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.

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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.

Why Evolution Is True

why-evolution-coyneJerry A. Coyne from the University of Chicago is a distinguished biologist of Speciation fame and a well-known figure in the intelligent design vs. evolution debate. He for some reason felt obliged to lay out the evidence for evolution, but unlike the one mentioned above, which is a highly technical textbook (co-authored with H. Allen Orr) and an embarrassingly difficult read even for professionals, Why Evolution Is True is a delightful book designed for the average reader.

Isn’t this so-called ID-evolution debate already settled? Apparently not. Not in America, at any rate. While it’s not really an issue in Europe, a great number of people in the United States flatly reject evolution and literally interpret the Bible as the ultimate truth.

But here’s the thing: the evidence for evolution is overwhelming. It’s there for all to see. Paleontology, geology, plate tectonics, biogeography, comparative anatomy, genetics, molecular biology – all these disciplines have their share to add to the ever-growing pile of evidence. You have to be blind or just plain stupid to deny it.

At any rate, Dr. Coyne makes his attempt to impart this intelligence to the lay people. After explaining in the first chapter what evolution is, in the following chapters he makes his case clearly with numerous examples from the above disciplines. Chapter 2 deals with fossils, how paleontologists work, radioactive dating methods, prominent transitional fossils like Tiktaalik (fish to amphibian), Archaeopteryx (reptile to bird), Indohyus (an artiodactyl ancestor of whales). This is really just an excerpt. There are a lot more.

Chapter 3 happens to contain my favourite example, one from ontogenesis. Not the easiest to understand, but I hadn’t known about it before. I recommend medical students pop this to their anatomy teacher: why the heck does our left recurrent pharyngeal nerve go all the way down to the heart and come back only to innervate the larynx?

The answer lies in ontogenesis and common ancestry:

One of nature’s worst designs is shown by the recurrent laryngeal nerve of mammals. Running from the brain to the larynx, this nerve helps us speak and swallow. The curious thing is that it is much longer than it needs to be. Rather than taking a direct route from the brain to the larynx, a distance of about a foot in humans, the nerve runs down into our chest, loops around the aorta and a ligament derived from an artery, and then travels back up to connect to the larynx. It winds up being three feet long. In giraffes the nerve takes a similar path, but one that runs all the way down that long neck and back up again: a distance fifteen feet longer than the direct route! When I first heard about this strange nerve, I had trouble believing it. Wanting to see for myself, I mustered up my courage to make a trip to the human anatomy lab and inspect my first corpse. An obliging professor showed me the nerve, tracing its course with a pencil down the torso and back up to the throat.
This circuitous path of the recurrent laryngeal nerve is not only poor design, but might even be maladaptive. That extra length makes it more prone to injury. It can, for example, be damaged by a blow to the chest, making it hard to talk or swallow. But the pathway makes sense when we understand how the recurrent laryngeal nerve evolved. Like the mammalian aorta itself, it descends from those branchial arches of our fishlike ancestors. In the early fishlike embryos of all vertebrates, the nerve runs from top to bottom alongside the blood vessel of the sixth branchial arch; it is a branch of the larger vagus nerve that travels along the back from the brain. And in adult fish, the nerve remains in that position, connecting the brain to the gills and helping them pump water.
During our evolution, the blood vessel from the fifth arch disappeared, and the vessels from the fourth and sixth arches moved downward into the future torso so that they could become the aorta and a ligament connecting the aorta to the pulmonary artery. But the laryngeal nerve, still behind the sixth arch, had to remain connected to the embryonic structures that become the larynx, structures that remained near the brain. As the future aorta evolved backward toward the heart, the laryngeal nerve was forced to evolve backward along with it. It would have been more efficient for the nerve to detour around the aorta, breaking and then re-forming itself on a more direct course, but natural selection couldn’t manage that, for severing and rejoining a nerve is a step that reduces fitness. To keep up with the backward evolution of the aorta, the laryngeal nerve had to become long and recurrent. And that evolutionary path is recapitulated during development, since as embryos we begin with the ancestral fishlike pattern of nerves and blood vessels. In the end, we’re left with bad design.

The following chapters deal with the geography of life, how animals came to live in the separate continents, island biogeography, bees killing giant hornets by heating them up to 80 degrees centigrade, evolution in the test tube, drug resistance, a whole chapter on sexual selection, speciation (the process of distinct species formation), population genetics, human evolution (including Homo floresiensis, the hobbit), etc.

All in all, a profoundly satisfying read, a rare gem in the market of popular science books. Last words:

We are the one creature to whom natural selection has bequeathed a brain complex enough to comprehend the laws that govern the universe. And we should be proud that we are the only species that has figured out how we came to be.

Running bull kills

It’s the time of the year when the running of the bulls (encierro) takes place in Pamplona, Spain. Popularized by the excellent Hemingway novel The Sun Also Rises, courageous, or should we say stupid, young men run in front of a group of vexed oxen to demonstrate their virility. The run ends when the bulls enter the bullring where they will eventually meet their fate at the hands of the toreros later the day.

This time the bulls killed someone on the run. I don’t really feel sorry for the guy, to put it mildly. It must be a very nice and spectacular tradition, in which animals are willfully tortured and killed for the sake of fun. How can such an event still flourish in an era when the European Union rigorously regulates even what you may or may not feed your own swine? I don’t get it.

Oh, it sounded like I’m some animal rights activist or something.

Gargantua and Pantagruel

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Gargantua and Pantagruel (La vie de Gargantua et de Pantagruel) is a French satire from the 16th century written by Francois Rabelais, a medical doctor. The tome consists of five books that chronicles the life history of two honourable giants, Gargantua and his son Pantagruel. The author is a ruthless social critic, sparing nobody from uppity academics to the clergy. Bawdy and extremely vulgar and violent at times, the stories revolve around the everyday routine of the giants and their sidekicks as they mock and tease everybody who is unfortunate enough to get in their way.

It’s definitely not a novel, the chapters are loosely connected with not much of a plot. I laughed out loudly several times while reading it, I guarantee your eyes will not be left dry, should you give it a try.

I’m quite certain the English translation could not entirely convey the humour and poignancy of the French original, but allow me to give you some excerpts to give you a taste. On one occasion Pantagruel is browsing the books in a library, and the author lists the titles (on several pages) our good giant comes across:

The Testes of Theology;
On the Art of Discreetly Farting in Company, by Magister Noster Ortuinus;
Tartaretus: On how to Defecate;
Three Books On How to Chew Bacon, by the Reverend Father Provincial of Drivell;
Magister Noster Rostock-Assley: On the Serving of Mustard after Dining, Fourteen Books;
Eleven Decades on the Taking-off of Spurs, by Magister Albericus de Rosate;
Marforio, a Bachelor lying in Rome: On Skinning and Smudging Cardinals’ Mules;
Putting Things into the Mouths of Masters of Arts;
The Surgeon’s Kiss-me-arse.

Another time, young Gargantua imparts the art of arse-wiping to his father. After listing about a hundred ways and means to wipe one’s bottom, here’s his conclusion:

But to conclude: I affirm and maintain that there is no bottom-wiper like a downy young goose, provided that you hold its head between your legs. Believe me on my honour, for you can feel in your bumhole a mirifical voluptuousness, as much from the softness of its down as from the temperate heat of the young goose which is readily communicated to the arse-gut and the rest of the intestines until it reaches the region of the heart and the brain. And do not believe that the blessedness of the heroes and demi-gods in the Elysian Fields lies in their nectar, asphodel or ambrosia, as these old women would maintain: in my opinion it consists in the fact that they wipe their bums on a young goose.

Highly recommended.

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