Sacrifices made in the name of lust

Some spiders have a serious problem: runaway evolution sometimes produces maladaptive conditions. Here’s a spider, Tidarren sisyphoides, that exhibits extreme sexual dimorphism — males have about 1% of the mass of the females.

Male and female T. sisyphoides in copula. The minute male (indicated by the arrow) on the female’s ventrum is ≈1% of the female’s mass. (The scale bar represents 1 mm.)

That’s not the problem, though. The problem is that the males maintain a massive pair of palps. Really gigantic. They probably clang when they walk. Look at these two big boys, and the monster intromittent organs dangling from the front of their faces.

You may notice that the top spider has the normal two palps, which are so large that they’re interfering with each other. The bottom spider has only one palp. The surprise is that this is a product of self-mutilation.

During copulation, males generally use both pedipalps in an alternating fashion to inseminate the paired spermathecae in the female. In Tidarren, however, one pedipalp is removed (either left or right pedipalp, seemingly at random) before sexual maturation which has also been described for another spider of similar size and closely related to Tidarren (Echinotheridion). Just after molting to the penultimate instar, the male secures one of its pedipalps to a silk scaffold and then twists it off by turning in circles and pushing the bulb with the third and fourth pairs of legs.

Ouch. There’s a reason for their partial emasculation, though.

We found that, for male Tidarren sisyphoides, maximum speed increased (44%) significantly and endurance increased (63%) significantly after pedipalp removal. Furthermore, spiders with one pedipalp moved approximately 300% greater distances before exhaustion and had a higher survival after exertion than those with two pedipalps. Removal of the pedipalp may have evolved in male Tidarren because of enhanced abilities to search for females (higher endurance and survival after exertion) and to out-compete rival males on the female’s web (higher maximum speed). Our data also highlight how the evolution of conflicts can result in the evolution of a novel behavior.

Not recommended for humans, unless your testicles are the size of basketballs.


Ramos M, Irschick DJ, Christenson TE (2004) Overcoming an evolutionary conflict: removal of a reproductive organ greatly increases locomotor performance. Proc Natl Acad Sci U S A 101(14):4883-7.

Summer research presentation time!

My students talked about their work today — this picture was taken before the crowds put them to work.

Violet took full advantage of the medium, a big screen connected to a laptop, and instead of a static display, the ‘poster’ rotated through a big collection of images. They had the prettiest poster of the group, as long as spiders are considered to belong to the category “pretty”.

Synchronicity is just another word for coincidence

Lately, I’ve been having these odd dreams in which I’m traveling to Quito, where I’m expected to take a ride in the space elevator. I’m oddly anxious about it, and I don’t know why, and I don’t board the silly thing. The End.

Anyway, this morning I discover that Angela Collier has a video about space elevators, and she dismantles the concept with math and engineering, which was very satisfying.

Very convenient. Next time this dream pops up in my subconscious playlist, I’ll just dismiss it and say it’s not possible, go away, and get back to that nice dream where I can talk to spiders.

A horror scenario

Could a disease arise that killed half the human population? And that inflicted horrifying neurological effects as the victims slowly died? Sure could. It’s happened in other animals. It’s happening right now in moose.

Minnesota saw a 58% decline of the moose population in the northeastern part of the state between 2006 and 2017.

If you’ve ever seen a moose, you know they’re huge and intimidating — you don’t want to tangle with one. The bulls are temperamental and cranky, the cows are fiercely protective, and you really don’t want to have to deal with a 700kg angry beast. But here’s what’s bringing them low.

A primary driver of the decline is brainworm, a parasite that affects the animal’s nervous system ultimately leading to paralysis and death. Researchers from the University of Minnesota and the Grand Portage Band of Lake Superior Chippewa recently discovered evidence that moose in Minnesota consume species of gastropods —slugs and snails—which are known hosts for the brainworm parasite (Parelaphostrongylus tenuis).

This massive die-off is a consequence of climate change: the worm is moving north as the weather warms, migrating with resistant deer populations whose range is overlapping with that of moose. When people talk about new diseases accompanying climate shifts, this is the kind of thing we’re talking about.

It can happen to us, you know.

I do sometimes wonder if Republicans have been eating snails.

The algorithm may have killed another expert for me

It’s a real shame. I used to watch Sabine Hossenfelder videos regularly — she was explaining stuff far outside my background, so it was good to learn about it. Her recent escapades have me wondering how good her explanations actually were — maybe they were great? I don’t know. But now I’ve unsubscribed and all of her videos are unappealing, because they’re long and sometimes technically challenging and now I can’t trust her enough to make the effort.

Yeah, Sabine does it again. Her strongly pro-capitalist position is backed with bad and sloppy evidence, fails to recognize the deep flaws in capitalism, and is beginning to remind me of Ayn Rand. No, thanks. (If I found someone fanatically supporting communism with the same kind of mangled evidence, I’d also drop them from my approved list — this is not an ideologically framed decision.)

Oh, well. Youtubers are a dime-a-dozen, I’ll find a replacement.

By the way, I do wonder if what ruined Sabine Hossenfelder for me was capitalism — the need of prominent Youtubers to feed the sacred algorithm with click-baity bullshit. So capitalism is bad?

What’s the worst job?

I can think of lots of candidates for the worst job humans could do. Commercial fishing is incredibly dangerous, and requires exhausting effort in miserable conditions. Stoop labor, like what we compel immigrants to do, is going to mess your body up in the long term, with chronic pain in the back and limbs, as well as being degradingly disrespected. You probably have your own examples of work that you would never want to do. But in my opinion, there is one job that is the ultimate worst.

Astronaut.

Human beings are not adapted to microgravity and high radiation. We’ve got enough data now on the consequences of long-term living in space (where long-term is a matter of months — no one is going to be able to live their lives in space).

Human bodies really can’t handle space. Spaceflight damages DNA, changes the microbiome, disrupts circadian rhythms, impairs vision, increases the risk of cancer, causes muscle and bone loss, inhibits the immune system, weakens the heart, and shifts fluids toward the head, which may be pathological for the brain over the long term—among other things.

It’s a devastating combination of effects with long-term consequences. A short hop into space, like billionaires like to play at, is one thing, but staying up their long enough for your physiology to try to adapt is another. It’s a long gamble in which you try to determine which systems fuck up first.

She also wants to figure out how to help astronauts’ faltering immune systems, which look older and have a harder time repairing tissue damage than they should after spending time in space. “The immune system is aging quite fast in microgravity,” Schrepfer says. She sends biological samples from young, healthy people on Earth up to orbit on tissue chips and tracks how they degrade.

Vision and bone problems are also among the more serious side effects. When astronauts spend a month or more in space, their eyeballs flatten, one aspect of a condition called spaceflight-associated neuro-ocular syndrome, which can cause long-lasting damage to eyesight. Bones and muscles are built for life on Earth, which involves the ever present pull of gravity. The work the body does against gravity to stay upright and move around keeps muscles from atrophying and stimulates bone growth. In space, without a force to push against, astronauts can experience bone loss that outpaces bone growth, and their muscles shrink. That’s why they must do hours of exercise every day, using specialized equipment that helps to simulate some of the forces their anatomy would feel on the ground—and even this training doesn’t fully alleviate the loss.

Perhaps the most significant concern about bodies in space, though, is radiation, something that is manageable for today’s astronauts flying in low-Earth orbit but would be a bigger deal for people traveling farther and for longer. Some of it comes from the sun, which spews naked protons that can damage DNA, particularly during solar storms. “[That] could make you very, very sick and give you acute radiation syndrome,” says Dorit Donoviel, a professor at the Baylor College of Medicine and director of the Translational Research Institute for Space Health (TRISH).

Then there are the big questions.

And an even simpler ethical question is, “Should we actually send people on these sorts of things?” Green says. Aside from incurring significant risks of cancer and overall body deterioration, astronauts aiming to settle another world have a sizable chance of losing their lives. Even if they do live, there are issues with what kind of an existence they might have. “It’s one thing just to survive,” Green says. “But it’s another thing to actually enjoy your life. Is Mars going to be the equivalent of torture?”

Yes.

Wow, it’s always nice to see a grand ethical question that can be answered so easily.

But is the pioneer way of life virtuous? I don’t think so. We have our own on-planet example of the American westward expansion, which was not at all about heroic, noble adventurers pushing back the foreskin of the wilderness. It was all about colonizers ripping up the environment, killing any people who stood in the way (at least we don’t have to worry about that in space), and suffering hellishly. I think you need to be a psychopath to want this way of life.

On this question, science-fiction scholar Gary Westfahl casts doubt on space travel’s inherent value. In his vast analyses of sci-fi, he has come to view the logic and drive of the enterprise as faulty. “I inevitably encountered the same argument: space travel represents humanity’s destiny,” he says of the impetus for writing his essay “The Case against Space.” Space explorers are often portrayed as braver and better than those who remain on their home planet: they’re the ones pushing civilization forward. “Philosophically, I objected to the proposition that explorers into unknown realms represented the best and brightest of humanity; that progress could be achieved only by boldly venturing into unknown territories,” Westfahl says. After all, a lot of smart and productive people (not to mention a lot of happy and stable people) don’t spend their lives on the lam. “Clearly, history demonstrates no correlation between travel and virtue,” he writes. “The history of our species powerfully suggests that progress will come from continued stable life on Earth, and that a vast new program of travel into space will lead to a new period of human stagnation,” he concludes ominously.

The article also talks about the Biosphere studies, which is a cartoon version of space exploration. It’s on Earth, so no peculiar gravity regimes or bombardments by radiation, and they’re swimming in plentiful air and water, so all they’re really testing is the human psychological response to prolonged isolation. It messes people up.

Kowalski’s talk at the Analog Astronaut Conference at Biosphere 2 was called “Only Eight Months.” The goal of those eight months was to study the medical and psychological effects of isolation. She and her teammates regularly provided blood, feces and skin samples so researchers could learn about their stress levels, metabolic function and immunological changes. Researchers also had them take psychological tests, sussing out their perception of time, changes in cognitive abilities and shifts in interpersonal interactions. Inside they had to eat like astronauts would, guzzling tubes of Sicilian pizza gel and burger gel. Kowalski would squeeze them into rehydrated soup to make meals heartier. Via their greenhouse, they got about a bowl of salad between the six of them every three weeks.

Kowalski missed freedom and food and friends, of course. But the real struggle came with her return to the real world once the isolation was over: “reentry, not to the atmosphere but to the planet,” she told the conference audience. She didn’t remember how to go about having friends, hobbies or a job and had trouble dealing with requests coming from lots of sources instead of just mission control. In the Q&A period after the talk, Tara Sweeney, a geologist in the audience, thanked Kowalski for talking about that part of the experience. Sweeney had just returned from a long stay in Antarctica and also didn’t quite know how to reintegrate into life in a more hospitable place. They had both missed “Earth,” the real world. But it was hard to come back.

These effects were reported at a conference of space enthusiasts. You can guess how they responded.

Still, the Analog Astronaut Conference crowd remained optimistic. “Where do we go from here?” conference founder and actual astronaut Sian Proctor asked at one point. On cue, the audience members pointed upward and said, “To the moon!”

I think maybe the real psychopaths aren’t the extreme loners who go out into the dangerous frontier, but the well-off people who send them there.

Grading…

My trial policy of taking care of grading the instant everything is turned in is biting back today: the first cell bio exam was thrown over the transom last night. I have been locked to my desk this morning. Will continue until it’s done.

The good thing about this practice is that I don’t have work hanging over my head all the time to feed my anxiety. The bad thing is that it demands bursts of focused work.

Empty noise, lazy science

Your disappointingly vapid opinion piece is not going to encourage your book, Benjamin Oldroyd. There’s nothing there. I’m referring to an article titled Epigenetics and evolution: ‘the significant biological puzzle’ of sexual orientation. The author is plugging a new book, Beyond DNA, and is trying to persuade us that maybe he has an answer to why gay people exist by going through a couple of hypotheses.

The first hypothesis is that it is a product of kin selection.

Briefly, the kin selection idea is that a gene that promotes homosexual behaviour can spread in a population if homosexual people contribute significantly to the reproduction of close relatives. Although this idea is plausible, the lack of any genetic marker that is reliably associated with sexual orientation is a strong argument against it.

There is no such thing as a gay gene, though, so you can’t postulate the existence of one and build up an adaptive scenario around it. I agree with Oldroyd. It’s a useless hypothesis.

Another idea is that there are antagonistic alleles.

The “antagonistic alleles” idea is that there are certain genes that are selected in different directions, that is, positively selected in males, but negatively selected in females and vice versa. Hypothetically, because no such gene has been identified, a gene that promotes testosterone production could be at a selective advantage in males if it promoted traits such as muscle development, risk taking, opposite-sex sexual attraction and increased sexual attractiveness to females. But if the same gene were expressed in the same way in females it might be disadvantageous for reciprocal reasons. This means that selection could pull in different directions in males and females, maintaining different gene variants in a population. By that I mean, gene variants that have different selective advantages in males and females can potentially coexist in a population because neither is unambiguously better. If so, sexual orientation may be more fluid than one might expect based on biological sex alone. (Well, “der”, I suspect you are now thinking, but please don’t shoot your even-handed messenger.)

He explains it well, but…”might” and “could be” are not evidence. Again, this hypothesis falls apart because there is an absence of evidence for the existence of such alleles undergoing differential competition in males and females. It’s another adaptive just-so story. It’s a useless hypothesis.

Therefore, if you rule out two hypotheses, the third alternative must be the answer, right? Cue dramatic entrance of Intelligent Design…no wait, not that. Oldroyd knows better than that. But it’s the same rationale: we think we have evidence against the conventional alternatives, therefore that counts as evidence for a different hypothesis.

No, it does not. Now the magical mcguffin we’re all looking for is epigenetics.

The epigenetic hypothesis for the widespread occurrence of human homosexuality is based on the possibility of epigenetic inheritance of adjustments to a foetus’s testosterone sensitivity. Like most other epigenetic marks, sex-specific epigenetic marks are established anew in the early embryo following fertilisation.

Substituting hypothetical “epigenetic marks” for a hypothetical “gay gene” gets us nowhere unless you’ve got something concrete and specific. If you do, that would be very interesting…but epigenetics, by it’s nature, is fuzzy and hard to pin down. That is not to say that epigenetics is non-existent — it’s very real and important — but that you can’t slap a simple causal explanation on many complex phenomena, whether it’s a gene or a epigenetic marker.

My preferred explanation is also a bit fuzzy. We have to get beyond the bogus genetic determinism that appeals so strongly to naive minds, and epigenetic determinism would be just as bad. I think we have to accept that human behavior is sloppy and variable as hell. We are built by a long chain of probabilistic interactions, from molecules bouncing around in a messy cell, to a tangle of cells communicating chaotically with one another, to incompletely specified individuals that are shaped by interactions with a variable, changing environment to end up as people with mostly unpredictable characteristics. Physics and chemistry are biased by biological constraints, but the end result is not rigidly locked in by your genes — there is a messy cascade of genetic, epigenetic, and environmental interactions that is skewed by evolution to produce a generally viable outcome, but is tolerant of variability.

We have to abandon these mechanistic notions of a clockwork biology that spits out adults who were specified at conception by the chemistry of nucleic acids. It just doesn’t work that way. We are all products of stochastic processes.

My personal belief is that evolution has worked to take a population of apes and favor a hierarchy of properties that are all weakly specified, and we’re lucky if the majority of individuals conform to that hierarchy. First in priority is cooperation, building a social environment that promotes mutual aid (we all know how poorly that often works out). The way I look at it is that biology is telling us to love one another…and then it is far less fussy about the details. We don’t need a deterministic explanation for why individuals vary, it’s the nature of how they are built.

Another bad memory

Oh, no. You must understand, in the late 80s and 90s, growth cone navigation was my jam. It’s what I was doing research on, and my head was full of papers from that era. Netrin, robo, slit, various molecules that attracted or repelled growing axons to establish the pattern of connections in the early developing brain…that was what I did. Now I learn that some of those papers, those written by Marc Tessier-Lavigne, were a lie.

Marc Tessier-Lavigne, the former president of Stanford University who resigned following scrutiny of his published papers and an institutional research misconduct investigation, has retracted a third paper, this one from Cell.

Last week, Tessier-Lavigne retracted two articles from Science that had been published in 2001.

The Cell paper, A Ligand-Gated Association between Cytoplasmic Domains of UNC5 and DCC Family Receptors Converts Netrin-Induced Growth Cone Attraction to Repulsion, was published in 1999. It has been cited 577 times, according to Clarivate’s Web of Science.

In my circles, Tessier-Lavigne had a colossal reputation — he was turning out all this work from a prestigious, well-funded lab with an army of students and post-docs. I was teaching developmental biology, talking about netrins, with a textbook that already cited the Tessier-Lavigne work. Such cool stuff, and it can’t be trusted anymore.

Worse, can we trust Cell magazine? They’ve posted the retraction, and it admits that the editors didn’t care about faked data.

In 2015, we, the authors, consulted with Cell editors about issues that had been brought to our attention about this paper, specifically image splicing in Figures 3C, 5A, 5B, and 7B–7D and duplication of blank blots in Figure 7C. Cell declined to publish a Correction at that time because in 1999, when the paper was published, the journal did not have policies prohibiting unmarked image splicing and because, for the duplication, there was insufficient information to determine intent, and the impact of the duplication on the paper’s conclusions was limited. In 2022, when new concerns were raised, Cell posted an Editorial Expression of Concern (Cell 186, 230 [2023], https://doi.org/10.1016/j.cell.2022.12.019) while an institutional investigation was conducted. The investigation is complete and has revealed further issues including manipulation of data-containing portions of Western blot images in Figures 3A–3C, 7A, 7B, and 7D, undermining confidence in the paper’s conclusions (https://boardoftrustees.stanford.edu/wp-content/uploads/sites/5/2023/07/Scientific-Panel-Final-Report.pdf). As a result, we are retracting the paper. We regret the impact of these issues on the scientific community.

Yikes. All it should take is one fudged image to cast doubt on the entire paper. If you’re faking data, we have sufficient information to determine intent — I was brought up with strict instruction that you never never never never ever do that.

What a disgrace. Shame on Tessier-Lavigne, and shame on Cell.

MORE SPIDERS

I saw the mommy spider spin the egg sac on 21 August, and this morning, the 6th of September, they finally emerged. These are Parasteatoda tepidariorum — note the leopard pattern on the abdomen. That’ll turn into a more complex mottling as they get older. Also see how the legs are mostly pale, but with distinct bands.

Steatoda triangulosa has a longer incubation time of 30 days, and the spiderlings emerge with pale abdomens and black, hairy legs.

The important thing about this is that we can nail down how long the incubation period for both species is under our specific culturing conditions. Now we wait for the Steatoda borealis egg sac to hatch out so we know its incubation period. Then…comparative embryology!

By the way, the lab was hectic this morning, with 150 tiny baby spiders, each about 3/4 of a millimeter long, emerging all at once and immediately trying to disperse. There was a cloud of barely visible dots all radiating out instantly from the locus of their home vial, while I was frantically trying to gather up individuals and put them in separate containers. Some, I’m sure, escaped.

Hmmm, is it ever a good thing when a scientist says that?

Since I avoid posting spiders here, you’ll have to go to Patreon or Instagram to see the baby picture.