Everything is the way it is because it got that way.
Why Females Are Stripey
Each of us is made of a mixed-up jumble of cells. Most of you is you, but a few of your cells actually belong to your mom, stowaways that she left in your body.
But thanks to our sex chromosomes, it’s females who are the real mosaics. In this video from Veritasium, you’ll learn how biological females are like calico cats. Early in a female’s life, way back when her embryonic body was little more than a ball of cells just beginning to fold into basic patterns, a molecular coin was flipped inside each of her nuclei, and one of the two X chromosomes was silenced forever.
Why is this? Although our sex chromosomes are tiny compared to the other 44, they contain vital genes. But just like a genetic knockout can cause problems, so can too much of a gene product. Each cell in a female nucleus only expresses the genes on one of the two X chromosomes, muting the other so that the "dose" of X genes is pretty much the same between XY and XX individuals.
Heads or tails, that epigenetic pattern persists for life, and although we can’t see them … women have “stripes”!
Bonus: Features the wonderful molecular animations of Drew Berry!
In my latest video, I mentioned the Stark family’s fearsome emblem: the dire wolf. What many people don’t know is that the dire wolf (Canis dirus) was a real animal, common throughout the Americas until 10,000 years ago, going extinct around the time the last Ice Age ended.
Over at Nerdist, my friend Kyle Hill has written a great history of this ancient carnivore. Thousands of them are buried in Los Angeles’ La Brea Tar Pits, one of the richest fossil sites in the world, a portal to the Pleistocene that’s just 500 feet from a Starbucks.
It never ceases to amaze me just how much science is lying right under our noses… and feet.
Once you’re done learning about canine megafauna, check out the Science of Game of Thrones:
What does a nerve synapse, the point where a signal is passed to the next neuron, really look like? Your biology textbook probably had a picture like this:
The reality, reported by German scientists this week in the journal Science, is much, much more complex. They pieced together the blobby jumble through microscopy and advanced protein science, giving us the best picture yet of what a nerve synapse really looks like.
We’ve already talked about how cells are not bags of water filled with a few organelles, and the synapse is no exception, as it has to shuttle packages of chemicals in and out of the cell sometimes dozens of times per second. The 100+ trillion synapses in your brain all depend on this seemingly chaotic (but really it’s highly regulated) architecture to function.
Looking at this, it’s a wonder that our nerves work at all. But they do, and despite what looks like chaos, they work quite well. I mean, think about it (there they go working again) … they’re what let us figure all this out in the first place.
A 3D model of synaptic architecture. ”We used an integrative approach, combining quantitative immunoblotting and mass spectrometry to determine protein numbers; electron microscopy to measure organelle numbers, sizes, and positions; and super-resolution fluorescence microscopy to localize the proteins. Using these data, we generated a three-dimensional model of an “average” synapse, displaying 300,000 proteins in atomic detail.” Via.
Mmmmmm… BACON SCIENCE
Bacon is perhaps nature’s most potent distillation of deliciousness. To those of us who fall in the category of “bacon lover”, there are few more innately pleasurable smells than sizzling bacon.
The heat-induced chemical reactions catalyzed by the hot pan combine with compounds introduced by the process of smoking and curing bacon to launch a cornucopia of volatile flavor compounds into the air, and in turn your nose, stimulating salivary production and drawing you out of bed aloft on the wafting wonderfulness like a classic cartoon character.
Everything that’s delicious, we owe to chemistry.
My favorite bacon compound? When researching my next video (which also has a food-related theme, but you’ll have to wait until Monday to find out), I discovered guaiacol:
It’s a humble little molecule with a mouthful for a name, but it’s one of the most delicious chemicals on Earth. Here’s why it’s special…
Wood contains lots of lignin, a polymer that helps strengthen plant cell walls. When that lignin burns, like when bacon is smoked over applewood or coffee beans are roasted and toasted, some of its ring-like aromatic structures are converted into guaiacol (as well as hundreds of other compounds(, which is the main flavor compound behind the smoky taste in all sorts of foods… including bacon
Here and there awareness is growing that man, far from being the overlord of all creation, is himself part of nature, subject to the same cosmic forces that control all other life. Man’s future welfare and probably even his survival depend upon his learning to live in harmony, rather than in combat, with these forces.
It’s been said that we know less about our own oceans than we do some other planets. So perhaps it’s not surprising that we only need to go for a dive to come face to face with “alien” biology.
Of course, no terrestrial life form, no matter how frightful or exotic it may be, is truly “alien”. But evolution, in its many trials and transformations, has molded some very strange forms from the clay of Earth’s long history. Many of these creature features, via their novelty, spark feelings of shock and discomfort in our terrestrial brains.
Moray eels are one of those forms. Morays are a group of more than 200 species of bony fishes that inhabit all of the world’s oceans. Along their evolutionary journey, the many families of eels (of which morays are but one) have gradually slendered and lost their fins, some to a degree that they look more like snakes than fish. It’s a wonderful example of convergent evolution, two only distantly-related organisms meeting the same end result (long and slithery body shapes) independently.
It’s natural to feel a bit unsettled when you first lay eyes upon such pelagic poltergeists and benthic beasts, whether it’s the relatively familiar eel or the spiral of dental terror that is a lamprey’s mouth:
Can I just say NOPE?
Our disquiet makes biological sense. Human neural circuitry evolved in the presence of (and has adapted to recognize) the body forms of terrestrial fauna, so when faced with the incomprehensible biological distortions resulting from eons spent evolving in a wet, dark world quite unlike our own, a little unease is to be expected. We recognize that these aquatic animals are alive, that their bodies have directions we can understand and parts that we can name, but there’s something that’s just… off about ‘em. I came across a Latin term that fits these oddities quite well: ”xenomorph” meaning ”strange shape.”
Xenomorph is also the name given to the deadly parasitoid extraterrestrials from the Alien movies. They, too, reside in that uncanny valley between familiar forms (head/mouth/arms/hands/legs) and extraordinary strangeness, creepy chimeras with skulls but no eyes, familiar bipedal anatomy sheathed in insect-like armor stretched over quasi-mechanic skeletons oozing with acidic blood. Oh, and we can’t forget their second set of jaws, ready to snap through your skull like a toothy bolt pistol.
Yet that second set of jaws is not alien at all. We find it in our friends the moray eels.
Morays possess a second set of retractable chompers called pharyngeal jaws (seen in the GIF up top), which are crucial to how they feed. Many fish have realted crushing structures in their throats, but none are able to extend them to grab prey like the moray. So why do eels have them? We think it’s because they had to make an evolutionary tradeoff.
Most fish gulp down their prey using suction. By very quickly extending their jaws open wide, they create a flow of negative water pressure that they use to slurp prey down their throat:
But to do that, gulping fish need wide, flexible jaws that they can expand blazingly fast. The moray eel family has adapted such a narrow head and body shape that they lost the ability to create that suction motion. So instead, it grew a second mouth!
In 2007, scientists from UC Davis used high-speed cameras to capture moray eels using their second jaws to snag prey. To hunt, the eel waits in its dark coral crevice or murky hollow, eyes unblinking and mouth agape, doing its best impression of scenery while it waits for something edible to float near its mouth. Then, in the blink of an eye, it snaps its forward jaws shut around the prey, extending its second pharyngeal set to pull the food down the throat. What a way to go.
Alien monster designer H.R. Giger, who passed away May 12, maintained his movie monster wasn’t inspired by the moray eel, or any other animal. He said his only goal with the Alien xenomorph was to make something “frightening and horrible.”
He certainly succeeded, and in doing so accomplished some convergent evolution of his own. Two sets of pharyngeal jaws, each unsettling in their own way, blending the familiar with the unfamiliar, keeping one terrifying foot rooted in reality and by resting the other just outside the bounds of what we know. Whether a creature is from outer space or just the shadowy parts of the sea, sometimes they’re just too close for comfort.
Why do we feel hungry?
Because tacos. And science. Both of which are explained in the latest BrainCraft video!
One question left unanswered is how our brain decides to go from simply “hungry” to “SO HANGRY”. I’ll be on the lookout for the sequel.
Could Godzilla Exist?
Short answer: Of course not.
But that’s no fun. Instead, let Jake from Vsauce3 break down the science of why. This video is a hulking, city-crushing monster of awesome.
Did you know that genetically male cells have been found in the brains of women?
Or that up to 6% of the DNA in a pregnant woman’s bloodstream doesn’t belong to her?
Or that children can help heal their mom’s heart after a heart attack without even lifting a finger?
Find out how in this week’s special Mother’s Day edition of It’s Okay To Be Smart, which would make a perfect gift for your mom in case you forgot to get her flowers.
Watch it here: