In my opinion, an interesting example is evolution in liverworts. If we take the family Lepidoziaceae, there is evolution from more complex forms with distinct leaves to thalloid genera only a few cells wide such as Zoopsis and Pteropsiella, which superficially seem much more “simple and primitive”, but are actually more derived. I find it interesting because many people have this misconception that evolution is about organisms becoming more and more complex, but it’s not always the case at all.
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There is one factoid that I see frequently in the non-scientific conservation magazines, the idea that species have evolved to live in artificial habitats. For example “many wildflowers have evolved to live in meadows” or “house sparrows have evolved to live in cities”. At worst, this suggests these species didn’t exist until humans created meadows/cities. At best, it suggests these species have changed radically in order to live in these habitats. While I accept there will have been some genetic changes in these species over the centuries, it would be truer to say meadows/cities provided the conditions or habitats that enabled flowers/sparrows to colonise and thrive. I don’t believe they have had to evolve a great deal in order to do so.
Maybe it is also worth pointing out that not all changes in a species’ ecology require a fresh burst of evolution. Some species are adaptable (no doubt as a result of evolution) and so can rapidly exploit a new opportunity or withstand a new threat without having to undergo genetic change.
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Meadow is not an artificial type of habitat though, it’s a diverse group of plant communities with own soil types. So, it’s correct to say many species evolved to live in meadows. It’s also interesting (probably) that many meadow plants are feeling good in cities.
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Great example! Another one from the plant kingdom is Psilotum, which superficially resembles the earliest vascular plants from the fossil record but actually is basically a fern that has lost its roots and leaves.
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Some of the paleobotanists (I am told) are still rather salty about molecular phylogeny robbing Psilotum of its purported status as an enation-bearing “missing link” to the bryophytes.
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Nice irony there. Adaptationist thinking is one of the most powerful ways to investigate whether or not a biological trait evolved by natural selection (or via some other mechanism). The real fallacy is to suggest that this kind of approach is somehow misguided.
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I think one of the things to emphasize in teaching evolution is the length of geologic time. Some evolution happens very quickly, but my impression is that much happens over tens of thousands of years. If there’s some way to make these long time periods concrete to your students, I think that will help them understand how evolution can work. For example, here in New England in the US, the glaciers retreated somewhere around 15,000 years ago (I think?). Fifteen thousand years is not that long in terms of the length of time life has existed on Earth, but it’s long enough that the students may be helped to understand how much things have changed. Where once there was only ice, there is now thick vegetation in most places. Some species of plants colonized New England more rapidly than others after the glaciers retreated. Can the students grasp how such changes may have contributed to evolution?
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In Britain meadow means a piece of grassland which is mown for hay or silage, compared to pasture which is grassland that is grazed. It isn’t a clean distinction, as meadows are often grazed after they have been mown. But if it isn’t mown, it isn’t meadow.
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Wow! A lot of great comments here, thank you. I’m afraid I can’t give every comment the response it deserves, but I will make a few replies.
Certainly evolutionary thinking has been misused, since it was first invented, to support whatever biases and preconceived notions people in power wanted. I recently reread part of “The woman who never evolved” by Sarah Blaffer Hrdy, who lays out how early evolutionary thinkers (mostly upper-crust English men) committed all sorts of logical fallacies in using evolutionary language to argue that men, and particularly upper-crust English men, were not only superior but genetically predetermined to be superior and therefore entitled to all their privilege. The Nazis misused evolutionary thinking, but they didn’t originate that misuse, they just reused the fallacies.
In most circumstances, I agree. When we are trying to be precise, the difference is that adapted implies that something is the result of natural selection, whereas evolved means that it results from some evolutionary process, which could be natural selection, but could be mutation, interbreeding, genetic drift, or more likely some combination of these.
It is! A moth that looks almost exactly like a wasp is an excellent example of mimicry, which is a special category of convergence. Mimicry leads to many wonderful convergences. One of my favorites in my area is Hedge Nettle, a mint, which mimics Stinging Nettle.
I have trouble reading Barbara Kingsolver because she vastly oversimplifies everything about nature to make it more poetic. Darwin’s theory of evolution is based on those points, but that surely isn’t his theory “in total,” it is shorthand for a summary of the CliffsNotes.
I agree. Anyone who outright rejects evolution is unlikely to join my class. I am likely, however, to get some naturalists who are curious but don’t yet understand evolution well enough to have formed an opinion on it.
No, I mean ‘inform’. Evolutionary thinking is likely to bring some information and concepts to naturalists, and therefore to inform their understanding. This is standard usage in the versions of English I am familiar with.
A good point, and a good example of the non-directional nature of evolution.
This is a good example of a situation where phrasing has to be precise. There is ample evidence that many species have undergone rapid selection in response to artificial habitat pressures, resulting in clear changes in morphology, behavior, physiology, etc. And it is clear that for some species these genetic differences are large enough that populations in cities, for example, are better suited to living in cities than their country cousins. But I am not aware of any entirely new species having arisen in artificial habitats.
Yes, evolved plasticity is a very important point. It can be really quite complicated to prove that you have a selective response rather than individual plasticity or maternal effects.
The adaptionist fallacy is not the same as thinking in terms of adaptations. The adaptionist fallacy is assuming that everything can be explained as an adaptation. That is, some traits can result from random mutation, or from random genetic drift, or as side effects of selection on other traits that are genetically linked but clearly separate on the phenotypic level, or from that trait simply being inherited from ancestral populations. There is no reason to believe that every trait of every organism results from selection on that trait.
This is a good question, and a really hard point to have students internalize. Humans just aren’t wired to think in terms of cumulative effects over hundreds of millions of years. Here in California where the landscape has signs of tectonic action all over it, some can grasp it in terms of how long it took bits of continents to move, earthquake by earthquake, from other parts of the world.
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It might be helpful to clarify that evolution doesn’t “disprove” religion (or vice versa). It contradicts certain interpretations of the Bible, but most people are unaware that there are a lot of other interpretations. In my experience, people (religious or otherwise) are often relieved that it’s not a dichotomy of picking evolution or faith. If you’re not confident enough to defend this yourself, you can point people to other resources like BioLogos and the ASA.
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You are right on this. I forgot to check online.
Religious people can be told that evolution and God do not have to be separate and that some scriptures in the bible can be regarded as metaphorical or comparable to scientific fact. Towards the great explosion is the light, the 7 days of creation could represent 7 divisions in millions of years and the forbidden fruit of the tree of intelligence the evolutionary conversion of Homo neanderthalensis a Homo sapiens.
I’m interested in this - how to not only teach a blank slate, but overcome serious ingrained or even cherished misconceptions. So on reading below, it looks like I spent an hour or two riffing.
Teleology always irritates me, although I do it all the time.
I wonder if it’s a function of the english language, or maybe all languages spoken by Homo sapiens, but it’s difficult to talk about evo without actively implying teleology, (giraffes evolved long necks so that they could reach the tree-tops, moths went black for comouflage in the industrial revolution).
Even if you avoid using teleology, and put a result after a cause, (giraffes with longer necks got the most food and so had more kids, moths with darker wings got less eaten so had more baby moths), the audience still hears teleology. If you ask them later, they’ll say the ‘so that’ part, with an identified need (more food) and a plan (get long neck).
To overtly call it out is almost like another subject - linguistics or philosopy or system dynamics or stochastics or something, so you might have to prepare them and present it like a sidebar or a breakout box or whatever - a separate but necessary pre-requisite.
The notion of ‘highly evolved’ or the pinnacle of evolution, like a bacterium with a 4 billion year ancestry is not as good as a primate with a 4 billion year ancestry. This is often accidentally implied by phylogenetic trees, eg in https://en.wikipedia.org/wiki/Evolution_of_the_wolf see “Phylogenetic tree of the extant wolf-like canids”. This seems to represent ‘dog’ as the end product, with other more primitive animals flaking off from the process along the way.
‘Every animal is perfectly adapted for it’s environment.’ No it’s not, it just works well enough so that it survives.
‘Every trait is functional.’ No it’s not, lots of traits just aren’t bad enough to matter. The colour of my liver or bones doesn’t matter.
Evo as a get out of jail card. Extinctions won’t happen because animals will just evolve a way of living with global warming and not needing water.
Cladistics - the species, genus, family, order, class… heirarchy is useful for labelling things in libraries and doors in science departments. But it doesn’t really represent the major developments along the way, so we patch it up with sub- and super- increments, or invent tribes, or just use ‘clade’. I’m working up a metaphor like hanging things on a ladder is useful, but not everything is a T-shirt, some are bedsheets, some are socks. Hmmm…
Recapitulation https://en.wikipedia.org/wiki/Recapitulation_theory (although largely discredited in its sensu stricto) might be useful, ie 'When you’re that big (fingers held up almost touching) inside your mum, you have gills, 6 kidneys", etc etc, and explain why. Or why most Fabeaciae have similar leaves & flowers.
Convergent evo - again, there wasn’t a plan and a best path. Humans being able to benefit from cows milk has evolved several times, by several different pathways. Eyes have evolved tons of times, differently.
Stuff takes a really really long time. This is a good way to characterise it.
https://drive.google.com/file/d/1ZlNQdD0anV3nVTlk6JCB-i5cq4YD-yCI/view?usp=share_link
Maybe a bit of linguistic analysis. “Evolution” is one of those words that masquerades as a noun, a thing, but isn’t. It is really a verb, an action, a process, a thing that happens within complex situations. So maybe clarify the etymology of the word - things unroll, unfold, reveal themselves. (like vulva, convulvulus) And maybe give out chocolate frogs for anybody who catches you using the word ‘evolution’, because you’ve promised to re-construct your sentences to use the word evolve, or ‘result in’ or something that signifies a stochastic process.
The flat-earth creationist who shouts over the group. Hmmm… Dunno what to do here, but it is an issue. Similarly a couple of on-line evo courses I’ve done, seem to have been targeted by creationists. The organisers seemed to deal with this by sticking to the script and not engaging, easier online than in person. But (I don’t know how), avoid attracting one of those social network hate campaigns.
As far as I can see, there’s no conflict between evo and creationism, unless you want to manufacture one. How old was Adam when god made him? Apparently an adult, who at least could walk and talk and understand god telling him stuff, as if he’s had a normal childhood.
In fact, nobody can disprove the following: God made everything at 7:43am on the 15th of March 2004. He didn’t just partially make everything. He made it complete, including with a necessary past. He gave me memories of a childhood, he gave me a book dated 1982 about Queen Victoria. He made fossils of dinosaurs. He made zircons 4 billion years old.
So as far as I can see, the existance of a creative god is a null argument. You might just have to say, ‘nothing in biology, or medicine, or farming , or whatever makes sense without evolution, so if you pretend you believe in it, this will be easier.’
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I haven’t read the details on why adaptationist fallacy is a fallacy. I guess it is all theory. Practical real life situations will vary. If someone is considering adaptation thinking, one will have to make some assumptions. In natural selection, an organism produces some progenies. It is assumed that they all have very slight differences. This is not the same for all organisms of course. Some organisms will produce almost similiar offsprings that the human eye can see. That will cover the genetic drifts, mutation part, because it is assumed to be random happenings. When a zygote is formed, due to male gamete fertilizing the female gamete, there is some mixing of the genes. When plants are cloned, there is very little variations, but mutations called sports may still occur.
A bunch of trees in the same habitat have different leaf shapes. Let’s assume some trees are different species and some are same species. If one is to think about it, every tree is limited by its genetic code. It has a range of flexibility in the expression of its traits built in its genetic code. In lower light level of the forest floor, the leaves of saplings grow larger and are darker green. When it reaches the top, its leaves are smaller. Some species of trees also have nectar glands as part of the leaves, this invites interaction with insects. The leaves of trees are all adapting to the conditions of its environment, growing larger or smaller with the nutrients available to the roots or dropping leaves to prevent water loss in droughts. Leaves of different species often look different, because they are limited by their genetic codes. Adaptation logically is present. People might be thinking of adaptation in terms of evolution. The adaptability of species may need to consider the whole population.
Do you mean Fabaceae ? Fabaceae are quite varied in leaf shapes. Many have compound leaves. The variations are in the number of compound leaves and shape of the flowers. There are other differences.
Evolution and Creationism. There were very fierce arguments from back in the day 19th century. It is clear there are some conflicts. People wrote books. I must have seen several books on both sides. It is mentioned as being a very long argument until today. because Science really can’t prove the existence or non-existence of god and some other supernatural phenomena.
concepts that I do not fully understand:
- Circumstellar habitable zone(Goldilocks principle)
- Entropy and life
- Primordial soup
- L.U.C.A
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With regards to teleology, I agree with a lot of what you said. I think there are a couple of other points worth mentioning. One is that it is just a really useful linguistic shortcut that makes sense. Even evolutionary biologists use it all the time in conversations with other evolutionary biologists. And (hopefully…
) those biologists all implicitly recognize it’s just a shortcut and understand what is really meant. The bigger issue becomes that this shortcut is so ingrained, scientists use it when communicating with people who don’t implicitly recognize it and unintentionally add to confusion/misunderstanding.
Relatedly, if you’re a scientist talking with other scientists, and point out the issue with teleological language, someone will (jokingly or not) call you a pedant and point out that “everyone knows what I mean” or similar. Talking about teleology without sounding pedantic and turning off listeners is a challenge.
Lastly, I think some of the issue stems from the recent focus on using storytelling to communicate science. Stories involve characters with agency doing something and changing over time.
isn’t a very interesting story to most.
is a much better one. So in many cases, storifying science leads to more interest or excitement from the audience, but there’s often a tradeoff for accuracy.
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Yes, I am well-aware of this straw-man argument (i.e. as promoted by Stephen Jay Gould, amongst others). But the so-called “adaptationist program” is a myth. There’s no harm at all in making the default assumption that every trait results from selection, since the large majority will be. Each case needs to be carefully considered in its own right. If it turns that natural selection isn’t the best explanation, so be it.
The view you are arguing was widely supported among evolutionary biologists 50 years ago. It no longer is. Thousands of pages have been written arguing both sides of this, and I’m certainly not interested in rehashing all those arguments here.
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There seems to be alot of discussion here on the virtues of creationists vs. evolutionist perspectives. Not that I’m very interested in entering into this discourse, but all I will say is: Surely a truly talented Creator would be more than capable of sculpting not only a living but reactive world that can change and adapt to its circumstances on its own volition? I would think so anyway…
Going beyond this, I think your evolution course would do well to frame evolution on a lifetime scale, selecting a few taxa and tracking their progress through when they first came to be, to when they had reached maximal range and vitality, and to what selective pressures came to bear on their phylogeny and contemporary dispersion (intra/inter-species competition, changes in climate and pollinator assemblage). Using biogeographical examples of various types of endemics should drive the message home even further
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