationists who say that they "just don't believe in evolution" because it runs counter to the Bible, think we should give up on all modern attempts to treat and manage infectious diseases, because such attempts are rooted in an understanding of evolution?
And what about organ transplants and related procedures for people whose organs are failing? Groundbreaking work in these fields also requires at least a basic understanding of evolutionary principles--otherwise you'd end up killing the patients! Understanding basic principles of evolution (including in relation to molecular genetics) is essential to trying to figure out how to best handle organ transplants (which often fail when a human body rejects them), or even to "grow" organ substitutes as human "spare parts." Understanding evolutionary history allows us to understand:
That a human's immune system (itself the product of millions of years of biological evolution) would be less likely to "reject" a replacement organ if such an organ could be "grown" from scratch from the person's own (or at least another human's) undifferentiated stem cells (cells which are not yet functionally specialized and so are still capable of developing into any kind of organ tissue); next best and more currently feasible would typically be an organ transplant from a genetically closely related individual.
That any attempts to transplant organs into humans from other species (a tricky and problematic proposition from a number of angles in any case) should currently not even consider using organs of species which are not at least close evolutionary relatives of humans. This is because only organs of species which shared common ancestors with humans in the relatively recent evolutionary past would have enough similarities with human organs to have even a chance of being accepted into a human body. Even among mammals (the group of animals to which humans belong) some organ transplants would be more likely to be rejected than others. Species of mammals which have shared common ancestors with the human lineage in the more recent evolutionary past (such as apes, or slightly more distantly related pigs) have organs which have more features in common with those of humans--and are thus less likely to be rejected--than would be the case with more distantly related mammalian species.3
The point of all this is not to argue that cross-species organ transplants (from other species into humans) are necessarily the best approach to providing "spare parts" for sick humans (in fact, cross-species transplants are so problematic from so many different angles that I tend to think that developing research into "growing" brand-new functional organ tissue from unspecialized stem cells will turn out to be the more promising avenue to pursue). But the point here is that we wouldn't have a basis to understand any of this if we didn't draw on what we have come to understand about how evolution works and how evolutionary processes of the past have shaped the way living species (and their body parts) exist and function today.
Again, it is our understanding of evolutionary biology (combined with molecular and developmental biology) which allows us to see that one of the best ways to eventually provide "spare parts" for sick people (new kidneys, livers, hearts, skin for burn victims, nerve cells for paraplegics, etc.) will likely be to try to channel the growth and development of previously undifferentiated human stem cells, rather than trying to make use of organs taken from non-human species. The theory of evolution actually allows us to expect certain health problems both when the donor and recipient species are not related closely enough (greater likelihood of rejection) and also when they are much too closely related (greater likelihood of transfer of disease organisms along with the transplant). None of this would even be an issue in research or in health care if the Bible Creation story were true and humans and other living species had actually been created as completely "separate" and "unrelated" entities rather than being descended from a series of common (shared) ancestors.
Creationists in the United States today are not just individuals who believe in God and happen to be misinformed about the facts of evolution. They are an organized, right-wing, political and ideological movement , and they have been waging a determined and systematic campaign (in the media, in the schools, in the courts, throughout society) to try to undermine and discredit the science of evolution and replace it with their favorite religious dogma: the theory of divine Creation.
There are a number of different kinds of Creationists (as we will review below) but their opposition to the science of evolution (and to secular scientific methods in general) is what ties them all together. In an act of blind religious faith, the majority of current Creationists simply reject and dismiss all the scientific evidence which clearly supports the theory of evolution. They choose instead to "believe" that life never evolved and that a force outside the material natural world (a super- natural god) created all the different living species "out of nothing," as separate and completely unrelated entities. Today in the United States the most traditional and politically reactionary of these Creationists are part of the Christian fundamentalist movement which originated in the rural Bible- belt but which now has representatives in every state in the country--and in fact, from early on this "movement" has had backing from highly placed forces among the powers-that-be in this country.
As a political tactic (to try to force the teaching of their nonsense in the public schools), many of these Creationists have tried in recent years to pass themselves off as being "scientific," arguing that the Biblical theory of divine creation is a legitimate "alternative" scientific theory which should be taught alongside evolution in the science classrooms. But any examination of their arguments shows there is absolutely nothing scientific about their so-called "scientific Creationism" (also called "Creation science") or about any of their methods. These Creationists are simply promoting the imposition of religion (and only Christian fundamentalist religion). To these Creationists it is a basic act of religious faith to say that the Bible is the literal Word of God and that nothing in its pages could possibly be wrong. Therefore, these people not only continue to insist-- despite all the scientific evidence to the contrary--that God created all the plants and animals and people completely separately, out of nothing, in just six days, and only a few thousand years ago; they also insist, literally , that Adam and Eve were the first humans and that all the living species of plants and animals we see today are the surviving descendants of the "two of each kind" that the Bible says Noah managed to fit in his one boat ("Noah's Ark") when God supposedly flooded the whole world with a devastating flood lasting 40 days and 40 nights. Some of them even make elaborate drawings of what they think this Ark looked like and how it could have had enough room to fit representatives of all the different species into it.
Could it possibly be true, as the Bible says, that there really was a global flood that killed off all the living creatures on earth except Noah and his family and "two of each kind" of the species we see on earth today (which the "scientific creationists" claim are all unchanged descendants of the creatures Noah packed into his boat)? Of course not. First of all, there is no historical geological evidence that such a flood ever took place, and it is essentially impossible for this to happen--for a flood to occur that would cover the whole earth at once. And even today human beings could not possibly build a boat big enough, or even a thousand boats big enough, to contain even just two of each living species.
Of course, the human authors of the Bible lived some 2,000 (or more) years ago in the area we now call the Middle East and they did not realize what a huge blooper they were putting in the Bible, because they were not very familiar with the natural world, all around the world: they would only have known a small portion of even the species which lived in their own region, let alone the rest of the planet. And so they had no idea just how many different living species of plants and animals have populated the earth (then or now). But since today's Creationists believe that all the species alive today had to already have existed at the time God created everything all at once (otherwise they'd have to admit the Bible is wrong on this), they are pretty much stuck. All they can do is try to make ridiculously silly arguments about how "two of each kind" that is around today must, somehow, have been able to fit in Noah's boat. They're asking us to believe that the ancestors of ALL the hundreds of millions of living species--all the different species of mammals, all the different species of birds, all the different species of reptiles, and amphibians, and fish, and insects, and marine invertebrates, and of course all the many different living species of plants also, the many different species of flowering plants, non-flowering plants, mushrooms, and all the different species of bacteria and other microorganisms (which of course are not even mentioned in the Bible)--TWO OF EACH KIND of all of these species are supposed to have fit into one boat? Come on!
Let me ask: Is this what science teachers should be forced to teach to kids in school, as a supposedly "legitimate alternative theory"? The scary thing is how close these Creationists have come to succeeding on a number of occasions in recent years: they have actually managed to get entire school districts in a number of states to consider giving "equal time" to both "Creation science" and "evolution science" in the science classroom, and it has taken huge battles in the courts and the rallying of expert testimony of hundreds of prominent scientists to (so far at least) prevent this insanity from becoming established law . And even where they have failed to impose their full program (to get the state to introduce their religious views in opposition to established science in state-funded public schools, and in the science classrooms!) they have succeeded in confusing a lot of people into thinking that maybe the facts of evolution aren't so sure after all, and they have gotten a number of corporate publishers of school textbooks (who are more concerned about controversy and lawsuits than about what is actually true!) to stick little "disclaimers" inside quite a few high school science textbooks telling students that evolution is a controversial theory (no it's not--at least not among 99.9% of scientists!) and that some students may hold religious views which run counter to evolution so it's OK for students to make up their own minds about what's true!!! Do we tell the students it's OK to make up their own minds about whether the earth is flat? Or whether bacteria and viruses can cause diseases in human beings and that there are steps human beings can take to prevent or combat this? Or about any other basic scientifically proven facts?
Traditional Creationists not only reject the many different kinds of evidence that show that living species have evolved; they also reject the clear geological evidence that this has been going on for billions of years, and that the earth itself is billions of years old (and that things like mountain ranges and the Grand Canyon, for example, were formed by natural processes of geological uplift and erosion taking place over millions and hundreds of millions of years). Any knowledgeable geologist will tell you that the Creationist idea that the earth's landscape features were formed "all at once" just a few thousand years ago (and have since then changed only as much as could be explained from just a few thousand years of wind and water erosion) is completely nuts! Modern science can actually establish the age of different rocks in a number of different ways, and these various dating techniques have revealed that the earth itself is about 4 1/2 billion years old. In addition, modern geologists now know and understand much of what's actually been involved in the dynamic and large-scale processes which have refashioned the face of the planet multiple times over the past millions and billions of years. Even though most of these processes have unfolded incredibly slowly and over almost inconceivably long periods of time from a human perspective, modern geologists can still detect and even measure such things as: how large land masses spread apart or crashed into each other; how huge mountain ranges got pushed up from below (and later became worn down, only to sometimes get pushed up yet again some millions of years later); how the earth's oceans have repeatedly grown or shrunk at different times in earth's history; how inland seas sometimes drowned out the interior of continents for millions of years; how deep land and undersea canyons were formed; how cracks repeatedly ripped open the planet's surface crust, providing outlets for hot steam and magma from deep inside the earth to come to the surface in volcanic eruptions which at one and the same time destroy and build new land. They can detect and measure how many of these processes shaped the planet in the past, and also how many of these processes are continuing to take place today (for instance, some mountain ranges are continuing to "grow," and the rate at which this is happening can be concretely measured , even though it's happening so slowly that we can't see it with the naked eye).
In short, there is no question that our physical planet is
itself a very dynamic place--its features are
constantly changing, and in the course of millions and
billions of years the Earth has dramatically restructured
itself quite a few times--but all of these changes can be
explained in terms of completely natural processes
(requiring no supernatural intervention) that are today rather
well understood by the science of geology. And it's also
important to realize that geologists the world over are
overwhelmingly unified in insisting that the really big changes
that have molded the contours of the earth that we see today
could not possibly have taken place in just a few thousand
years (the amount of time a literal reading of the Bible
would suggest has passed since God's Creation). They could only
have happened over millions, hundreds of millions and even
billions of years!
1 Previous installments of this series, "The Science of Evolution," are: Part 1, An Overview, RW #1157, June 30, 2002; Part 2, The Evidence of Evolution Is All Around Us, RW #1159, July 21, 2002; Part 3, A Few Words About Adaptation, RW #1160, July 28, 2002; Part 4, How Evolution Produces Whole New Species, RW #1163, August 18, 2002; Part 4b, More on Reproductive Isolation, Speciation and the Emergence of Evolutionary Novelties, RW #1164, August 25, 2002; Part 5, Evolution Is a Proven Fact--The Evidence Is Concrete and Comes from Many Different Directions, RW #1170, October 13, 2002; The Evolution of Human Beings: Part 6a, Where Did We Come From?, RW #1179, December 15, 2002; Part 6b, What It Actually Means to "Become Human," RW #1180, December 22, 2002; Part 6c, The Clear, and Growing, Evidence of Evolution From Apes to Human Beings, RW #1181, December 29, 2002; Part 6d, The Two Biggest Leaps in Hominid Evolution, RW #1182, January 12, 2003; Part 6e, Summary and Overview, RW #1183, January 19, 2003.
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2 The horrible brain-wasting disease known as "mad-cow disease" is caused by virus- like bits of proteins called prions, which have gotten into and sickened normally herbivorous (non meat- eating) cows when they were made to eat a highly unnatural diet of growth-enhancing high-protein feed supplements made up of the ground-up organs of related mammals, such as sheep. These prions then passed into human beings (who are also mammals) when people unknowingly ate the meat of these diseased cows and as a result also contracted a devastating and fatal brain-wasting disease. The practice of feeding ground-up carcasses or organ remains (offal) of butchered domesticated species (such as pigs, sheep, cows, etc.) to other domesticated animal species across species lines--despite the fact that nothing in these species' evolutionary history would have led them to encounter and process these particular food sources in the past--has apparently become rather commonplace in modern agriculture. An understanding of even some of the most basic principles of biological evolution can sound the alarm about such unwise practices--which, if unchecked, will no doubt lead to an increased occurrence of devastating diseases.
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3 Even though pigs are not quite as closely related to us as are chimpanzees and other apes, it is thought that pigs may actually be better candidates for cross-species organ transplants into humans than primates. Why? Because while apes are by far our most closely related relatives among currently living species (thereby making their organs especially similar to ours), they appear to be actually too closely related to us to be good sources of replacement organs for sick people. For one thing, exactly because chimpanzees are our closest living relatives and have so many features in common with us, many people find it deeply disturbing (and even ethically and morally wrong) to consider routinely killing any of the great apes (chimpanzees and also gorillas and orangutans), even if it could benefit human beings. But even leaving aside for now this complex question (as well as problems having to do with the need to keep these very endangered species from going extinct), a knowledge of evolution tells us that transplants from apes could be very dangerous to humans because the fact that the human lines and ape lines split from a common ancestor not so very long ago (a mere 4 million years ago or so, which is not much considering the 3 1/2 billion years life has been evolving) means that there is an increased chance that viruses and other disease-causing organisms in apes could spread to humans through such organ transplants, and that what sickens apes could also sicken humans. So pigs are considered an interesting compromise, because their relationship to humans in evolutionary terms is recent enough (at least recent enough to have very similar organs), but distant enough that disease organisms they may carry have themselves evolved separately for a longer period of time and are therefore at least somewhat less likely to be able to sicken humans.
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