Saturday 29 May 2021

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.

Sunday 23 May 2021

Out of Your Hole

Many animals dig burrows. They can be used for shelter when sleeping, or as a safe place to raise young and, while they may take more effort to construct than finding a natural rock crevice or hiding beneath a log, it's often worth it. Especially if you happen to live in an environment - open grassy plains, for example, where such alternatives are hard to come by. Although, admittedly, this does tend to apply only if the animal in question is small; not only would it take more effort for a large animal to dig a burrow, there's less that's likely to eat it, and it would be harder to hide the entrance anyway.

But some small mammals go further than merely digging burrows to sleep in. They spend almost their entire lives underground, being able to feed off earthworms, roots, and the like. It's a peculiar environment to live in, entirely lacking in light, and requiring constant work to maintain, as well as often being low in oxygen. But it is undeniably safe, not just from most predators, but also from inclement weather (so long as you're not somewhere that's prone to flooding). 

Sunday 16 May 2021

All the World's Deer: Endangered and Beyond

Eld's deer
A significant number of deer species are endangered. As primarily forest-dwelling animals they are particularly vulnerable to habitat loss, especially in those parts of the world with high human population density and intensive agriculture. Indeed, of the species of deer formally listed as endangered by the IUCN, all but one live in southern and eastern Asia.

Among these is Eld's deer (Panolia eldii), first described by Percy Eld, a British officer working for the Commissioner of Assam, and then more formally written up by army doctor John McClelland in 1842. There is some dispute about the correct scientific name of the animal, due to a number of conflicting studies about where exactly it fits in the deer family tree. It was originally placed in the genus Cervus, along with red deer, but that didn't mean much at the time, since it was 17 years before the theory of natural selection, let alone modern phylogeny. 

Sunday 9 May 2021

Miocene (Pt 26): Planet of the Monkeys

The primates are one of the major mammalian orders alive today, with a great many species spread across three continents: Africa, Eurasia, and South America. They have an ancient history, and, even by the dawn of the Miocene, were already divided into the two main groups we have today: the prosimians and the anthropoid primates (most of which are monkeys, or 'simians').

It's probably fair to say that most scientific attention has been paid to the latter of those groups, but we do have a number of fossil prosimians from the Miocene. Madagascar, where most prosimian species are found today, was already an island, and had been since the time of the dinosaurs, but there are few known fossils of the relevant age there to tell us much about the early history of lemurs and their kin. Nonetheless, during the Miocene, prosimians were more widely spread than they are today. 

Sunday 2 May 2021

Mammals That Sense Magnetism

Traditionally, there are said to be five senses: vision, hearing, taste, smell, and touch. From a modern scientific viewpoint, however, this is clearly a significant underestimate, since things are rather more complicated than that.

How many senses even a human can be said to have is a matter of definition, although it's generally agreed to be more than five. An extreme way of counting would be to consider every specific type of sensory cell as representing one 'sense'. This, however, results in the conclusion that vision is four separate senses: one for black-and-white (the rod cells) and one each for the primary colours (the cone cells). This, it's probably fair to say, is not something that's widely considered helpful - although it may well be useful to neurobiologists.

If we don't go that far, then, we can still consider vision, hearing, taste, and smell to be singular senses. It is, however, not uncommon to consider the ability to sense temperature as distinct from the ability to sense that you are physically touching something. Pain can also be considered a distinct sense, since you can obviously 'feel' when you have, say, a headache, but it's hard to argue that that should count as 'touch'.