Lesbian Lizards that will survive the apocalypse

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Does that sound like the name of a hardcore metal grrrl band to anyone else? No? Well, when I tell you that there are multiple species of lizard in Mexico and the US Southwest that are all female and that no male members of these species exist, I am not kidding (nor am I writing a science fiction novel). It’s a real thing, kids. A species of animal that needs only one sex to reproduce is called parthenogenetic, and surprisingly, it happens in over 70 species of vertebrates. Some species of snail, some pythons, hammerhead sharks and Komodo dragons are parthenogenetic (or will occasionally revert to parthenogenesis, depending on the circumstances). Also, just as a fun fact, the name itself comes from the Greek words parthenos or “virgin” and genesis or “creation”.

Parthenogenesis usually evolves in species that are extremely isolated–from other groups of similar organisms, from members of the opposite sex, or both. These lizards, hanging out in the baking deserts on the border between North and South America, fit the bill.  Until recently, scientists were stumped as to how these lizards could produce fully formed offspring: in ‘normal’ sexual reproduction, the female contributes half the chromosomes in her egg while the male donates the other half through his sperm, and the two mix in different creative ways to generate genetic diversity within the population (not that DNA can get ‘creative’ per se, but you get my drift). So if there are no males involved in this process, how are the offspring getting the full complement of genes? As it turns out, the mother provides both sets of chromosomes all on her own.

These resourceful mamas start out the reproductive process with eggs that have twice the number of chromosomes as sexually reproducing females, meaning their offspring will be genetically identical, excluding the random mutation that is bound to occur. They also undergo some pretty fab-tastic genetic recombination with sister chromosomes to make sure the genes stay heterozygous. Although their method of reproduction can decrease the genetic diversity of the population and thus make the individuals more susceptible to disease and predation, it also means that a single lizard could explore and inhabit a new territory and populate it all on her own! (Think about how handy this would be if you were the only woman standing after the zombie apocalypse…)

Even though these lady lizards do not need a male partner to fertilize their eggs, (got it covered, bro, thanks!) they still need to engage in a copulatory act. This means that two female lizards, even though neither can (or needs to) fertilize the other, will perform the movements of traditional copulation. This sends the trigger to their brains that allows them to lay their eggs. The fact that mamas still need faux-copulation as a mechanism to signal egg-laying indicates that males were once an essential part of the species, and though the male population has been lost, the copulation trigger has been conserved as what animal behaviorists call a ‘fixed action pattern’ within the species. (below, two lady lizards helping each other out).

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The BBC, as always, has some pretty awesome videos on the subject of parthenogenesis, as well as some commentary on the whiptail lizards themselves, so check it out! Revel in the fact that there are species on Earth that will produce countless virgin births in the years to come–someone tell the Pope.

 

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Can You Smell It?

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It’s not exactly something one talks about at the dinner table, but it does start with something one eats at the dinner table. Marcel Proust put it finely when he recorded in his diary, “[asparagus]…played at transforming my humble chamberpot into a bower of aromatic perfume”. Although Proust found it delightful, not everyone likes the smell of asparagus in their urine and as it turns out, not everyone can smell it. If you’re following me so far, you’ve probably inherited the gene for a chemical receptor in your brain that recognizes the chemical compound mercaptan (officially known as methanethiol). If you’re totally weirded out by now, you’re probably lacking the gene—and where’s your sense of scientific curiosity?!

Since being able to detect an asparagus-like scent in your urine after you’ve eaten the vegetable isn’t necessarily life-saving stuff, not much research has gone into exploring it. But a team of curious scientists figured ‘why the heck not?’ and delved into the issue in a study published in Chemical Senses, a sub-branch of Oxford Journals. Apparently when asparagus undergoes the human digestive process, almost all of it gets broken down–except for what scientists think is something similar to mercaptan, a compound closely related to sulfur. (This is the compound that is also responsible for the scent of bad breath and flatulence, so thanks a bunch, mercaptan). The exact compound that produces the asparagus-in-urine scent hasn’t been identified though, shrouding the whole issue in a touch of alluring mystery…if you’re into that kind of thing.

Since this molecule comes out the other end in the same shape in which it entered, it is discernible by some as different from the scent of ‘normal’ urine. The ability to detect the scent is associated with a certain allele, or version, of the gene that codes for a scent receptor in the brain—those who have a certain allele of the gene can detect the scent and those without it, cannot.

The study also revealed that even though everybody produces it, some people produce it in very low quantities, making it difficult to detect, and some produce it in very high quantities, making it easier to sniff out. Those who don’t produce the scent as strongly may not be able to recognize it, not necessarily because they lack the gene but because they may never have been exposed to it at high enough concentrations to learn to recognize it. About 6% of the subjects in the study could not detect the scent because of their genetic profile. There was also an interesting, though unrelated, racial difference—the allele had many different variations in Caucasian participants but there was not any genetic diversity found in the allele of subjects of African descent. The whole asparagus situation has now provided a basis for understanding why some people may be able to smell odors, like coffee or certain types of alcohol, in their urine and some may not. (Oh, to have the power!). The scent is stronger when one is dehydrated, and is only possible with substances whose molecular structure remains unchanged after the digestive process.

Fascinating, I know. But you really never know what information may be useful in your exploration of the rest of the world. Or, you know, at parties.

Do Your Genes Code for Monogamy?

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Sex and relationships are tough, but luckily we’ve got behavioral psychologists, molecular geneticists, and evo-devo people working on that. In our world today, when communication is instant and the number and diversity of people one meets in a given moment would astound someone from a few decades back, relationships are nothing if not more complicated than they were, say….200,000 years ago. There are obviously huge social differences between us and our hunting-and-gathering ancestors but biologically, we’re pretty much the same. So–can we use our biology to help us understand our behavior…even when it comes to staying faithful to a partner?

There are currently some pretty heated debates about the nature of human relationships and whether or not humans, as animals, are biologically meant to be mated for life. Ryan and Jethá’s New York Times bestselling book Sex at Dawn: The Prehistoric Origins of Modern Sexuality discusses the evolutionary psychology of monogamy. They argue that many human physiological traits, such as copulatory vocalization (uh, sex noises), testicle size, and sexual dimorphism indicate that monogamy was not a common practice in our more primitive ancestors. Evolutionarily speaking, most animals are polygynous—for females, mating with multiple males usually means there’s a greater chance that offspring will be fathered by the most fit individual while for males, the more females he mates with, there’s a greater chance that he will father a greater number of offspring. Perhaps it is only modern bias, in which monogamy is the only really socially acceptable relationship choice, which has resulted in a misinterpretation of our ancestors’ sexual mores.

So why is it that human beings form life-long pair bonds? (Or at least…we try our best). It’s much more likely that sexual behavior shifted from a ‘promiscuous’ system in the hunter-gatherer stage toward long-term pair bonding with the development of agriculture, accumulation of wealth, and a different social structure. The authors of the book argue that the shift toward monogamy is fundamentally at odds with our animal nature.  While carefully staying away from any moral pronouncement about what may be ‘right’ or ‘wrong’, the authors simply take the position that people should be more informed about the behavioral history of our species and go into relationships with a more complete picture of the choices they can make.

But what if a quick peek into our brains could tell us even more about the evolution of our species’ relationships? There are very few animal species who practice monogamy, mostly because usually, it’s more evolutionarily advantageous to mate with diverse members of the opposite sex. One of the lesser known monogamous species is, surprisingly, the prairie vole. Why surprising? Being rodents, voles reproduce fast and often, usually trying to gain an advantage by mixing up their mates. Prairie voles are one of the only species of rodent who mate with one specific individual, and scientists are just beginning to understand why—the answer lies in the structure of their brain.

When male prairie voles mate with same female a number of times in succession, their brain releases the hormone vasopressin, giving them a pleasurable feeling in the reward center of their brain. (They’re really cute too—they like to spend lots of time ‘cuddling’ with their chosen mate. Very scientific stuff, cuddling voles). This reward system makes the voles want to keep mating with the same female. These voles have probably developed a different kind of evolutionary advantage—when a male mates with just the one female, there is a higher chance that he will be the only father of all of her offspring. This behavior can also be explained physiologically: Prairie voles, unlike most other branches of their species, have a high number of vasopressin receptors in their brain, making this feedback loop powerful for them. Polygynous voles are lacking or have reduced version of the gene that codes for vasopressin receptors and so are unable to feel (or feel a greatly reduced version of) the positive sensation the results from monogamous mating.

But wait! It gets even better. Further experiments have shown that females can tell when males have increased levels of this receptor and will always pick them over males that have decreased vasopressin receptor levels. The hypothesis here is that males who mate monogamously are more likely to stick around to help take care of the kids (a much better choice of mate for the ladies). Larry Young and his lab at Emory University have even gone so far as injecting the gene that codes for vasopressin receptors into non-monogamous voles. The result? Voles who like to play the field suddenly became….monogamous. Adorable snuggle time with one specific mate ensued.

Could human brain chemistry give us more insight into the nature of our relationships? Could we genetically alter our mates to make them more faithful? Or is it not quite that simple? As always, social and cultural variables play a role in relationships and unfortunately, not everything is as black and white as science can make it seem. Humans are messy, and it takes a lot more than neurobiology to figure out why we behave the way we do. Let’s keep poking around in rodent brains and see what turns up.

So dudes. There’s this book.

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(I’m gonna call y’all dudes because anybody who reads about science is a dude. Guys, chicks, your dog, your grandmother, everyone. Everyone is a dude).

Let me tell you about thing that you should read. It’s called Spillover, by David Quammen. First of all, don’t let the cover deceive you—this book is not terrifying. Well, at least, not in a ‘man-eating baboon apocalypse’ kind of way. More in the ‘there are diseases everywhere and they kill you by eating you from the inside-out’ kind of way. So slightly terrifying. But mostly just really fascinating and cool.

David Quammen, just for your own edification, is awesome. He was a Rhodes Scholar who graduated from Yale and then did his postgrad at Oxford. He’s written an overwhelming of columns and articles about nature, travel, and adventure-y type things, as well as 15 books. That’s right, 15. 5 of which are fiction and the other ten of which are about wicked cool science stuff. Like Song of the Dodowhich is above all, an amazing title for a book, and also an in depth look at why island ecosystems are so susceptible to extinction and how humans contribute to that process.

Spillover is his latest book and is actually what has inspired me to be a science writer (lemme tell you why). In this work, he explores the vast concept of zoonotic diseases, or diseases that are transmissible from animals to humans. I admit, it sounds pretty gross and scary, but Quammen’s focus on the personal lives of both the human researchers and the oddly relatable life-cycle of the diseases makes his coverage of a potentially gruesome subject much more palatable and, well, personal.

He takes separate outbreaks of diseases (both viral and bacterial) and groups them into families based on similarity; of discovery, of treatment, of geographical proximity, of life cycle. These diseases become intertwined in a narrative that is more gripping than horrifying. It addresses outbreaks or diseases that you’ve vaguely heard about—on the news or in pamphlets at the doctor’s office—and makes them understandable and relatable. Even before you’ve realized it, Quammen has taken something biologically, ecologically, and sociologically complex, broken it down with a healthy dose of anecdote and snark, and suddenly you understand with perfect clarity the intricacies of the Hanta virus.

In general, Quammen is one of those writers who makes you want to be whatever he writes about. He writes about ecological diversity, you want to be a conservation biologist. He writes about disease transmission, you want to be a virologist. He writes about The Reluctant Mr. Darwinyou want to be a biographer and historian. After being taken on all these fantastic rides by Mr. Quammen, I figured I’d just cut to the chase and become a writer like him. That way, I get to be all of them.

10/10

Whoah, bro…San Francisco is WILD

ImageAnyone who’s been to San Francisco knows that it’s a hub of…well, pretty much everything. It’s got the booming downtown financial district with all its high-powered stress; it’s got cultural community so diverse you can walk down the street and hear five languages you never knew you didn’t know. People, clothes, and lifestyles from all over the world and every background imaginable come together in this city on the edge of the world, making it one of the most colorful and distinctive cities EVER.

And for those of you who have not yet been to the fair city of St. Francis (named after the Spanish mission established in the name of St. Francis of Assisi), let me tell you, it has some of the best, most eclectic food you will ever encounter. Try food trucks that sell sweet potato tater tots with mango chili ketchup. Or the best Vietnamese food this side of the Pacific. El Salvadorian pupusas stuffed with melted cheese and juicy pork. Grilled tofu, mushrooms, avocado, and eggplant sandwiched between crispy, sweet yellow corn biscuits. Seriously, it’s just ridiculous.

But I didn’t write this to make you drool. Some may also know San Francisco as a center of development and innovation in technology and biotechnology. I have a theory that all of the crazy stuff coming out of the Bay Area is born of an attitude unique to the west coast; a combination of a laid-back, ‘no rush man’ attitude and minds that are as eclectic and surprising as the city’s food.

Take, for example, David Holz’s lifelong passion for pursuing projects in everything from biomedicine to physics. While working on his PhD in North Carolina, his frustration with the 3D modeling software on his computer sparked a solution that may forever change human-computer interaction. David has created the Leap, which allows you to use your own hands to digitally touch your computer’s interface. The technology uses a small device that resembles a miniature iPhone, which you simply place in front of your computer screen, on your desk. The Leap, like a camera, senses the way the light travels around the objects in front of it, picking up on the user’s hands, tracking how shading and light change as the hands move. This image is transferred into real-time 3-D motion in your computer screen, where you can move and mold things at will. With your hands. Say what?! (you can watch the demo, which went viral, here. It’s freakin’ incredible)

The 24-year old Holz founded the company Leap Motion with his middle-school friend Michael Buckwald and they’ve since set up shop in the Soma area, near the Bay Bridge. Since the age of 8 when he built a wind tunnel in his garage to test his experiments, David has been thinking out of the box, leaving his PhD program to begin this start-up project.  And it seems that his gamble is paying off. David’s technology and Buckwald’s business sense have landed them contracts with NASA, Google Earth, and some pretty neat ideas from other innovators in the tech and art worlds (AirHarp, anyone?)

The really crazy thing is, Leap Motion is not even close to the only epic thing going on in the Bay Area. EksoBionics is, as the name suggests, essentially making exoskeletons for humans. The technology is helping those who have lost the use of their legs to walk again, fitted out in a robotic suit that supports them while they get to control their own steps. The company has been receiving a pretty steady influx of press, and you can check out a video about their product and their story here.

Hang on to your shorts though bros, ’cause the ‘out-of-this-world’ doesn’t stop at robotic human exoskeletons. Shinya Yamanaka, a researcher at UCSF, won this year’s Nobel Prize in Physiology or Medicine for inventing technology that creates stem cells—without using human embryos. This is a development that could change the face of modern medicine.

And just to add a little green to the palette, Solazyme is a 10-year old start-up whose aim is to re-engineer algae to provide a renewable fuel source. Along the way they’ve delved into other markets that have benefitted from their green goo—including food and cosmetics. This foray hasn’t stopped them from achieving their original goal, though–while the company is still developing and improving their technology,  the Navy has already run one of its battleships on Solazyme’s fuel product, as has a commercial jet.

This doesn’t even scratch the surface. In addition to being a start-up mecca, San Francisco also happens to be the go-to place for conferences, awards presentations, and leaders in the science world to turn up and say, “Hey y’all, let’s do something cool”. But why? San Francisco draws creative thinkers, those who approach problems differently and have something to offer that could change the way we think about science. It’s a city with a history of being home to the outsiders, those who came west to seek a fortune or to escape a past. The west coast still has that vibe, welcoming nutso ideas and tolerant of pretty much everything…except those who say it can’t be done.

Seriously bros, come to San Francisco. Watch the future happen.