blogs posts over at Why Evolution Is True, on the subject of (appropriately) evolution, with a list of its components, and following with a list of what would falsify the theory. The former is concise and clear, and the latter is the sort of thing you would never see from a creationist regarding creationism: intellectual honesty is too risky when your worldview hangs from a thread.
However, it is obvious that he is talking about Evolution by Natural Selection, and since I don’t want to at the moment, I’m taking a hard left and reevaluating his lists in terms of what would apply to evolution more generally, including artificial selection and genetic engineering:
Evolution occurs, that is, there is gene frequency change in populations over generations.
Check. Unless you are really bad at artificial selection (or you have chosen a population without variation regarding the desired trait), you will see a change.
Significant evolution takes time—that is, it usually (though not always) requires hundreds to thousands of generations to occur. It is not instantaneous, and it is the population and species rather than the individual that evolves.
A lot less time with artificial selection. With control over the surrounding environment, and the ability to send any of the (for instance) cattle with a less desirable trait away from the group you want to change, you can get results with just a few generations.
Lineages of organisms split, or speciate, so that the single lineage that gave rise to life 3.5 billion years ago has undergone numerous splitting events to produce the millions of species alive today (and also the even more millions that went extinct).
Except for laboratory experiments. And possibly on other planets.
The converse of #3: any pair of living species has a common ancestral species some time in the past. That is, if you trace any pair of twigs on the tree of life, you will find a node where the line from the trunk bifurcates to produce them.
The process producing the appearance of design in organisms is blind, purposeless natural selection. (There are, of course, evolutionary forces other than selection, including genetic drift, but they don’t produce the marvelous design that was once seen as the prime evidence for the hand of God.)
Or the Hand of Man! (Cue Mad Scientist Music) Ahem, to the second list: Is anomalous for natural selection anomalous for artificial selection?
Fossils in the wrong place (e.g., mammals in the Devonian). If the fossil record were all out of order like this (a single anomalous fossil might not overturn everything, of course, since it could be in the wrong place for other reasons), we’d have to seriously question the occurrence of evolution.
Not applicable. Although given enough time, we might feel sorry for future paleontologists finding the remnants of a nonfiction version of Jurassic Park.
Adaptations in one species good only for a second species. There are plenty of adaptations in species that are good for other species, but also help members of the first species: these are the basis of mutualisms. (Cleaner fish, for example, remove parasites and dead tissue from other marine fish, but thereby gain a meal.) But we don’t expect to see—and don’t see—adaptations in one species that evolved solely for the benefit of another species.
This is an interesting one! Corn has adaptations that are good primarily for humans, but at the same time, those very adaptations are what increased the likelihood of humans spreading corn far and wide. Similar thing with the temperament of pets… Pets. Oh. I submit for your attention: The French Bulldog. A breed of dog often unable to breed and which has 80% of litters being born through caesarean section.
A general lack of genetic variation in species. Evolution depends on genetic variation. If most species had none, they couldn’t evolve. However, the universal efficacy of artificial selection (I’m aware of only three lab experiments that failed to show a response to such breeding experiments), shows that genetic variation is ubiquitous in nearly all species.
I could see this going either way: on one hand, we are likely to focus on increasing food yields and reducing disease, but on the other, humans are amazingly creative, and we might gengineer anything given long enough.
Adaptations that could not have evolved by a step-by-step process of ever-increasing fitness. This is of course the contention of advocates of Intelligent Design like Michael Behe. But adaptations like the flagellum, which Behe and other IDers cite as features that couldn’t have arisen by a step-by-step process of increasing adaptation, have been shown to plausibly arise by just that process. We don’t need to completely reconstruct the evolution of things like flagella, but simply show that their evolution by a stepwise adaptive process was plausible.
While we will probably be borrowing a lot from existing structures, we will probably play “what combinations work best?” and come up with results that can’t be traced as a stepwise linear process, as it will derive more from inspiration and nonlateral problem solving.
The observation that most adaptations of individuals are inimical for individuals or their genes but good for populations/species. Such adaptations aren’t expected to evolve often because they would require the inefficient process of group or species selection rather than genic, individual, or kin selection. And indeed, we see very few features of organisms that seem inimical to organisms or their genes but useful for the population or species. One possible exception is sexual reproduction.
I could imagine some schemes with bio-mechanisms that could have this result.
Evolved “true” altruistic behavior among non-relatives in non-social animals. What I mean by “true” altruistic behavior is the observation of an individual sacrificing its reproductive output for the benefit of individuals to which it is either unrelated or from whom it does not expect to receive return benefits. In this “true” altruism your genes give benefits to others and get nothing back, and this shouldn’t evolve under natural selection. And, indeed, we don’t see such altruism in nature. There are reports that vampire bats regurgitate blood to other individuals in the colony to whom they’re unrelated, but those need confirmation, and there may also be reciprocal altruism, so that individuals regurgitate blood to those from whom, one day, they expect a return meal. Such cooperation can evolve by normal natural selection.
I could absolutely see true altruism being programmed into a species by humans for humans benefit, of course. We didn’t evolve that way, after all.
Complete discordance between phylogenies based on morphology/fossils and on DNA. While individual genes can show discordance by lateral transfer—rotifers, for example, have incorporated into their genome from DNA from very unrelated organisms, and this is also common for bacteria. But lateral transfer of genes, as opposed to their direct descent from parent to offspring, is relatively uncommon. So, for example, if we sequenced the genome of a blue whale and found that on the whole the species was more closely related to fish than to mammals, we’d have a serious problem for the theory of evolution.
Of course, gengineering would likely have a lot of lateral transfers as people try things just to figure out what works.
Obviously, artificial selection is an entirely different ballgame using the same basic concepts. It is amazing how much a little bit of evolution granted intelligence can change things.
Now, if only we had a reliable way to gengineer things without a high risk of causing cancer: I want humans to not be so susceptible to diabetes, I want our eyes to be wired correctly, and oh, yeah- can we do something about our backs being poorly designed for walking upright?