Homo Floresiensis—Our Hobbit Cousins—Evolved From Homo Erectus
Every announcement of a new hominid species prompts questions and debate: Is it really a new species? What characteristics set it apart from known species? Where does it fit on the family tree? But few discoveries have been as head-scratching as that of Homo floresiensis, better known as the “Hobbit” species.
In 2003, researchers discovered a cache of fossils—partial skeletons of at least nine individuals—on the island of Flores in Indonesia. What made them remarkable was that the most complete remains belonged to a 30-year-old female who stood 3½ feet tall, with a brain the size of a chimp, and who lived only 18,000 years ago. How did these early humans get so small? Had they evolved from a larger early hominin? Did they evolve elsewhere and then come to Flores? Could they be merely abnormal Homo sapiens?
A study released Friday in the journal PLOS ONE argues that H. floresiensis is indeed a distinct species, one that evolved from Homo erectus. H. erectus is by far the most successful hominin species in terms of how long it lasted. It is believed to have evolved 1.9 million years ago and endured until some point within the last 100,000 years. Along the way, H. erectus spread from Africa to Turkey and Asia, may have been the first species to control fire, and made advances in the stone tool technology first employed by Homo habilis.
Japanese paleoanthropologist Yosuke Kaifu and his fellow researchers did an exhaustive study comparing 40 teeth of floresiensis to hundreds of teeth of other species, including Homo habilis and Homo ergaster from East Africa, a Homo erectus from Java, and two ancient Homo specimens from East Asia.
The teeth were similar in size to those of smaller modern humans, implying that H. floresiensis could be unusual examples of Homo sapiens, but the teeth included too many primitive traits for that to be the case. The scientists then determined that those traits were more in line with H. erectus than with the older Homo habilis or perhaps an even older Australopithecus series.
"For me, this work will turn the tide about the question of evolutionary origin of H. floresiensis," Kaifu told Live Science.
There is more significance to the study than just declaring that H. floresiensis is indeed its own species. Ruling out those ancient ancestors for H. floresiensis argues against the idea that a species before H. erectus might have migrated out of Africa. It is also in line with previous artifacts discovered on Flores. Mike Morwood, the archaeologist who discovered H. floresiensis in 2003, had previously found crude stone tools of the sort used by H. erectus, dating to 840,000 years ago.
As the authors conclude in the new study, "H. floresiensis is not evidence for unexpectedly early hominin dispersal into Asia but is more likely an example of considerably greater flexibility in hominin physical evolution as originally proposed."
These Animals’ Breathing is Breathtakingly Bizarre
If your lungs are working properly, you probably don’t think about them all that much. They’re pink. There are two of them. Smoking makes them sad. What else is there, really?
Well, did you know your right lung is bigger than your left, which has to share space inside your chest cavity with the heart? The right one is also built up of three lobes, while the left has only two.
And while breathing in and out seems like the most obvious thing in the world, something we all have in common, a gander around the animal kingdom reminds us that life is anything but simple.
Consider the Fitzroy River turtle, a native of Australia. Turtles have lungs that pull oxygen out of inhaled air, just like you and I do, and yet lab tests show the juveniles of this species can stay underwater for at least 72 hours. How do they do it? They utilize a highly sophisticated gas exchange apparatus known as their butts.
I’m being serious. Fitzroy River turtles have tiny, specialized papillae lining the walls of their cloaca—the one-stop-shop turtles use for urination, defecation, sex, and egg-laying. These papillae act somewhat like the alveoli in our lungs do, siphoning off oxygen molecules and absorbing them into the bloodstream. These baby turtles breathe through their butts.
Things get even weirder when you look at other reptiles.
“Most snakes have only one fully functional lung,” says Harvey Lillywhite, author of How Snakes Work. Lillywhite, of the University of Florida, explains that most of the organs in snakes have become cigar-shaped over the millennia, and the lungs are no exception. As in humans, the left lung seems to have gotten the short end of the stick. The left lungs are so shrunken in some species of snake, in fact, that they’re considered vestigial, leftovers from a time when they used to serve more of a critical function.
There’s actually still a lot we don’t know about how animals breathe. But we’re getting closer to understanding thanks to a scientist named Colleen Farmer and her experiments with live alligators and disco fog.
Alligators have weird innards. They have “teeny, tiny hearts because they’re aquatic, ectothermic, sit-and-wait predators,” says Farmer, a comparative physiologist at the University of Utah. They don’t need big, strong hearts like endurance athletes. But their lungs are huge. Weirder still, the lungs are intricately connected to the pericardium, the sac that contains the heart, something you don’t see in other animals.
As she was dissecting an alligator one day, Farmer says, an explanation dawned on her: Each beat of the heart could be tugging on the lungs in such a way as to stir up the air already inside, effectively circulating air to more areas where blood vessels can grab oxygen. If true, this breath by heartbeat (so to speak) would be a handy trick for a predator that likes to sit very still for hours on end—it could literally hold its breath while waiting to ambush its prey.
Just one thing: How do you test the fluid dynamics of airflow inside the body of a reptile?
Well, if you’re Farmer, you concentrate disco fog vapor in an e-cigarette, attach it to some tubing, and shotgun the vapor into a live alligator. Using an endoscope, she could watch the fog roll through the gator’s respiratory system. (“How’s work?” asks Grandma at Thanksgiving. “Oh, you know, same old, same old.”)
Farmer found that, in two minutes of holding its breath, an alligator can circulate the same amount of oxygen throughout its lungs using this “cardiogenic flow” as if it were sucking in fresh air.
Bird lungs look nothing like alligator lungs or human lungs for that matter. Open up a bird and you’ll find air sacs that look like bubbles made out of pink Saran wrap. And there are tons of them! Air sacs that push up into the neck, air sacs extending into the wings, air sacs down by the tail.
“There are just air sacs all over the place,” says John Hutchinson, professor of evolutionary biomechanics at the Royal Veterinary College at the University of London. “Pretty much everywhere there isn’t other stuff, there are air sacs.”
Anyway, all of these air sacs connect to the lungs in a closed circuit. This means that when a bird breathes in, the air doesn’t just come in and out again. It flows through a one-way network of tubes that get smaller and smaller. This unidirectional flow is a far more efficient way to breathe than passing air in and out through the same routes and a system long thought unique to birds.
However, Farmer is finding that unidirectional breathing—not to be confused with Tenacious D’s “inward singing”—may be a lot more widespread than we thought. She found it in her alligators: Their heartbeat-driven breathing only works because their lungs have tiny valves that coax air in one direction. She has since rigged up respiration experiments with monitor lizards and green iguanas and shown that both are also capable of unidirectional breathing. Next she wants to look at tuataras, turtles, and amphibians to see how deep the deep breathing goes.
Of course, if amphibians are capable of unidirectional breathing, it may well be the least bizarre trick in their repertoire. Many amphibian species can breathe through their skin, wicking oxygen out of the air like the weird little mutants that they are. And salamanders are weirder than most.
“There’s tremendous diversity in salamander respiration,” says Hutchinson. “They go through metamorphic transition where they transform from gill-breathing larvae to lung-breathing adults.”
And then some species have just given up on the whole lung enterprise. These salamanders, of the Plethodontidae family, breathe entirely through oxygen absorbed through their skin and the roof of their mouth. Best of all, you don’t even have to travel to some deep, dark jungle to find a lungless sally. Just go to Indiana.
Even amphibians that don’t breathe through their skin breathe strangely. We breathe by creating negative pressure inside our chest to suck in air, sort of like how a turkey baster draws all those delicious juices into its bulb. But frogs go the opposite way, says Farmer. They take two or three little gulps of air into their mouth, plug up their nostrils, and then shove that air down into their lungs.
Of course, birds, reptiles, and amphibians don’t have a monopoly on weird breathing. Mosquito larvae live underwater but breathe air through what can only be described as a butt snorkel. And a predator of mosquito larvae, the diving bell spider, is able to spend much of its life underwater by keeping air bubbles attached to its chest with tiny, hydrophobic hairs.
Mammals also have some fascinating representatives. Arctic ground squirrels go so stone-cold when they’re hibernating, you can seal them inside jars of noxious gases without making them stir.
Walruses and other marine mammals can store a ridiculous amount of oxygen in their blood and muscle thanks to enhanced levels of hemoglobin and myoglobin.
“It’s their own on-board scuba tank,” says Shawn Noren, an associate research scientist at University of California, Santa Cruz.
Male walruses also have large air sacs in their head and neck that they inflate during mating—“I guess the females find them sexy,” says Noren—though the floaties may also be used in the water for buoyancy.
Understanding how respiration works could change the way we think about how and why our ancient ancestors first made the lurch from sea to shore—and in some cases back again. In fact, whales—marine creatures that evolved from terrestrial creatures that evolved from marine creatures—may have the most bizarre breathing apparatuses of all. Through millions of years of evolution, their windpipes migrated into blowholes in the middle of their backs. Breathtaking.
Stressed-Out People Love UberKITTENS, but Do These Programs Stress Out Pets?
Some people have pet allergies or really hate dogs, but in general nothing sounds better to stressed-out students or office workers than some playtime with puppies or kittens. So calming, so adorable. Hangouts with visiting dogs and cats have become increasingly popular in the United States, and while the benefits to humans seem clear, you might start to wonder how the pets are feeling about it. It's actually a controversial question.
You may have noticed that Thursday was National Cat Day.
To celebrate, ridesharing company Uber held the third years of its UberKITTENS promotion, where you can request that the company bring a batch of kittens to your office for 15 minutes. The first UberKITTENS was in three North American cities. The second was in seven. This year the event was held in 55. National Cat Day is scaling up.
Uber partners with local no-kill shelters in each city (they worked nationally with the American Society for the Prevention of Cruelty to Animals for the first two years of the program) to promote adoption and help socialize the kittens. The company has also run some UberPUPPIES events. Uber calls ahead to vet the locations it is bringing animals to and always has two representatives at each office the pets visit—one from the local shelter and one from Uber itself. "We make sure that the environment is safe," said Uber spokesperson Sarah Maxwell from inside one of the cat cars on Thursday. "The kittens really love it, they’re having lots of fun."
The trend has caught on in schools around the United States as well. Many colleges and universities bring pets to campus to help students de-stress during exams. These animals are often trained therapy dogs, and some schools even house therapy dogs on campus all year.
There are also regional programs like the Humane Society of Broward County's Snuggle Delivery service in southeast Florida. Similar to Uber's program, Snuggle Delivery is meant to increase the visibility of adoption initiatives and raise awareness about humane society efforts. For a $500 donation, HSBC will bring puppies or kittens to your office for an hour. (Uber collects a $30 fee for 15 minutes that it donates to its local shelter partners.) Snuggle Delivery even allows for on-site adoption. "We’ll bring all the necessary paperwork with us, and the pets will be spayed/neutered prior," Adam Goldberg, a spokesperson for HSBC, told the Huffington Post in March. UberKITTENS gives information to people interested in adoption so they can follow up with their local shelter. The company says that more than 20 kittens were adopted last year.
Emily Weiss, the ASPCA's vice president of research and development, told Slate in a statement that “The ASPCA supports creative ways to promote and find loving homes for animals within the community. Above all, the welfare of the animals is our top priority and as long as a safe and stress-free environment is provided, these types of engagements can be an enriching activity for both humans and animals alike.”
Overseas the topic is much more controversial, though.
The United Kingdom Royal Society for the Prevention of Cruelty to Animals shared a document with Slate dedicated to its “concerns regarding fundraising and rehoming initiatives which involve cats or kittens being transported from rescue centres/shelters into different offices.” It outlines potentially stressful conditions for the animals like unfamiliar environments and inappropriate handling and points out that the events “lack of benefit to animals” and could encourage “spontaneous/impulse adoption.”
In February, the tech site shinyshiny published a piece opposing UberKITTENS in Australia. Nicky Trevorrow, the behavior manager at U.K. feline charity Cats Protection, told the site, “Raised stress levels could affect feline health, causing conditions like cystitis and a lowered immune system, increasing vulnerablility to infectious diseases. Kittens already have a weaker immune system than adult cats."
It's a bummer. Do we really have to feel bad about wanting lots of kittens and puppies in our offices all the time? John Bradshaw, the foundation director of the Anthrozoology Institute at the University of Bristol in England and the author of Cat Sense and Dog Sense, said that it's positive to spread awareness about animals in need of adoption. "I’m in favor of animals in the workplace whenever possible," he said.
He noted, though, that events at offices can set "false expectations. What most of these shelters have is lots of adult cats that nobody wants, not kittens." He also raised concerns about potential health consquences for kittens and puppies. “The idea of using young animals who are not really adapted to this and who may find it stressful if the experience becomes overwhelming—I’m not in favor of that,” he said.
For now, these dichotomous ideologies seem to be resulting in on-location events with puppies and kittens being much more popular in the U.S. than in the U.K. It's so easy to think they just want my love. But the concerns linger. Daniel Mills, a professor of veterinary behavioural medicine at University of Lincoln in England, quickly responded to an email about these types of events. “Is this real? Sadly I guess it might be. This sounds like a really bad idea to me. So many physical and psychological risks.”
Vampire Bats Can Walk, Jump, and Run on the Ground
It begins as a slow creep. One wingtip is placed in front of the other—left, right, left, right. Slowly, methodically, the vampire bat inches across the ground toward the sleeping tapir.
Vampire bats can stalk prey many thousands of times their own size, so one wrong move can mean a lost chance at a meal or worse, a hoof to the skull. Blood-feeding requires the stealth of a snow leopard, not the rash aerial acrobatics of the vampire bat’s insect-catching cousins. And so the vampire crawls.
From a distance of six inches, special sensors in the bat’s nose allow it to use infrared radiation to detect the heat of blood close to the skin. The only other animals with this superpower are few snakes like the pit vipers.
Once it zeroes in a hot spot, the vampire bat uses scalpel-like incisors to carve tiny divots in the tapir’s flesh. The bite is so fast and clean, the tapir doesn’t even stir in its slumber. An anticoagulant in the bat’s saliva (appropriately named draculin) causes the blood to flow freely. As the crickets and cicadas hum into the night, the vampire bat licks its lips and prepares to suck the lifeblood from another mammal.
But here’s where all the vampire lore gets it wrong. True vampires do not suck blood. They lick it.
“When they feed, I think they look rather more like a cute cat lapping up milk,” says Gerald Carter, a postdoctoral researcher at the Smithsonian Tropical Research Institute.
Whether it’s the lapping or the loping, there’s clearly a lot about the vampire bats that popular depictions like Bram Stoker’s Dracula and Vampire Bats (the made-for-TV movie) get wrong. Which is a shame, because vampire locomotion is fascinating—and their creeping is almost as creepy as the whole blood-licking business.
“Unlike other bats, [vampires] can walk, jump, and even run on the ground,” says Carter, who studies these animals in Panama.
What’s interesting here is that there are more than 1,300 known species of bats in the world. And precisely one of them is able to run. That’d be Desmodus rotundus, or the common vampire bat. We know this because of Dan Riskin.
Riskin is a man of many talents. He’s a respected bat expert, an adjunct professor at the University of Toronto Mississauga, and cohost of Discovery Channel’s Canadian science show Daily Planet. But he’s also the guy who put vampire bats on treadmills. I probably should have led with that.
Riskin has spent a great deal of time studying bat biomechanics on the ground. Most bat species do not do well under such circumstances. They are awkward and slow, easy pickings for a predator.
But where the others look like a fish out of water, the vampire is able to gallop like a spider-bunny.
By coaxing vampires onto tiny treadmills, Riskin found that the flying mammals could run at speeds of nearly 4.5 miles an hour. He suspects that they might be able to summon nearly twice that speed in a pinch. Like maybe if OK Go needed extras for a new music video.
“I think [the vampire gait] is a nice reminder that we move the way we do because of physical laws of stability and power, but also because of our evolutionary history,” says Riskin.
For example, squirrels and frogs developed a bounding gait because they were already on an evolutionary path guided by powerful hind limbs. Bats went in the opposite direction, giving up lower limb strength in exchange for powerful breast and arm muscles to command their wings. But then the vampire bat started to double back on that path.
“Vampires had the motor up front,” says Riskin, “so when they evolved a bounding gait it was forelimb-driven.”
This front wheel drive, as he refers to it, makes the vampire bat’s running stride “kinematically different from that of any other tetrapod.”
Other bat species do many more interesting things with their webby wings.
Bats in the genus Tadarida use their wings to swim. The Cheiromeles and Mystacinidae bats have slots on their sides that they can tuck their wings into to keep them out of the way when they’re resting or crawling. Bats of the Saccopteryx genus have little fanny-pack pockets on their wings, which scientists believe are used by the males to store urine, glandular secretions, and Mentos—everything you need to woo a lady bat.
Some bats use their wing as a sling to catch their babies as they’re born. Other species’ wings have blood vessels built to dilate when the bats need to cool off.
Bat biologists have identified more than 60 different ways bats use their wings besides flying. These include defense, hiding, courtship, grasping, grooming, and fanning. For instance, says Carter, most people don’t realize that bats catch insects in the air using their wings as nets.
There’s even a bat with suction cups built into its wings. It’s called Spix’s disk-winged bat (Thyroptera tricolor), it lives inside tents made of waxy leaves, and Holy Halloween, Batman, it’s my new favorite animal.
Clearly, we all could all stand to spend a little more time around these wonderful, wingèd beasts. Thanks to a partnership with the Organization for Bat Conservation, Carter has set up a citizen science project that allows you to watch a captive population of vampire bats and log what you see. He calls it Vampcam, and after spending way too much time there one night, I can tell you it is all kinds of addictive.
Stick around long enough and you might just see a bat take a buddy under its wing and regurgitate a blood meal—which is basically the fun-size Snickers of the vampire bat world. Trick or treat!
In memory of bat expert Michael J. "Mick" Harvey, who this summer was called to the great roost in the sky.
Hung Like a Howler Monkey
Just hours after stepping off the plane in Costa Rica, I was confronted with my first pair of monkey testicles.
My wife and I were on our honeymoon, our destination a spa and hot springs at the foot of the Arenal Volcano. I was anxious to get away from the city we flew into, San Jose, as quickly as possible, mostly because I wanted to see some wildlife. And then, less than an hour’s ride from the airport, our bus driver pulled over so that we could snap a few pictures of a monkey. A mantled howler monkey, to be precise.
I remember being disappointed upon looking out my window. The monkey was straddling a power line stretched across the mountain road. Not exactly the candid wilderness shot I was hoping for, but I pulled out our fancy new camera all the same. And that’s when I saw them.
Huge, white testicles—slung over the side of the power line in a way that recalled a few choice original verses of the children’s song “Do Your Ears Hang Low?”
Forget about the beaches and the all-inclusive dining and the couples massage—I knew right then, staring down the barrel of two of the biggest, baddest gonads I’d ever laid eyes on, that we had come to the right place.
Most people probably don’t think about testes when they see the words howler monkey. The animals are known for having one of the loudest calls in nature, a grunting, vibrating cacophony that sounds like an enormous, angry bullfrog trapped in a trash can.
But now, in what very well may be the most fun scientific paper of the year—the veritable chocolate-in-my-peanut-butter moment of 2015—scientists have managed to bring these two aspects of howler anatomy together in a study that investigates the relationship between vocal tract size and testes dimensions.
Naturally, they’re calling it the “calls and balls” paper.
“Of course, you can only say that so loud at the university,” says Leslie Knapp, a primatologist and chair of the anthropology department at the University of Utah.
At the base of the calls and balls paper is a bunch of data that doesn’t seem to be related to anything. Knapp and her co-authors worked with zoos to conduct testes volume measurements, analyzed recordings of howler monkey calls, and traveled to museum collections around the world to measure a particular bone found in howler monkey throats. Called the hyoid, this large, hollow structure acts like a resonating chamber, which amplifies the primates’ primal screams.
Anyway, it’s when Knapp and company put all of this information together that some mighty interesting correlations started to emerge.
For starters, howler monkey species with larger hyoid bones were able to create vocalizations with a deeper pitch. This part isn’t so surprising. Howler monkeys produce a bass pitch comparable to animals of much larger body sizes, such as red deer and elephants, and in general, larger vocal chambers can produce deeper sounds.
Much of the howler monkey’s characteristic croak is thanks to the hyoid bone. Humans and many other animals have hyoids, by the way, but none are so big and hollow as the howler’s. Magnetic resonance images of the howler’s throat also reveal extremely long vocal folds for an animal of its size. Some species’ folds are more than two-and-a-half times the length of a human’s.
It’s thought that male howler monkeys use this apparatus and the hoots it produces to guard territory from neighboring troops. Deeper bellows tell rivals that they’re dealing with a big monkey who doesn’t take any guff. Presumably, says Knapp, this also helps the male ingratiate himself with the ladies.
Now, this brings us to the second part of Knapp’s study. You might think that the howler monkey species with the largest hyoids—the biggest badasses, as it were—would have the biggest balls. But you would be mistaken.
“To make a long story short, what we find is that when males have a large hyoid bone, they also have smaller testes,” says Knapp.
That strapping howler I saw on my honeymoon? Turns out, this species (Alouatta palliata) had the smallest hyoid bones of any howler species surveyed but the largest testes. (To that, I can teste-fy.) (Sorry.) And we’re not just talking about a little bit bigger. The mantled howler’s testes are close to six-and-a-half times as big as the red howler featured in the video above.
To understand what all of this might mean, Knapp says you need to look at yet a third correlation found in the paper—the fact that howler monkey species with larger hyoid bones tend to have fewer males per troop.
This is important because group size and composition can tell you a lot about an animal’s anatomy. Humans, for instance, have relatively small testicles for our body size when compared to other closely related primates, such as chimpanzees. Knapp says this is likely because chimps live in multi-male/multi-female groups where everybody’s competing with everyone for reproductive rights. Thus, chimps have evolved big, honking testicles that produce tons of sperm in the hopes that this will give them an advantage over their rivals. Male humans, on the other hand, don’t have to invest as many resources into competitive sperm thanks to the benefits of monogamy.
Getting back to the howlers, Knapp says what the calls and balls paper seems to show is an evolutionary tradeoff. Each howler monkey species displays a different strategy of resource allocation. Some, like the mantled howler monkey, whose picture has been up on my computer all day and which my wife keeps laughing at, invested in enormous testicles to help them pass on their genes. Others blew their evolutionary wad on raucous hyoid bones, the better to impress females and keep other males at bay.
But wait, you may be wondering, why wouldn’t some monkey invest in both big balls and deep calls? After all, if deeper, Barry White–like vocalizations help you get laid and larger testes increase the chances of fertilization, wouldn’t it behoove the howlers to go big on both?
“If it was possible for males to have large testes and also large hyoids, we would have observed that in the study,” says Knapp. “It really seems to be one or the other.”
Knapp says this is probably because either route requires a vast amount of limited resources, and with all the things a howler must deal with in the wild—finding food, avoiding predators, fighting off rival males—there simply aren’t enough resources for the howler to have it all.
Of course, the calls and balls study is far from the final word on the teleology of howler testes. For starters, Knapp says they’d like to do genetic tests within species to determine whether deeper calls result in more offspring. (Hyoid size and call pitch vary within species, too, mind you.)
Furthermore, these are only a few of many potential variables involved in sexual selection. And all you have to do is look at the pictures I took of howlers on my honeymoon to spot another. I mean seriously, why would a monkey covered in thick, dark fur have a scrotum that looks like it’s been waxed and bleached?
“Maybe if the females aren’t impressed with the male’s vocalization, they can look at the testes size,” says Knapp, humoring me. “Or maybe it looks scary to another competing male.” (Or it may be that bald, pale testicles contribute to temperature control—there are a lot of theories about testicle evolution.)
Holsters for sperm, indicators of fitness, and maybe even dangling devices of intraspecies intimidation—I’ll bet you never look at testicles the same way again.
Vampire Birds Thirst for Blood
Ticks, leeches, mosquitoes, vampire bats—when it comes to creatures that live by the vein, these are the usual suspects. But what if I told you there was a little blood-slurping birdy more diabolical than all of those guys put together?
Scientists call it Geospiza difficilis, but you can call it the sharp-beaked ground-finch or vampire finch for short.
Unlike bald eagles, harpy vultures, horned owls, and all the other big, scary birds that eat meat, the vampire finch looks like an animal that could be found at your backyard feeder. It weighs less than an ounce, has no vivid colorations or vicious talons, and generally just looks like any one of a dozen species flitting across your neighborhood as we speak.
Fortunately for all the birds of suburbia, vampire finches live only on the Galapagos Islands. It’s likely that the remoteness and harshness of this locale are what has driven the birds to draw blood. Their prey is boobies and other large seabirds that may be 50 times the finches’ weight.
“The Galapagos have an environment that fluctuates tremendously, and the birds go through droughts where there’s just not a lot to eat,” explains Ken Petren, an evolutionary ecologist and dean of arts and sciences at the University of Cincinnati. “And it’s in that context that we see birds being very creative about what they can try to eat.”
Of course, what strikes an evolutionary ecologist as creative, the rest of us would probably call horrific. That’s because the vampire finch isn’t the least bit nice about its bloodletting.
Vampire bats have teeth so surgically sharp, their victims can sleep through the ordeal. Mosquitoes and ticks anesthetize your skin before they suck. Leeches are aided by the numbing effect of cold water. Some of these bloodsuckers can go unnoticed indefinitely, so polite is their disposition. Who, us? Why, we wouldn’t think of imposing!
But the vampire finch of the Galapagos’ Wolf Island just hops right up onto a blue-footed booby’s back and jams its sharp beak into the seabird’s skin again and again until blood rains down. And once the vein is open, more finches arrive to the party like that blood-rave scene in Blade.
Why the boobies endure the abuse is up for debate. It might be that the boobies have no choice—Petren says Wolf Island has the highest density of vampire finches of any island, thousands and thousands of them in a very small area. It’s also quite far from the rest of the island chain, which means it’s extra remote. Add to that the fact that depending on the time of year, the boobies may be incubating eggs or caring for chicks, both of which the vampires are more than happy to peck at.
Interestingly, because the shells of booby eggs are too strong to penetrate using their beaks, the finches have developed a life hack that affords them yet another food source. Petren says the birds put their beaks on the ground in a sort of headstand, kicking the egg with their feet until it rolls off a cliff and breaks. Add a little Hollandaise and you’ve got Eggs Beelzebub.
Obviously, I don’t mean to give the impression that vampire finches are in any way evil. They’re simply animals making the best of a bad situation. On a string of islands in the middle of the Pacific, nutrients are hard to come by and an open wound might as well be an oasis.
After all, the finches of the Galapagos are sort of famous for adapting. There are now more than a dozen finch species on the islands, and each has a special way of surviving. Some eat seeds, others eat insects, and some have devised several different ways to carve up cacti. There’s even a Tim “The Tool Man” Taylor finch that hops around the island grunting and using sticks, cactus spines, and other tools to pry insect larvae and spider eggs out of tree cavities.
Whatever their mode of survival, the finches of the Galapagos have over time developed beaks to match each enterprise. These birds are some of the first and most famous avatars of evolution, which is why they are sometimes called Darwin’s finches.
Vampire finches aren’t even the only blood-drinkers on the Galapagos. The hood mockingbird has also been known to nuzzle into open wounds on boobies and iguanas and ingest the afterbirth of sea lions. There are even records of hood mockingbirds trying to drink from blood dripping down the leg of human researchers.
But the Galapagos don’t have a monopoly on bloodthirsty birds. Across the world, on the savannahs of Sub-Saharan Africa, there’s another vampire with an excellent common name—the oxpecker.
Until rather recently, oxpeckers were one of those species held up as an example of mutualism because it was thought that they provide an ecological service to large herbivores by eating their ticks, botfly larvae, and other parasites. The zebra gets rid of all its nasty hitchhikers while the oxpecker gets a fancy dinner full of protein—everybody wins, right?
Well, maybe. And maybe not. One study conducted in the scrubland of Zimbabwe found that cattle allowed to mingle with red-billed oxpeckers did not have significantly fewer ticks than those who had the birds relentlessly shooed away from them. (From the acknowledgements section of the paper: “Phineas Ndlovu, for scaring the oxpeckers.”)
What’s even more interesting, however, is that the paper also noted every pock, scab, and lesion on the cattle during the time of the study. And get this: The cattle that were allowed visits by the oxpeckers not only had a higher proportion of wounds that reopened or failed to heal, but they also had a higher number of wounds overall. This is because oxpeckers are notorious for pick-, pick-, picking their way into their hosts.
Do a quick YouTube search for oxpeckers, and you’ll find videos of these birds digging into hippo flesh, fighting over buffalo blood, and straddling the head of an antelope just to get at a face wound.
And then there’s this video of a giraffe with more red-billed oxpeckers on him than he has spots. There are birds on his head, neck, chest, back, and legs. Some comb his hair for dead skin and tick nymphs, others pluck off engorged adult parasites. But still more oxpeckers harry an open wound on the giraffe’s chest, dipping their entire heads into the red crevasse.
As the camera pans upwards, we see the bull has a stump where his left ear used to be. The narrator wonders if it isn’t the result of a tick wound opened up and never allowed to heal, thanks to the giraffe’s hungry avian hitchhikers.
No one seems to have observed an oxpecker actually creating a wound, as vampire finches are known to do. But the study mentions watching the birds deliberately peck at the place where a tick was attached to the cow’s skin without any apparent interest in eating the tick itself. It seems likely then that the oxpecker knows it can use a wound created by a parasite to open up a fountain of blood.
So if anyone is still looking for a scary costume this Halloween, I’d encourage you to pass over the werewolves, witches, and bats. Instead, be a little black bird with a beak built for bloodletting. They’ll never see you coming.
The Strangest, Most Amazing Lactation Methods Ever Seen in Mammals
My wife has amazing breasts.
I should explain that I’m talking about her mammary glands, in particular. (All mammals have mammary glands, though not all mammals have breasts. Some of them don’t even have nipples. But we’ll get to that.)
A few weeks ago, my wife and I welcomed our second child into the world—a wee little squeaker named June. After nearly nine months of sipping her meals through a straw in her belly, this bitty baby popped out, threw some shade at the doctor, and immediately began to suckle from my wife’s breast.
And I guess that’s when it struck me—not only did my wife’s body just funnel all of its resources into the creation of this animal, rearranging organs and increasing its blood supply by 50 percent in the process, but once it had expelled her, my wife’s body shifted modes like a Transformer to further accommodate its mewling creation.
In the hours and days to come, my daughter’s near-constant stimulation would trigger hormones to wash over my wife’s body, initiating lactation. Her mammary glands would produce colostrum, a concentrated proto-milk full of immune cells, antibodies, and protein that kick-starts the infant’s digestion and growth. The colostrum would give way to a more regular supply of milk composed of thousands of bioactive molecules that ward off infection, prevent inflammation, promote immunity, spur organ development, and cultivate a healthy microbiome.
My wife’s body would produce just as much milk as my daughter could drink, replenishing the supply in between feedings, and tweaking the recipe as the baby grew. Human milk is made to order depending on the time of day, the length of the feed, and the diet of the mother.
Like I said: absolutely sucking amazing.
So in honor of my daughter, my wife, and amazing mammary glands, I did some digging into the wonder that is mammalian lactation.
More than 200 million years before the “Got Milk?” campaign, the first mammals crawled onto the scene. Mammary glands are the main unifier of all us mammals—from moles, dogs, and koalas to tigers, lemurs, and platypuses.
“There are over 5,600 species of mammal, probably closer to 6,000 once they all get described, and they all start life on a diet of milk,” says George Feldhamer, professor emeritus at Southern Illinois University and author of the widely used textbook Mammalogy. But as Feldhamer points out, lactation can differ greatly among those of us in the milk-maker tribe.
Human milk, for instance, is a watery brew with just 3.8 percent fat and 1.2 percent protein. Compare that with the milk of a blue whale, which is 38.1 percent fat and 12.8 percent protein. Blue whale milk has the consistency of “loose, runny cheese” and smells like it was made in a Bass-O-Matic.
As the largest creatures to ever live, blue whales also hold the record for the biggest bazookas—each mammary gland is nearly 5 feet long and weighs almost 250 pounds. Like humans, blue whales have two such glands, which means each adult female is carrying around a quarter of a ton of milk-producing machinery. Of course, all this milk-making power is what helps the blue whale calf pack on 37,500 pounds during its suckling period.
But the leviathans aren’t even the fattiest milk producers in the animal kingdom. That prize goes to hooded seals. Their milk can reach 61 percent fat, a richness even Paula Deen would find excessive.
But decadence in nature is never needless—hooded seal mothers nurse their pups for just four days on pack ice before returning to the sea to find food. This is the shortest lactation period of any mammal. That means the pups must pack on as much weight as possible, as quickly as possible, or die alone on the ice. Drinking nearly 45,000 calories of liquid butter each day is the only way such an arrangement can work.
While we’re talking about marine mammals, I should probably clarify that neither seals nor whales are swimming around with anything resembling cleavage. All marine mammals lack breasts as we know them and keep their working parts inside the body proper.
The pinnipeds (seals, sea lions, and walruses) have retractable nipples, which sounds like a burn straight out of the junior-high locker room but in truth just means the nipples tuck inside when they’re not in use. This likely cuts down on drag in the water and protects the tidbits from the cold.
The cetaceans (whales, dolphins, porpoises, narwhals, and the like) take this trick a step further by burying their nursing parts below a fold of skin called the “mammary slit.” These nipple-housing envelopes are found on either side of another, longer slit, which contains the genitals.
Because dolphins and whales don’t really have lips like most mammals, it’s been posited that the mother’s abdominal muscles actually squeeze the mammary glands and eject milk into the calf’s mouth. There’s some evidence that the babies can assist the process by curling their tongues into troughs, the better to create suction and gulp down their liquid lunches.
Of all the sucklers though, opossums are the most committed. Following a gestation period of just 12 days, baby opossums emerge from their mother’s vaginas blind, deaf, naked, and with brains that are only 9 percent developed, which isn’t much of a brain even for an opossum. About the only thing these marsupials have going for them is a massive set of claws, which they use to climb up the mother’s body and into her pouch. Once inside, those who find a teat latch on and don’t let go for two straight months.
The nipples swell inside the babies’ mouths, creating a lock so tight that scientists have found that trying to forcefully separate a baby from its mother can result in torn lips and nips. (I think I just heard my wife shudder from the next room.)
Over the course of 60 days, the opossum’s nipple will stretch and grow up to 35 times its original length. This creates a tether between mother and child not unlike an umbilical cord and every bit as vital. A baby opossum that does not find a nipple after birth will be dead in minutes. And the same goes for any offspring that become detached before they’re ready to wean.
Nipples—what strange little bio-valves they are. For all the time we spend talking about nip slips and Instagram’s nipple censorship policies, we pay scarcely little attention to the wild nipples all around us.
According to the 2015 edition of Guinness World Records, the animal with the most nipples is the female shrewish short-tailed opossum, which can boast a 27-gun salute. When scientists dart and collar female polar bears, they can determine an approximate age by nipple size, since the teats get longer and wider as the animals become teenagers. Kangaroos nurse two different generations of joeys at a time, which means one nipple is devoted to carbohydrate-rich milk for the neonate in its pouch and another nipple delivers fat-rich milk for the yearling living outside. (Kangaroos are baby-making machines.)
In porcupines, bleached fur around the nipples is proof that the female has reared young in the past. Uldis Roze, porcupine expert and author of The North American Porcupine tells me that porcupettes (really, that’s what they’re called) have also been documented to play a little game of Simon with their mother’s nipples. They first tug at one nipple, then another, then another, suckling milk from each gland in an order that they will repeat throughout their nursing months.
Anyone who has owned a cat or dog knows that nipple placement also varies throughout Mammalia. Ours are near our armpits, as are elephants’. But many other animals—cows, squirrels, giraffes—keep theirs toward the hindquarters.
And then there are bats. Bats are already pretty special when it comes to mammals, because they’re the only ones that said, “Eff it, we’re conquering the sky!” Bats also have fascinating sex lives. So perhaps it’s not so surprising that they have awesome nipples.
Like us, bats nurse from teats on the upper body. But reports kept coming in over the years from scientists seeing another set of nipples located down on the pelvis of some species. In many cases, the “pubic teats” did not seem to be attached to functioning mammary glands. So what possible purpose could these extra nipples serve? Oh, an awesome one.
Pubic teats “are used as devices for the young to hold onto when the mother is flying,” says Nancy Simmons, curator-in-charge of mammals at the American Museum of Natural History.
The pup simply latches onto the mom’s pubic teat, wraps its legs around her neck like it’s doing a reverse-hurricanrana, and then the two fly off into the night.
All of this is described in Simmons’ 1993 paper in which she examined the nipples on 1,723 bat specimens representing 206 species. Her work remains the definitive word on bat nipples—which one can only hope affords her plenty of free drinks in every bar on Earth.
While we’re talking about lactating Chiropterans, I should at least mention that the only male mammal that has been shown to produce milk in the wild is also a bat.
Dayak fruit bats captured in Malaysia have been shown to express a relatively small amount of what appears to be milk. However, before you start lauding these guys for being some sort of male milk nurses, I should also say that there’s no evidence that they help nurse the pups. And their drippy nips may be more of an effect of their diet than some sort of evolutionary advance.
“It is likely that Dayak fruit bats ate leaves or fruits containing plant estrogens, which stimulated their mammary tissue, which then produced some secretion,” says Paul Racey, professor emeritus at the University of Aberdeen and author of a dissenting opinion on whether male bats truly lactate.
Whatever the case, there’s a yet more impressive feat than males making use of their nipples—and that’s nursing young without any nipples at all.
I refer of course to the monotremes, the only mammals left alive that lay eggs.
“The platypus and echidnas don’t actually have nipples,” says Feldhamer. “They have mammary glands, they secrete milk, but it just drips out onto tufts of fur.”
Still, there’s a lot to be said in support of nipples. In addition to guiding the milk directly into the baby’s yawning maw, nipples minimize the milk’s exposure to microbes. Perhaps this is why scientists have found the presence of an antibacterial agent that occurs exclusively in monotreme milk.
This is far from an exhaustive list of everything interesting about mammalian lactation. The Stejneger’s beaked whale, for instance, has milk that’s blue-green in color. Rodents and many other mammals (including humans) tend to have half as many offspring per brood as they do nipples. The dwarf mongooses of Tanzania are one of the only wild mammals in which females that have never been pregnant will spontaneously lactate to cooperatively care for other young in the pack.
Every way you look at it, lactation is biological alchemy. That jug of cow’s milk in your fridge or breast milk in the freezer? It’s evolution in a bottle.
But now if you’ll excuse me, I have a baby to burp.
Why Elephants Don’t Get Cancer
Being an elephant is risky business. I'm not talking about poaching, habitat loss, or fighting with males in musth—I'm talking about the simple fact of living. Every time an elephant cell divides, it runs the risk of going haywire and developing into an out-of-control tumor. Since elephants have 100 times the number of cells that human beings do, they should have 100 times the risk of getting cancer. That's a lot of mistakes waiting to happen.
In reality, given their size and prodigious lifespans, elephants have one of the lowest cancer mortality rates in the animal kingdom: 4.8 percent, compared to a range of 11 to 25 percent for humans. How can this be?
Scientists at the Huntsman Cancer Institute, University of Utah School of Medicine, and Primary Children’s Hospital helped figure out the answer, published Thursday in the Journal of the American Medical Association. Another team, made up of University of Chicago researchers and their colleagues, posted a related paper this week. As it turns out, elephants have developed some ingenious safeguards against developing cancer. Understanding their cellular protections might help us learn more about how to suppress cancer in humans.
There are countless ways that cell division can go wrong. That’s why—as we learned from the winners of this week’s Chemistry Nobel Prize—your cells come equipped with a host of repair enzymes whose sole purpose is to prevent or repair genetic mistakes. These cellular copy editors proofread each strand of newly divided DNA, identifying errors and repairing the faulty bits to ensure that your DNA stays fresh and clean and functional. In humans, just one of those enzymes can fix a thousand different kinds of errors. Not too shabby!
But elephants have one-upped us. For the JAMA study, researchers first compared cancer rates across the animal kingdom to find out that elephants were remarkably cancer-free given their size. (Other animals fared well, too. For comparison, rock hyraxes have a 1 percent cancer mortality rate, African wild dogs have an 8 percent rate, and lions have a 2 percent rate.) Then, they scoured the elephant genome to find out why.
The answer resided in a key tumor-suppressing protein called p53, known as the "guardian of the genome." Compared to humans, elephants had far more genes for this protein: 38 versions versus just two. The result was a superior genetic safety net for correcting errors and ensuring that damaged, tumor-prone cells get nipped in the bud. "The enormous mass, extended life-span, and reproductive advantage of older elephants would have selected for an efficient and fail-safe method for cancer suppression," the authors write.
To see how the genes suppressed tumors, researchers teamed up with Utah’s Hogle Zoo and Ringling Bros. Center for Elephant Conservation to isolate elephant cells and subject them to cancer triggers. (No elephants were harmed; this was all during routine wellness checks.) When they compared elephant cells to human cells, they found something amazing: The damaged cells in elephants were far more likely to resort to cell suicide—known as apoptosis—to avoid propagating errors in their descendants. It was a brutally efficient, even ruthless, system for protecting the organism at all costs.
To behold an elephant in the wild is to be humbled before majesty. Yet perhaps it isn't just their tremendous size that contributes to this sense of smallness. It's also all the things we can't see: from their advanced memories, to their long lifespans, to their individual cells, so altruistic that they are willing to die for the benefit of the many. From these cancer-resistant Methuselahs, we humans have much to learn.
There Aren’t Enough Male Squirrels to Mate With All the Females
Do you ever look in the mirror and think there’s something wrong with you? That maybe your tail isn’t bushy enough, your pelt’s lost its luster, or you’ve eaten a few too many acorns lately? Well, cut it out! I’m here to tell you that it isn’t you—it’s them. No, it’s not your imagination, single women: There literally aren't enough men out there!
That last sentence is the actual headline of a Vice article that presumably exists to make single women feel better about themselves and their supposed predicament. But it’s also scientifically true—at least if you’re a yellow ground squirrel. In the past, zoologists had thought that female squirrels’ lack of romantic encounters stemmed from their body condition, age, or competition from other female squirrels. Now, we know that the main reason some females aren’t having babies is that there aren’t enough males around—and the ones that are around are having a hard time finding them.
A shortage of males has been shown to be a factor in female reproductive failure in some insects, fish, and spiders. But in most mammals, it’s the reverse: Females tend to be the limiting factor. After all, one male can impregnate plenty of females. Plus, raising the young takes time and resources—just ask your mom!—and most of that burden falls to the females. Sadly, male squirrels aren’t really into parenting: “They mate, and they eat,” as zoologist and study author Nina Vasilieva puts it.
But when Vasilieva studied the sex lives of wild squirrels near the Russian village of Dyakovka over four years, she found some unusual traits that made females the scarcer resource. First, female yellow ground squirrels live alone in single-squirrel burrows, where they spend nine months out of the year quietly sleeping. Second, when they finally do emerge, they have a very limited span of time—as short as a single day—in which they are receptive to mating. If they fail to mate within that time, they have to wait until the following year. And, given that their lives last a brief two to three years, that's cutting it close. "I actually saw with my own eyes some sad females which were not visited by any males," Vasilieva says forlornly.
Before you feel too sorry for the females, though, consider that it's no walk in the park to be a male squirrel either. After all, he's stuck chasing an elusive, silent target that pops up once a year. Where’s squirrel Tinder when you need it?
Make no mistake: These females want to mate. In squirrels, “it’s reasonable for females to invest in reproduction as much as possible, even if she is in bad physical condition,” says Vasilieva. “Female ground squirrels have a very low reproductive cost. Actually, reproduction does not affect female survival and future reproduction in yellow ground squirrels at all.” But they aren’t exactly making it easy for the male squirrels. As a result, researchers found that 30 to 40 percent of sexually mature females failed to reproduce, they reported Friday in the journal Science Advances.
This finding goes well beyond squirrels: The dearth of males at the right time and place could also apply to lemurs or to other hibernating rodents, Vasilieva says. But perhaps there’s a larger message here for us all. Ladies, stop blaming yourself for the fact that there don't seem to be enough eligible men around. You’re perfect just the way you are. But also, best not to spend the majority of your time in an underground hole.
Watch a Majestic Siberian Tiger Get Released Back Into the Wild
It’s Friday. Fall (and football) is here. Weather’s supposed to be decent. All that being the case, at about 4 p.m. this afternoon, you’ll likely be pacing around your office like a tiger in a cage, ready to be released into the wild of the weekend. And for an idea of what that will look like, watch the video above.
The video in question—which comes to us from the good people at GoPro—shows Zolushka, a Siberian tiger, being returned to the wild. Rescued from poachers by the International Fund for Animal Welfare as a cub, her re-entry is just one example of the organization’s larger attempts at restoring the global tiger population. While there were once more than 100,000 wild tigers in Asia, that number is now believed to be somewhere between 3,700 and 4,200.
So not only is the incredible footage a thrill to see, it also affords us the opportunity to watch good, meaningful work in action—and, of course, provides a little Friday afternoon inspiration as well.
But be warned: Should you try to mimic Zolushka’s sprint for freedom after clocking out today, be prepared to be significantly less majestic in doing so.