Why Do Pirates Love Parrots? (4 page)

G
iraffes are among the most taciturn of animals. We’ve never heard a giraffe vocalize but it turns out that they’ve been dissing us, for they possess larynxes and vocal cords and actually make a variety of sounds.

The heroine of our story is Elizabeth von Muggenthaler, a bioacoustician and president of Fauna Communications Research Institute in Hillsborough, North Carolina. Muggenthaler reckoned that because giraffes are highly social, and are forager-vegetarians who are the prey of other animals, it was highly unlikely that they could survive without intraspecies communication. The giraffe’s anatomy was another clue to Muggenthaler—if they don’t speak, then why are their ears shaped like parabolas, which seem perfectly designed to pick up on sounds?

Giraffes do vocalize occasionally. Calves, especially, utter a bleating mewl. Mothers utter a “roaring bellow” when looking for their young, who are often left alone in the forest while the parent forages. And males are known to seduce partners with a “raucous cough.” Occasionally, adults also bleat (Muggenthaler compares them to goat bleats) and “moo” as if imitating cows. When threatened, the giraffe’s yelling side emerges—they are capable of mustering up a roar when in danger. Still, these vocalizations are exceptions rather than the rule, and it is possible even for those who work around giraffes to think they are mute.

Could giraffes speak in ways humans couldn’t understand? Scientists had already determined that whales and elephants communicated via infrasonic sound—vocalizations at such low frequencies that humans could not hear them. Scientists discovered the songs of the humpback whale more than forty years ago, and researchers like Muggenthaler and the Bioacoustics Research Program at the Cornell Lab of Ornithology have documented the complexity of infrasonic vocalizations. A Cornell researcher, Katy Payne, discovered the elephants’ infrasonic communication when she found her ears throbbing near elephant cages. It reminded her of singing in a church choir, where the pipe organ was almost inaudible at the lower frequencies but the pressure in her ears palpable.

While studying the low-frequency vocalizations of elephants, Muggenthaler discovered that rhinoceroses also utilized infrasonic vocalizations, and she suspected that giraffes did, too. In 1998, she confirmed it by studying eleven giraffes in two zoos. Measuring infrasonic communication is difficult in the controlled atmosphere of a zoo, since passing cars, ambient wind, and even water create infrasound, but it is even more difficult in the wild, where other animals also can compete with the giraffes’ vocalizations.

Muggenthaler and her fellow researchers discovered that the giraffes’ infrasonic vocalizations were associated with two physical movements: a “neck stretch,” when giraffes lift their head and necks over their bodies, and the “head throw,” that features a lowering and quick raising of the chin. Almost every time a giraffe was observed performing a neck stretch, an infrasonic vocalization accompanied it. Head throws were more common, but there giraffes vocalized only 25 percent of the time.

Although it hasn’t yet been proven, Muggenthaler’s theory is that the infrasonic vocalizations might be caused by

If giraffes are capable of vocalizing in a higher frequency through their mouths, why bother with the low-pitched stuff? One obvious advantage is that low-frequency sounds can travel farther than higher-pitched ones, a crucial advantage to giraffes (and elephants), who often are separated from their families by greater distances than their voices can reach. And although Muggenthaler’s team did not study how the giraffes use infrasonic vocalizations to communicate with each other, she does speculate about why infrasonic communica-tion might aid in giraffes’ survival. Evidently, we are not the only animals who can’t hear their low-frequency emissions:

Submitted by Peter Lanza of Stamford, Connecticut.

W
hen you think about slot machines, chances are you conjure up glassy-eyed gamblers in Sin City, Nevada, with cigarettes dangling from their mouths—hardly the setting for showcasing images of fresh fruit. Yet fruit was associated with slot machines almost from the time of their invention—in fact, in England, slot machines have always been known as “fruit machines.”

Although there were mechanical gambling devices before, including a primitive precursor of today’s video poker machines, Charles Fey invented the first one-armed bandit in 1895. Fey’s Liberty Bell slot machine, with three reels sporting three of the four suits found in a deck of cards (clubs were the odd suit out) and the now-familiar cracked Liberty Bell. The highest jackpot, the princely sum of ten nickels, was won if you could line up three Liberty Bells in a row.

Edibles came into the picture when the Mills Company of Chicago redesigned Fey’s original Liberty Bell and created a special machine for the Bell Fruit Gum Company. While most early slot machines were gambling devices placed in taverns (prizes were often a free drink or small amounts of money), Bell wanted a machine that could be played for a family audience at fairs and carnivals. Instead of playing cards, Bell placed drawings of fruits that represented the flavors of Bell Gum. If three watermelons or lemons were aligned, the machine would dispense a pack of Bell Gum. With the great popularity of this machine, the fruit symbols prevailed, and are still depicted on some modern machines.

And if we may throw in our own mini-Imponderable, we always wondered what the bar symbol on slot machines signified. We assumed they were meant to be gold bars, but they weren’t tapered like them. It turns out that the bar was a stylized version of Bell Fruit Gum’s logo, now an example of obsolete product placement.

With the advent of nine-line slots with themes ranging from Monopoly to
I Dream of Jeannie,
the fruit symbols are a withering but not yet dead symbol of old-school gambling. It’s hard for a lemon to compete with Elvis-or
Star Wars
–themed slot machines for a gambler’s attention.

Submitted by Faye Railing of San Diego, California.

W
e’re always pleased to meet a source who is enthusiastic about his work. Matt Bragaw, the lightning specialist at the National Weather Service Forecast Office in Melbourne, Florida, is such a guy. He shares his passion about lightning on his corner of his office’s Web site (at http://www.srh.noaa.gov/mlb/ltgcenter/whatis.html, including a nifty animation of a lightning strike). Matt was kind enough to answer some of our incessant follow-up questions. He warned us that although lightning was one of the earliest remarked upon natural phenomena, it is one of the least understood, with many of the major discoveries about it having been made in only the past fifteen years.

Although there are other kinds of lightning, such as heat lightning and Saint Elmo’s fire, the familiar zigzag lightning we’re talking about here is cloud-to-ground lightning (lightning inside a cloud, also known as cloud-to-cloud lightning, is actually more prevalent). Before we see any sign of lightning on the ground, turbulent wind conditions send water droplets up the cloud while ice particles fall downward. The top of the cloud usually carries a strong positive charge and the bottom a negative one. During the movement of the ice and water droplets within the cloud, electrons shear off the rising droplets and stick to the falling ice crystals. The opposite charges attract until a tremendous electrical charge occurs within the cloud. When the cloud can no longer hold the electrical field, sometimes a faint, negatively charged ladder channel, called the “stepped leader,” materializes from the bottom of the cloud.

While it might appear to us as if the bolt of lightning strikes the earth instantaneously, in one zigzag strike, what you are actually seeing is a whole series of steps, which are only about 50 meters in length. In an e-mail to
Imponderables,
Bragaw elaborates:

Once the leader hits the ground, all of the other branches of the stepped leader’s channel stop propagation toward the earth.

We mentioned that the stepped leader is faint as it leaves the cloud and heads toward the ground. If so, then why is lightning usually so bright? The negatively charged stepped leader repels all negative charge in the ground, while attracting all positive charge, which sends energy back from the ground to the clouds. This “return stroke” occurs in less than 100 microseconds, which is why we can’t differentiate cloud-to-ground movement from ground-to-air. But this upward process, according to Bragaw, “produces almost all the luminosity” that we see when we think we are observing cloud-to-ground lightning strikes.

Twenty to fifty milliseconds (thousandths of a second) after the initial return stroke stops flowing up the channel, “leftover” electrical energy in the cloud often sends more leaders down to the earth in the same channel. Because these “dart leaders” use an already-established channel, they discharge continuously instead of in steps. Even though these subsequent dart leaders don’t need to stop to look for places to hit, as their route is the same as for the first leader, you’ll still see the familiar zigzag. As Bragaw puts it:

Submitted by Robert Underwood of Blue Ridge, Virginia.