A History of the Honey Badger

Traditionally the weasel family was divided into three subfamilies: the otters, the skunks, and everything else. Sometimes the badgers were added as a fourth subfamily, but that was about it. As more modern genetic analysis came along, showing us some of the underlying relationships that weren't apparent from anatomy alone, it became clear that things were a good deal more complicated than that, and we now recognise about eight subfamilies of mustelid. (And that's not counting the skunks, which turned out to belong to a different group).

The badgers, in particular, turned out to be more varied in their origins than we had previously thought. Their superficial similarities were due to them all having evolved to be heavily-built digging animals, rather than because they all shared one single ancestor. In particular, two kinds of badger, the American and honey badgers, are now recognised as representing their own distinct subfamilies, with just one living species each, and diverging from the other "weasels" very early on - probably before the "true" badgers of Eurasia had first appeared.

Miocene (Pt 17): A Diversity of Dogs

Eucyon

As North America dried out in the Late Miocene, and slowly transitioned towards the deserts and open grasslands that became dominant across the central parts of the continent, it wasn't just the herbivores that were forced to adapt. Carnivores may not have been affected so directly, but, if their food source was changing, they had to do so too.

There were two particularly significant changes among the North American mammalian carnivores that took place around this time. One was the extinction of the bear-dogs, a group with a long history on the continent that was, by this time, typified by relatively large animals that would have looked more like bears than dogs (although they were neither). Over in Europe and Asia, the bear-dogs survived for rather longer, although even there they struggled...  but in North America, the changes were too extreme for them to cope with, and they died out as the Late Miocene dawned.

Miocene (Pt 13): The Time of No Cats

Aelurodon

Today, there are a number of native cat species in America. The North has its bobcats, lynxes, and puma/cougar/mountain lions while, further south, there are even more species (ocelots and jaguars being merely the most obvious). At the dawn of the Miocene, 23 million years ago, however, it was a somewhat different story.

While there was nothing similar in the south, there had been plenty of cat-like animals on the northern continent before. True, they had not literally been cats, but rather nimravids, a group of remarkably cat-like animals that lived long before actual cats existed. The climatic changes of the Early Miocene seem not have suited them, however, and almost died out as the new epoch dawned. It's possible that one, Dinictis, a bobcat-sized sabretooth, did manage to struggle on for a few million years, but even that is debatable. But, otherwise, while their relatives, the barbourofelids, continued on in Europe, to eventually be replaced by actual cats, in North America... there was nothing.

The Giant Chinese Badger-Otter

Otters and badgers are both members of the weasel family, the Mustelidae. As a result, while they are visibly quite different, they have a number of anatomical similarities, reflecting their shared ancestry. Indeed, some of the similarities, such as those in the precise shape of their teeth, are rather greater than one might expect simply from them belonging to the same family. On the basis of this, it was being suggested as recently as the 1990s that otters were essentially aquatic badgers - descendants of early badger species that had entered the water, developing webbed feet, a long muscular tail, and so on, in the process.

We now know, from various genetic and molecular studies, that this isn't so. The closest living relatives of otters are probably the weasels themselves and/or the zorillas and their kin, with badgers representing a rather earlier branch in the mustelid family tree. Given this, the apparent strong similarities between the two are either a case of parallel evolution, perhaps due to the fact that, by the standards of weasels, they're both fairly large animals, or, perhaps more likely, that they are ancient features of the group that happen to have been lost in their other relatives.

The Largest Weasel Ever?

The weasel family were the first group of mammals that I decided to spend a year describing in detail on this blog, back in 2011-12. I concluded the series with a look at their fossil history, stating, among other things, that the fossil genus Enhydrodion "may" have been the largest member of the family to have lived. This, however, relies on guesswork relating the size of the body of the animal to its skull, which is all we have in any completeness. But there are, in fact a number of other fossil members of the family with even larger skulls, so a lot rests on their exact bodily proportions, which are often a mystery.

Such examples include the giant wolverine Plesiogulo (for which we have not only the skull, but, just possibly, the penis bone), the giant hypercarnivorous honey badger Eomellivora, and the relatively long-legged Ekorus, whose relationship to other mustelids is unclear. But, according to a new analysis, the largest mustelid skull known belongs to an animal called Megalictis ferox.

Of course, calling Megalictis a "weasel" is a bit of a stretch. The weasel family is very diverse, including such animals as otters, badgers, and wolverines, as well as more obvious examples such as polecats and stoats. So, yes, it's really only a weasel in the same sense that a badger is... and that's assuming it's a member of the weasel family at all. So, let's start with that - what is this animal, and is it really a mustelid?

Teeth of the Giant Honey Badger

Skeleton of a modern honey badger

Honey badgers (Mellivora capensis) have something of a reputation as particularly fierce animals. As is often the case, the reputation is somewhat exaggerated, but it isn't entirely false, either, and they are rather more purely carnivorous than the European badgers of Hufflepuff fame. They are, of course, members of the weasel family, on which I have posted at some length before, and, these days, are usually considered distinct enough to warrant their own subfamily within that group.

According to one study of the evolutionary relationships between mustelids, honey badgers represent one of the earliest branches of the weasel family tree. Assuming a relatively constant rate of genetic change between species after they diverge, and calibrating with the ages of some known fossils, the same study estimated that they should have first appeared about 11 million years ago, during the mid Miocene epoch, and probably in Asia. Naturally, for most of that time, they would not have been the same species that they are today, something that likely arrived much later - it's just that none of their closer relatives survived until the present day.

What Does the Otter Say?

Animals use a variety of different means to communicate with one another. For we humans, speech is the primary means of communication, but even we also have body language as a useful adjunct. (And writing, of course, although that's arguably just a representation of speech, and it's not, that we know of, something our species has always done). For other mammals, scent is usually at least as important.

The human sense of smell is pretty rubbish, by broader mammalian standards, but for those species where it functions effectively, scent can be an effective and useful means of communication. All you have to do is urinate on a lamppost or do what bears do in the woods, and you've left a long-lasting message that conveys all sorts of handy information to anyone who comes by later. But, on the other hand, it does have its limitations. In particular, it's not much good for rapid signalling, such as alarm calls. So, while we may be the only species to "speak" (in the sense of having complex syntactical rules), it's not surprising that we aren't the only ones to make vocalisations.

Having said that, unless you're a whale, vocal calls are really only useful for communicating with other animals that are at least in your general vicinity. As such, they're much less useful to animals that don't lead rich social lives. If you live all your life on your own, then it may be that the only sound you need to make is something to warn off intruders, and perhaps a little something for the breeding season. Apart from that, scent may well be sufficient to meet your needs.

Q&A 2012

This is a synapsid, and not a reptile. Yes, really.

This will be the last post at Synapsida before the New Year, so I thought I'd do something a little different this time. A lot of the hits on this blog are from Google searches, with a few from similar services like Bing. Often, the searches that bring people here are questions, and the blogger.com interface lets me see what those questions were. I don't check it religiously, so I'm sure there must be many questions that brought people here that I've never seen. But, just for fun, this week I'm going to answer some of the ones I have seen.

It's not going to help the people who asked the questions in the first place, of course. And, if anyone asks the question again, there's no guarantee they'll be directed to this page, rather than wherever they were directed before. But what the heck - why not, right?

So without more ado:

Is [X] a Synapsid?

This seems to be among the top two or three questions that bring people to the site. Is a cow a synapsid? Is a tiger a synapsid? What about a monkey? Or a kangaroo? And so on.

Weasels in Stone: Mustelid Evolution

Sthenictis, a fossil mustelid

Last September, I began a survey of the weasel family, the largest, and arguably the most varied, family of carnivorous mammals. Since then, I have managed to give at least a brief description of every living species in the family, from stoats and badgers to otters and wolverines. But how do all these animals relate to one another, and where did they come from?

In the past, scientists would work this out by examining the physical features of animals, reasoning that those with the greatest similarity were the most likely to be related. By adding in information gleaned from fossils. such as their age and location, and any evolutionary changes they may have undergone, it's possible to get quite a lot of information this way. However, today, it is more common to use molecular and genetic information, seeing how genes and the proteins they produce have changed in subtle, often invisible ways, over the course of time. Taken together with the fossil information, this can reveal many relationships that might otherwise remain obscure.

In the very first attempt at scientific classification of animals, way back in 1735, weasels were grouped together with martens, polecats, and civets as a sort of collective group of small slender mammalian carnivores, although otters and badgers were placed separately.  However, it was not until 1817 that the weasel family was formally named by German naturalist Johann Gotthelf Fischer von Waldeheim. That, of course, was still before we understood evolution, and it's hardly surprising that we've moved on since then.

Weasels of Mystery: the Ferret-Badgers

Chinese ferret-badger

So far, in my survey of the weasel family, I have covered a number of familiar species: stoats, badgers, and otters, among many others. There have also been a few species probably less familiar to those of us in the west, such as zorillas, grisons, and tayras. But the least studied of all belong to the last subfamily I have to cover: the ferret-badgers.

Ferret-badgers are, of course, neither ferrets nor badgers, but entirely their own group. As the English name implies, they have features some way between the two animals for which they are named, although they are distinct in a number of ways, too. Their total body length is not far off that of a ferret, but they have the stocky build of a badger, and so somewhat resemble a smaller, slimmer, version of that animal. Proportionally, though, their tail is longer than that of a badger, and they have a narrower, more pointed snout. They have greyish or brownish fur over most of the body, which, again, looks quite badger-like, and black-and-white markings on the face.

However, these markings are not the clear stripes of a badger, although they aren't really the 'mask' pattern found on ferrets, either. One distinctive feature of the markings is a white stripe running from the forehead down over at least the neck, and often further down the middle of the back. American badgers have something similar, but it's often more striking in the ferret-badgers. Like many other members of the weasel family, the creatures are said to have a strong odour, and they're also quite fierce, so it could be that the highly visible markings serve as a warning to other animals.

Weasels on the Savannah: Zorillas and their kin

Saharan striped polecat

Even before we had good molecular and genetic evidence for how the various members of the weasel family were related to each other, there were a number of different schemes proposed for dividing up the family into smaller groups. Otters were almost universally agreed to be something different from the other weasels, and, in the simplest scheme, everything that wasn't an otter was considered a "musteline". Once the genetic information arrived, it wasn't a terribly great surprise to learn that the martens were a group, the 'true' badgers were a group, and so on. Removing badgers, martens, and the like, meant that the term 'musteline' now referred only to the weasels themselves, and their closest relatives: stoats, polecats, and mink.

What was rather more surprising though, was that one group of what seemed to be quite clearly weasel-like animals actually constituted an entirely separate branch of the family tree. Mostly living in the southern hemisphere, it had not really been obvious before that these animals were especially closely related to one another. Because of that, unlike badgers, otters, and martens, they had no collective name in English. The scientific term for members of this group is "galictines", and that remains the best word we have for them.

Weasels Digging Holes: American and Honey Badgers

American badger

It was thought at one time that the various species of badger were fairly close relatives within the weasel family. More recent genetic evidence has shown us that that's not the case, and that there is more to their story than one might guess from simply looking at them. While the majority of badgers do indeed belong to a single, related, group - what we might call the "true" badgers - there are some exceptions.

In fact, the badger body plan and lifestyle appear to have evolved at least three times within the weasel family. One instance led to the "true" badgers, with at least four species, and possibly more not yet formally recognised. The other two are no more closely related to the "true" badgers, or even each other, than they are to, say, otters or stoats. In each case, only one member of the lineage survives today, giving us two "subfamilies" with just one living species each.

Of the two, the better known is surely the American badger (Taxidea taxus). Despite being as genetically distant from the European badger as its possible to be without belonging to an entirely different family, it's really not hard to see why early American colonists chose to give it the same name as the animal they were already familiar with. In addition to the short limbs typical of all members of the weasel family, it has a compact, muscular body, wedge-shaped head, and powerful digging claws. That's not really so surprising, when you consider that there are only so many ways to modify the body of a weasel to make it into an effective digger.

Weasels in Burrows: the 'True' Badgers

European badger

The word 'badger' has been applied to a number of species of stocky, moderately sized, members of the weasel family, that are not necessarily all closely related to one another. That's not due to any sort of carelessness with the names, because, for a long time, it was thought that they were closely related.

It's hardly an unreasonable conclusion, because they do look strikingly similar to one another, even to the extent of having similar coat markings. Modern genetic analysis, however, has shown that they are rather more different from one another than appears at first glance. Indeed, one group of 'badgers' - the stink badgers - turned out not to belong to the weasel family at all, but, instead, to the skunk family.

The stink badgers are obviously beyond the scope of this series on mustelids, but the various other species are not. The remaining badgers, however, still do not constitute a single group within the weasel family, as was once thought. That's because they don't have a single ancestor from which all other badgers - and crucially, nothing but badgers - are descended. All badgers are related, because everything is related, if only you go back far enough, but they're often more closely related to other animals than they are to each other.

Weasels at Sea: Sea and Giant Otters

Sea otter mother with pup

Most otters are considered to be 'semi-aquatic' animals. That is, they spend most of their time swimming in rivers or lakes, where they catch the great majority of their food, but they return to dens on the bank in order to sleep and raise their young. However, there is one exception: an otter that is fully aquatic, and is, in fact, the only truly aquatic mammal to have feet, rather than flippers - all the others are seals, whales, dolphins, and the like. This is the sea otter (Enhydra lutris).

Most other otter species will enter salt water on occasion, especially if they live on small islands where fresh water is scarce. The marine otter is unusual in that it habitually hunts at sea, and only occasionally enters rivers, but it still creates dens along the shoreline, and so is considered only semi-aquatic. Generally when otters do swim in the sea, they avoid water that's any deeper than most rivers, and even marine otters won't venture more than about 150 metres (500 feet) offshore. Not so the sea otter.

Sea otters live along the coasts of the northern Pacific. In the south, they reach as far as California, and once even reached the west coast of Mexico, but the majority are now found off the southern coast of Alaska, and there are also sea otters along the coasts of far eastern Siberia and the extreme north of Japan. They are not close relatives of the other American otters (Lontra spp.), but are instead later arrivals on that continent, closer in origin to the various Old World species.

Weasels in Warm Rivers: Otters of the Tropics and the South

Hairy-nosed otter

The body plan of otters is evidently a successful one in evolutionary terms. While the two species of "common otter" are the only ones inhabiting the rivers of the northern temperate zone, there are at least ten species in other parts of the world, and most of them look remarkably similar. They all have long, sinuous, bodies with short legs and webbed feet. Their tails, quite unlike the slender or stumpy appendages of other members of the weasel family, are powerful and muscular, and somewhat flattened to better help propel them through the water when swimming. Their fur is dense and, in most cases, short and sleek.

Furthermore, they are all more or less the same colour. Otters, of all species, are brown over most of their body, and they usually have paler underparts with a particularly noticeable patch of pale fur on the chest, which may extend up onto the chin. Compared with the variety of weasels, or even martens, the visible differences between most species of otter can be subtle, and it's hard tell them some of them apart.

The closest living relative of the familiar Eurasian otter is the hairy-nosed otter (Lutra sumatrana) of South East Asia and western Indonesia; the two species probably diverged during the early Ice Ages. It is also a highly endangered species, and, combined with its remote jungle location, that means we know relatively little about it. This story of threats to otters is, sadly, one I'll come back to a lot in this post. Of all the members of the weasel family, the otters are the ones most at risk, probably because their riverine habitat makes them particularly susceptible to pollution, and may also make them easier to hunt for their valuable fur.

Weasels in Cool Rivers: The Common Otters

Eurasian otter

The otters are, arguably, the least weasel-like of all the members of the weasel family. Although the relationship has been clear for a long time - the first scientific description of an otter, by Linnaeus in 1758, actually placed it in the genus Mustela, to which stoats and weasels belong - so have the differences. As early as 1771, Danish zoologist Morten Thrane Brünnich split them off from their fellow mustelids, erecting the new genus Lutra to describe them.

By 1838, at least three genera of otter had been described, and the group were raised to 'subfamily' status to distinguish them from their terrestrial kin. Other subfamilies were erected later, largely to distinguish the badgers, but the otters have remained as a clearly distinct group within the overall weasel family.

Genetic studies in the last four years have given us a much clearer picture of how the various kinds of mustelid are related to one another, and it turns out to be more complicated than we thought. For example, martens turn out to have been around longer than otters have, which was something of a surprise. The otters, however, survived the revision unscathed, confirmed as a genuine evolutionary group, albeit one that is younger than we might have guessed. Their closest relatives within the family turn out to be the mustelines, the group that, among others, includes the semi-aquatic mink.

Weasels in the Tundra and the Jungle: Wolverines and Tayras

The largest terrestrial member of the weasel family is the wolverine (Gulo gulo). Indeed, by the standards of weasels, it's exceptionally large, around twice the weight of badgers, and about three feet long, not counting the tail. Within the weasel family, it belongs to the same evolutionary branch as the pine martens and their kin, and, size aside, that is apparent in its appearance.

Compared with martens, however, the wolverine is not only larger, but stockier, and much of its weight - three times that of the next largest marten-like animal, the fisher - is muscle. Indeed, they may well be the most physically powerful of all mammals in their size range. Other martens vary in the degree to which they live in the trees, but wolverines are the most terrestrial of them all, although they remain capable of climbing trees when the need arises. Compared with other marten-like animals, they have flat-soled feet, which are large and furry, making them ideal for running on snow. They also lack the pale 'bib' commonly seen on the throat of martens, although there is generally a band of paler fur running across their flanks to the base of the tail. Their fur is also exceptionally thick, which makes them look even larger than they are.

More Weasels up Trees: Sables and Other Martens

Sable

Today, true pine martens venture no further east than the Ural Mountains. But it was not always so, for, at one time, their immediate ancestors ranged across a wider swathe of forest. During the Ice Ages, those in the east became separated from their western cousins, and became a distinct species. Today, beyond the Urals we find, not pine martens, but their close relatives, the sables (Martes zibellina).

Indeed, sables and pine martens still look very similar, although the former have shorter tails, and the 'bib' on their chests is usually less distinct, varying from pale brown to yellowish. Their fur is rich and luxurious, especially during the winter months, and can be anything from pale brown to the near-black colour for which they are most famous. Largely on the basis of this variation in colour, up to thirty different subspecies have been identified, although, personally, I suspect that the animal is just rather variable in appearance, and many of these subspecies won't turn out to be valid under more thorough investigation.

Like pine martens, sables inhabit both deciduous and coniferous forest, although they prefer the latter. They were once found across the vast forests of Siberia, into Mongolia and northern China, and, even today, they inhabit the islands of Hokkaido and Sakhalin either side of the Japanese/Russian border. They can, of course, climb trees, but they seem to do so less than pine martens do, and they make their homes in underground burrows, sometimes of considerable length, with entrances partially concealed beneath tree roots or similar cover.

Weasels up Trees: Pine and Beech Martens

Pine marten

In my survey of the weasel family, I have so far looked at the mustelines; those members of the family that are most closely related to the weasels themselves. Aside from the numerous kinds of "true" weasel, this has included stoats, polecats, and mink, but, of course, the mustelines are not the only members of the weasel family. It is now time to turn to a second grouping within the family, the marten-like animals.

The oldest fossil martens date from the Pliocene; the epoch immediately before the great Pleistocene Ice Ages. By this time, they had already begun to develop some of their distinctive features. Martens are much larger than true weasels, and within, or slightly above, the size range of the largest mustelines, the European polecats. Where mustelines have evolved narrow bodies for chasing prey down into their burrows, the martens have never needed to do so, and while they have the short legs typical of most members of the family, their bodies are noticeably more compact. They are generally brown in colour, and most species have a highly visible 'bib' of paler - usually yellowish - fur on their chest.

The most distinctive feature of the martens is that they spend much of their lives in the trees, quite a different habitat from other members of the family. By heading up into the trees, they have been able to find a source of food quite away from their ground-dwelling kin, and over much of their range (although by no means all), they are the only small carnivores that hunt among the branches.

Weasels, Weasels, Everywhere

Long-tailed weasel

The most successful body plan within the weasel family has been that for which it is best known: the small, slender, agile carnivore that feeds on prey too small for larger predators to bother with. In Europe and Canada, the best known such animals are probably common weasels and stoats, both remarkably widespread animals across the temperate regions of the northern hemisphere. But, of course, they are far from alone, just two among a total of fourteen currently recognised species of what, for lack of a better term, we can call "true weasels".

In North America, common (or "least") weasels and stoats are found in Canada and in the northwestern and northeastern corners of the US; they generally do not venture into warmer climes, as they do in many parts of Europe and Asia. That's because, in America, there is another species of weasel better adapted to those regions. This is the long-tailed weasel (Mustela frenata), and it, not the common weasel, is the one best known in most parts of the USA.