I checked on my colony this morning — no news to report. However, Trillian was just being herself, hanging out all relaxed in her web, legs spread out, and so I had to snap a picture.
Spiders do have personalities. Trillian is a casual exhibitionist, happy to sprawl out in her web, while, for instance, Mary Jane is shy and timid, tending to huddle in a corner. Trillian wins on photogenicity, that’s for sure.
Steatoda triangulosa
I am currently running into the same problem I encountered last year: male spiders are weak and fragile, and I’m running low on studs. I’ve been shuffling one eager male from cage to cage to service the females, who are all going strong, but there’s a serious lack of depth in the roster. Yesterday, I left this male (males don’t get names, sorry to say) with Rio, a young P. tepidariorum who was barely larger than he was, after two weeks of at least attempted ardor with a sequential collection of lovely ladies.
This morning…
…he was dead.
He was not cocooned and sucked dry, so I don’t suspect Rio of murdering him. He was suspended from a drag line in the very center of the cage, curled up and looking cocky, but motionless. I’m going to list “amorous exhaustion” as the cause of death on his death certificate.
I don’t usually name the males — he was previously in a tube with the label “P. tep ♂” — but in his honor, I posthumously name him Mr. Studly.
Another day in the lab, waiting for spiders to hatch out. They keep teasing me. While I was looking for egg sacs, though, this guy stood out. That’s a chonky big Steatoda borealis.
Note the light horizontal band across the front of the abdomen, and the hint of a midline stripe, all against a darkly pigmented body. These are true native spiders, found in the northern US in the midwest and east, and also in Canada. Parasteatoda tepidariorum is, apparently, also native to North and South America, but has spread all around the world, unlike these stay-at-homes.
S. borealis is also more stocky than P. tepidariorum. Here’s the latter to remind you what they look like.
Now I’ve got to wonder what has made S. borealis so well-tuned to these places with snowy winters.
There’s an interesting argument that’s been raging for decades about women’s orgasms: are they useful or not? Normal people, especially women, are probably wondering how that can even be a question — you probably find them very nice — but that’s missing a deeper point, which is, do women’s orgasms increase their fertility? Which I would argue masks an even deeper question, which is about women’s Ultimate Purpose. And apparently, the ultimate purpose of having a woman orgasm is that it makes her cervix more likely to slurp up the manly ejaculate, a phenomenon called upsuck or insuck.
On to this paper by Robert King, Maria Dempsey, and Katherine Valentine. It’s a weak paper, but the authors, to their credit, acknowledge the weaknesses and submit it as primarily a method of testing one aspect contributing to potential fertility problems that individuals can test for themselves in their home. The procedure is simple. Six women (they also admit that their n was tiny) were each given a Mooncup, a rubbery device usually used as an alternative to tampons or pads, a supply of an artificial semen simulant, a 10ml syringe, a spoon, and a surgical glove, and sent home to masturbate. Their instructions were to first use the syringe to squirt 5ml of fake semen into their vaginas, and then flip a coin. Half the time they would masturbate to orgasm, and the other half they would masturbate for roughly the same amount of time, but then stop before orgasm, as a control. The next step was to place the mooncup over their cervix, and after an hour, remove it and measure how much of the fake semen had flowed back out of the upper reaches of their reproductive tract, which they were then to measure with the syringe.
Sounds romantic, I know.
The hypothesis was that muscle contractions during orgasm would propel semen deeper into their bodies, and that as they later relaxed, it would flow back into the mooncup, so they could compare the amount squirted up into the uterus/fallopian tubes/etc. in orgasmic vs. non-orgasmic situations. The prediction was that if orgasm were effective at increasing semen flow into relevant parts of the reproductive tract, they’d see more retention of semen after an orgasm. The answer is…they did.
I have a few problems with the study. As already mentioned, it has a minuscule number of participants, but also, it is not at all a blind study. The subjects knew what the expected result should be! I would not accuse them of outright cheating, but it’s very human to see an experiment that is purportedly testing the potency of your orgasms as a judgment, and that maybe a little fudging in one direction or another is acceptable. I’m also wondering why the contribution of the women’s fluids to the outcome wasn’t taken into account; they specifically excluded situations where the women produced female ejaculation, but as the investigators must know, women will produce more vaginal fluids with orgasm than without, which would have contributed to the volumes they measured.
One of the biggest problems of interpretation, though, is that nothing in this study actually tests fertility and the odds of conception. I would take it for granted that triggering vigorous contractions in a muscular, fluid-filled tube is going to move those fluids all over the place, but the question is whether this contributes significantly to successful fertilization. Maybe it does, maybe it doesn’t, nothing in these observations answers that question, or even whether this is a relatively significant factor compared to all the other variables in conception.
But that is the biggest problem of them all. If you’re trying to determine whether there is a selective advantage to a woman having an orgasm, why focus exclusively on the mechanical effectiveness of getting her pregnant? Humans are psychologically and sociologically complex, responsive to all kinds of subtle and not-so-subtle cues, and with a huge amount of individual variation. Looking at what is essentially the very last step in an elaborate courtship dance and declaring that that is the critical thing that evolution is looking at tends to kind of minimize an intricate behavioral complex that is also subject to evolutionary forces.
This reductive, narrow approach to a tiny aspect of a question is a common approach in some disciplines. Another subset tends to view programmed female responsiveness to male signals as the mechanistic goal of evolution. Evolutionary psychology, I’m looking at you.
King R, Dempsey M, Valentine KA (2016) Measuring sperm backflow following female orgasm: a new method. Socioaffect Neurosci Psychol. doi: 10.3402/snp.v6.31927
Behold, a discarded lump of chewed birch pitch from Denmark:
Awesome, I know. Heating up birch bark produces this dark, sticky substance that can be used as an adhesive, and also can be chewed like chewing gum. It apparently has some antiseptic properties. No one has told me yet what it tastes like, I guess I’ll have to try it for myself sometime.
That lump was thrown away 5700 years ago, after someone had been chewing on it for a while. What’s cool is that lots of DNA was extracted from it, and we know a bit about the person who’d been using it.
We successfully extracted and sequenced ancient DNA from a 5700-year-old piece of chewed birch pitch from southern Denmark. In addition to a complete ancient human genome (2.3×) and mitogenome (91×), we recovered plant and animal DNA, as well as microbial DNA from several oral taxa. Analysis of the human reads revealed that the individual whose genome we recovered was female and that she likely had dark skin, dark brown hair and blue eyes. This combination of physical traits has been previously noted in other European hunter-gatherers, suggesting that this phenotype was widespread in Mesolithic Europe and that the adaptive spread of light skin pigmentation in European populations only occurred later in prehistory. We also find that she had the alleles associated with lactase non-persistence, which fits with the notion that lactase persistence in adults only evolved fairly recently in Europe, after the introduction of dairy farming with the Neolithic revolution.
We also know that she had duck for dinner and had been snacking on hazelnuts. She carried the Epstein-Barr virus, so she’d probably had mononucleosis at some time in her life. She probably wasn’t a farmer, but was a member of a known hunter-gatherer population in central Europe, which fits with her diet of wild game and foraged nuts. Her descendants would eventually migrate north to colonize central Scandinavia, and intermingle with other hunter-gatherers migrating from the east.
Oddly, most of the popular press reports I’m seeing on this story call the gum-chewer a girl. I don’t know why, maybe it’s based on this reconstruction, but I don’t see any evidence in the paper to characterize her age — she could have been the Svyltholm Old Lady, for all we know.
I don’t chew gum, but maybe I should start, just to leave some trace of me to be found in 7000 AD. Now I just have to figure out where to leave my wads of gum to maximize their odds of being found…
Jensen, T.Z.T., Niemann, J., Iversen, K.H. et al. A 5700 year-old human genome and oral microbiome from chewed birch pitch. Nat Commun 10, 5520 (2019) doi:10.1038/s41467-019-13549-9
The spiders were all fed this morning, and I continued my efforts to get breeding to happen. Maybe it did; I’d left the female New Arya (it’s a cursed name, we’ve gone through three Aryas so far, although this one seems to be lasting) with a male over the weekend, and initially I wasn’t certain what was going on. New Arya is slightly peculiar, having built a nest of debris in one corner of her cage, rarely leaving it. When last I left our two lovebirds, the male was hovering about the nest, plucking forlornly at the web, and New Arya was just waving a tootsie at him.
This morning, though, New Arya was outside (she’s on the left) near the male (on the right), and the two were just resting…in post-coital bliss, perhaps? I hope? I didn’t have the heart to break up the peaceful pair today, so I left them alone, for now. That male has more copulatory duties with other females, though, so I’m going to have to break them up this week.
See? Female spiders aren’t necessarily cannibalistic widow-makers.
Speaking of nesting, I found Mary Jane huddled in a corner with a dome built over her head. It looks cozy.
She seems quite content to have a home of her own. I suppose I’m going to have to introduce a male at some point, though, and wreck her maleless paradise.
I get complaints all the time about my spider photos. No matter how gorgeous they are, there are always a bunch of people who dislike seeing them. They’re not cats, you know? Everyone wants cats. Nothing but cats. Adorable little kittens frolicking about.
Well, PZ don’t do that. I’m willing to compromise, though, so here…a non-spider. It’s kind of the antithesis of a spider, which makes it more like a kitty cat. Enjoy your penis worms.
Here’s a big bucket full of penis worms.
And a beach covered with penis worms.
You like that, huh? You want more? ARE YOU HAPPY NOW??!? Are you going to continue criticizing my spiders?
I played hooky last year, taking two semesters off (at half-pay, ouch) for this thing called a sabbatical. As it turns out, my university expects me to justify and explain myself and tell them what I did with my lazy time off, and I guess it’s not enough to fire off a quick note saying that I was playing with spiders. So now today I’m late for the division holiday party because I had to hammer out a longer rationalization. OK, sure, so I include it here, too, as well as mailing it off to my dean and division chair.
Latrodectus umbukwane is a breath-takingly gorgeous spider from South Africa. Look at those colors!
As you might guess from the genus, it’s related to black widows, which means of course everyone gets worked up about its potential venomous nature. It hasn’t bitten anyone that we know of! Get over it! It seems to be, if anything, unusually shy.
Also, you want to see some sexual dimorphism? Take a look at this.
Well, this is a stupid sensationalist headline: New Species of Spider Found in Mexico Able to Rot Human Flesh. Yeah, so? This is a common property of many venoms, such as those in some wasps and snakes, and it makes sense that a spider, which relies on injecting toxins and enzymes that break down cells and tissues, would do so. How else would they slurp out the digested guts of their prey? These spiders have no interest in eating people, or “rotting human flesh”, so it’s an obnoxious way to distort the story.
I can just imagine spider tabloids running stories title “New Species of Primate Found With Large Fleshy Butts Capable of Crushing Innocent Spiders”. It completely misses the story.
Here’s a pic of the lovely beast in question.
It’s called Loxosceles tenochtitlan, and it’s distinguishing characteristic is not that it has a remarkable venom, but that males and females have unique genitals in a lock-and-key arrangement, which is also common in invertebrates.
In a statement released by the university, Valdez-Mondragon explained the difference: “As L.tenochtitlan is morphologically similar to L.misteca, it was initially thought that it had been introduced to this region by the shipping of ornamental plants. But when doing molecular biology studies of both species, we realized that they are different.” Valdez-Mondragon described the species and noted the difference between L.tenochtitlan and L.misteca lies in the male spider’s palp or the organ that enables touch in arachnids. It is also noted that the female L.tenochtitlan has a distinct looking sexual organ compared to L.misteca. Valdez-Mondragon explains that at first glance, the two species of spiders can look identical, but L.tenochtitlan can be identified because of its dark brown color which is dull compared to the other species and on its back is a very visible violin pattern.
The story goes on to claim that “humans are naturally repulsed at the sight of “creepy crawlies” like spiders.”
The Science Times is not one of my approved popular science sites. Too much trash written by people who have only the most passing acquaintance with science.
