Plants are People, Too

What Can Plants Do?

I haven't written a blog post since 2017. I've missed it, but, well, life has intervened. But, I've just read The Light Eaters, by Zöe Schlanger, a book describing a tidal wave of new thinking about plant behavior, and it has moved me to write.  It's a New York Times bestseller.  It's exciting stuff.  

Schlanger writes of research on plants that seem to make decisions, that plan ahead, plants that anticipate where light will be when, altruistic plants, plants that treat close kin better than distant kin or unrelated plants, vines that can mimic the plants they are parasitizing, plants that seem to have some way to "see," though it's not at all clear what the mechanism would be, she describes eusocial plants, in which, like bees, some contribute to the survival of others without reproducing themselves, plants that emit the exact chemical to attract parasites of insects that have attacked them, roots that seem to forage.  Ultimately, she wonders whether plants might have the equivalent of a brain, a centralized organizing something.  Many others ponder the same question.  Schlanger eventually asks if the entire plant is equivalent to a brain but, again, the mechanism is a puzzle.  

And there's so much more.  

The author is very measured in her discussion of what all these new findings might mean.  She cautions about the importance of the traditional scientific method and of questioning results. She reminds us that The Secret Life of Plants, by Tomkins and Bird, published in 1973, was an "irresponsible, best-selling book that nearly snuffed out the field for good." That book told us that plants have emotions, they prefer Beethoven to rock-and-roll, they can read our minds, and so on.  It was quickly debunked.  

Serious botanists who are thinking about plant behavior these days want to be very careful not to be taken for similar fantasists.  The young field of plant neurobiology applies generally accepted methods to ask how plants process the information they glean from their environment, and it's these kinds of results that Schlanger reports in her book.

Schlanger is a journalist.  She's not producing new findings herself, she's writing about them, as are many others.  A June 11 essay by Rachael Petersen in Aeon asks "Do Plants Have Minds?"  She writes about Gustav Theodor Fechner, a 19th century intellectual from Saxony who contemplated this question.  

He reminds me that the best way to apprehend the unseen in plants is to take off the blindfold and look. He reminds me that what we stand to gain by looking at nature with new eyes is nothing short of the world, and nothing short of each other.

Looking at nature with new eyes seems to be just what's happening in much of Botany.   

But, there are cautions.  E.g., an April 23 piece by Daniel Immerwahr, in The Guardian, warns that a lot of the data are being over-interpreted (the importance of the underground fungal network between trees, in particular) but that there are many interesting discoveries being made. And, he writes respectfully of Schlanger's book.  

So, the question of what to make of all these new observations of plant behavior is in the air but we are far from a deep understanding.  I like this Wikipedia discussion of the Chilean Boquila trifoliolata plant, a vine that mimics other plants, even plants it didn't evolve anywhere near, which Schlanger discusses at length, and even visits in Chile. 

The exact mechanism by which mimicry occurs is not well understood but may involve chemical, odor, genetic, metagenomic, transcriptomic, proteomic, metabolomic, epigenetic, and/or microbial cues to identify and mimic the species it is attached to.

It would seem that the inexact mechanism by which mimicry occurs is not well understood, either.  

Anthropomorphizing

People who study non-human life have long been careful about anthropomorphizing their study subjects.  But, this seems to be changing.  There's an interesting June 6 piece in The Atlantic by Katherine J. Wu about this. She suggests that, by denying human characteristics to other living beings, we may be missing important truths about their behavior.  

Schlanger notes repeatedly that botany has a history of discouraging the anthropomorphizing of plants. And yet, it is possible that there's no better, or even no other language in which to describe the new discoveries.  There seems to be a new openness to applying what we know about humans to plants.  If we strip all life down to organisms that strive to survive and reproduce, maybe that's as it should be.  We are all trying to solve the same problems; knowing where we are in space, finding food, spotting danger and figuring out ways to avoid it, finding mates, or otherwise reproducing.  Let's throw in protecting kin, sensing our environment, and solving problems.  We all do at least some of that, even single-celled organisms.   

So, let's assume that the results reported in this book are verifiable, and even revolutionary. Plants really can do all these things, and more, and it is meaningful to describe them in human terms. Let's keep looking, and cataloguing and generalizing.  

But, will anthropomorphizing plants get us anywhere?  We still don't really understand human, or, generally, primate behavior. We're still squabbling over whether it's genes or environment, so once we describe plants in our terms, have we actually understood them any better? And, how would we know?

You Are Not "You"

 As I’m revising my upcoming book, I’m reflecting on its past, present, and future. 

 

You Are Not “You”

 Believe, at least for the time being, that you are anyone and everyone, including me.

That’s how you wanted to open your book on human evolution, whose earlier incarnations regularly employed the second person perspective: You got into paleoanthropology for reasons. You used to think one way. Now you think another. Trying on the author’s perspective helps us see how blind we’ve been to the personalities that have crafted the facts of life and have perpetuated the make-believe narratives we’ve accepted as science. With that newfound sense, we can tell new stories, better stories, or no stories at all about where we came from and who we are, about human nature.

But before you could pitch that prophylactic opening, sure to ward off reader discomfort bound to bubble up down the line when they first read “you”;

before you could defend the second person as a necessary tool for shifting the reader’s evolutionary thinking away from distinct, competing individuals to an always interconnected, collaborative whole, something more powerful than “we”;

before you could defend this point-of-you as showing, rather than telling, how personal perspective shapes science and the fictions we tell with facts, they told you to “ditch the second person.” Something about a feted New York novelist getting away with it long ago, but it not serving your book. “There are places where it’s like watching you talk to yourself.”

You is confusing. Early on, your manuscript included, You’re always reading your way through the books around the house, which made your partner look up from the page and blurt, “No I’m not!”  After the uproar, the literary significance of what immediately followed [something about Metamorphosis being about the sister’s transformation, which is a section you later struck] was lost.  

 Oh boy. Did you just say “literary”? That’s probably where you took a wrong turn.

See, you have no idea how to write. You have no business having literary ambition. This is merely a science book you’re writing and even it demands a level of writerly competence that you’re struggling to realize.

So far, much of the feedback you’ve received from the pros is comprised entirely of words you know well, but in new combinations that you do not. So sometimes you nod along with what they’re saying, uh-huh, just like when you’re tired of asking someone to repeat what they’ve already said three times too softly and quickly for your ears and brain to comprehend.

Ignorance, ineptitude, lack of skill and talent, and an aging auditory apparatus. All that must be the root of the problem here, not necessarily the second person itself. Someone else with lettered or unlettered skill and talent would be able to write the book you’re trying to write. Not you.

Sure, with the second person you had success on your blog. Your you…you… you … posts resonated more than others—maybe engaging readers the way that you’d become N.K. Jemison’s protagonist in the Broken Earth Trilogy. But when you applied the second person to your book’s pages, it did no such thing.

Immersion into another person and away from one-man-army individualism, you believed, and still do, is the key to transforming human evolutionary thinking. But you fumbled the script. You dropped it down the shithole. And nothing, not even throwing your phone and wallet down after, could make you save it now. Say no more. You heard them loud and clear.

They read “you” but they couldn’t be you. You is annoying, jarring, disorienting. And, so, you are. It’s not just a better writer who could write the book you are trying to write, it’s a better person. A more relatable person. And an admirable one who earns the reader’s committed effort to walk in their shoes. Not only did you fail to bring people on board, but you turned them off: no one wants to be a crazy person who talks to themselves [sic]. The Second Person, whoever they are, is only who you wish you were: someone people could stand to pretend to be for a little while.

You are clearly a First Person. Real, typical, and yet somehow also not easy for real, typical readers to transform into. Readers can only metamorphose into exceptional people—people who can make the bedrock quake, people who can behead a troll, people who are fiction, made-up. Those people, Novel People, imaginary people invite readers into their skins. Fiction People can be Second Person, can be you. Non-Fiction People, like you, cannot.

Reading your First Person p.o.v., I… I… I… means they can empathize with you or not. It’s their choice. If you’re too different from who they are, in their minds, then they’re probably not very deep into you and they’re able to keep their distance, if that makes them more comfortable. But why must everyone be so comfortable? (Oh, must be the money.)

In reality, in Nonfiction Land, we don’t choose to be who we are and we can’t choose to be distinct from anyone. There is no First Person in 3.7 billion years of connected life on Earth. Reality is, I am you, as you are me, so we are we, and we are all together. The Walrus wasn’t wrong.

Atomized organisms comprised of atomized traits built by atomized genes is a fiction and it’s why mainstream evolutionary thinking doesn’t make any sense to you. It’s not merely philosophy, it’s the storytelling game, and it’s the practical and logistical limitations of speech and language. Explaining why mainstream evolutionary thinking doesn’t make any sense to you, and isn’t good enough science, takes more than explanation, more than talking the talk. It takes walking the walk. One way to walk the walk is to put the reader in your shoes.

Are we really supposed to assume that readers of non-fiction are so different from fiction readers? Are they that terrible at transforming themselves? At imagining? At trying something on? If so, then why even bother to change their minds about human evolution at all?  The evidence, they’re thinking; it’s the evidence that will change their minds. But they’re thinking wrong. If the facts were enough, then we’d be free already.

While you makes everyone you, and while, together, you are a more fitting adversary for old make-believe stories than I is, you is weird. You’ve got to find a way forward as I. They win. But you can make I work so you win too:

I contain multitudes and those multitudes are you.

Not yet mainstream, non-traditional, logical and reasonable evolutionary explanation for the average greater strength of human males

Common question I hear (including common "truth" about the evolution of men's strength): 

From an evolutionary standpoint, it doesn't really make sense that men are stronger than women. Of course I know men evolved that way to fight off other males to get mating opportunities, but shouldn't women also evolve strength to protect their kids? Wouldn't it make more sense for women to evolve a greater muscle mass to protect their kids from danger?

Answer: 

You’ve hit on one of the most important questions about human evolution, so I hope you’ll forgive me if this goes a little long. I’ve learned that it’s better to say too much than too little when you’re asking people to question (and maybe reject entirely) some of Charles Darwin’s ideas. One hundred and fifty years ago, he couldn’t have possibly gotten everything right. In 2024, science is still just a baby.

Though, it’s only taken humanity 150 years to know that evolution (=change over deep time throughout all lineages which are all related to, and interconnected with, one another) is true.

But there are the facts of evolution and then there are the stories we tell about those facts.

It’s a fact that males are on average stronger than females, and it’s a fact that humans (and every organism) evolved from earlier forms/ancestors, but the story we tell about why male humans evolved to be on average stronger than females is very far from fact.  

Unfortunately, that story is taken for granted as such a fact-of-life in our culture right now that questioning its truth can earn you some serious eyerolls or can make people leap to the conclusion that you’re doubting the truth of evolution itself. But enough about my personal problems. Let’s answer your wonderful question.

We can start by considering the fact that female humans are actually, already, totally evolved to be totally capable of protecting their children—wits-wise, strength-wise, throwing-projectiles-wise, fire-wise, booby-trap-wise, and otherwise, and probably have been for millions of years (considering we’re primates and knowing what female primates are capable of: surviving and helping others to too). And remember, few of our ancestors were ever isolated and alone. Group-living with complex culture and highly social coalitional behavior is rampant among primates and the human primate takes sociality, cumulative culture, and cooperation to the extreme. So, from the perspective where female humans are perfectly strong enough to care for themselves, their kids, and their loved ones (just as any female primate is), then it remains a mystery why males evolved to be even stronger. But because we started from a different assumption about the evolution of females compared to tradition/pop culture, then our scientific imagination can be open to non-traditional explanations for the evolution of male-female differences in strength.

Ever since Darwin, it’s become common sense to explain male-female differences in human strength to be about males fighting other males, the winners getting to mate more, and therefore putting their winning/strong genes into more sons than the other guys. Eventually that common sense story included males fighting other males to protect their wives and babies from imaginary Stone Age marauders. In our cultural tradition, male-female differences in strength have become evidence for a belief about human nature that has us loving only our close family, all others we battle to the death. But (combined with our initial understanding that females are perfectly physically strong enough to survive and to help others’ do the same) the fact that daughters would clearly benefit from evolving the same level of strength as sons, as you point out, is exactly why we should question that common sense story.

There is obviously a male-female difference in average strength, with males being stronger and having more total muscle mass, on average—though it is less pronounced in people who have been active since childhood and throughout their lives. And there is obviously a male-female difference in physical violence, with males fighting more than females. However, fighting (and the winners of the fights passing down more winning genes, ratcheting up strength in only sons in the future) need not be the reason physical differences exist between the sexes.

After all, fighting is not the reason for another major difference in male and female biology. Fighting’s not the reason that gonads and genitals are different between the sexes. And, while all bodies count on both testosterone and estrogen to develop and to function (and while estrogen in all bodies is synthesized from androgens), testes in male bodies produce more testosterone than is found in female bodies, while ovaries in female bodies produce more estrogen than is found in male bodies.  (And both of those hormones are also produced elsewhere all bodies, like the brain.) A delicate balance of both of those hormones (and many others), not too little and not too much, is required of all bodies to reproduce (to produce gametes and to facilitate in their meeting gametes of the other sex). And so, evolutionarily changing the levels of those hormones risks preventing that change from existing into the future. That is, evolving to have more or less testosterone or estrogen is a risky evolutionary process, given it could prevent evolution/life from continuing. Greater testosterone is the best explanation we have for greater male strength, by its promotion of the development of muscle mass. But males’ greater testosterone is fundamentally linked to their reproductive biology in the first place. Messing with testosterone levels, up or down, in males risks lowering male reproductive success. That’s true for females, too.

Bear with me because there is not a whole lot of well-understood biological science here, but it’s not likely that a female with male levels of circulating testosterone, which could make her stronger, would actually be able to reproduce. Remember, we all need a certain level of estrogen and testosterone to do so and producing so much testosterone would probably affect female reproductive ability (it may also cause a reduction in estrogen which would add to the problems, but that’s just an educated guess).

The point is, given what we know about how estrogen and testosterone contribute to reproductive biology (and if we also assume that female bodies are good and strong enough to do what humans need to do to survive and to help others to too), then it’s easy to imagine why daughters of strong men are not as strong as strong men’s sons. 

We could say that males' higher testosterone and the resulting increased muscle mass is just a consequence of being not-female. When bodies are so intricately linked through hormones to the complexities of sexual reproduction, it’s probably wise to appreciate those hormones' crucial roles in reproduction. When we do, we can see how sex differences in bodies, like muscle mass and height, could be by-products of the evolution of the reproductive system.

That is, since the reproductive system differs between males and females, then why would we expect everything else that’s developmentally linked to the reproductive system to be identical? The old common-sense story about males being stronger because of selection for fighting ability assumes that all humans would be the same if not for male-specific selection for strength. But we’re not the same in ovaries and testes. We’re not the same in hormone levels. All that difference in our gonads is doing the fundamental work with eggs and sperm to sustain our lineage.

One by-product of those hormone levels caused by our gonads is our height difference. Because males don’t have the higher levels of estrogen that ovaries produce for the ovulatory/menstrual cycle, male bodies keep growing for longer than females’. That’s because, in all bodies, estrogen drives long bone growth and an even higher level of it is needed for growth plates to fuse and for height to stop increasing. Females stop gaining height early in puberty because of the high levels of estrogen. Males keep growing for up to a few more years because there is nothing stopping them so soon like there is in females. Male-female differences in height are therefore not because of selection for big, tall males (despite that being common sense story since Darwin); they are because of reproductive biology’s side-effects on bone growth duration resulting in patterned variation where on average females are shorter than males.

I suspect that the same side effects are happening with muscle mass and strength. There’s no reason to expect us all to be the same and then, from there, to require a male-specific adaptive tale for the difference. Selection is already building ovaries and testes and from there viable/successful human variation forms (height, strength) and we’re clearly doing fine with all this variation because our ovaries and testes keep putting all this variation into the future. (There is probably something about the increased fat mass in female bodies compared to males, because it is linked to estrogen and to successful reproduction. And so, there may be something about building fat in bodies with more estrogen and, in the absence of lots of estrogen, building more muscle instead.)

That leaves us wondering why human males fight so much more than females (and so much more than other primates) if they have not necessarily evolved to do so. It may have lots more to do with culture than old evolutionary stories have led us to believe. It may even have a little bit to do with telling boys and men that they have evolved to be fighters.

As you point out implicitly in your question, what I’ve written here isn’t mainstream (yet), but, like I said, science is still a baby. Keeping an open mind about human biological variation and remaining skeptical of the stories we tell to explain human variation is, I think, the strongest way to face human evolution with science.