Would you like some free biological illustrations that aren’t the products of an AI’s unrestrained imagination? NIH BioArt is such a source.
These are bold, simple illustrations with limitations. There is a section on arthropods, but it doesn’t contain any spiders, or much of anything outside ticks and mosquitos. If you want a graphic of a tick, it’s got you covered. Here’s a tick for you:
External appearance of three-week-old heads of large felid cubs, right lateral view: (A) Homotherium latidens (Owen, 1846), specimen DMF AS RS, no. Met-20-1, frozen mummy, Russia, Republic of Sakha (Yakutia), Indigirka River basin, Badyarikha River; Upper Pleistocene
I understand that the internet likes cats, so here’s one, a 30,000 year old mummified sabre-toothed kitten.
It has a distinctively large mouth and massive neck muscles, but the canine teeth haven’t elongated yet — they say the age is equivalent to a 3 week old lion cub. I would guess that sabre-tooth canines might interfere with nursing.
The frozen mummy of Homotherium latidens (Owen, 1846), specimen DMF AS RS, no. Met-20-1, Russia, Republic of Sakha (Yakutia), Indigirka River basin, Badyarikha River; Upper Pleistocene: (A) external appearance; (B) skeleton, CT-scan, dorsal view.
It has toe-beans!
In that treasure trove of old documents from my mother, I found this little surprise: she’d also saved one of my extra figures from my research at the University of Oregon, the stuff that led to me working with Judith Eisen.
Photograph of horseradish peroxidase labeled spinal motoneurons
That’s another oldie — Mom must have asked what the heck I was doing in the lab, and I gave her an old print and tried to explain it to her. And she salted it away for 40 years!
My experiences in grad school were mostly happy ones, and I credit that to the fact that I was lucky to work with good people. I entered the lab of Charles Kimmel, working on zebrafish neuroscience, and stumbled my way through several projects before Chuck suggested a new one: he recommended that I use a fluorescent lineage tracer dye, rhodamine dextran, injected into midblastula cells, which we’d allow to develop into a larva in the hopes that some of that dye would end up in the neurons I was interested in.
This was a cunning strategem. First of all, this was a labor-intensive project; we’d have to do a hell of a lot of injections to get the dye into the few cells we cared about by happenstance. We’d eventually do the experiment and get a yield somewhere under 5%. The other angle is that he already had someone lined up to work on the idea, and I was being drafted to assist in the experiment.
I didn’t mind. That someone was a new post-doc, Judith Eisen, and I think we worked well together. Judith was intimidatingly intense, but nice. We got into the rhythm of this experiment smoothly. In the evening (this was a timing-dependent experiment, you had to start with embryos of a certain age) we’d get together over a beaker with hundreds of embryos, and then we had to work fast, because there was a narrow window of time to get the injections done. I’d line up ten or so embryos on a slide, and pass them to Judith, who was poised over the microscope with a microinjector, and bang bang bang, she’d shoot up single cells with the dye. I was the loader, she was the gunner. We’d set up maybe a hundred embryos before stopping and letting them then develop.
The fun work started the next day. We’d go through the previous night’s collection, put each embryo under a fluorescence microscope with a silicon intensified target camera and take pictures. Most of them we’d throw out — they had labeled skin cells, or labeled kidney, or labeled notochord, or whatever, which might be useful to someone, but not us. We wanted labeled spinal neurons. We’d get a few.
The next step might sound crude, but it was the 1980s, it was what we could do. We’d see a glowing cell on the video monitor, and we’d tape a piece of transparent plastic on the screen and outline all the cells with a sharpie. Then we’d come back to that special cell over the course of the day, and draw on that same piece of plastic with a different color. Our data was these sheets with the changing shape of labeled cells.
I vividly remember our eureka moment. We were going through our daily labeled embryos, and we had this one fish that looked familiar, a cell that looked like one we’d seen before. We sat there and made a prediction, I bet we knew exactly how that cell would develop in the next few hours. Judith grabbed all our data and spent an afternoon manually aligning all these drawings — our simple technique had some virtues, in that we could so easily align analog pictures — and came back and could say that we had precisely three cell types that had a stereotyped pattern of outgrowth.
Those were great times, and it was most excellent working with Judith. Some of my happiest memories of working in science were from those years in Chuck’s lab, partnering with Judith, so the latest news from Oregon makes me even happier: Judith Eisen has been elevated to the National Academy of Sciences! That is a well-deserved honor, and I’m happy for her.
What I learned from that experience was that a key ingredient of good research was collegiality, mutual support, and cooperativity. I think that’s what I took away from my training, that I should model my own mentorship in the years since on that of Judith Eisen and Chuck Kimmel.
Professor Dave demolishes Sabine Hossenfelder.
I feel that. The topic of my history class last week and this week is about bias in late 19th/early 20th century evolutionary biology, and how we have to be critical and responsible in our assessment of scientific claims. It’s tough, because I’m strongly pro-science (obviously, I hope?) but I keep talking about dead ends and errors in the growth of a scientific field, and I have to take some time to reassure the students that our only hope to correct these kinds of problems is…science. I also have to explain that the way the errors are discovered is…science, again.
I’m not specifically interested in Sabine Hossenfelder — I don’t watch her videos, not even the ones that might contain good information — but I am concerned with the general problem of how anti-science propaganda manages to advance the causes of dogma. If science gets something wrong, as it does sometimes, it does not mean that superstition or bigotry are right. Raging against the whole of the scientific establishment and the scientific method is how you get RFK Jr put in charge of the NIH. I don’t think that even Hossenfelder believes that will be an improvement.
I’m not a fan of phys.org — they summarize interesting articles, but it’s too often clear that their writers don’t have a particularly deep understanding of biology. I wonder sometimes if they’re just as bad with physics articles, and I just don’t notice because I’m not a physicist.
Anyway, here’s a summary that raised my hackles.
Chromosphaera perkinsii is a single-celled species discovered in 2017 in marine sediments around Hawaii. The first signs of its presence on Earth have been dated at over a billion years, well before the appearance of the first animals.
A team from the University of Geneva (UNIGE) has observed that this species forms multicellular structures that bear striking similarities to animal embryos. These observations suggest that the genetic programs responsible for embryonic development were already present before the emergence of animal life, or that C. perkinsii evolved independently to develop similar processes. In other words, nature would therefore have possessed the genetic tools to “create eggs” long before it “invented chickens.”
First two words annoyed me: Chromosphaera perkinsii ought to be italicized. Are they incapable of basic typographical formatting? But that’s a minor issue. More annoying is the naive claim that a specific species discovered in 2017 has been around for a billion years. Nope. They later mention that it might have “evolved independently to develop similar processes”, which seems more likely to me, given that they don’t provide any evidence that the pattern of cell division is primitive. It’s still an interesting study, though, you’re just far better off reading the original source than the dumbed down version on phys.org.
All animals develop from a single-celled zygote into a complex multicellular organism through a series of precisely orchestrated processes. Despite the remarkable conservation of early embryogenesis across animals, the evolutionary origins of how and when this process first emerged remain elusive. Here, by combining time-resolved imaging and transcriptomic profiling, we show that single cells of the ichthyosporean Chromosphaera perkinsii—a close relative that diverged from animals about 1 billion years ago—undergo symmetry breaking and develop through cleavage divisions to produce a prolonged multicellular colony with distinct co-existing cell types. Our findings about the autonomous and palintomic developmental program of C. perkinsii hint that such multicellular development either is much older than previously thought or evolved convergently in ichthyosporeans.
Much better. The key points are:
Cool. The idea is that this organism suggests that single-celled organisms could have acquired a toolkit to enable the evolution of multicellularity long before their descendants became multicellular.
I have a few reservations. C. perkinsii hasn’t been sitting still — it’s had a billion years to evolve these characteristics. We don’t know if they’re ancestral or not. We don’t get any detailed breakdown of molecular homologies in this paper, so we also don’t know if the mechanisms driving the patterns are shared.
I was also struck by this illustration of the palintomic divisions the organism goes through.
a, Plasma membrane-stained (PM) live colonies at distinct cell stages, highlighting the patterned cleavage divisions, tetrahedral four-cell stage and formation of spatially organized multicellular colonies (Supplementary Video 5). b, Actin- (magenta) and DNA-stained (blue) colonies at distinct cell stages showcasing nuclear cortical positioning, asymmetrical cell division (in volume and in time) and the formation of a multicellular colony. This result has been reproduced at least three independent times.
Hang on there : that’s familiar. D’Arcy Wentworth Thompson wrote about the passive formation of cell-like cleavage patterns in simple substrates, like oil drops and soap bubbles, in his book On Growth and Form, over a century ago. You might notice that these non-biological things create patterns just like C. perkinsii.
Aggregations of oil-drops. (After Roux.) Figs. 4–6 represent successive changes in a single system.
Aggregations of four soap-bubbles, to shew various arrangements of the intermediate partition and polar furrows.
An “artificial tissue,” formed by coloured drops of sodium chloride solution diffusing in a less dense solution of the same salt.
That does not undermine the paper’s point, though. Multicellularity evolved from natural processes that long preceded the appearance of animals. No miracles required!
It was hard to get motivated this morning — Fridays are typically low attendance days in the classroom, and I had worked hard to get today’s topic condensed down into a lot of digestible information (we’re talking about the rediscovery of Mendel, the biometrician and Mendelians arguing with each other). I had a presentation that was pretty tight and I thought would help make the conflict comprehensible to a group of liberal arts majors, none of whom are biology majors.
So I get to class today, and was pleasantly surprised to see that I had 80% attendance, which is kind of a miracle. I tell you, standing at the front of a classroom with only 3 students who don’t really appreciate the work you put in to the class is mighty depressing. So I was temporarily heartened that maybe this lecture wouldn’t go to waste, I fired up my laptop and the projector and got ready to tell this exciting story…and the projector is glitched out. It’s not connecting to anything, and is showing me a message that the projector and microphones were not receiving any data since 5:21pm yesterday. Isn’t technology nice that it has become so sophisticated that it can tell you precisely when it broke down?
I fumbled with it for about 15 minutes — that was the show today, watching the old geezer prof toggling switches and poking at a keyboard in front of the class, and seeing everything fail. I ended up giving up, giving them a brief oral summary of the history of biology from 1900-1915, telling them I’ll give them all the details on Monday, and sending them home early. So many smiles from the students! I didn’t tell them that I don’t find that encouraging at all.
Now I’m sitting in an empty classroom waiting for the IT people to show up. At least I can cheer myself up by thinking, hey, this isn’t the worst thing to happen this week.
This is nice because it focuses mainly on deep evolutionary history, talking about how, contrary to common opinion, spiders are not particularly closely related to insects.
They’re all crunchies together, rather than squishies. Isn’t that enough to combine them in an evolutionary taxonomy?
(Nope.)
Yes. But they’ll feel like they’re the one who failed.
Today, I had 3 students (out of 11) show up for what I thought was a scintillating talk about the immediate aftermath of publishing The Origin. Wilberforce and Huxley! Huxley humiliating Owen on the hippocampus minor question! Fleeming Jenkins’ extremely awkward question! Darwin’s epic genetics failure! How can you not want to discuss these dramatic events?
Maybe I’m not as scintillating as I thought. How are these students going to learn anything if they don’t keep up? Less significantly, how do they expect to pass?
Retirement looks ever more attractive.
P.S. I should mention that my entire class is not at risk of failing. Some are. Others may be working on a lower grade than they want.
Fridays are the worst, from a teacher’s perspective, and Mondays are great. Students start out the week full of enthusiasm and slowly deflate, so today I’ve only got 50% attendance…and that’s typical. I try to pack Mondays with all the deep information, while on Fridays I try to do something different.
We’ve been talking about Darwin this week. I’ve given them an in-class exercise to browse through the Darwin project and begin to put together a short essay. Here are their instructions.
In your next essay, you’re going to be a real historian: I want you to read a few samples of primary historical references from Charles Darwin, and interpret and explain what he is writing about.
The Darwin Correspondence Project (https://www.darwinproject.ac.uk/) is a massive archive of letters to and from Charles Darwin, containing about 15,000 documents that have all been indexed and made publicly available. I want you to dive into this pile of letters, pluck out a few, and read them carefully. You may have to do additional research to figure out who these long dead people were, but the Darwin Project has actually done a lot of that work for you.
Write a 750 word essay that explains the context and meaning of the letters you choose. Unlike most scientific writing, this kind of essay encourages quoting your source — but don’t use up more than 250 words in direct quotes.
You get to choose the topic of the letters. Some might contain heavy scientific arguments, others might be friendly chit-chat, some are questions about that flower you were supposed to mail to me. They’re all good and interesting! Peek into the mind of a famous scientist, and you’ll find both deep revelations and mundane conversation.
In class: before you go, summarize to the group what you intend to write about, or tell us something interesting that you found.
I’m in class, working in parallel with them, and occasionally interrupting to get an idea of what they’re focusing on. I was most interested in Darwin’s “fool experiments“. These were experiments where you figured that it would never work, or that the answer would be obvious, but you go ahead and do the experiment anyways.
‘I love fools’ experiments. I am always making them’, was one of the most interesting things the zoologist E. Ray Lankester ever heard Darwin say. ‘A great deal might be written as comment on that statement’, Lankester later recorded, but he limited himself to stating that ‘the thoughts which it suggests may be summed up by the proposition that even a wise experiment when made by a fool generally leads to a false conclusion, but that fools’ experiments conducted by a genius often prove to be leaps through the dark into great discoveries.’
That’s a really good idea. I should go do a fool’s experiment this afternoon, maybe I’ll be surprised.
My students are right now digging into Darwin’s religious beliefs, his love life, his speculations about the age of the earth, and are going to give me the details next week. This should be fun.
