As I reported the other day, New Scientist has a special issue on evolution (photo below), which apparently consists of their admission that Darwin was right after all, along with a “feature special” described as follows:
Our modern conception of evolution started with Charles Darwin and his idea of natural selection – “survival of the fittest” – to explain why certain individuals thrive while others fail to leave a legacy. Then came genetics to explain the underlying mechanism: changes in organisms caused by random mutations of genes. Now this powerful picture is changing once more, as discoveries in genetics, epigenetics, developmental biology and other fields lend a new complexity and richness to our greatest theory of nature. Find out more in this 12-page feature special.
The article, which you can’t access online—though judicious inquiry will yield you a copy—consists of 13 numbered scientific areas that are supposedly prompting a reboot of modern evolutionary theory. I’m not going to reprise all of them, as I’ve done so already about many of the “buzzwordy” areas, including epigenetics and niche construction, but I will single out, over the next week, several of the areas that are, to my mind, exaggerated or grossly misrepresented. For readers who’ve said that New Scientist isn’t so bad, my response is, “Well, its coverage of evolution, at least, is dreadful if you know things about modern evolutionary biology.”
True, in some of these areas the article pays lip service to the fact that they’re “controversial”, but the impression one gets is that evolutionary biology is teeming not just with new ideas, but with new ideas that are non-Darwinian and promise a dramatic revision of the theory. The problem is that most of these new areas are either mistakenly conceived or don’t constitute much of a change in evolutionary theory. In fact, none of them do more than put a new duckling under the wing of Darwinism, and none of them replace the mother duck.
Today’s target is GENETIC PLASTICITY, the first of the supposedly “new” areas of evolutionary biology. It’s described under the clickbait-y title “Genes Aren’t Destiny.”
My immediate response is that we’ve known about genetic plasticity for over a century. But let’s back up: what is genetic plasticity?
It’s simple: it’s the observation that for many genes, their expression depends on the environments in which the organism that carries them (and hence the genes themselves) develops or experiences. There are a gazillion examples. For some genes, you get a permanent effect depending on the environment obtaining during the organism’s growth. One example, which I and two colleagues used in an experiment on the temperature flies encounter in the wild, is the mutant allele white-blood, which affects eye color. The expression of the mutation is sensitive to temperature during just a narrow window of time when eye color forms in the pupal stage. If the temperature is high, the eye can turn out very light yellow or even white, but if the temperature is lower, the eye is darker, down to dark purple. After this sensitive period, the eye color stays the same for the fly’s life. The color is said to be “plastic with respect to temperature.”
Likewise, if you don’t get enough food as a kid, you’ll be permanently small after puberty. That’s because the genes involved in creating “height” are sensitive to the amount of nutrition the organism gets, making “human height” a plastic trait. There are a gazillion genes that are plastic in related ways; in fact, I know of very few genes whose expression isn’t affected by the environment (perhaps genes for polydactyly in humans and cats are examples of the latter).
Some genes can vary their expression over an organism’s lifetime. Cats get thicker coats in winter and revert to shorter coats in summer: the genes producing hair are reversibly plastic to temperature. Snowshoe hare become white in winter and brown in summer, a reversible case of pigment genes sensitive to temperature.
The fact is that since the advent of Mendlian genetics at the beginning of the 20th century, geneticists have recognized the plasticity of genes and the traits to which they contribute. The terms back then were that genes had “variable expressivity” or “variable penetrance” depending on the environment. (White-blood was described in 1945.) The idea of plasticity is not at all new, and was featured in the founding works of the Modern Evolutionary Synthesis in the 1930s and 1940s. It was an integral part of our modern view of development, which has long recognized that almost no traits are produced as invariant by genes acting independently of the environment, while the expression of most genes and traits involve an interaction between genes and environment.
I give you this primer because New Scientist, in #1 of its litany, pretends this idea and its instantiation in organisms is something new and exciting. In fact, they say, citing the Human Genome Project, that we now realize that this kind of interaction refutes genetic determinism:
The more we learn about genetics, the clearer it becomes that “genetic determinism” – the idea that genes and genes alone fix our destiny – is a myth. A given set of genes has the potential to produce a variety of observable characteristics, known as phenotypes, depending on the environment. An Arctic fox changes its coat colour with the seasons. The presence of predators causes water flea Daphnia longicephala to grow a protective helmet and spines.
The power of flexibility
Even a change in social environment can prompt a shift. In the European paper wasp (Polistes dominula), for example, when the queen dies, the oldest worker transforms herself into a new queen. But she isn’t the only one to respond. Seirian Sumner at University College London and her colleagues found that the death of a colony’s queen results in temporary changes in the expression of genes in all workers, as though they are jostling genetically for succession. This flexibility is key to the survival of the colony and the species, says Sumner.
The power of genetic plasticity can be seen in the humble house finch. In the past 50 years, it has colonised the eastern half of North America, moving into habitats ranging from pine forests near the Canadian border to swampland in the Gulf of Mexico. The finch’s underlying developmental plasticity provided the raw material from which novel features evolved, including a range of new colourings and other physical and behavioural traits, says David Pfennig at the University of North Carolina at Chapel Hill. “Stop thinking about this as being like genes or environment, because it’s a combination of the two,” he says.
That’s all she wrote (the author of this section is Carrie Arnold).
Let us note that some plasticity, like hair growth in mammals during winter and coat color in snowshoe hares, has evolved: the changeability of the genes in new environments is an adaptive phenomenon (creating more warmth with longer hair and better camouflage in winter). Plasticity is not always a given and inherent characteristic of genes and traits, but in many cases has evolved as organisms have experienced different environments during their species’ evolutionary history, making lability an advantage over fixity.
Further, one can construe “genetic determinism” in two ways, which the article conflates. First, one can see it the proportion of variation in one trait in one population of organisms that’s caused by the variation among the genetic endowment of individuals. The proportion of variation among individuals in a population due to variation in their genes is called the heritability of that trait, and ranges from 0% to 100%. In humans, for example, the heritability of height in many populations is about 80%, meaning that about 80% of the variation in human tallness that we see in a given population is due to variation in genes. This does not mean that height itself cannot be affected by the environment, for it clearly can (I used the example of nutrition above). But under the existing conditions in a population, one can construe the heritability as an index of genetic determinism in a given population under existing environments.
But one can also construe genetic determinism as the degree to which the expression of a trait or gene in an individual is affected by the environment. If this is what the article means, and I think it does, yes, plasticity does show that genes are not the be-all and end-all of a trait.
The important thing, though, is what I said above: THIS IS NOT NEW AT ALL!. It is simply either ignorant or mendacious of New Scientist to pretend that genetic plasticity is both a recent discovery and one that has revised neo-Darwinism. Genetic plasticity was recognized well before neo-Darwinism was formulated in the 1930s as a fusion of genetics, natural history, and evolution, because genetic plasticity was known since the very early days of genetics—almost since Mendel’s work was rediscovered in 1900.
So, if you are masochistic enough to read the entire New Scientist article, you can just move along when you get to point 1; nothing to see here. It’s almost as if the authors touted the claim that the idea of natural selection (which really wasn’t widely accepted until the 1920s) is a new and exciting addition to Darwinism.
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This sentence really does her in. Leave it out and the section is a good description of genetic plasticity for a lay audience. I do think the intent in including it is precisely to make it seem that young modern scientists are over turning the misconceptions of older scientists (that is to say, white men).
Yes, but the purpose of the section is not to describe well known phenomena. Rather, it’s to list all the “new” discoveries that are supposedly dramatically changing evolutionary theory.
Are the wasps just suppressing certain genes in the presence of a queen? I was told if you take a group of worker ants – Lasius niger & perhaps others -then one will become a queen…?
It is also a silly way to think about genetic determinism. Does that Arctic fox have any choice about coat color? Why no, it is bound to change its coat color with the seasons. It is in fact genetically determined that it will do so.
This is indeed old wine in new bottles. “Genetic plasticity” is not a thing: the gene is not plastic, and the gene is not varying over time within the organism depending on circumstances or environment. It’s the expression of the gene and its phenotypic effect that are plastic and varying over time. We used to have a phrase for that. What was it now? “Wumben”? “Wimpund”? “Woomud”?
Oh, no, it was “phenotypic plasticity”! Knew I would get there.
In my view Kevin Laland has a lot to answer for.
https://www.nature.com/news/does-evolutionary-theory-need-a-rethink-1.16080#/yes
Thanks for this! I look forward to your dissection of the remaining topics!
Jerry, I hope you will do “niche construction” next. It’s my favorite of the extended evolutionary synthesis tropes.
Yes, that’s coming, but first, my forte: the claim that “Species do not exist.”
As a member of a species, I am looking forward to that.
Speciesist!
😜
Right, “Genetic plasticity” is what we used to call phenotype. The author of this stuff has apparently not heard of Jacob and Monod, let alone ts phenotypes. I suspect the writing is meant to convey to unwary reader an implication that the genes themselves are “plastic”, which also animates the popular buzz around the word “epigenetics”.
I am reminded of an episode of “Science for the People” I met at a British university during the heyday of the so-called New Left.
It was a little group who had lost their heads to vulgar Marxism, and had taken to analogizing DNA to “the ruling class” and ribosomes to “the proletariat”. No kidding.
It’s ironic that this “extended evolutionary synthesis” nonsense is derived from better knowledge:
Before the molecular biology revolution we could characterize some genetic variation through protein electrophoresis and through laborious DNA or RNA sequencing. And we could assess phenotypic plasticity of organisms. But we couldn’t connect those two things to each other: how does plasticity arise from expression of genetic information?
Now our understanding of gene expression, networks of interaction between gene products (proteins and RNAs), and signalling between cells has all generated this very rich understanding of how molecular biology, physiology, and development interact to generate the phenotype from information in the genome plus information from the environment.
In that thick layer of molecular biology knowledge there is space for careerists to claim to have found something importantly different from genetic variation and natural selection, and call it an “extended synthesis”. But it’s all just semantics applied to a better understanding of molecular biology, and its only goal seems to be to raise the media profile of some evolutionary biologists who say they want a revolution.
Thanks for the work you’ve put into this and the work to follow. As we say, I can’t wait for the analyses to follow.
I appreciate your work.
Hear hear. I also really appreciate the effort you put in to construct coherent science-based arguments. Unlike some of those you are engaging with, unfortunately.
It is hard to believe that more than a decade has passed since that awful “darwin was wrong” cheap marketing tool of a new scientist cover. An honest journal would have given the letter written by jerry, dennett, dawkins, and myers, four internationaly recognized subject matter experts, some cover-type real estate, rather than letter to the editor status if i recall correctly. In any case, i was through with new scientist as a result of that cover. At the time i was involved with a team of science and engineering subject matter experts in an attempt to educate our state board of education (k-12) and state dept of education regarding structure and content of science and engineering in the 21st century. Misleading covers such as this from new scientist make a job that was difficult due to many k-12 educators’ and the general public’s long held,ingrained, but severely dated knowledge and beliefs even more difficult. Clearly new scientist either was more interested in selling magazines than the veracity of their content (the cover being an editor’s choice is not an excusable reason) or they did not take the time to vet their science writer’s material with a subject matter expert. In any case, i felt that i could no longer trust the content of their articles and simply have not picked a new scientist off of my local bookstore shelf since. Now i guess their marketing niche shifted 180 degrees, but as i read jerry’s note today, they have still failed in their content. I know they have a tight publishing schedule, but all that is required is a technical read-through and comments on an article meant for the general public to the author from a subject matter expert…not a peer review panel.
“the idea that genes and genes alone fix our destiny – is a myth.”
The real myth is that such a myth exists!
Thank you. I’m guessing that 100% of people who call “genetic determinism” a “myth” believe in libertarian free will. Some of them may call themselves “compatibilists” but let’s not be fooled. They clearly believe we can alter our desires by sheer will thanks to genetic plasticity!
There may be some UFC fighters who, had they grown up in a different environment, may not have become UFC fighters. But odds are, whatever environment they grew up in, they were going to punch a lot of heads in their lifetime.
Ditto!
Grrr! That was a reply to Armando at #4, but WordPress made me log in again when I posted the (truly exciting) comment and it ended up down here…
I think WordPress is channelling Britney Spears. https://en.m.wikipedia.org/wiki/Oops!…_I_Did_It_Again_(song)
“It is simply either ignorant or mendacious of New Scientist to pretend that genetic plasticity is both a recent discovery”
Obviously the business of publishing makes this inevitable. The upside is that even if some readers get the wrong impression, they will at least be interested enough to maybe read some of it and come to understand it to some degree. Without the come-on click bate, they might never learn anything about evolution.
Interesting post! Thanks Jerry!
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I can’t wait. So what’s next? Do they get all gushy and flirty over the ENCODE thing and how there is all this mysterious “dark DNA”?
Yes, they will. Or maybe they did, ENCODE was a long time ago. I love the phrase “dark DNA”, it captures everything that’s wrong with the ENCODE interpretation of how genomes work: that the genome is stuffed full of noncoding regulatory RNAs, all of them are expressed, and everything is functionally important.
It seems that “keeping a lid” on overhype, underwhelming misinformation, sneaky feelings about the evolutionary process could keep the head spinning.
Maybe they take the NEW in their name a little to earnestly.
That was a great explanation of phenotypic variation and heritability. This might be a little off-topic, but I find that a lot of people seem to misunderstand heritability. Take the example that height is 80% heritable in our current society. A lot of people seem to think that number is inherent in our biology. But it’s really a biology by environment interaction. If we had widespread (but not universal) starvation for a decade, we’d see the heritability of height go down.
Thank you for explaining that, Professor.
I’d heard of plasticity but never really knew what it was.
Cool!
D.A., J.D., NYC
https://whyevolutionistrue.com/2020/06/10/photos-of-readers-93/
I would think an animal or bird spreading like that finch was merely taking advantage of available habitat? I know nothing about this finch but perhaps it likes the human created habitats, like sparrows which spread with agriculture. I do not see a particular connection with genetics? I’d also guess that there may be other species that were there but have gone as they did not like human created habitats…?
I will eventually read it, but I will do so with PCC[E]’s words ringing in my evolutionary ears, which unlike his, do not wiggle!