Back in August 2019, a female komodo dragon named Charlie gave birth to three little dragons at the Chattanooga Zoo. The zookeepers had previously tried to hook her up with a sweet dragon fella named Kadal, but the two never really seemed to hit it off — not that the staff could observe, anyway. And now that they've tested the DNA of young Onyx, Jasper, and Flint, it's finally confirmed: Charlie and Kadal did not hit it off at all, so Charlie took it upon herself to bring the kids into the world. From the Chattanooga Times Free Press:
The DNA results showed the babies were the result of parthenogenesis, which is a type of reproduction where the female produces offspring without male fertilization. […] Female Komodo dragons carry WZ sex chromosomes, while males carry the ZZ type. When parthenogenesis happens, the mother can only create WW or ZZ eggs. Since eggs with the sex chromosomes of WW aren't viable, only ZZ eggs are left to produce all male hatchlings. Parthenogenesis is considered very rare, with the first case of a successful parthenogenesis reproduction in Komodo dragons recorded in 2006.
I was personally fascinated to learn that there are so many different categorizations of asexual reproduction, and that it can indeed occur spontaneously in vertebrates without any fertilization. In 2007, there was apparently a bit of a scandal involving a lab-grown human embryo that was allegedly cloned, but turned it to be a productive parthenogenesis. There are also living human beings with some unique chimeric complications in which they were both fertilized by a male, but also underwent some kind of parthenogenesis at the same time, resulting in a male offspring with Y-chromosomes in his skin, but not in his blood. Read the rest
A new study argues that it's "ethically permissible" for dead men to "register their desire to donate their sperm after death for use by strangers." Dr. Nathan Hodson of the University of Leicester and Dr. Joshua Parker of Manchester's Wythenshawe Hospital conducted their research as a response to a shortage of sperm donors in the United Kingdom. From CNN:
"If it is morally acceptable that individuals can donate their tissues to relieve the suffering of others in 'life-enhancing transplants' for diseases, we see no reason this cannot be extended to other forms of suffering like infertility, which may or may not also be considered a disease," the study says.
The mechanics of donating, they say, are entirely feasible through either electroejaculation or surgical methods.
Sperm would be cryopreserved following collection and thawed when chosen for reproduction, the authors said...
The process would address the ongoing shortage of donor sperm in the UK, argue the authors, which has led to Britain importing commercially donated sperm to cope with demand from couples struggling to conceive.
More: "The ethical case for non-directed postmortem sperm donation" (Journal of Medical Ethics)
image: "Sperm and ovum fusing" (public domain)
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A video making the rounds shows fertilized chicken eggs incubated outside their shells. It's fascinating, but not a first. Read the rest
Science suggests that, despite popular belief, human women's menstrual cycles don't necessarily synch up when they live together. Banded mongoose females, on the other hand, do synch up their reproductive cycles enough that mongoose babies are all born right around the same time. Read the rest
Your morning dose of weepies — in which a family is formed and loss turns into love. All with the help of science. Read the rest
Fun fact you might not be aware of if you are not the owner of a uterus: Periods go hand-in-hand with pooping. Not every person who gets a period will end up with diarrhea, but it's not uncommon because the same hormone that makes a uterus contract (a necessary step in the whole period process) can also end up making your intestines contract. Francie Diep explains this effect — as well as the other hormone-related reason why periods and poops can be linked. Read the rest
Across the United States, politicians are passing laws limiting abortion that are based on the idea that a fetus can feel pain after 20 weeks gestation. But the science underlying this assertion is a lot more complex than it's made out to be. Most scientists don't think fetuses have the neural circuitry to experience pain until later. And the scientists whose research is most often cited as evidence of fetal pain at 20 weeks don't think their work is saying what anti-abortion activists think it does. Read the rest
Mei Xiang, the female panda who lives at the Smithsonian National Zoo, gave birth today. Above is a screen shot from the Zoo's Panda Cam, showing the baby shortly after birth.
Why should you care about this not-quite-yet-but-soon-to-be adorable baby animal more than you care about any other adorable baby animal? Because the scientific oddities of panda reproduction make its story very interesting. Read the rest
Mafeteng Districts Hospital, Lesotho, 1988. A young woman comes in with a stomach ache. Turns out, she's pregnant and in labor. The problem: She has no vagina. Just a uterus, with no path to the outside. So how'd she get pregnant to begin with? Oh, yes. It involves oral sex and a knife fight. Read the rest
"Born in the caul" is a phrase that's connected with a lot of cross-cultural myths and superstitions — babies born in the caul are supposed to be destined for lives of fame and fortune (or, possibly, misfortune and grisly death, depending on which legends you're listening to). Biologically, though, it refers to a baby that's born with part of the amniotic sac — the bubble of fluid a fetus grows in inside the uterus — still attached. Usually, a piece of the sac is draped over the baby's head or face. These are called caul births, and they're rare. But, about once in every 80,000 births, you'll get something truly extraordinary — "en-caul", a baby born inside a completely intact amniotic sac, fluid and all.
There's a photo of a recent en-caul birth making the rounds online. The photo is being attributed to Greek obstetrician Aris Tsigris. It's fascinating. But it's also pretty graphic, so fair warning on that. (If the sight of newborn infants and blood gives you the vapors, you might also want to avoid most of the links in this post, as well.) Read the rest
I've been linking Double X Science a lot lately. That's because they're great. It's rare to get such smart, fascinating, science-centered discussion about female anatomy and reproductive issues that goes beyond the surface dressing we all already kind of know. Case in point: This piece by Emily Willingham about the development of the human heart in utero. You've probably heard at one point or another that a fetus' heart starts beating around 6 weeks (an age which is, by the way, calculated from the date of the mother's last period, NOT from the date of actual conception; so the fetus itself is really only about 4 weeks old at this point, and its mother only missed her period two weeks ago). But what's the heart actually like at that point? Turns out, absolutely nothing like what you imagine. Very cool stuff. Read the rest
In a study of 6,455 semen samples (yup), scientists at Israel's Ben-Gurion University of the Negev found that human sperm were most atheletic — and were found in the highest concentrations — in winter. There was a marked decrease in sperm motility and numbers in spring, summer, and fall. It's an interesting and logical addendum to the fact that sperm counts and motility decrease in men who subject their testicles to warm conditions; in hot tubs, say, or a pair of overly tight underpants. Read the rest
There is definitely a seasonality to human births, writes Beth Skwarecki at Double X Science. The complicated bit is that human baby season isn't necessarily the same (or as strongly expressed) from place to place and culture to culture. In the United States, significantly more babies are born in July, August, and September. Meanwhile, in Europe, babies seem to make their way into the world in spring. So there's clearly a cultural component to this — but culture doesn't explain it, entirely. Skwarecki's piece explores a messy place where culture, genetics, and circadian rhythms intersect. Read the rest
You might as well be warned. This video contains a sea cucumber money shot.
This is a book about "doin' what comes naturally". Which is to say, sex. But what kind of sex? With whom? And to what purpose? At what point do things like gender expression, sex, reproduction, and child-rearing stop being "normal and natural" and start being something weird that humans do because we are diverse/perverted/sinful/creative (depending on your personal point of view)?
In reality, the word "natural" is mainly how we tell each other which behaviors and traits are the socially correct ones. Calling something natural is often more about specific human cultural standards than it is about what actually happens in nature. Crime Against Nature is artist Gwenn Seemel's attempt to correct that mistake. Filled with gorgeous, Klimt-esque illustrations, Seemel's book shows readers just how diverse nature can be and just how often it fails to conform to our ideas of what is normal — from girls who are bigger and tougher than boys; to boys who give birth; to boys and girls that don't have sex or reproduce at all (and don't seem to mind one bit).
The issues at play here are hefty and potentially uncomfortable, but the book itself is light, playful, and pleasantly un-preachy. It's also set up in a way that allows it to evolve with kids as their reading skills improve — pairing simple statements like "Boys can be the pretty ones" with longer but still easy-to-read paragraphs explaining, for instance, the most recent scientific theories about why male peacocks are so much more colorful than females. Read the rest
Back in May, I posted about how the Smithsonian National Zoo took another shot at inseminating Mei Xiang, a female giant panda. Female pandas are only fertile once a year, for 24-72 hours, and the zoo had already tried unsuccessfully to get Mei Xang pregnant for eight years in a row. This year, though, they pulled it off, and Mei Xiang gave birth just a little over a week ago. The bad news, which you may have already heard, is that the baby died last weekend. Nobody really knows why just yet.
Reading the stories about the baby panda's death, I noticed that zookeepers had tried to revive the baby using CPR. And that got me curious. Just how, exactly, do you give a panda CPR. At Slate, L.V. Anderson tackles this question. Turns out, the process isn't all that different from resuscitating a human.
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CPR is appropriate when a patient’s heart has stopped (whether or not the patient is human), and the goal is to maximize the amount of blood flowing out of the patient’s heart into other vital organs and to get some air into the patient’s lungs so the patient’s blood will be oxygenated. Some animals, including humans and baby pandas, have bodies shaped in such a way that the best way to pump the heart is to directly compress the chest. Other animals, Iike most dogs and cats, have much rounder chests, which makes it harder to directly compress the heart. With these animals, vets recommend compressing the chest from the side, which puts secondary pressure on the heart.
Sea urchin egg undergoing mitosis with fluorescent-tagged/stained DNA (blue), microtubules (green).
Cells divide. One single piece of life tugs itself apart and splits in two. It sounds like a purely destructive process, reminiscent of medieval woodcuts where the hands and feet of some unfortunate thief are tied to horses heading in opposite directions. But that's the macro world. On the micro scale, to split is to live. A dividing cell doesn't just rip itself to pieces. Instead, the cell first makes a copy of its genetic information. When the cell splits, what it's really doing is making a new home for that copy to live in. Make enough copies—and enough copies of the copies—and you eventually end up with a living creature.
Back in May, I took part in the Marine Biological Laboratory Science Journalism Fellowship, a 10-day program that gives journalists hands-on experience in what it means to be a scientist. The program is split into two tracks. As part of the environmental track, I went to the Harvard Forest, where nature is one giant laboratory. But, at the same time, other journalists were busy in a different sort of lab.
Steven Ashley is a contributing editor at Scientific American and writes for a host of other publications. He took part in the fellowship's biomedical track. Ashley and the other journalists fertilized the eggs of sea urchins and other small ocean creatures, and then used specialized biomedical microscopes and cell imaging software to create brilliant photos and mesmerizing movies of cell division and growing animals. Read the rest