Snow leopard

Now that Apple has released the latest operation system for Mac, OS X 10.6 Snow Leopard, here’s a short clip about what it takes to capture an image (one of which is included in the desktop pictures) of this elusive animal in its natural habitat 5,000 metres above sea level:

Evolution in action

PD*30858692 I’ve just come across an interesting evolution item in the news. A North American mouse species has changed its fur colour from brown to blonde in a mere 8,000 years. It is a very fine opportunity to understand natural selection at work.

Let’s consider a mammalian species that lives in an environment it has adapted to through the millennia. Let it be a mouse and let’s pick a particular trait – fur colour. When the mouse lives in an area where the soil is dark, it is advantageous to sport a dark fur in order to avoid predators. But if an ice age happens to occur and a glacier deposits sand (which is much lighter in colour) onto that particular area, then, all of a sudden, the dark brown pelage turns disadvantageous and counter-adaptive. What this means is that the brown mice against the yellow background are too conspicuous to evade the attention of predators. Now, if a random mutation occurs in the colour, say blonde, and it happens to be advantageous, natural selection will preserve it. How? Let’s say in a litter of eight mice, seven is brown and one is blonde. Only one gene regulates fur colour in mice, and the blonde allele (variant of the same gene) happens to be dominant. In a light-coloured environment, the one blonde mouse is hugely favoured with respect to camouflage as opposed to its brown siblings. All the browns are selected out, and the light-coloured individual has increased chances of survival, because it blends in the colour of the sand dunes. Then in a couple of  generations (this means, of course, given the reproduction rate of mice, thousands of generations) the new colour will be fixed and the species will have adapted to its new environment.

It took about 8,000 years for the deer mouse (Peromyscus maniculatus) population of this area in Nebraska to gradually change from brown to blonde. How do we know they used to be brown? Deer mice of surrounding areas of darker soil all wear dark brown fur.

Athletic gibbon

I’ve always been fascinated by the gibbon’s mode of locomotion. It swings from branch to branch using mainly its ridiculously long arms. It is called brachiation. Here’s a short clip I recorded today of a male black crested gibbon (Nomascus concolor) brachiating:

His voice is great as well.
(Szeged Zoo)

Bamboo lemurs – food specialists

1635644Three species of bamboo lemur exist in the same (and ever-shrinking) tiny area in Eastern Madagascar. They provide us with a singular example of adaptive radiation. All three eat bamboo, but in a very civil manner they feed on different parts of the plant. Why do they have to split the bamboo that way? Short answer: niche partitioning. A somewhat extended answer: closely related animals living in the same area (sympatric species) can not occupy the same biological niche (which can be a habitat or merely a certain type of food, like in this particular case), because sooner or later the stronger one would displace the other.

Ha-bs.1024Now, the gentle bamboo lemur (Hapalemur griseus) eats the leaves, while the greater bamboo lemur (H. simus), a more robust species, eats the pith of mature stalks. The golden bambo lemur (H. aureus) confines itself to the new shoots, leaf bases and the pith of narrow stems.

Here’s the catch: the parts that H. aureus recklessly gobbles up contain cyanide. No small amounts of this lethal substance is consumed by this unheeding furry creature. About 4 mg/kg of body weight would certainly kill a dog. It has been estimated that the golden bamboo lemur eats 78 mg/kg on a daily basis. Scientists are understandably baffled at this self-poisoning behaviour and can only guess in what way the animal tackles it, for the digestive system of this species has never been studied. It is another great mystery of nature that remains to be revealed. But again, evolution through adaptive radiation has found a way to allow three very similar animals to co-exist peacefully.

Primary source: The Song of the Dodo by David Quammen, one of my favourite non-fiction books.

Aging

Sometimes I wonder what’s the point of growing old. We get old because we can. Medical improvements and health care systems allow us to do so. But are we prepared for all the hardships of old age? Are we ready to lose all who are dear to us, as well as not being able to take care of ourselves due to the pain that hurts us in every single part of our body? Take a moment and think about our evolutionary past.

A couple of thousand years ago people seldom lived through their thirties. One could easily die of a tooth inflammation or a broken finger. Not to mention ‘intraspecific conflicts’, i.e. wars. People in their forties were considered exceptionally fit and resistant to diseases. It is not incidental that humans are sexually mature at 12-13 years of age. You are evolved to procreate and pass your genes on as early as you can before you suffer an unexpected accident or malady and meet your demise.

You look askance at teenage girls with child nowadays (if you ever see one), however, bearing children at so youthful an age used to be considered quite normal not very long ago. At the same time, I’m well aware of the fact that people did not have to mind their money-making careers in the Bronze Age. One didn’t have to work 9 to 5 every day just to make a living. But still, in young twenty-ish people of today, who could easily afford one or two children, the thought of starting a family does not so much as cross their minds. Most people are so busy making money that they completely miss the purpose for which they were brought upon this earth. Not few women only come to their senses (if ever) when they reach 30-35 years of age, by which time serious health issues might be involved for both mother and offspring.

My personal opinion, with hindsight, is that people should have children in their early twenties. At 24-25 at the latest. I know it might be difficult but nature did not endow most of us with much time to spend with our children.

And to all money-grubbing bachelors in their late thirties and forties: When in the course of your life do you intend to sit down, take a deep breath and tell yourself: ‘now I’ve made enough money, now’s the time for children’? At forty? Forty-five? Well, I’ve got a thing for you: you might not live to see them grow to adolescence.

Therefore I hereby call upon everyone to go grab your partner and reproduce before it’s too late!

(P.S.: Look who’s talking! The author of this piece might not be completely authoritative on the subject.)

The kiwi’s egg

My colleagues incredulously rejected the notion that the chicken-sized kiwi lays eggs six times the size of a chicken egg. Well, it wasn’t just a fancy, it really is the case. A couple of days before the egg is laid, it assumes so gigantic proportions that it fills the female’s whole body cavity, forcing the bird to fast. It’s a huge burden for the kiwi, while developing the egg, it needs to eat three times as much as usual. The kiwi has the largest egg-to-body ratio (1:5) among all birds.
kiwi with egg

I wonder what adaptive advantage this bird gains by producing such a monster egg. I think the answer lies in the lack of natural predators. No native mammals exist in New Zealand (except for bats) that could prey on them, which is the primary reason for the loss of most of the birds’ ability to fly (think of the kakapo or the takahe, all flightless) on the island. The energy necessary to fly is turned over to producing enormous eggs. Not incidentally, the lack of predation allows for the birds to have very low reproduction rates, raising only one chick per season. As a matter of course, the whole agenda is turned upside down by the introduction of invasive species like rats, pigs and feral cats, wreaking havoc in the bird nests and effectively reducing the population size of these wonderful, but hapless birds.

An X-ray image:
Kiwi egg

Zebra in Gaza Zoo

090722_SS_4 What a nice zebra! Except that it’s not a zebra. It’s a donkey painted to look like a zebra. Even the ears are striped! I understand that they can’t really afford to obtain and keep expensive animals in the Gaza Strip, but I don’t think the solution is to counterfeit one. The solution is to shut down the ‘zoo’ completely. Why do people in a war-stricken area even bother to open and run a zoo? They also keep a lion that’s currently for sale, because its mate has allegedly been killed by a shrapnel.

Fallen

Teeth of a plant eater, claws of a meat eater

A most interesting fossil – Nothronychus graffami – has been found in Utah. Four metres tall, huge belly, small head, herbivorous teeth. 22 cm sickle-shaped claws. Odd coupling, wouldn’t you say? For what on earth does a leaf-eater need claws of such gigantic dimensions? Scientists have no idea. I mean, they do have some ideas, what they are in want of is evidence. Sure enough, the claws might have been great assistance in pulling down branches. They could just as likely have used them to deter predators. They might have had some reproductive advantage.

But really, all these fine hypotheses belong in the business of guesswork. Such great findings have the effect of disenchantment, and make one realize how little we know of the world around us.

Back to medieval times

A brand new blasphemy law has been introduced in Ireland. As of now, whoever dares so much as sneer at Christian faith is liable to a fee up to €25,000 in 21st century Ireland.

A couple of questions have been spat out by the neuronal network that resides inside my head.

Does it apply only to atheists or between religions as well? Any good Muslim would claim that Muhammad is God’s final prophet, would that be a blasphemous remark?

How would they intend to uphold this utterly despicable law, anyway? They revert to the methods of good old communism and denounce whoever takes the Lord’s name in vain? That would be childish, wouldn’t it?

Here’s what Richard Dawkins has to say on the matter:

“It is a wretched, backward, uncivilised regression to the middle ages. Who was the bright spark who thought to besmirch the revered name of Ireland by proposing anything so stupid?”

What’s next, Orwellian thought crime? Next thing you know is people getting locked up for merely thinking about nasty things of Jesus Christ. Free speech has been criminalised in a developed European country.

« Older entries Newer entries »