Curio Cabinet

When playing the genetic lottery, your odds may be worse than a coin flip. A recent paper published in Science Advances by researchers from Harvard University shows that the odds of a couple giving birth to a male or female baby might not be quite as even as previously thought. Aside from intersex conditions like extra chromosomes, androgen insensitivity syndrome, and other cases where a person’s gender doesn’t necessarily match up neatly with their chromosomes, the formula for a male or female person is simple. Two X chromosomes, one from each parent, results in a girl. One X chromosome from the mother and one Y chromosome from the father results in a boy. And since each sperm has a 50/50 chance of carrying either an X or Y chromosome, it would seem that the birth rate for each sex would be the same. Not really, though. Researchers looked at data regarding 58,007 women in the U.S. who collectively gave birth to 146,064 children between 1956 and 2015. Instead of finding a simple binomial distribution of the sexes, they found a beta-binomial distribution, meaning that families could tend to skew toward producing one sex more than the other. The researchers compared it to a weighted coin toss, where the odds weren’t completely random. One of the telltale signs was that it was much more common than it should have been for some families to have all boys or all girls. A possible factor appears to be the age of the mother, as women 28 and older had an elevated chance of giving birth to multiple children of one sex over another. Researchers noted that the data might be affected by a behavior they call “coupon collecting,” which is when a couple continues to have children until they have a child of their desired sex. Compared to actual coupon collecting, that sure sounds expensive.

[Image description: The symbols for “female” and “male” with a pink-and-blue background.] Credit & copyright: Author-created image. Public domain.
 

Are those raindrops on the water’s surface? Or something far more lively? Water striders are some of summer’s most common insects, but that doesn’t mean that their incredible ability to “walk” on water should be taken for granted. These insects are masters of physics. In fact, they’re so good at what they do that some even live in the open ocean.
 
There are nearly 2,000 species of water striders, all in the family Gerridae. Most are less than an inch long, as they must be light enough to stand on the surface of water. They do this by utilizing water’s natural surface tension. Surface tension happens because water molecules like to stick close together. Below the surface, these molecules are evenly spaced because of the push and pull of other, nearby water molecules. At the surface, however, there are no water molecules to push down from above. Thus, molecules group more closely together there, forming an extremely thin, film-like barrier. It’s this “film” that water striders have evolved to walk on. The secret is in the long, water-repellent hairs called hydrofuge hairpiles that cover their bodies. These hairpiles contain even smaller microhairs that are grooved to trap tiny pockets of air. This makes them hydrophobic, or water-repellent. This, combined with water’s surface tension and their small body size, allows water striders to lift themselves into a standing position on the surface of water. They can then move forward in a gliding motion by pumping their three sets of legs.
 
Water striders are found on every continent except Antarctica, and some species in the Halobates genus, commonly called sea skaters, even live in the open ocean. They are both predators and scavengers, mostly eating terrestrial insects that fall into the water. They’ll also stalk and eat other aquatic bugs, like water beetles and snails. Their specialized jaws are designed to pierce the exoskeletons of insects and suck out the juices inside, yet the vast majority of water striders pose no threat to humans. Their jaws are too small to pierce human skin, but they are perfectly able to eat harmful, disease-spreading insects like mosquitos. Who knew these aquatic ballerinas were performing a public service?

 
[Image description: A close-up photo of a brown water strider “walking” on top of water.] Credit & copyright: TimVickers, Wikimedia Commons. The copyright holder of this work has released it into the public domain. This applies worldwide.

Is there anything that climate change can’t ruin? The library of a 1,000-year-old monastery in Hungary is fighting to save its books against the ravages of drugstore beetles, and the changing climate is partly to blame. The Pannonhalma Archabbey, a Benedictine monastery located in western Hungary, has a bit of a pest problem. Their 400,000-book library is under attack from a horde of Stegobium paniceum, more commonly known as drugstore beetles or bread beetles. The library doesn’t hold ordinary books; The monastery is a UNESCO World Heritage site and contains irreplaceable treasures that have been entrusted to its care since it was founded in 996 C.E. Unfortunately, the beetles aren’t interested in the historical value of the tomes they’re munching on. They’re actually attracted to the centuries-old books for the starch and gelatin used in their construction.
 
Library staff first noticed the presence of the beetles when they found a strange dust on some of the shelves. Upon closer inspection, they found several books with holes bored into the spines. It’s no coincidence that the beetles are only a problem for the books now, after a millennium of safe storage. Drugstore beetles favor dark, warm, undisturbed places, while in their larval stage. A library housed in a 1,000-year-old building is perfect for them during the summer. As temperatures all over the world continue to rise each year the likelihood of beetle infestations grows. Even at the best of times, beetles are hard to get rid of. Since they’re experts at burrowing and hiding, it’s easy to miss them, and any that remain can produce up to two generations in a year if the weather’s warm. For now, around 100,000 books have been removed from the monastery’s shelves, and they’re set to be placed in an all-nitrogen environment for six weeks, where the beetles will hopefully die from lack of oxygen. In the meantime, the library will be thoroughly inspected and cleaned, and restorers will do what they can to save any books that have already been damaged. At least we know they’ll do things by the book.

 
[Image description: A close-up photo of Stegobium paniceum, a golden-brown beetle with black eyes.] Credit & copyright: Francisco Welter-Schultes, Wikimedia Commons. This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.

Even in the world of paleontology, some things are only obvious in hindsight. A paleontologist recently discovered a new reptile species that lived around 145 million years ago, and he did it just by visiting a couple of museums. In the 1930s, an enterprising—albeit not particularly ethical—individual sold a fossil of an ancient reptile. That would have been fine, except for the fact that they’d cut the original fossil in two and sold the other half to another, unwitting buyer.
 
Decades later, along came paleontology student Victor Beccari, who visited Senckenberg Natural History Museum in Frankfurt, Germany, and the Natural History Museum in London, U.K., both of which were displaying their half of this fossil. Thanks to Beccari’s extremely keen eye and good memory, the fossil halves have now been reunited. Beccari and his colleagues named the “newly” discovered reptile Sphenodraco scandentis, and published their findings in a scientific journal. According to Beccari, S. scandentis belonged to a group of reptiles called rhynchocephalians, from which only one extant species remains, the tuatara. Although the fossil clearly shows a reptile from the Late Jurassic period, it's not a dinosaur. Based on its skeletal structure, which forms a short body with long limbs and long digits, Beccari and his colleagues believe that it was a tree-dwelling lizard.
 
As for why it took nearly a century for anyone to notice that the two fossil halves were related, the one at the Senckenberg Natural History Museum had been misidentified as one belonging to Homoeosaurus maximiliani, another rhynchocephalians found in the same region in southern Germany. It’s also rare for a fossil to be split in two and for each half to retain parts of the skeleton. Usually, one half gets the skeleton and the other only gets an impression of it. No wonder the original buyers had no bones to pick—they thought they were getting it all.

 
[Image description: A fossil of Homeosaurus maximiliani, a species related to the newly discovered Sphenodraco scandentis.] Credit & copyright: Daderot Wikimedia Commons. This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.