I’ve been hearing a lot on the news lately about Evolution vs. Intelligent Design, and I agree with the ID proponents on at least one point: it’s a good idea to look critically at evolutionary theory and examine alternative hypotheses. So, other than Intelligent Design or Creationism, what other scientific theories exist for the origin and/or progression of life on Earth? The only thing that comes to mind is Lamarckian evolution, which doesn’t differ very much from the Darwinian variety…so what else is there?
There are other scenarios in popular culture. For example, in Star Trek, Captain Picard learns a race of aliens seeded the stars with their DNA, which led to similar bipedal races such as the humans, Vulcans, Klingons, etc. Another example is 2001, A Space Odyssey, where a mysterious monolith appears and advances some nearby chimps. The problem with these (and ID) is that there isn’t good evidence to support these alternate theories.
The real issue here is that Intelligent Design and Evolutionary Theory are two different beasts.
Evolution simply describes the means by which species change over time.
ID describes this same function and posits a being that began the process.
Apples and oranges, in my look at it.
I don’t know anyone of any reputation who would argue that species change over time and that evolution is the means by which this occurs.
Nah, IDers also talk about “irreducible complexity” like that of the eye i.e. organs or systems that could not have evolved since the functioning of these organs depends on the serendipitious combination of their constituents and the (supposed) evolutionary ancestors of these organs couldn’t have functioned in their incomplete state.
I adhere to the notion that I came into being spontaneously when another universe comprised primarily of roast been sandwiches and veggie lasagnas collapsed into a singularity. I am the sole survivor of that catastrophe and am compelled to consume roast beef sandwiches and lasagna whenever the opportunity arises.
Élan vital (Henri Bergson). The life force is inherently energetic and creative, and seeks to express itself through living forms.
Well, there is Lamarckian evolution. Things are the way they are because their parents did something that carried over. For example, a giraffe has a long neck because earlier giraffes stretched up for higher leaves.
A few years ago Skeptic Magazine reviewed a book about the origins and evolution of life. The author was trotting out the usual bogus mathematical arguments about how achieving the necessary number of mutations in the given amount of time is far too improbable. He didn’t turn to God to solve this conundrum, however. Instead he declared that there are clouds of DNA floating around the galaxy in various places. Every so often the Earth wanders into one of these clouds and gets showered by this interstellar DNA. Organisms on earth somehow incorporate this DNA and thus evolution happens.
As you can probably guess, Skeptic was not too impressed by this hypothesis.
I wish I could remember the name of that book.
There aren’t any. Lamarkism is not only defunct but was not an alternative to evolution in any case. It was merely a hypothetical explanation for adaptation which was formulated before the discovery of genetics.
The fact that species adapt and change into other species is not a “hypothesis” but an observed fact. Lamarckism and natural selection were simply proffered explanations as to why. Before we knew about genetic heredity and DNA it was still a mystery as to why specific physical traits were passed from parent to offspring.
As to evolutionary theory as a whole. It is one of the most confirmed theories in science. There are no competing theories. The evidence for evolution and common descent is as solid as the evidence for the atom.
I seem to recall an essay (no cite yet, but I’ll get looking) in which a non-darwinian evolutionary theory was mentioned shortly. Basically it said that evolution did not occur continously, as in natural selection, but rather there were periods of time, in the tens/hundreds-of-thousands-of-years range, followed by periods of stagnation, then another period of evolution.
Off to find a cite.
Punctuated equilibrium. The favorite of Gould, especially. Darwinian evolution still occurs, but sometimes it goes faster than other times when greater stresses are put on a population.
Yep, that’s the one that I was thinkin’ of.
“Punctuated Equilibrium”.
“Irreducable complexity” is sometimes described in a slightly different way, which form two postulates of ID: 1. That many features of organisms are “global”- that is, they only make sense in terms of all the features of the entire organism and it’s lifestyle, and 2. That these features could not have plausibly arisen by random modification of previously existing features. And that therefore, some intelligent or teleological principle is at work Now IF these postulates could convincingly be demonstrated for one or more organisms, then ID would have a case. But so far, every specific example that’s been trotted out has been shot down. Doesn’t keep the ID crowd from trying (or re-presenting the same old arguments to new audiences who are unaware of the rebuttals.)
I’ve heard it reported that there is evidence that some bacteria when stressed by hostile environments seem to modify their genome in a way that actively adapts to the environment. So some wiggle room for a quasi-Lamarkism.
I’ve spoken to several people who are evolution doubters, and actually none of them are fundies. It’s simply that evolution seems to be counter-intuitive to a lot of people.
Right. The American ID-ers (hey, like “Creation Science” it’s a mostly American phenomenon) have given up on “Creation Sicence”'s attempt at refuting the Adaptation-and-Change part of Evolution, and have fallen back on arguing that some events and phenomena in the course of A&C exhibit a trait of “irreducible complexity” that can “only” be explained by an intelligent design (e.g. free-spinning flagella in bacteria). That could be a worthy subject for a brief sidebar in the course, but then they betray their roots when they ask that the curriculum be adapted to declare it an alternative to the entire theoretical edifice. They don’t ask for a notice that “there are debates on the specifics of Neo-Darwinian Synthesis and Punctuated Equilibrium and other such parts of Evolutionary Theory among scientists”, or that “many segments of society are uncomfortable at the implications of naturalistic evolution”, they ask for a blanket warning that the very concept “EVOLUTION” is unproven and controvertible as science. But the concept of evolution itself is “controversial” only socioculturally, not scientifically
Contrast this to “theistic evolution”, wherein evolution happens as the evidence shows and the science explains it happens, but it so happens this IS how God intended it all along anyway, and you need not bowdlerize the Bio textbook over it, since every new scientifically-sound discovery is part of God’s plan anyhow. This BTW has caused some confusion recently because apparently some European Catholic theologians (including many in the new Pope’s inner circle) call THIS “intelligent design”.
Perhaps the first thing you need to do is pin down exactly what you are looking for.
The first thing to realise is that no evolutionary theory accounts for “the origin … of life on Earth”. That’s a line that Creationists push, and it’s a total strawman. All scientific theories of evolution attempt to account for the diversity of lifeforms, but none of them attempt to account for the origin of life. That is a subject known as abiogenenesis. Within that field there are a multitude of competing hypotheses, all equally [un]convincing. And while it makes for interesting reading and speculation it has nothing whatsoever to do with evolution. Evolution is solid science, abiogenesis hypotheses are at best tentative science, and often not even that.
WRT evolution itself, be aware that the “Darwinian variety” of evolution has long since been debunked and abandoned by mainstream science, not least because Darwin was such a strident Lamarkian. So if you are simply looking for alternatives to Darwinian evolution then the options are limitless. The most compelling alternative ATM, and the one accepted by the vast majority of scientists, is a composite theory known as mostly as the Synthetic Theory of Evolution: synthetic because it is literally a synthesis of bits of Darwin, bits of Wallace and lots of genetic evolution.
Aside from the synthetic theory there is some scope for various scientific alternatives, often with varying degrees of Lamarkism or inbuilt evolvability factored in. But at this level you are either talking about fine distinctions, or else exceptional broad, first-principles qualifications. That’s because no scientists, AFAIK, dispute that genetic evolution and radiation occurs. There’s far to much evidence to dispute that. Instead these competing theories seek to look at the importance of factors that aren’t accepted into Synthetic theory, such as evolvability itself, or the importance of group selection rather than individual selection. However because synthetic theory is good science it is constantly evolving (heh), and once any of these notions become well-supported by evidence they are promptly incorporated into the Synthetic theory. SO it could be argued that none of these alternatives are actual competitors to the Synthetic theory, they simply seek to modify it.
I assume you’re referring to prion modulated gene expression. It’s been well documented in yeast, fruit flies and even mice. But strangely enough AFIAK bit’s never been recorded in bacteria.
Let’s look at the avilible options are besides evolution by natural selection.
The Lamarkian view, which is unfortunately named after a guy who likely would have supported Darwin if he had lived long enough, suggests that animals develop certain characteristics through use, and pass on to their decendants these characteristics. This suggests that, for example, a blacksmiths muscles can somehow alter his sperm so that his children are predisposed to have strong mucles. Not only does genetic data show no evidence of thise can of back-coding, but it’s also stastically shown to be untrue. Mechanically, genes don’t opperate this way. Genes are not a blueprint, they’re a recipie. They code for proteins (mostly) and then those proteins ar built, and do whatever it is their chemical and physicaly properties cause them to do, as guided and effected by the other proteins in their environment, and the environment itself.
Mutantism was an early twentieth century idea that grew up around Gregor Mendel’s rediscovered papers. some people thought that genetics would somehow disprove evolution, rather than prove it. This idea is that since mutations happen naturally, all creature somehow spontaneously have mutations that make them better. Personnaly, I think this idea, along with later fears about neuclear technology, is what spawned matinee movies like “THEM!” and the X-Men comics, but that’s just my opnion. The major flaw here is that such is not the case. Most mtuations are harmless, or dangerous, not benefical. It is the environment that opperates on the orgnaisms with mutations, and natural selection does well, what it does.
I.D. Intelligent design. Many arugments in favor of I.D. hinge on the idea that some orgnaisms and organs are so fascinatingly complex that they could not have been created “by chance”.
They’re right.
Evolution by natural selection is the exact opposite of chance. Noone is seriously suggesting that one day, an eyeless mollusc was swimming around the sea, and then one day, it happened to meet another mollusc it found attractive. They mated, and viola, their offspring had a perfectly formed eye. I.D. people say that “half an eye is useless”. They are of course, wrong. I am nearsighted in my left eye. So, by the logic I.D. uses, should I pluck it out? It is less than perfect. Many people have the lenses of their eyes removed for medical reasons, but their eyes are still capable of determining the pressence o light, and that’s far better than nothing.
In fact, why do I.D. people use human eyes as an example? We have very poorly designed eyes. A hawk’s eyes are much superior in the clarity and range they can see. Why not an owl’s eyes? Or an octopus? In fact, octopus eyes are extremely similar to our eyes, except in one crucial difference. In our eyes, we have an abundance of rod and cone cells, cells for detecting the pressence of light. The cells are narrow and elongated. They have a thick bundle of layered photorectpor membranes, and then next to that, a mass of mitochondria to power the cell, and then a nucleous, and then an axon. The axon is a wire used to send that signal to other nerves, and to the brain. In our eyes, all our cones and rods are backwards. All the wires are situated on top of the retinas, not beneath them. This means that the wiring, and powerhouses for each cell in our retinas lie in the way of the photrecptors. In an octopus, their cones and rods are situated the way a deisgner, aand intelligent designer, would have put them in.
Ever notice those indistinct blurs in your vision that swoosh around when you move your eyes? Those are called floaters. They’re remnants of arteries that were there when you were a fetus. They get pinched off when your eye closes up and then they die. The bits of the arteries are trapped, never get absorbed, and in some people, cause serious vision problems requiringdelicate surgery.
Incidentally, evolution is not a theory. The Theory of Evolution refers speficially to the idea that all life on earth evolved from earlier forms, via the processes of natural and sexual selection, back to a common ancestor. Althhough it’s possible that it happened more than once, it’s most likely that all living organisms have a common ancestor, as recent genetic investigations have suggested. The reason that it’s a theory is because it’s difficult to falsify. Noone has yet gone back in time to see what really happened, all we have is evidence.
Evoltuion doesn’t disprove, or prove, the existance of god. It happens to disprove a very narrow and litteral interpretation of the Bible. there are no other rigorous and scientific explainations for the existance of life other than Evoltuion. That doesn’t mean god doesn’t exist. It’s simply a question of faith. It’s never going to be possible to disprove the existance of god, and I sincirely doubt we’ll ever prove that any type of god does exist.
I ommitted from my eye argument the following bit.
Even the littlest bit on eye is damned useful. Many phytoplankton use simple eyes to sense the pressence of light in the water, and the move towards it. Since light is vital to their production of food, a tiny, primitive light sensing cell is extremely benefical to them. A predator with a bad eye, whose eye happens to be better than its prey’s eye, is going to have a tremendous advantage. This sort of predator/prey arms race is stadnard fare in the evolutionary history of the Earth. Even the tiniest advantage can mean the difference between a horrible painful death, and a long anf fruitful life with many offspring.
First, there are no theories for the origin of life. There are a number of hypotheses and several more Wild Ass Guesses ranging from the plausible to the batshit crazy, but there is not yet enough evidence to support any of that speculation to merit the word theory. (This includes Darwin’s Theory of Natural Selection acting upon Random Variation: his theory addresses the development of life, but not its origins.)
Next, we know that neo-Darwinian Theory of Evolution does not explain all variation in life. There are some related or similar phenomena that do not fall directly within the scope Darwin’s Natural Selection (although none of these phenomena have the direct bearing on variations in life forms as Darwin’s Theory). One such phenomenon is that of Genetic Drift.
Finally, Darwin’s Theory of Natural Selection has been successfully beating off challenges for nearly 150 years. In the 1920s, Theodosius Dobzhansky showed that Gregor Mendel’s work with genetics provided the “engine” to drive the changes for which Darwin admitted that he had no adequate explanation and the theory has been called *neo-*Darwinism from that time, but Dobzhansky’s application of Mendel’s information simply illuminated Darwin’s original hypothesis and the actual principles that Darwin proposed have been reaffirmed by every subsequent challenge and investigation (which is why he gets to keep his name on the theory).
At this point, a theory that replaced Darwinian Evolution would be as radical an event as the physics of Einstein replacing the physics of Newton–and no current challenge or alternative hypothesis has come anywhere near Darwin’s Theory in terms of explaining the great breadth and depth of diversity of life. Even the ID people can only nibble at the edges without proposing an actual Theory to substitute: Behe’s Irreducible Complexity actually relies on Darwinian Evolution for most biological events, only trying to insert a god of the gaps into a tiny number of places where Behe’s imagination fails to propose a real-world solution to a puzzling event; Dembski simply whines that he does not understand how Darwin’s Theory works; and the non-biologist Johnson simply states that he does not like the materialistic nature of the Darwinian Theory without actually proposing an alternative that could be identified and tested through Science.
ITR Champion, are you thinking of panspermia theories, as proposed by the late astronomer Fred Hoyle? His notion was that planets (such as Earth) are visited by lumps of rock blasted off other planets by meteors, and are also subject to comet particles raining down whenever one is in the right area. He wasn’t suggesting DNA contamination, but rather seeding by the simpler building blocks of life, and indeed comets have been shown to contain some amino acids, among other organic compounds.
It’s not an alternative theory to evolution, of course, just a theoretical complementary factor, and maybe an accelerant for biogenesis. It did effectively scupper Hoyle’s career though.