Slate’s animal blog.

Oct. 15 2014 10:55 AM

Marriage Equality’s New Mascot: A Hermaphroditic Snail

In what may be the oddest honor of the year, scientists in Taiwan have named a newly discovered hermaphroditic land snail in honor of same-sex marriage.

The snails, named Aegista diversifamilia, native to eastern Taiwan, were long thought to be members of another species, named A. subchinesis. But in 2003, researchers noticed physical differences between the snails east and west of Taiwan’s Central Mountain Range: Those east of the mountain range have bigger, flatter shells than their more conformist A. subchinesis counterparts to the west.


Following up on this observation, Ph.D. candidate Chih-Wei Huang at National Taiwan Normal University studied the snails’ molecular markers and morphology, and the verdict was in: It’s a new species.

The researchers published the study Monday in the open-access journal ZooKeys. Taiwan and many other parts of the world have been struggling for equality in marriage rights. This inspired the researchers, while they were preparing their manuscript, to pick the snail’s name. Aegista diversifamilia translates to “the diverse forms of human families.” It is particularly fitting because the snails are hermaphroditic animals, meaning they all have both male and female reproductive organs.

“They represent the diversity of sex orientation in the animal kingdom,” said Yen-Chen Lee of Academia Sinica in Taipei in the research press release. “We decided that maybe this is a good occasion to name the snail to remember the struggle for the recognition of same-sex marriage rights,” said Lee, who was one of the first to notice the snails’ physical distinction.

The newly dubbed, albeit sluggish, mascot could be seen as an oddly apt, optimistic representation for the same-sex marriage struggle: Slow and steady wins the race.

Video Advertisement

Oct. 7 2014 4:24 PM

The Hardest Thing About Being a Cheetah

Why are wild cheetah populations declining so precipitously? In 1900, Africa was home to around 100,000 of the dappled predators; in 2014, that number has shrunk to 10,000. Conventional wisdom holds that cheetahs, like wild dogs, are prime victims of kleptoparasitism, or prey theft by larger predators. The slender cats, which usually weigh between 110 and 140 pounds, are great at catching antelopes, but not so good at fending off bigger beasts, like lions and hyenas.

This narrative has gained traction in conservationist circles: Pity the graceful under-cat of the grasslands, working hard to catch prey that is then stolen from its claws. (By the way, cheetah claws are a specialized marvel. Because the felines run so swiftly—accelerating, at times, from zero to 60 mph in just three seconds—their hare or gazelle dinner might try to thwart them in the chase by zigzagging. But cheetahs use distinctive, protruding nails to give them traction during lightning-fast turns.) The idea of the bullying lion or opportunistic hyena fits into our somewhat anthropomorphized vision of the animal kingdom—and, sure, other mammals do poach off these cats’ labor occasionally. But a new paper in Science suggests that the real culprit in the decline of the cheetah isn’t some jungle despot exacting his meaty tribute. It’s us.


The researchers wanted to directly test the claim that kleptoparasitism was pushing cheetahs “over an energy precipice”—that, after exhausting all their resources running down lunch, the cats were deprived of the means to replenish the store after their food was stolen. To do this, the scientists had to figure out how much energy cheetahs actually spent chasing their food. Feline test subjects were captured from two South African wildlife reserves, injected with water labeled with distinctive isotopes, released, and tracked. The ratio of isotopes in the cheetahs’ waste revealed how much oxygen they were using for a given activity—how hard they were breathing, and thus, how strenuously they were working.

After collecting and analyzing the waste, the researchers reached a surprising conclusion. Unlike wild dogs, which often pursue a target with dogged determination over long distances, cheetahs don’t actually blow a lot of their daily energy tailing prey. (A typical chase only lasts a few seconds.) What saps their strength is walking. The cats under observation walked miles and miles searching for quarry they could hunt—miles that were necessary only because human development has so depleted their meal options. The fences we’ve built separate them from impalas, hares, and antelopes. The habitat we’ve razed was once a predator supermarket.

In short: Cheetahs would be fine with lions and hyenas occasionally mooching their food if humans weren’t forcing them to walk themselves to death.

As John Wilson, one of the study authors and a biologist at North Carolina State University, put it bluntly, “Cheetahs aren’t weak. It’s us making them weak.”

We can’t deflect responsibility for our ecological impact onto a bunch of (surprisingly well-mannered!) lions and hyenas.

Oct. 6 2014 1:20 PM

Some Sharks Are Socialites, Some Want You to Go Away  

“I am a nice shark, not a mindless eating machine,” intones Bruce the Shark in 2003’s hit kids’ movie Finding Nemo. He is trying so hard. Unfortunately for him, according to his creators, to be a shark does pretty much consist of mindlessly, mechanistically eating things. Struggling to transcend biological destiny, poor one-dimensional Bruce is played for laughs.

It was cruel, and wrong. A study last week in Behavioral Ecology and Sociobiology suggests that not all sharks (#notallsharks) are alike. The paper, “Shark Personalities? Repeatability of social network traits in a widely distributed predatory fish,” finds that these terrors of the deep may vary by social temperament.


Specifically, researchers discovered that some individual sharks are convivial and some are emo. Some prefer to band together into gangs, while others camouflage quietly into the background. The scientists observed 10 different groups of juvenile small spotted catsharks in large tanks that contained three different habitats. The habitats differed in their structural complexity, from a few rocks and plants to dense underwater foliage. The researchers’ aim was to observe how the teenage sharks—who, like most human high school students, are prone to feel vulnerable—interacted in environments with various amounts of cover.

And? In the words of behavioral ecologist David Jacoby, “socially well-connected [shark] individuals remain well-connected under each new habitat.” (Being well-connected when you are a catshark is a literal as well as figurative condition: It means you tend to lie on top of other catsharks, i.e. spoon.) Likewise, weirdo loner sharks isolated themselves no matter where they were, even shading their skin color to blend in better with the gravel substrate at the base of the tank. (If only I could have done that at my school dances.)

“We define personality as a repeatable behavior across time and contexts,” said Darren Croft, a professor at the Center for Research into Animal Behavior at the University of Exeter. Many animal species exhibit what scientists think of as personality traits, but Croft and his team are the first to seek out such qualities in sharks—creatures popularly viewed as uniform in their terrifying appetites, the most coolly insatiable of our underwater villains.

Of course, both the gregarious catsharks and the shy ones probably like eating fish. The second kind are just more likely to go home afterward and curl up with an old movie.

Sept. 10 2014 10:30 AM

Why I Gave Mouth-to-Mouth Resuscitation to a Turtle

As my lips slowly moved toward the mouth of the turtle in my lap, I admit to momentarily wondering how my life’s choices had brought me to this point.

As a research fellow with the Alabama Natural Heritage Program at Auburn University, one of my responsibilities is to help out on surveys and monitoring efforts so we can figure out how populations of rare species are doing in the state. One of Alabama’s most iconic species is the Alabama red-bellied turtle (Pseudemys alabamensis); this species is the official state reptile, but it is also listed as endangered by the U.S. Fish and Wildlife Service. The turtle has a very restricted geographic range—only a few rivers leading into Mobile Bay in Alabama and two nearby rivers in Mississippi—and that is the main reason why biologists think it is so vulnerable to extinction. But there have been remarkably few studies that actually attempted to estimate how many turtles are left.


A few weeks ago I was in Mobile Bay, assisting Jim Godwin, the Heritage Program’s aquatic zoologist, on a turtle survey. Our sampling protocol was to set a number of mesh traps—usually referred to as hoop traps because they are held open by a series of hula hoop-type structures—in the water and then come back and check them every day for a few days. Turtles swimming around in the water will encounter the nets and be funneled into an area that is difficult for them to escape from.

Now, what you may not know is that this coastal area of southern Alabama is a very important place for reptiles and herpetologists alike: There are more kinds of native turtles here than just about anywhere else in the world, with the possible exception of a couple of spots in Southeast Asia. So we may be targeting Alabama red-bellied turtles, but our traps are not selective, and it is not unusual to get some really cool bycatch, such as alligator snapping turtles and softshell turtles, not to mention things like the occasional ornery alligator.

Trapping turtles in this area can be unpredictable for a few other reasons, too. Because these rivers are so close to the ocean, they are subject to tides, and sometimes water levels fluctuate more than we expect. This sometimes causes the water to rise above the trap’s air pockets we leave inside for the turtles to breathe, pockets that are usually held open by a floating plastic container. In these rare cases, a drowned turtle is a very real possibility.

As we motored to a trap one morning, we were dismayed to see that the entire trap was underwater. And, as we feared, there was a large and completely limp turtle on the bottom of the trap. The animal wasn’t an Alabama red-bellied turtle; it was a closely related adult female Florida cooter. Although the two species look similar, the Florida cooter is common and widespread throughout the Southeast. That didn’t make the sight of this drowned turtle any less frustrating, though.

It’s hard being a young turtle—the silver-dollar-size animals are scarfed down by just about everything with a mouth. However, once a turtle reaches maturity, there aren’t many predators that can mess with it. This allows the population to compensate for the high juvenile mortality because adults can survive and produce a lot of young over many years. That is, as long as a couple of biologists don’t accidentally drown them.

I placed the lifeless turtle on the bottom of the boat and figured that we could at least donate it as a specimen to the Auburn Museum of Natural History; the collections there are useful for research and teaching. Then I turned my attention to helping measure and mark the other cooters we captured. (Fortunately, the rest of the turtles in that trap were all alive and doing well.)

After some time, my eye caught a slight movement from one of the turtle’s limbs. I knew that turtles were incredibly resilient animals and I had even heard of researchers resuscitating turtles that had spent too long in submerged traps. Thinking back to a first aid class I had taken a few years earlier (and egged on by my partner, Olivia, who was tagging along on the trip), I decided to try CPR. The first thing I did was hold the turtle upside down to let any liquid escape, then I placed the turtle on my lap, held its jaws open, and blew into its open mouth.

I’ve been bitten by a lot of turtles in my life, and it hurts. A lot. Because I was afraid of a suddenly alert turtle chomping down on my tongue, I tried to maintain a slight distance between our mouths. I was hoping that this would also reduce my chances of smelling any of the turtle’s last meal … or contracting salmonella.  

Although I could hear that air was entering the turtle, there was no reaction. I tried blowing more air. Nothing. Then I remembered that chest compressions might help with blood circulation and might even expel air and any remaining water from the lungs.

Pushing down on the turtle’s chest was not an option—the animal’s shell prohibited it. So I reached back under the shell and attempted to push the skin forward. I heard air coming out of the turtle’s mouth and was even more encouraged when, after a momentary and tense pause, the turtle took a deep breath of its own.

Almost immediately, the turtle became more active and starting flailing around with its limbs. Perhaps more entertaining is that at this point air started coming out of other orifices too (something you can hear on the video).

Although things were looking up for this Florida cooter, we decided she was still too weak to be immediately released, so we held onto her for another hour or two while we checked the rest of the traps, always making sure she was staying cool by keeping a wet cloth on her. At the end of the day, we motored back to the site where we had first captured her, placed her in the water, and took a sigh of relief as she propelled herself into the murky darkness of the river.

A boatload of alligator snapping turtles captured in researchers' traps.

Courtesy of Jim Godwin

Sept. 9 2014 9:00 AM

A Parrot Passes the Marshmallow Test

Can your kid pass the “marshmallow test”? And what does it mean if he can’t, but a parrot can?

The marshmallow test is pretty simple: Give a child a treat, such as a marshmallow, and promise that if he doesn’t eat it right away, he’ll soon be rewarded with a second one. The experiment was devised by Stanford psychologist Walter Mischel in the late 1960s as a measure of self-control. When he later checked back in with kids he had tested as preschoolers, those who had been able to wait for the second treat appeared to be doing better in life. They tended to have fewer behavioral or drug-abuse problems, for example, than those who had given in to temptation.


Most attempts to perform this experiment on animals haven’t worked out so well. Many animals haven’t been willing to wait at all. Dogs, primates, and some birds have done a bit better, managing to wait at least a couple of minutes before eating the first treat. The best any animal has managed has been 10 minutes—a record set earlier this year by a couple of crows.

The African grey parrot is a species known for its intelligence. Animal psychologist Irene Pepperberg, now at Harvard, spent 30 years studying one of these parrots, Alex, and showed that the bird had an extraordinary vocabulary and capacity for learning. Alex even learned to add numerals before his death in 2007. Could an African grey pass the marshmallow test?

Adrienne E. Koepke of Hunter College and Suzanne L. Gray of Harvard University tried the experiment on Pepperberg’s current star African grey, a 19-year-old named Griffin. In their test, a researcher took two treats, one of which Griffin liked slightly better, and put them into cups. Then she placed the cup with the less preferred food in front of Griffin and told him, “wait.” She took the other cup and either stood a few feet away or left the room. After a random amount of time, from 10 seconds to 15 minutes, she would return. If the food was still in the cup, Griffin got the nut he was waiting for. Koepke and colleagues presented their findings last month at the Animal Behavior Society meeting at Princeton.

At every time period tested, Griffin successfully waited at least 80 percent of the time, even at the maximum 15 minutes. That’s the best performance ever seen in an animal, comparable to Mischel’s original results with preschoolers.

Human children faced with the test use a variety of strategies to distract themselves from the tempting first marshmallow. Similarly, the bird didn’t always just sit in peaceful anticipation of receiving his treat. Sometimes he tossed the lesser food away or gave it a taste, or he distracted himself with preening. (Koepke and colleagues produced this video directly comparing Griffin to children put through the test.)

What does it mean? Well, we already know that Griffin is a pretty smart bird. He has a large vocabulary, knows the names of dozens of objects, and can recognize colors, shapes, and numbers. Pepperberg has compared his intelligence that of a five- or six-year-old child. Perhaps it shouldn’t be all that surprising that he could master the marshmallow test.

However, Gray noted, “I don’t believe Griffin was unique.” Members of other bird species would probably be able to accomplish the same thing, given the right circumstances, she said.

Goffin’s cockatoos were put to the test by researchers at the University of Vienna last year and could manage only a bit over a minute at best. But these birds had to hold the reward in their beaks, rather than look at it on the table. “It’s a little unfair,” Koepke said. How many of us would be able to resist eating something tasty if it were put in our mouths? If these birds were tested in the setup used for Griffin, they, too, may have succeeded.

But the marshmallow test isn’t necessarily one about smarts. A couple of years ago, researchers discovered that trust was a key factor. When the experiment was altered so that kids had no reason to trust the experimenter telling them to wait, they often didn’t bother. Griffin, Gray noted, lives in a trustworthy environment—he has no reason to doubt that the promise of a treat will be fulfilled.

But wouldn’t it be interesting to watch what would happen, Gray speculated, if he were confronted with an experimenter he didn’t trust? Perhaps he’d be just as unwilling to wait as anyone else.

Sept. 3 2014 4:54 PM

Marmosets Can Learn New Tricks—by Watching a Video

Finally, irrefutable evidence that not all TV is bad for your brain. In an attempt to determine whether monkeys can acquire new skills and behaviors from outside of their immediate social group, biologists used a video tutorial to train wild marmosets to open a box. The team, led by Tina Gunhold from the University of Vienna, first recorded already-trained marmosets opening the box (which contained a treat), then outfitted a tree with the box and video, and finally showed the recording to marmosets in the wild.

The video above shows the savvy marmosets in action. All phases of the experiment are on display—from the monkeys watching the video, to the implementation of what they've learned, to their gleeful retreat after they've secured their prize. In addition to being downright cute, it serves as an exceedingly fascinating display of animal ingenuity.


The results of the study were published in Biology Letters, with the authors stating that not only was the experiment mostly a success (only 12 of the 108 marmosets opened the box, but of those, 11 had watched the video), it was also, to their knowledge, "the first study that used video demonstrations in the wild and demonstrated the potent force of social learning, even from unfamiliar conspecifics, under field conditions."

Aug. 30 2014 9:15 AM

What Happens When You Raise Walking Fish Entirely on Land?

Native to freshwater African riverbanks, bichirs are famous for their strong fins and lungs, allowing them to “walk” and breathe out of water. But the serpentine fish prefer aquatic habitats, and tend only to travel on land when they must.

For a new study published in Nature, researchers from the University of Ottawa and McGill University decided to find out what would happen if they raised bichirs entirely in terrestrial environments for eight months. They hoped to learn more about the transition of sea animals to land some 400 million years ago, an evolutionary turning point that bichirs may be uniquely poised to help us understand.


The team was surprised to find that the fish not only survived, but seemed to adapt and thrive in their new homes. As explored in the Nature-produced video above, the land-dwelling bichirs provided an exciting snapshot of a crucial moment in the evolutionary record.

Aug. 29 2014 2:42 PM

A Normal Lion Cub, and Another Normal Lion Cub, and a White Lion Cub

I'm of the opinion that there is nothing cuter than a lion cub. Those little bundles of apex predator are the most adorable things on the planet, and if I were to raise one as my own at some point—with that relationship culminating in a Christian-esque reunion and lion hug, obviously—I would die a happy man.

Well, it turns out I was wrong. There is something cuter than a lion cub—a white lion cub.


In the video above, you can watch the Johannesburg Zoo's three new lion clubs—Sabi, Jubba, and Letaba, born with a rare white coat—acclimate to their new home. The four month-old cubs are triplets, and had been in quarantine at the zoo since July.

The white furred Letaba is, as mentioned, freakishly adorable, but if you need more reason to fall in love with the little guy, here's the woman responsible for managing the zoo's lions (and other big cats), Agnes Maluleke: "The white one is a leader and he is very playful, but he plays very rough, because he is actually thinking that we are all lions and we have fur to protect our skin. So you need to be very careful around them."

Such a little rascal, that Letaba. As long as he's cool with lounging in a first-floor apartment in Brooklyn for the foreseeable future, he's welcome in my pride anytime.

Aug. 27 2014 1:22 PM

The Legend of the Loneliest Whale in the World

This article is excerpted from “52 Blue,” the newest single from the Atavist. You can purchase the full story from the Atavist’s website. It is also available on Amazon.


Dec. 7, 1992: Whidbey Island, Puget Sound. The World Wars were over. The other wars were over: Korea, Vietnam, the Persian Gulf. The Cold War was finally over, too. The Whidbey Island Naval Air Station remained. So did the Pacific, its waters vast and fathomless beyond an airfield named for an airman whose body was never found: William Ault, who died in the Battle of the Coral Sea.


But at that naval air station, on that day in December, the infinite Pacific appeared as something finite: audio data gathered by a network of hydrophones spread along the ocean floor. These hydrophones had turned the formless it of the ocean and its noises into something measurable: pages of printed graphs rolling out of a spectrograph machine. These hydrophones had been used to monitor Soviet subs until the Cold War ended; after their declassification, the Navy started listening for other noises—other kinds of it—instead.


On Dec. 7, the it was a strange sound. The acoustic technicians thought they knew what it was, but then they realized they didn’t. Petty Officer 2nd Class Velma Ronquille stretched it out on a different spectrogram so she could see it better. She couldn’t quite believe it. It was coming in at 52 hertz.


She beckoned one of the technicians. He needed to come back, she said. He needed to take another look.

Aug. 25 2014 8:07 AM

Are Humans Any Good at Pheromones?

Excerpted from Wild Connection: What Animal Courtship and Mating Tell Us About Human Relationships by Jennifer L. Verdolin. Out now from Prometheus Books.

As if your face, your eyes, your symmetry, your hair, your waist, your teeth, and sometimes even your feet weren’t enough, there’s even more going on than meets the eye, and this other consideration may just be the ultimate deciding factor in initial mate attraction—it’s how you smell. When discussing mating systems with my students, I always tell them, “It wasn’t that you saw each other across the room; you smelled each other!” There is one man I know who I could probably smell a mile away. And I mean that in a good way. For me, his natural scent is so thoroughly intoxicating that I can barely think when I am around him. Worse still, I am like a basset hound when it comes to sensing his presence in my environment, and I am convinced it is because I smell him before I see him!


The idea that one can become inebriated by the natural smell of another is not as strange as it may sound. Both males and females of many species succumb to the scent of desire. Just look at the delightful, pudgy, brown lemming male: He has a keen sense of smell when it comes to the ladies. It’s a rough life for lemmings. They are pretty much on the bottom of the food chain, and they only live for about a year and a half. Not one for dillydallying, this little rodent packs a lot into that short life span.

Despite living in the arctic, lemmings are active all year round. With the clock ticking down, there is no time to hibernate for these guys. Females can have several litters a year, raising anywhere from four to nine babies at a time. Females have the uncanny ability to sniff out better mates, and their noses lead them right to the dominant male. Have you ever walked into a room and said, “Boy, you can just smell the testosterone in the air?” Apparently this is what female brown lemmings are discussing as well.

Male lemmings not only have a knack for smelling females that are ready to mate but also for smelling those that haven’t already mated with another male.

When females mate with multiple males, it is harder for males to be sure of their paternity.

Male lemmings try to get around this by detecting whether a female has already mated. This, of course, implies that males leave a chemical calling card that other males can detect. From beetles to bees and lizards, females do give off a different scent if they have already mated or if they are ready to mate.


What does all this chemical calling card stuff have to do with us? Lo and behold, we are just as sensitive to the scent of the opposite sex as the humble lemming. Humans can discriminate odors in just a single whiff, which at a minimum takes approximately 400 milliseconds. Like male beetles, bees, lizards, lemmings, and a whole suite of other species, men can discern the scent of a woman ready to become pregnant.

They find the smell of sweat from women who are close to ovulation more pleasing and even sexier.

And not just their body odor, men also prefer the voice, the complexion, and basically everything about a woman near ovulation. The thing is, men know women are ovulating because they can smell it, but they don’t know that they know!

One of my friends swears by this phenomenon. She claims that she gets a lot more attention from men right before she begins ovulation. Whether it is holding the door open for her, buying her a cup of coffee or a drink, or being asked out, like bees to honey the men flock to her, only to disappear again once she passes that magical time. Women, the same holds true for us. When we are ovulating we strongly prefer the scent of a male, but not just any male, a more symmetrical male.

Beyond the simple fact of whether one prefers certain scents, there is increasing evidence that how an individual smells, the person’s pheromone signature, if you will, may be linked to that person’s genetic health—specifically, his or her immune or disease-fighting genes. These are known as major- histocompatibility-complex, or MHC, genes. By distinguishing at a cellular level between self and other, they are involved in identifying and fighting off invading pathogens.

Mothers, fathers, and close relatives like grandparents and aunts and uncles have been shown to be able to identify the odor of a related infant compared with an unrelated one. In the case of fathers and other relatives, they can do this even if they have had no prior exposure to the baby! When we look to animals, we find similar results. Individuals seem to be able to tell the difference between relatives and nonrelatives based on smell alone. And it is largely thought that this is due to the scent one gives off based on the particular set of MHC genes you have.

While this is fascinating—and potentially a topic for another book—what does this have to do with finding and choosing a mate? Studies with lab mice reveal that, all other things being equal, individuals will choose a mouse mate that is most dissimilar in the MHC genes.

This phenomenon extends far beyond the lab. One of the cutest species I have had the pleasure of studying is the gray mouse lemur. This nocturnal primate, native to Madagascar, is small enough to fit in the palm of my hand, reminding me of a miniature Topo Gigio, an Italian television puppet character popular when I was growing up.

Looking at gray mouse lemurs in the wild reveals that their mate choices are also MHC-dependent.

The benefits of this are twofold. First, they avoid mating with relatives, and second, by combining different genes from two parents, offspring have the maximum diversity in their disease-fighting genes. This second benefit may help offspring survive better when fighting off infections and disease.

I mentioned that mothers and other close relatives can distinguish the smell of a related versus nonrelated infant, but does this extend to detecting the best genetic match based on MHC composition? Yes, indeed. Just like paper wasps, the house mouse, seabirds, primates, and countless other animals, human females have a stronger sexual interest in the odor of males who differ from them on the MHC-gene level. Even more interesting is that in already-paired couples, women were less sexually responsive to and had fewer orgasms with partners who had similar MHC compositions.

Perhaps this is why some men are constantly obsessed with whether or not a woman has an orgasm? As if that weren’t bad enough, closely MHC-matched couples also engaged in a higher number of extrapair copulations. Translation: more cheating.

Similarity of MHC composition may also explain why some couples have difficulty getting pregnant, and it may even explain the frequency of spontaneous abortions.

With nature guiding the way and with such severe consequences, how do we ever end up mismatched?

One argument for how we end up mismatched is that we don’t have the capacity to detect MHC composition using our olfactory ability, especially since we lack the Jacobson’s organ, which is found in the nasal cavity of many animals. This organ is first in line when it comes to olfactory sense and processing. Next time you see your cat smell something and hold its mouth open with upper lips curled and teeth exposed in what is called the flehmen response, you can bet something tweaked its Jacobson’s organ.

Although you may never have heard of it, scientists have been hotly debating whether you have a Jacobson’s organ, or vomeronasal organ. This mysterious and contentious organ is the secondary sensory organ of the accessory olfactory system with specialized neurons that process chemical cues, separate from those associated with primary olfactory processing center. Interestingly, fish lack this accessory organ, suggesting that perhaps, life on land may have been the impetus for the evolution of the Jacobson’s organ. Where, if you have one, would you find this special structure? Depending on the species, it can be located at the base of the septum or in the roof of the mouth.

So who has it and who doesn’t? As usual, except for fish, there is no simple answer to this. Since we are primates, let’s just investigate what’s going on with this group. For the families that include bush babies and lemurs, also known as the strepsirrhine primates, we find a fully functional, anatomically complete vomeronasal organ. In the catarrhine primates, like macaques, it is generally absent, or reduced, with some indeterminate function.

When we start looking at the group that includes tarsiers, monkeys, apes, and us, things get a little messier. Perhaps ironically, this group, the haplorhine primates, literally translates in Greek to mean “simple-nosed” primates. Some species have it, some species don’t, some have it but it doesn’t work, and more importantly, throughout the order, its size is greatly reduced. For instance, both night monkeys and spider monkeys have a Jacobson’s organ, but it is not functional in the spider monkey.

When it comes to humans, it is clear that developing embryos have a Jacobsen’s organ which then seems to disappear. In adults a depression, or pit, consistent with the Jacobson’s organ is present at least on one side of the nasal cavity about 2 centimeters up into the nostrils, but it looks more like a remnant structure. So is this pit, or pits if you are one of a few that have it bilaterally, a functional Jacobson’s organ, or is it just a leftover of our evolutionary past?

There are a few things to consider. First, the epithelium tissue lining these depressions in humans is not well-developed. Second, there is a lack of sensory neurons that even if the tissue were functional could connect it to the brain, sending along whatever chemical information was being perceived. Third, and perhaps more importantly, almost all of the genes involved in protein expression of a functional vomeronasal organ are pseudogenes in humans dating back as far as 23 million years ago— around the time we went our separate ways from Old World monkeys. What are pseudogenes? They are dysfunctional copies or relatives of functional genes. Put simply, they don’t work.

But why all the fuss? What does this little organ actually do? Some have suggested that its purpose is solely for the detection of pheromones, or hormones involved in a variety of social functions, from recognizing individuals to mate selection. The implication then being that we, and other species that lack a functional Jacobson’s organ, cannot detect, process, or even respond to pheromones. That is quite a leap. Indeed, we have other genes, separate from those linked to this touchy organ that are involved in detecting pheromones. Not surprisingly, they are linked to the main olfactory system. MRI studies have shown that molecules involved in discriminating between “self” and “other” odors, called peptide ligands, activate not just the vomeronasal organ in animals but also parts of the brain. Though humans lack the organ in our noses, we certainly have brains, and these same molecules, when we smell them, light up the same area in our brains, too. This then means that regardless of which camp you fall into, the “we do” or the “we don’t,” the scales are tipped in favor of our ability to detect and respond to pheromones. So sniff away because even if we don’t have a functional Jacobson’s organ, we have noses with lots of neural connections to our marvelous brains with which to process information in the very functional main olfactory system we do have.

However, this brings us back to the question then—why do we end up mismatched?

It might have something to do with birth control pills. The irony, or perhaps tragedy, of hormonal birth control is that it interferes with how a woman’s nose knows. When women take birth control pills, some studies suggest that this natural ability to discriminate between similarity and differences in MHC composition may be disrupted. The research isn’t entirely clear, but this could cause women to be more sexually attracted to the odor of males with MHC genes more similar to themselves. Not the best match.

I was discussing this with my friend Stacey, who exclaimed, “That must be why I couldn’t stand the smell of my ex-husband!” She went on to explain that when she met her first husband she had been taking birth control pills. Several years into their marriage, after she discontinued the pill, not only was she unable to get pregnant, but she no longer cared for the smell of her husband.

My advice: sniff a potential mate. I personally like the neck. Good for smelling babies and good for smelling men. If you are not on birth control and he (the man, not the baby) passes the sniff test, then that is just one more step toward finding a potentially good mate.

Excerpted from Wild Connection: What Animal Courtship and Mating Tell Us About Human Relationships by Jennifer L. Verdolin Out now from Prometheus Books. 

Wild Connection: What Animal Courtship and Mating Tell Us about Human Relationships