Death of Ice Age Giants Shaped Today’s Landscapes

The extinct Bison antiquus at the Page Museum. Photo by Brian Switek.
The extinct Bison antiquus at the Page Museum. Photo by Brian Switek.

I can’t help the impulse. Whenever I’m hiking through the western forests, prairies, and deserts, my mind conjures up images of Ice Age beasts. I guess I keep engaging in the fantasy because I know I just missed them. Ten thousand years is nothing from a geologic perspective. Shasta ground sloths wouldn’t seem out of place shuffling through groves of Joshua trees, mastodons should still be cracking conifer boughs in the woods, and the grasslands were so recently the place where deer, antelope, and camels played.

But the places I scuff my boots aren’t the same as they were back in the heyday of North America’s enormous herbivores. While there have only been a few clicks of the Cosmic Clock since the end of the Pleistocene, the world hasn’t remained in stasis as if waiting for the return of our missing megafauna.

In fact, as Elisabeth Bakker, Jacquelyn Gill, and others argue in a recent review, the extinction of the great Ice Age beasts has created a world dramatically different than the one roamed by shaggy proboscideans and enormous sloths.

Herbivores are plant predators. It might be strange to think of them that way. A horse plucking up grass or an elephant chawing a mouthful of leaves isn’t as violent or gory a spectacle as a pack of wolves taking down an elk. Yet ecologists call the feeding habits of herbivores “predation” for good reason. The interactions may be slower and harder to see, and there is cooperation in addition to competition, but there are still arms races between herbivores and the plants they rely on. And this constant shuffle is what helps create the landscapes we see all around us.

Consider the American mastodon. This “bubby toothed” elephant was a browser, preferring tree branches and other woody vegetation to the diet of grass enjoyed by its distant cousin, the woolly mammoth. But the mastodon didn’t just eat trees and shrubs. The beast would have trampled down paths through the woods and scraped its tusks against tree trunks, further altering the landscape around it by stamping out some young plants and hindering the growth of others. Mammut americanum wasn’t just a big vegetarian.

The beast, Bakker and coauthors write, was an ecosystem engineer.

The same was true of many other herbivores that lived around the world until very recently. Up until about 600 years ago, for example, giant, flightless birds called moas browsed in the forests of New Zealand, helping to create openings in the woodlands that allowed light-sensitive plants to thrive in the patches they opened up. Since their disappearance, however, the forest has closed, with wire plants—whose springy anatomy made them resistant to moa depredations—spreading in greater numbers.

Imagine the damage the claws of Harlan's ground sloth could have done to Pleistocene trees. Photo by Brian Switek.
Imagine the damage the claws of Harlan’s ground sloth could have done to Pleistocene trees. Photo by Brian Switek.

Modern, short-term experiments have shown the same pattern. When big herbivores or either eliminated or excluded from an area, Bakker and colleagues write, the woodlands start to close up. Not as many young plants are being pulled up and fewer adult plants are having to struggle to put out leaves against the onslaught of big browsers.

For example, experimental studies have shown that areas where African elephants have been excluded can host 42% more trees than when the mammals are stripping them and pushing them over. Through extinction and the restriction of our last few megaherbivores to parks and game reserves, we’re playing out a miniature version of what happened when the Pleistocene’s major plant predators went extinct.

So when I set out from my Salt Lake City apartment and climb up above the level of the Lake Bonneville shoreline, to where my Ice Age inspirations used to roam, I need to do more than picture Harlan’s ground sloth or a mastodon trundling through the stands of oak and aspen. I need to think about what those herbivores did. Of branches stripped bare, toppled trunks, and wide paths through the woods pressed down by the hungry herbivores.

The lost megafauna weren’t just charismatic characters from a closed act in Earth’s history. They helped make the world what it was. I am only sorry that I can’t see what they created.

Bakker, E., Gill, J., Johnson, C., Vera, F., Sandom, C., Asner, G., Svenning, J. 2015. Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation. PNAS. doi: 10.1073/pnas.1502545112

Science Word of the Day: Mastodon

I have a soft spot for the American mastodon. The beast lived at the same time as the famous woolly mammoth, yet the mastodon is not nearly as popular as its tundra-living cousin. I can relate to that. But even worse, the shadow of the woolly mammoth stretches so far that the mastodon is often confused for its shaggy relative. This is not a new problem.

Back in the late 18th century, when paleontology was a nascent science, many naturalists thought that giant elephant bones found in Europe, northern Eurasia, and America were from modern species that used to live there. Elephantine bones found in England, for example, were attributed to behemoths the Romans must have used as pack animals during their occupation, and French naturalist Georges-Louis Leclerc, Comte de Buffon suggested that huge bones found in Siberia showed that the world was once much warmer and allowed modern elephants to range further afield.

Georges Cuvier disagreed. Remembered as one of the founders of paleontology, Cuvier was just 27 when he stood before France’s National Institute in 1796 and explained that the elephant bones from Eurasia and those from North America – then referred to the “American Incognitum” – actually belonged to extinct species unlike those alive today. “The first suspicions that there are more than one species [of elephant] came from a comparison of several molar teeth that were known to belong to elephants, and which showed considerable differences,” Cuvier explained to his audience, “some [teeth] having their crown sculpted in a lozenge form, the others in the form of festooned ribbons.” And from the fossil teeth, Cuvier concluded, “These [fossil] animals thus differ from elephants as much as, or more than, a dog differs from the jackal and the hyena.”

This wasn’t just anatomical hair-splitting. Cuvier had offered fossil proof that extinction is a reality – a fact some naturalists still questioned despite the fact that humanity had already wiped out the dodo and other species. More than that, Cuvier proposed that the fossil elephants preferred different habitats than their modern relatives. The conditions that had sustained them had been wiped away, perhaps in a terrible environmental catastrophe of the sort Cuvier was just beginning to entertain as he pondered the depths of the fossil record.

But what to call such beasts? The Siberian form – with the ribbon-like pattern on its teeth – was already known as the mammoth. The bumpy-toothed American form was still commonly called the Incognitum, and Cuvier did not offer a replacement in his initial paper on the subject. This oversight came back to bite him.

American mastodon molars figured in Cuvier's 1806 paper on the mammal.
American mastodon molars figured in Cuvier’s 1806 paper on the mammal.

Despite their disparate teeth, the mammoth and Incognitum were often misconstrued as the same animal. Naturalists were not always careful to distinguish the two massive, extinct elephants from each other. Cuvier got fed-up enough with the confusion that in 1806 he wrote a paper that tried to sort out the mess.

Mammoth was still a fitting term for the Siberian animal, but, Cuvier decided, the North American animal should be called the mastodon. The name came from looking the animal in the mouth. Drawing from illustrations created by American artist and museum pioneer Rembrandt Peale, Cuvier noted that the bumps on the mammal’s molars looked like breasts. Since teeth were mainly what he and other naturalists were comparing, Cuvier took the Greek words for breast and tooth to coin mastodon – the “bubby-toothed elephant, as naturalist Thomas Jefferson would later put it.

How the American mastodon got its scientific name is a little more complicated. Scottish researcher Robert Kerr called the animal Elephas americanus in 1792, but, after Cuvier showed that the animal was distinct from all living elephants, German anatomist Johan Blumenbach replaced the genus name with Mammut in 1799. And even the common name can still cause a little confusion in the way it’s applied. By itself “mastodon” isn’t just the name for the American Ice Age species, but an entire group of breast-toothed elephants going back over 28 million years. The American mastodon just happened to be the last member of the group and the first that our species rediscovered as a fossil.

But the initial mammoth-mastodon division Cuvier zeroed-in on as a young scientist still holds true. You can immediately pick out a mastodon by its teeth. The next time you visit the bones of ancient proboscideans, look carefully at their massive molars. If the grinders remind you of toothy teats, you’re looking at the great American mastodon.


Cuvier, G. 1806. Sur le grand mastodonte. Annales du Muséum d’Histoire Naturelle. 8: 270-312

Rudwick, M. 1997. Georges Cuvier, Fossil Bones, and Geological Catastrophes. Chicago: University of Chicago Press. pp. 18-24

Semonin, P. 2000. American Monster. New York: New York University Press. pp. 354-356

Baby Mammoths Yield Hi-Res Details for Paleontologists

There’s only one fossil that ever made me cry. Lyuba, a one month old woolly mammoth, made me a little misty-eyed when I visited her body at New Jersey’s Liberty Science Center in October of 2010. She was beautiful, intact down to hairs in her little floppy ears, but the entire reason her body retained its composure was because Lyuba suffered a tragic death. Somehow she suffocated in Ice Age mud, coming to rest in the chilled mire. Even though I couldn’t see it, there was still sediment in her throat and lungs when I visited her corpse.

What I didn’t know was that Lyuba wasn’t unique. Not long after Lyuba’s discovery in 2007, paleontologists announced the discovery of a second Siberian mammoth calf mummy nicknamed Khroma. This second specimen was about a month older than Lyuba, but she died in almost the same way. Khroma, too, had suffocated to death.

Despite some damage caused by scavenging dogs and postmortem pecks by crows, respectively, Lyuba and Khroma are the best-preserved mammoths in the world. Other mammoth carcasses – such as seven month old Dima – have degraded over time or aren’t anywhere near as complete. And despite their tragic fate, Lyuba and Khroma were found at a time when science could see inside them without doing extensive, invasive dissections. Using CT scan technology, University of Michigan mammoth expert Daniel Fisher and colleagues have been able to investigate Lyuba and Khroma from the inside out.

Fisher and coauthors have published their findings in the Journal of Paleontology, laying out details briefly presented by Ethan Shirley and Fisher at the 2011 Society of Vertebrate Paleontology meeting. Despite being so close in age, the little mammoths are surprisingly different. Lyuba’s skull is much narrower compared to Khroma’s, and the bones at the front of her upper jaw – the premaxillae – have a comparatively thin, pinched form.

Time and space may account for the disparity. Both Lyuba and Khroma lived and died over 40,000 years ago, but they didn’t live at exactly the same time. The two little mammoths also lived about 3,000 miles apart from one other. The differences in their skulls, Fisher and colleagues suggest, could be the result of variation between mammoth populations separated by centuries and thousands of miles.

But age matters, too. Even though Lyuba died at about 35 days after birth and Khroma perished at around 57 days old, baby mammoths grew quickly. The anatomical differences could reflect differences in age as well as population differences.

If only Lyuba’s skull were better preserved! Khroma’s CT scan showed that the baby mammoth had a brain volume of about 2,300 cm3, a little less than that of modern elephants of about the same age. Such a measurement for Lyuba would have allowed paleontologists to get a rough handle on how mammoth brains changed early in life.

The respiratory tracts of both Lyuba and Khroma were clogged with sediment. Image from the University of Michigan Museum of Paleontology/AMNH.
The respiratory tracts of both Lyuba and Khroma were clogged with sediment. Image from the University of Michigan Museum of Paleontology/AMNH.

The new study didn’t only reveal details of mammoth lives, though. The scans also allowed Fisher and coauthors to get a more refined view of what happened to Lyuba and Khroma.

The sediment inside Lyuba’s respiratory tract included a blue mineral called vivianite. This mineral can form in the oxygen-depleted bottom waters of cold lakes, hinting that Lyuba died in such frigid waters. Additional vivianite formed in other places on her body after she perished, too, but nodules of the mineral on her skull hint at a chilling twist.

In a previous study, Fisher and coauthors suggested that as Lyuba was struggling to breathe, the mammalian “diving reflex” kicked in as a last ditch attempt to get her out of trouble. This would have shut down blood flow to much of the outer surfaces body, with the exception of the head. Sadly, it didn’t work. When Lyuba died, the blood that remained in her head became an iron source for vivianite to grow.

Khroma’s end was different. A previous dissection of her body found milk in her stomach, meaning that she had nursed shortly before her death. No one knows exactly what happened, but the combination of a spinal injury and suffocation hint that the little mammoth was caught in a mud flow or suddenly fell when the bank of a waterway collapsed, breaking her bones and causing the undoubtedly panicked mammoth to suffocate. A tragedy for Khroma and her mother, but an event that, tens of thousands of years later, has given paleontologists a rare understanding of a beast we can no longer see alive.


Fisher, D., Shirley, E., Whalen, C., Calamari, Z. Rountrey, A., Tikhonov, A., Buigues, B., Lacombat, E., Grigoriev, S., Lazarev, P. 2014. X-ray computed tomography of two mammoth calf mummies. Journal of Paleontology. 88, 4: 664-675

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Elephants Hear Age, Gender, Ethnicity in Human Voices

To most people, elephants sound the same. Unless, you’re very experienced, it would be hard to tell the difference between two elephants based solely on their voices. They, however, have no such problems with us.

Karen McComb and Graeme Shannon from the University of Sussex have now shown that wild African elephants can tell the difference between the voices of humans from two ethnic groups, and react accordingly. They can even discriminate between the sounds of men and women, and adults and boys.

This ability matters because, to an elephant, not all humans are equal. They have no quarrel with the agriculturalist Kamba. But they often come into conflict with the cattle-herding Maasai over access to water or land, and they sometimes leave these clashes with a flank full of spears.

Back in 2009, Lucy Bates and Richard Byrne from the University of St Andrews showed that elephants at Kenya’s Amboseli National Park can distinguish between the smell of Maasai and Kamba clothes. If they sniffed eau de Maasai, they were more likely to flee into long grass. They behaved in the same way if they saw the distinctive red colour of Maasai clothes. McComb and Shannon’s study is a sequel of sorts. They showed that elephants can rely on sounds as well as smells to assess the threats they face.

The team recorded 20 Maasai and 15 Kamba saying “Look, look over there, a group of elephants is coming” in their respective languages. They then played these recordings to 48 family groups of Amboseli elephants. The herds obviously couldn’t understand the meaning of the words, but they could tell the difference between the two languages. When they heard the Massai voices, they were much more likely to bunch up into defensive clusters and sniff the air with their trunks. They knew which group was more dangerous.

They also seemed to know which people within the groups pose the greatest threat: they behaved defensively when they heard Maasai men rather than women, and adults rather than boys. “I don’t find this at all surprising, since voice pitch alone enables that distinction,” says Byrne. “But the details that differ between Maasai and Kamba languages are presumably more subtle.”

But when McComb and Shannon altered the Maasai recordings so that the male and female voices had the same pitch, the elephants could still tell them apart. They must have been picking up on some features that are subtler than mere frequency.

Still, that’s not surprising. Elephants are big-brained and extremely intelligent. They communicate with a wide range of sounds. They are long-lived, so they can build up a substantial lifetime of experience, and they live in tightly knit social groups, so youngsters can benefit from the knowledge of their elders. “The surprising thing was just how clued up they were,” says McComb. “They were really able to make these distinctions very well and they rarely got it wrong.”

They can also tailor their responses to different predators. Their main threats are humans and lions. In an earlier study, McComb and Shannon found that elephants can tell the difference between the roars of male and female lions. They react to these roars by forming defensive circles and then noisily mobbing the source of the sound. (Watch them react below.)

But when they heard the Maasai voices, they were much less aggressive. “Coming towards humans with spears would be very detrimental,” McComb deadpans. “They behaved as if they were expecting to see Maasai.” They also went into stealth mode; they only made audible noises 10 percent of the time after hearing Maasai speech, compared to 67 percent after hearing lion roars.

In a related study, Joseph Soltis, who works at Disney’s Animal Kingdom, found that elephants react differently to two distinct threats: talking humans and buzzing bees. Bees can sting elephants in vulnerable places like their eyes or inside their trunks, and elephants are so scared of this that they’ll flee if they hear buzzing.

Soltis’ team showed that Kenyan herds make distinct alarm calls when they hear either humans or bees, and they can modify the tempo and pitch of the calls to show how urgent the threats are. They also react accordingly. When the researchers played the calls back to the elephants, they found that both alarms would prompt the herds to keep watch and run away. But the bee alarm specifically makes them shake their heads, presumably to knock away any nearby stings.

These studies are testament to the keen intelligence, rich social lives, and sophisticated communications of these largest of land animals. As Ferris Jabr beautifully writes, “To look an elephant in the face is to gaze upon genius.”

But the results also speak to the sad history of conflicts between humans and elephants. These conflicts must have played out many times over for the animals to build up enough experience about which humans are the most dangerous.

“The level of spearing has gone down quite considerably in recent years,” says McComb. The Maasai are now partners in Amboseli National Park. They also get compensated if elephants accidentally kill their livestock, which stops them from spearing the animals in retaliation. Still, the sound of Maasai still sets them on edge. This suggests that once at least some members of the family have a bad run-in with humans, the others learn from her and the fear stays in the group.

Still, McComb adds that “elephants are very good at living alongside humans by avoiding dangerous situations. But when we start doing something dramatically different, like a huge increase in poaching or using automatic weapons, they can’t adapt fast enough. That’s when we need to step in and protect them.”

Fritz Vollrath from Oxford University, who was involved in the bee study, adds, “Knowing how elephants perceive their social and physical environments and how the communicate their perceptions between one another will allow us to not only better understand them but also to better protect them in the wild.”

References: McComb, Shannon, Sayialel & Moss. 2014. Elephants can determine ethnicity, gender, and age from acoustic cues in human voices. PNAS

Soltis, King, Douglas-Hamilton, Vollrath & Savage. 2014. African Elephant Alarm Calls Distinguish between Threats from Humans and Bees. PLoS ONE

More on elephant behaviour:

And more from McComb:

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Elephants Can Tell Tiger Growls From Leopard Ones

In southern India, near the Bandipur Reserve, a hungry Asian elephant walks towards a farm in search of food. This region has one of the densest populations of Asian elephants in the world. During the dry season, when food is sparse in the forest, they find the surrounding farmlands irresistible. Conflict between farmers and crop-raiding elephants is a huge problem here. It costs some people a third of their income and, every year, it claims the lives of 400 humans and 100 elephants.

But this particular elephant doesn’t get close enough to farmland to cause a problem. Tripping an infrared beam that’s laid across the path, it triggers a nearby speaker. A low growl emerges, deep and loud. It’s the sound of a tiger, and the elephant knows it. Silently, it retreats.

The recorded growls were set up by Vivek Thuppil and Richard Coss from the University of California, Davis, who have been testing them as ways of diverting elephants from Indian farms. “We’d heard anecdotal reports that elephants are scared of tigers, and that farmers had used playbacks of growls to deter elephants from their fields,” says Thuppil.

They began by recording the growls of a leopard and a tiger at the Bannerghatta Zoological Park. In their paper, they write:

“To engender growling, both cats were agitated similarly when the keeper entered their cages and banged a stick repeatedly. We did not repeat this procedure with other individuals owing to the potential danger involved.”

You don’t say.

The two cats sound very different. Even when equalised, the tiger’s growl is deeper and feels louder, while the leopard is raspier and guttural. “Every human we’ve spoken to says the leopard growl sounds scarier,” says Thuppil.

The elephants clearly think otherwise. When Thuppil and Coss played tiger growls from their hidden speakers, elephants immediately backed away, slowly and quietly.

If they played leopard growls, they trumpeted and grunted, investigated the surrounding area, searched for sounds and smells, and kicked the dirt. Only then did they walk away.

Their reactions are prudent. Tigers are the greater threat, since they’ll occasionally kill elephant calves. Farmers find the body of a half-eaten calf at least once or twice a year, and scientists have found elephant remains in tiger droppings. But leopards are smaller and less powerful and there are no reports anywhere of them killing elephants.

However, the elephants might not be weighing any risks. Thuppil says that tigers will actually growl to deter an approaching elephant, while leopards would just retreat. Their agitated behaviour upon hearing the leopard growl might just be a reaction to something new. Still, they can clearly distinguish between the two types of sounds.

It’s not the most surprising result, given other studies about elephant behaviour. African elephants, especially the older matriarchs, can distinguish the sound of male lions, which pose the greatest threat to their herds. They can also smell the difference between clothes worn by Massai hunters who kill elephants, and Kamba cattle-herders who do not. Clearly, these are intelligent animals that can react in sophisticated ways to different degrees of danger. Still, no one had shown that they can tell the difference between the sounds of two big cats.

The growl playbacks worked to a point, but they weren’t a sustainable solution. “If you have elephants that come back repeatedly, they tend to habituate,” says Thuppil. “They learn that there’s no real threat.” He and Goss are now trying to adapt the playbacks to stop the elephants from getting accustomed to them. “One idea is to have a dynamic playback system, so the location of the sound keeps changing depending on where the elephant is. That would simulate a moving predator rather than a stationary one.”

Some people try to deter crop-raiding elephants by digging deep elephant-proof trenches, but rain can often transform these into gentle-sloping dips. Electric fences are commonly used, but elephants can destroy these with their tusks or by pushing trees onto the fences. Some farmers sit in tree platforms and harass the elephants with drums, shouts, torches, flashlights, or fireworks, but the agitated animals can sometimes run amok.

The imperfect nature of these solutions has prompted conservationists to search for alternatives. In Africa, Lucy King from the charity Save the Elephants has been using beehive fences to deter the giants. African elephants might stand up to lions, but bees can sting them in their eyes, behind their ears and inside their trunks. If they hear buzzing, they will flee. As a bonus, the fences also provide local people with a source of income: Elephant-Friendly Honey. You can find out more about King’s project here.

Reference: Thuppil & Coss. 2013. Wild Asian elephants distinguish aggressive tiger and leopard growls according to perceived danger. Biol Lett

Thuppil & Coss. 2012. Using Threatening Sounds as a Conservation Tool: Evolutionary Bases for Managing Human–Elephant Conflict in India. Journal of International Wildlife Law and Policy

Bronze Art Sparks Debate Over the Extinction of the Straight-Tusked Elephant

Today’s elephants are the ragged threads of what was once a greater blanket of proboscidean diversity. The mammoths, mastodons, and dwarfed island elephants of just a few thousand years ago are all gone, leaving only the African bush elephant, African forest elephant, and Asian elephant. But prehistory’s pachyderms didn’t slip away in lock step. It is not as if all archaic elephants everywhere keeled over at the exact same moment, ushering out the Pleistocene and marking the start of our present Holocene era.

Many of the lost elephants disappeared by about 10,000 years ago, while some of the isolated island mammoths persisted until about 4,000 years ago, spanning the gap between wild prehistory and the modern world. A group of Chinese scientists has even proposed that a kind of archaic, straight-tusked elephant survived until 3,000 years ago in northern China, but their controversial proposal does not convince fossil elephant experts.


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Will we ever clone a mammoth?

Here’s the eighth piece from my BBC column

Tens of thousands of years ago, woolly mammoths roamed the northern hemisphere. These giant beasts may now be extinct, but some of their bodies still remain in the frozen Arctic wilderness. Several dozen such carcasses have now been found, and some are in extremely good condition. Scientists have used these remains to discover much about how the mammoth lived and died, and even to sequence most of its genome. But can they also bring the animal back from the dead? Will the woolly mammoth walk again?

Akira Iritani certainly seems to think so. The 84-year-old reproductive biologist has been trying to clone a mammoth for at least a decade, with a team of Japanese and Russian scientists. They have tried to use tissues from several frozen Siberian specimens including, most recently, a well-preserved thighbone. Last year, Iritani told reporters, “I think we have a reasonable chance of success and a healthy mammoth could be born in four or five years.”

A few months ago, a second team led by Korean scientist Hwang Woo Suk also expressed interest in cloning a mammoth. While Iritani comes with impressive credentials, Hwang’s resume is less reassuring. He is perhaps best known for faking experiments in which he claimed to have cloned the first human embryo and produced stem cells from it. The fact that he has confessed to buying mammoth samples from the Russian mafia does not help to instil confidence.

Regardless of their pedigree, both teams have their work cut out. Any attempt to resurrect the mammoth faces an elephantine gauntlet of challenges, including the DNA-shattering effects of frost and time, and the rather unhelpful reproductive tract of the eventual surrogate parent—the elephant.


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Huge set of fossil tracks preserves march of the ancient elephants

In the desert of the United Arab Emirates, there is an unusual series of flat discs imprinted in the sand.  Each one is about 40 centimetres wide, and they snake off into the distance in several parallel lines, for hundreds of metres.

They are tracks. They were made by a herd of at least 14 early elephants, marching across the land between 6 and 8 million years ago. The track-makers are long dead, but in the intervening time, nothing has buried their tracks or eroded them away. Today, their social lives are still recorded in their fossilised footsteps.


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Meet the owner of the world’s largest collection of frozen elephant feet

It turns out that elephants have a sixth toe. They’ve adapted one of their wrist bones into a strut that supports their giant squishy feet. I wrote about this for Nature (excerpt below), but here’s my full interview with John Hutchinson, the man behind the discovery, and the owner of (probably) the world’s largest collection of frozen elephant feet.

Elephants walk on the world’s biggest platform shoes. Now, John Hutchinson at the Royal Veterinary College in London and his team have found that their footwear also contains hidden stiletto heels.

Even though an elephant’s leg looks like a solid column, it actually stands on tip-toe like a horse or a dog. Its heel rests on a large pad of fat that gives it a flat-footed appearance. The pad hides a sixth toe — a backward-pointing strut that evolved from one of their sesamoids, a set of small tendon-anchoring bones in the animal’s ankle.

This extra digit, between 5 and 10 centimetres long, had been dismissed as an irrelevant piece of cartilage. Almost 300 years after it was first described, Hutchinson finally confirmed that it is a true bone that supports the squishy back of the elephant’s foot. The ones on the hindfeet even seem to have joints.


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Early hunters killed mastodons with mastodons (Also, you can chuck a bone spear through a car. Who knew?)

To round off my brief stint at the Guardian, here’s a piece about a mastodon specimen with what looks like a spear-tip stuck in its rib. This specimen, the so-called “Manis mastodon” has been a source of controversy for several decades. Is that fragment man-made or simply one of the animal’s own bone splinters? Does it imply that humans hunted large mammals hundreds of years earlier than expected, or not?

Having re-analysed the rib in an “industrial-grade” CT scanner, Michael Waters thinks it’s definitely a man-made projectile. He even extracted DNA from the rib and the fragment and found that both belonged to mastodons. So these early hunters were killing mastodons and turning them into weapons for killing more mastodons. How poetically gittish.

Anyway, read the piece for more about why this matters. In the meantime, I want to draw your attention to this delicious tete-a-tete at the end between Waters and Gary Haynes, who doesn’t buy the interpretation. Note, in particular, the very last bit from Waters, which made my jaw drop.

But despite Waters’ efforts, the fragment in the Manis mastodon’s rib is still stoking debate. “It’s not definitely proven that it is a projectile point,” says Prof Gary Haynes from the University of Nevada, Reno. “Elephants today push each other all the time and break each other’s rib so it could be a bone splinter that the animal just rolled on.”

Waters does not credit this alternative hypothesis. “Ludicrous what-if stories are being made up to explain something people don’t want to believe,” he says. “We took the specimen to a bone pathologist, showed him the CT scans, and asked if there was any way it could be an internal injury. He said absolutely not.”

Waters adds, “If you break a bone, a splinter isn’t going to magically rotate its way through a muscle and inject itself into your rib bone. Something needed to come at this thing with a lot of force to get it into the rib.”

The spear-thrower must have had a powerful arm, for tThe fragment would have punctured through hair, skin and up to 30 centimetres of mastodon muscle. “A bone projectile point is a really lethal weapon,” says Waters. “It’s sharpened to a needle point and little greater than the diameter of a pencil. It’s like a bullet. It’s designed to get deep into the elephant and hit a vital organ.” He adds, “I’ve seen these thrown through old cars.”

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Older elephants know the best anti-lion moves

In natural history films, lionesses are usually portrayed as the hunters of the pride, while male lions mope around under shady trees. But males are no layabouts – they’re effective killers in their own right, particularly when they target larger prey like elephants and buffalo. Aside from humans, lions are the only predators powerful enough to kill an elephant. The males, being 50% heavier than the females, are especially suited to the task. It typically takes seven lionesses to kill an elephant, but just two males could do the same.

Even a single male can overpower a young elephant. Between 1994 and 1997, Dereck Joubert found that the lions of Botswana’s Chobe National Park were getting better and better at hunting elephants. He wrote: “In one notable case, a single male lion ran at nearly full speed into the side of a 6-year-old male calf with sufficient force to collapse the elephant on its side.”

Male lions clearly pose a great threat, and older elephants know it. Karen McComb from the University of Sussex has found that older matriarchs – the females who lead elephant herds – are more aware of the threat posed by male lions. If they hear recordings of male roars, they’re more likely to usher their herd into a defensive formation. Their experience and leadership could save their followers’ lives. “Family units led by older matriarchs are going to be in a position to make better decisions about predatory threats, which is likely to enhance the fitness of individuals within the group,” says McComb.


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Elephants give each other a helping trunk

In Lampang, Thailand, two elephants have a problem. They’ve walked into adjacent paddocks separated by a fence. In front of them is a sliding table with two food bowls, but it’s out of reach and the way is barred by a stiff net. A rope has been looped around the table and one end snakes into each of the paddocks. If either jumbo tugs on the rope individually, the entire length will simply whip round into its paddock, depriving both of them of food. This job requires teamwork.

And the elephants know it. Joshua Plotnik from Emory University has shown that when confronted by this challenge, elephants learn to coordinate with their partners. They eventually pull on the rope ends together to drag the table towards them. They even knew to wait for their partner if they were a little late. It’s yet more evidence that these giant animals have keen intellects that rival those of chimps and other mental heavyweights.


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Threatened by elephants? Try recruiting ants


It’s a classic David and Goliath story, except there are 90,000 Davids and they all have stings. On the African plains, the whistling-thorn acacia tree protects itself against the mightiest of savannah animals – elephants – by recruiting some of the tiniest – ants.

Elephants are strong enough to bulldoze entire trees and you might think that there can be no defence against such brute strength. But an elephant’s large size and tough hide afford little protection from a mass attack by tiny ants. These defenders can bite and sting the thinnest layers of skin, the eyes, and even the inside of the sensitive trunk. Jacob Goheen and Todd Palmer from Kenya’s Mpala Research Centre have found that ants are such a potent deterrent that their presence on a tree is enough to put off an elephant.


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Elephants and humans evolved similar solutions to problems of gas-guzzling brains

At first glance, the African elephant doesn’t look like it has much in common with us humans. We support around 70-80 kg of weight on two legs, while it carries around four to six tonnes on four. We grasp objects with opposable thumbs, while it uses its trunk. We need axes and chainsaws to knock down a tree, but it can just use its head. Yet among these differences, there is common ground. We’re both long-lived animals with rich social lives. And we have very, very large brains (well, mostly).

But all that intelligence doesn’t come cheaply. Large brains are gas-guzzling organs and they need a lot of energy. Faced with similarly pressing fuel demands, humans and elephants have developed similar adaptations in a set of genes used in our mitochondria – small power plants that supply energy to our cells. The genes in question are “aerobic energy metabolism (AEM)” genes – they govern how the mitochondria metabolise nutrients in food, in the presence of oxygen.

We already knew that the evolution of AEM genes has accelerated greatly since our ancestors split away from those of other monkeys and apes. While other mutations were reshaping our brain and nervous system, these altered AEM genes helped to provide our growing cortex with much-needed energy.

Now, Morris Goodman from Wayne State University has found evidence that the same thing happened in the evolution of modern elephants. It’s a good thing too – our brain accounts for a fifth of our total demand for oxygen but the elephant’s brain is even more demanding. It’s the largest of any land mammal, it’s four times the size of our own and it requires four times as much oxygen.

Goodman was only recently furnished with the tools that made his discovery possible – the full genome sequences of a number of oddball mammals, including the lesser hedgehog tenrec (Echinops telfairi). As its name suggests, the tenrec looks like a hedgehog, but it’s actually more closely related to elephants. Both species belong to a major group of mammals called the afrotherians, which also include aardvarks and manatees.

Goodman compared the genomes of 15 species including humans, elephants, tenrecs and eight other mammals and looked for genetic signatures of adaptive evolution. The genetic code is such as that a gene can accumulate many changes that don’t actually affect the structure of the protein it encodes. These are called “synonymous mutations” and they are effectively silent. Some genetic changes do, however, alter protein structure and these “non-synonymous mutations” are more significant and more dramatic, for even small tweaks to a protein’s shape can greatly alter its effectiveness. A high ratio of non-synonymous mutations compared to synonymous ones is a telltale sign that a gene has been the target of natural selection.

And sure enough, elephants have more than twice as many genes with high ratios of non-synonymous mutations to synonymous ones than tenrecs do, particularly among the AEM genes used in the mitochondria. In the same way, humans have more of such genes compared to mice (which are as closely related to us, as tenrecs are to elephants). 

These changes have taken place against a background of less mutation, not more. Our lineage, and that of elephants, has seen slower rates of evolution among protein-coding genes, probably due to the fact that the duration of our lives and generations have increased. Goodman speculates that with lower mutation rates, we’d be less prone to developing costly faults in our DNA every time it was copied anew.

Overall, his conclusion was clear – in the animals with larger brains, a suite of AEM genes had gone through an accelerated burst of evolution compared to our mini-brained cousins. Six of our AEM genes that appear to have been strongly shaped by natural selection even have elephant counterparts that have gone through the same process.

Of course, humans and elephants are much larger than mice and tenrecs. But our genetic legacy isn’t just a reflection of our bigger size, for Goodman confirmed that AEM genes hadn’t gone through a similar evolutionary spurt in animals like cows and dogs.

Goodman’s next challenge is to see what difference the substituted amino acids would have made to us and elephants and whether they make our brains more efficient at producing aerobic energy. He also wants to better understand the specific genes that have been shaped the convergent evolution of human and elephant brains over the course of evolution. That task should certainly become easier as more and more mammal genomes are published.

Reference: PNAS doi:10.1073/pnas.0911239106

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South African wildlife – Wait, that’s not a trunk…


This is a bull elephant firmly establishing why it is he, and not the lion, who is king of beasts. The elephant’s penis is not only massive but prehensile. As we watched in baffled amusement (and the faintest tinge of inadequacy), he used his penis to prop himself up (as in the photo), swat flies from his side and scratch himself on his stomach. David Attenborough never showed us that…

There’s good reason for elephants to have prehensile penises. It’s hard enough for a six-tonne animal to get into the right position for sex, let alone having to do the rhythmic thrusting that’s required. So he let’s his penis do all the work for him.

You’ll also note the dark stain behind his eye – that’s a leak from his temporal gland. It means that this male was entering musth, the period when their testosterone shoots through the roof and they get incredibly horny and aggressive. We tried to drive round this male and he basically charged us. Tramply doom was averted by our driver who slammed his palm against the car door as hard as he could. The elephant stopped and huffed and puffed. We did our best to not soil ourselves.


This picture gives you an idea of how close he was. After a seemingly infinite standstill, he moved aside, extended his enormous penis and had a wee. It’s amazing how terror can convert into comedy so quickly…