News in Brief #6

Japanese macaques

Baby Monkeys are Cute

For we humans, it's fairly easy to estimate how old another human is just by looking at them. It may not work perfectly, but we can instinctively assign someone to at least to a broad age class - young adult, middle-aged, and so on. There are plenty of clues to help us to do this, and it's a useful ability for shaping our interactions with one another, so it's not too surprising that other social animals can do the same thing. Perhaps one of the more striking examples is our reaction to the faces of our young.

Very young humans have a constellation of features that highlight their age: rounded face, large eyes in comparison to the face, and so on. The same set of features are found in other baby mammals, and were described by the great behavioural biologist Konrad Lorenz as "kindenschema". Perhaps a more everyday term for the same phenomenon is "cuteness". Cuteness triggers positive, maternal and protective reactions in humans, and its by no means restricted to our own species. Kittens and puppy dogs are undeniably also "cute" to the vast majority of humans and its for the same reasons. We can see the same phenomenon in the looks of toys such as teddy bears, the kawaii appearance of characters in Japanese cartoons, and so on.

Discovery of the World's Newest Monkey

Hamlyn's monkey (left) and lesula (right)

Even today, new species of mammal are being discovered all the time. The majority are small animals, often nocturnal, or otherwise difficult to find. Just in the last few months I've seen the announcement of four new bats and a mole, and that's without me particularly trying - there may well be more discoveries I haven't seen. In many cases - as happened with the bats, for example - it's not that the animal had never been seen before, it's just that it wasn't obviously a different species. Until you look closely, one mole may look much like another.

The discovery of larger species is a rarer event. Which is why the announcement of an entirely new species of monkey is so exciting. This new animal, the lesula (Cercopithecus lomamiensis), is the first new species of African monkey to be discovered since the critically endangered kipunji in 2004, and only the second since 1984.

News in Brief #4

A Rat's Idea of 'Vermin'

Arguably the most important factor in the success of humanity as a species is out ability to modify the environment around us, to take somewhere inhospitable, and not only make it habitable for our species, but enable it to support far more humans than any natural environment possibly could. The existence of cities, and of the great swathes of agricultural land around them are clear testaments to modify the world to the point of creating entirely new environments.

We may be the most spectacular example of a species that can do that, but many others do so, albeit on a smaller scale. They're not all mammals, or even vertebrates - consider termite mounds, of example. Often, the way that one species modifies it environment also helps others, whether intentionally, as in humans providing farmland for cattle, or as an unavoidable by-product, such as humans creating the perfect habitat for rats. This process is called "facilitation", and it seems to have been more studied in botany than it has in zoology.

However, Andrew Edelman, of the University of New Mexico, has been looking at the interaction between two animal species in the Chihuahuan Desert. Banner-tailed kangaroo rats (Dipodomys spectabilis) are, like many rodents, seed-eating herbivores. They make large mounds in the desert in which to live, and, while they're generally pretty anti-social, not letting other rats near their homes during their lifetime, the mounds can nonetheless be passed down from rat to rat for generations, sometimes surviving for over fifty years.

News in Brief #3

The Mandrill's Face

There are a number of colourful primates, but one of the more instantly recognisable is surely the mandrill (Mandrillus sphinx) whose adult males have strikingly blue and red faces. Under a strict definition, mandrills aren't really baboons, but they're very closely related to them, and the difference is pretty academic. Given that only the adult males have these extreme face-markings it's not surprising to learn that they are there mainly to advertise their masculinity and fitness as a potential father to female mandrills.

A study from 2005 confirmed that, yes, indeed, female mandrills find males with bright red noses to be particularly sexy. Oddly, though, until now nobody appears to have looked at what the bright blue patches on either side of the nose are for. In the new study, Julien Renoult and co-workers confirmed that the blue colour is more intense in dominant males, just as the red is. Indeed, it seems that what's really important is the contrast between the two. This suggests that, in the distant past, mandrills developed the red nose as a measure of their fitness, and the redder the nose, the more females liked them. So the noses of dominant males became ever redder... but there's only so red a nose can get. When some males began to develop a contrasting colour elsewhere on the snouts, the redness of their noses became more obvious, and, over the course of evolution, the bright blue/red contrast we see now developed.

News in Brief #2

Columbian ground squirrel

The Wooing Ways of Ground Squirrels

Male animals will go a long way to ensure that they become the father for a female's young. If the female isn't likely to be monogamous, they may chase off rivals, beat them up, display their masculinity, or just have giant gonads. But male Columbian ground squirrels (Urocitellus columbianus), it seems, like to try a bit of smooching.

Columbian ground squirrels (that's British Columbia, by the way, not Colombia in South America) live in complex, underground burrows. They mate in the early spring, after waking up from hibernation, and the females are sexually fertile for just one day during each year, making competition between males particularly important. Yes, the males do fight one another to establish territories, but, according to a new discovery, that isn't their only trick.

In short, they don't go too far on a first date. They sneak into the female's burrows at night, when she isn't sexually fertile, and spend the night with her, without doing anything. The next morning - and the more experienced males do seem to be pretty good at predicting in advance the one day when this is going to happen - the females wakes up feeling randy... and, well, who's already there?

Sex Without Pregnancy: how female macaques get what they want

Tibetan macaque (Macaca thibetana)

The females of most mammal species have some means of signalling to males that they are sexually fertile, and able to become pregnant. There is often some sort of breeding season, timed so that birth is likely to happen at a point in the year when food is abundant - spring, the rainy season, or whatever. But the cycles of female hormones mean that the female is only actually capable of becoming pregnant for periods of a few days, or even hours, during that season. Essentially, she comes into heat, and the males get excited.

That's the usual pattern. But there are some mammals that don't seem to do this. While they may not bother to mate outside of a mating season, they don't seem to be indicating to males when, within that season, they are likely to become pregnant. But is that really the case?