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Darwin Days: Giraffe (Giraffa camelopardalis)

by JR Kinyak on February 14, 2009

in Theme Weeks,Ungulates

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Tonight, we conclude our celebration of Charles Darwin’s 200th birthday with one last look at a mammal he wrote about in The Origin of Species.

Although Darwin’s work is widely available for free online (see The Complete Work of Charles Darwin Online, and you’re probably all set), I still find it easier and more satisfying to thumb through an actual book. It’s kind of like rewinding a cassette tape versus placing a needle on a record. For me, anyway. So I bought a Penguin edition of Origin. There were three different printings to choose from at my bookstore, and I picked the middle one, price-wise, which seemed to have decent paper. Turns out it’s a reprint of the first edition, and Darwin produced six editions total, each quite different from the previous. All this is to say that in the sixth edition, Darwin added a second chapter dealing with objections to his theory. In that chapter, he discusses the giraffe in great detail, discussing how and why it might be advantageous for a “nascent giraffe” to evolve a long, long neck.

It seems that the giraffe is still throwing people for a loop. When I was researching giraffe photos online for reference, I found one posted on Flickr that had a long, not overly polite discussion in the comments section about whether or not it was possible for a giraffe’s neck to evolve, or whether the very fact of the giraffe’s long neck was proof of the creation of the giraffe as a whole being, immutable and perfect. To me, it seems a textbook example of natural selection: the protogiraffes with the longest necks were able to eat more than the others. They lived longer because they ate longer. They reproduced more because they lived longer. More giraffes were born with long necks. And so on. But people still have problems with it because the giraffe seems unique, because it requires special structural adaptations in order to operate with such a long neck, or maybe because it looks like something someone like Dr. Seuss would have had to think up.

The giraffe reference I particularly like in Origin, though, is in my first-edition reproduction. After discussing the problem of the evolution of organs of seeming perfection (like the eye), Darwin addresses the problem of the evolution of “organs of little apparent importance.” In his charmingly open and self-effacing way, he writes, “I have sometimes felt much difficulty in understanding the origin of simple parts, of which the importance does not seem sufficient to cause the preservation of successively varying individuals.” Darwin goes on to point out that we shouldn’t be so arrogant as to presume we know what’s important and what’s not. And the example he uses is the giraffe’s tail:

“The tail of the giraffe looks like an artificially constructed fly-flapper; and it seems at first incredible that this could have been adapted for its present purpose by successive slight modifications, each better and better, for so trifling an object as driving away flies; yet we should pause before being too positive even in this case, for we know that the distribution and existence of cattle and other animals in South America absolutely depends on their power of resisting the attacks of insects: so that individuals which could by any means defend themselves from these small enemies, would be able to range into new pastures and thus gain a great advantage. It is not that the larger quadrupeds are actually destroyed (except in some rare cases) by the flies, but they are incessantly harassed and their strength reduced, so that they are more subject to disease, or not so well enabled in a coming dearth to search for food, or to escape from beasts of prey.”

First of all, don’t you love that 19th-century sentence structure, with endless commas, colons, semicolons, and then more commas? I love it. What Darwin is saying here* is that a fly-swatter is not as trivial as it seems. Fighting off flies saps a person’s energy, and so it makes sense that the best fly-flighters would have a reproductive advantage. I imagine this is why giraffes have such lovely eyelashes, too.

My husband Ted has a theory that sexual selection could play a part here (see my lion post of a couple days ago). In his theory, female giraffes would be more attracted to those male giraffes who coolly switched their tails, rather than those who itched and jumped because flies were crawling all over them. It makes sense to me.

*I should note that my mammalogy is completely self taught. Two of my worst teachers ever were my two biology teachers (7th grade and 8th grade). What knowledge I have of science is from my dad (a geologist and painter) and my own curiosity and love of animals. So if I’m telling you really, really obvious things about evolution, I apologize. I’m just learning it all myself.

Tagged as: books, darwin, evolution, sexual selection

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Darwin Days: American Mink (Neovison vison or Mustela vison)

by JR Kinyak on February 12, 2009

in Carnivores,Theme Weeks

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Welcome, readers of the Blog for Darwin blog carnival! (A blog carnival is a collection of posts from different blogs but on the same topic. I’m participating in one that compiles posts related to Darwin today through the 15th. Click the link above to read some of the other bloggers’ posts.) At the Daily Mammal, we’re celebrating Charles Darwin’s 200th birthday (today! happy birthday!) with a look at some of the mammals that Darwin mentions in his Origin.

Chapter Six of Origin is dedicated to answering some of the problems that Darwin anticipates people finding with his theory. One of these issues is the seemingly amazing perfection of certain natural structures, like the eye, and the incredulity with which people consider that such perfection could arise gradually through natural selection. Another is the apparent lack of transition species: if species are always changing one into another, why don’t we see all kinds of transition species, both now and in the fossil record? And how is it even possible that, for instance, a land animal could evolve into an aquatic one? How would the transitional species in between have lived?

That’s where this fellow, the American mink, comes in. Darwin writes:

“It would be easy to show that within the same group carnivorous animals exist having every intermediate grade between truly aquatic and strictly terrestrial habits; and as each exists by a struggle for life, it is clear that each is well adapted in its habits to its place in nature. Look at the Mustela vison of North America, which has webbed feet and which resembles an otter in its fur, short legs, and form of tail; during summer this animal dives for and preys on fish, but during the long winter it leaves the frozen waters, and preys like other polecats on mice and land animals.”

So, taking this mink as an example, if certain traits that lent themselves to living in the water began to be an advantage in the struggle for survival—say, water levels rose or predators pushed the minks out of their normal territory into one more waterlogged—the minks that were better adapted to aquatic living would be more likely to survive and reproduce their genes. And with successive generations, these characteristics would be strengthened, and as more and more minks were born with these adaptations, they would through greater numbers eventually take over, and perhaps we would have a new species. At least that’s this laywoman’s interpretation of the idea. Another example:

“In North America a black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.”

Another thing to ponder is the way humans, through hunting, for instance, are creating unnatural selection. A recent study found that as bighorn sheep are hunted for their gigantic, beautiful, curling horns, those with smaller, less impressive horns are more likely to survive and reproduce. The result seems to be a decrease in horn size across the population. And since it seems that those bighorns with the biggest horns are also the most healthy and strongest, hunters are creating a weakened population. Some are calling it “evolution in reverse.” Perhaps we would have seen something like this in the minks if fur farms hadn’t overtaken the hunting of wild minks, and if trappers and mink hunters could selectively trap and hunt only the minks with the lushest coats.

Mink are fairly solitary and fairly nocturnal. They live in burrows beside rivers and they dine on crayfish and frogs in the summer, as Darwin noted, and small mammals like shrews and rabbits in the winter. Sometimes they use fur from their prey to line their dens. They are good at swiming, diving, and climbing.

Tagged as: books, darwin, evolution

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Darwin Days: Lion (Panthera leo)

by JR Kinyak on February 11, 2009

in Carnivores,Theme Weeks

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It’s quite fashionable to equate the theory of evolution with Charles Darwin himself. Science magazines and books sell with covers blaring “Darwin Was Wrong,” “Was Darwin Wrong?,” and “What Darwin Got Wrong.” Meanwhile, intelligent-design and creationism proponents attack “Darwinism,” and the New York Times publishes “Darwinism Must Die So That Evolution May Live” and “Let’s Get Rid of Darwinism.” By creating an -ism, the New York Times pieces suggest, “Darwinists” devalue their own arguments, putting them on the same level as, for instance, creationism.

The fact, as far as I can tell, is that Darwin was right about many, many things, and most of those things that he was wrong about (mainly because things like genetics and continental drift hadn’t yet been discovered, and the man couldn’t do it all!) have nevertheless been built on his foundation. Many of the articles celebrating Darwin’s bicentennial point out how remarkable it is that after 150 years, On the Origin of Species is still relevant. Today we’ll talk about one of the ideas Darwin had before his time and that is still being studied and proven: sexual selection.

Basically, sexual selection refers to the favoring of certain traits solely because they are attractive to mates. As Darwin says in Chapter 4 of Origin, “This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring.” To attract females, males develop showy traits like bright feathers, big antlers, or electric guitars. The reasons why females are attracted to these things in the first place are not fully known; it could be that a male with big horns, for instance, has good genes in other ways; another theory holds that if a male can thrive despite the “handicap” of a huge tail or something, he must be pretty strong.

The lion’s mane has long been a puzzle. In 1859, in Origin, Darwin wrote, “The males of carnivorous animals are already well armed; though to them and to others, special means of defence may be given through means of sexual selection, as the mane of the lion, and the hooked jaw to the salmon; for the shield may be as important for victory, as the sword or spear.” The going theory for many years was that manes protected male lions from the claws and teeth of their rivals, but now it doesn’t appear that’s true because fighting lions don’t tend to go for the head and neck in particular.

Studies in the past several years have focused on the variations in mane length and color. Researchers found that the luxuriousness of a lion’s mane depended on its climate: lower, hotter, and more humid climates meant skimpier, lighter-colored manes because it can get hot under all that hair. The researchers were also surprised to learn that manes continue developing after the lion’s sexual prime has come and gone. In the hottest places, older males are the only ones with manes to write home about. It makes me wonder if there could be a reverse sexual selection going on there: if you don’t have a mane in a hot place, does it indicate that you’re younger and therefore more virile? I don’t know.

Scientists also fooled around with trying to lure both male and female lions with fake dummy lions of varying mane lengths. They found that males approached the shorter-maned dummies 9 out of 10 times, and females approached the longer-maned ones 13 out of 14 times. The males that intrigued the females intimidated the other males, in other words.

Here’s a book I read part of once that postulates that all human creative culture—from art to architecture to comedy to writing books, etc.—is the result of sexual selection. In other words, men do cool things because chicks dig it: The Mating Mind by Geoffrey Miller.

Tagged as: books, cat, darwin, evolution, sexual selection

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Darwin Days: Tuco-Tucos Six Ways (Ctenomys spp.)

by JR Kinyak on February 10, 2009

in Rodents,Theme Weeks

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The day after tomorrow, February 12, 2009, is Charles Darwin’s 200th birthday. (It’s also Abraham Lincoln’s.) I’ve recently begun reading Darwin’s The Origin of Species, and I’ve decided to try to do a little something in celebration of Darwin’s immense contribution. I’m going to be highlighting a few mammals that Darwin discusses in The Origin of Species, and I’ll try to tell you something of what Darwin says about them. Since I haven’t read the whole book, I’m going to be reading the sections that mention these mammals out of order and a bit out of context, but I’ll do my best, and maybe my more Darwin-literate readers can help out where needed. I also am pretty clueless as to where Darwin’s ideas have been expanded or improved upon. Incidentally, the book is actually quite accessible, and I’m sorry I didn’t read it earlier. You can read it online or download a PDF at Google Books.

Chapter Five of The Origin of Species is titled “Laws of Variation.” In a section called “Effects of Use and Disuse,” Darwin posits that the shrunken state of the wings of some birds on islands where they have no predators results from disuse. There’s nothing to fly away from, so generations of birds stopped flying and used their legs more, and through natural selection their legs were strengthened and their wings, eventually, made useless. As another example, Darwin discusses animals that live in underground burrows and caves and have small, furred-over, or absent eyes, thanks to disuse. It’s dark down there, so eyes aren’t very helpful, and gradually, they are selected out, while things like longer whiskers and antennae, which are helpful underground, are favored.

The tuco-tucos, of which there are some 50 different species, live in burrows in South America. Although they spend a lot of time underground, they do occasionally peer out of their homes, and their small but useful eyes allow them to do that without necessarily having to actually exit the premises. It’s easy for them to duck back under if need be. (The amount of time they spend outside their burrows varies from species to species.)

Darwin says that he was told by someone who caught a lot of tuco-tucos that they are often blind. A tuco-tuco that Darwin kept in captivity was blind, he says, thanks to an inflammation of the eye. As Darwin points out, animals that live primarily underground don’t really need their eyes, and eyes are just another thing that can get infected, so why not do away with them? (Eventually. Over generations.)

Genetic analysis of one tuco-tuco species, the colonial tuco-tuco (C. sociabilis) yielded surprising results a few years back. For the past three millennia, the colonial tuco-tuco has had almost no genetic diversity. Usually, a lack of genetic variation means doom for a species, but the colonial t-t has survived pretty well. The reason, researchers think, is that it has evolved a very social way of life, unlike the other tuco-tuco species. If everyone is related, there’s no reason to compete; instead, you can help your cousins breed, since they’re passing on your genes, as well as their own. (In a practical sense, I think I would be more likely to get along with everyone if they were more or less my clones, too, but personality clashes are probably not a significant factor in the colonial t-t’s survival.)

According to Walker’s Mammals of the World, “Systematic understanding of this complex genus is in a state of flux, and it is likely that there will be much change in the number and relationships of species…” In this drawing of the goofy-looking guys, clockwise from the upper right are C. fulvus, C. sociabilis, C. flamarioni, C. talarum, C. peruanus, and in the middle, C. haigi.

Tagged as: books, darwin, dna, evolution, multiples, taxonomy, tuco-tuco

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Proboscis Monkey (Nasalis larvatus)

by JR Kinyak on January 9, 2009

in Primates

click image to enlarge

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Well, here’s a good opposites-attract companion for yesterday’s tiny-nosed Tonkin snub: the proboscis monkey, which lives only in Borneo. You will have noticed his floppy nose (and it’s only the males who have such gigantic honkers), but you probably don’t want to stare. It’s okay: I bet this monkey feels about his schnozz the same way Edmond Rostand’s Cyrano felt about his: “…[B]e it known to you that I am proud, proud of such an appendage! inasmuch as a great nose is properly the index of an affable, kindly, courteous [mammal], witty, liberal, brave, such as I am!”

The proboscis monkey is not only witty and brave (maybe). It’s also a good swimmer, a skilled diver, and a maker of distinctive sounds variously described as howls, growls, or honks. Sadly, it’s quite endangered, too, thanks to traditional medicine, the bushmeat trade, and habitat destruction: the usual suspects.

I think these monkeys are quite charming with an endearing look to them, but the most common word the 19th- and early 20th-century naturalists used to describe them was “grotesque.” Here are some passages you may enjoy.

From The Naturalist’s Library by William Jardine, 1833:

“This singular monkey is at once distinguished by the extraordinary elongation of the nose, which is nearly four inches in length, and gives a grotesque appearance to the animal, at the same time far from pleasing.”

From The Living World by James William Buel, 1891:

“The Proboscis Monkey…resembles a shrivelled, bowed, long-nosed, little old man or woman, and is sacred in the eyes of the natives. Its noisy outcries, malignant disposition and fondness for irritating mischief, seem to add a fresh illustration to the truth that the uncivilized animal nature is perfectly unfit for the government of self or of others.”

From The Evolution of Man by Ernst Haeckel, 1903:

“…the well-shaped nose of which might well be coveted by men in whom this organ is too short. On comparing the face of this nosed monkey with that of specially ape-like human beings (e.g., the noted Julia Pastrana, Fig. 126), the former will appear a higher form of development than the latter. There are many persons who believe that the ‘image of God’ is unmistakably reflected in their own features. If the Nosed-ape shared in this singular opinion, he would hold it with a better right than some snub-nosed people.”

Finally, an illustration from the first book quoted above, The Naturalist’s Library (1833) by William Jardine. I love this illustration.

Tagged as: books, endangered, humans, monkey

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Mammals of Iraq: Smooth-coated Otter (Lutrogale perspicillata)

by JR Kinyak on July 1, 2008

in Carnivores,Theme Weeks

click image to enlarge

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To celebrate my boss Ramona’s successful trip to the Kurdish region of northern Iraq, as well as because we’re still at war there, I’m going to be spotlighting some of the mammals of Iraq this week. These two fine fellows are smooth-coated otters, who live in Iraq’s Mesopotamian marshlands, as well as in other parts of Asia. The otters have a way of forming a semicircle with the rest of their family and sort of herding fish in front of them. In India, people who noticed this have had some success in training smooth-coated otters to herd fish right into their nets!

Smooth-coated otters are classified as vulnerable by the International Union for Conservation of Nature (IUCN). One famous subspecies, known only to live in Iraq, may be extinct now. This variety was called Maxwell’s otter after an author named Gavin Maxwell. Maxwell found an otter in Iraq and took it back home with him, where he raised it in the Scottish highlands. The lovable otter, Mij, became the star of a best-selling novel, Ring of Bright Water, that was adapted into a popular movie in 1969.

Now, I had never heard of this book and movie, which is both a surprise, as I was an animal-book freak as a kid, and a relief, as it has, apparently, a heartbreaking ending. I’m telling you this without a spoiler alert because I’ve been reading horror stories of children and adults alike being traumatized by the sudden tragedy in what was a playful romp of a movie. If you have kids and you want to read a great book about a pet otter with no tears, I recommend the currently out-of-print Picaro by Dorothy Wisbeski, which was one of my and my dad’s favorites when I was little. It has really beautiful illustrations including, if I recall correctly, one of Picaro splashing in the toilet.

When Saddam Hussein’s Baath regime was in power in Iraq, they almost destroyed Iraq’s marshlands in an attempt to eradicate the Marsh Arabs, a society that had lived there for millennia. The regime drained the marshes, burned villages, and destroyed livestock and crops. In addition to displacing and destroying the livelihoods of thousands and thousands of Marsh Arabs, this likely led to the extinction of the Maxwell’s subspecies of smooth-coated otter. USAID runs a program to restore and reflood Iraq’s marshes and help develop the communities around them. Learn more about the Iraq Marshlands Restoration Program here.

Consecutive days of mammals: 1
Record: 16

Tagged as: books, humans

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Warthog (Phacochoerus aethiopicus)

by JR Kinyak on June 24, 2008

in Ungulates

click image to enlarge

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I need to go to bed, so I won’t say too much about warthogs, except that they live in Africa south of the Sahara and can go for months without water. And they dig holes to hang out in, keeping themselves warm when it’s cold out and cool when it’s hot.

The Wonders of Animal Life books I mentioned in my mountain lion post include a full-page color photograph of a warthog in the “Nature’s Strange Show of Freaks” chapter. Isn’t that mean? It gets even meaner. The caption reads thusly:

WARTHOG, A TUSKED AND SNOUTED FREAK OF THE AFRICAN WILD With grotesquely curving tusks, the hideous warts below the eyes which give this wild hog its name, and a draggle of coarse hair on head and back, this animal is indeed one of Nature’s freaks. The skin is as cracked as dried mud and the typical pig eyes, small and evil-shining, add to the generally grotesque and repulsive mien. The warts below the eyes may serve to protect them during the battles between the boars.

Evil-shining eyes? A repulsive mien? Preposterous!

Consecutive days of mammals: 5
Record: 16

Tagged as: books

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