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Fantastic Creatures

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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-01.width-990_T3WbZ0G.jpg"/>
<figcaption>The gorilla is one of many animals that remained mythical to Europeans for centuries before they themselves finally laid eyes on them.
        
        <div class="credit">© Roberto A. Sanchez/iStockphoto</div>
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<p>
	Intrigued by Stanley's report, Sir Harry Johnston, then Governor of Uganda, questioned some pygmies he met in 1899. "They at once understood what I meant," he wrote, "and pointing to a zebra-skin and a live mule, they informed me that the creature in question . . . was like a mule with zebra stripes on it." When they showed him the elusive creature's cloven-footed tracks, Johnston changed his mind. "I disbelieved them," he wrote, "and imagined that we were merely following a forest-eland." (The eland is a large African antelope.) Finally, when he got hold of a skin, Johnston changed his mind yet again: "Upon receiving this skin, I saw at once what [it] was—namely, a close relation to the giraffe."</p>
<p>
	From that skin, a pair of skulls, and the pygmies' tales, Johnston was able to conceive what the mysterious animal must look like. It was a strange beast. As the zoologist Bernard Heuvelmans has noted, it reminded one of those mythical creatures comprised of the body parts of various animals. It was like a large antelope but with no visible horns; it had ears similar to but larger than a donkey's; its hindquarters were striped like those of a zebra; and it had an anteater's long tongue.</p>
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-02.width-990_98Dp8Pg.jpg"/>
<figcaption>The antelope-donkey-anteater-giraffe, otherwise known as the okapi
        
        <div class="credit">© Heather Robertson/iStockphoto</div>
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<p>
	Could a more fantastical beast be imagined? Few Europeans believed it existed, but Johnston's persistence paid off. In the early part of this century, the animal finally became known to science as the okapi. Named for Johnston, <span class="science-term">Okapia johnstoni</span> is a heavy-bodied animal with a coat of reddish chestnut, yellowish-white cheeks, and thighs ringed with alternating stripes of cream and purplish black. Johnston's last guess about this oddball creature was right—it is related to the giraffe. To bring to light a huge, unknown mammal in this century astounded the world. As one scientist has written, we today have no idea of "the romance surrounding the discovery of the Okapi, nor of the excitement caused in natural history circles, first by the vague reports of its presence, and later by its actual finding."</p>
<p>
	Those who disbelieve indigenous tales of fabulous creatures might do well to remember the okapi, as well as certain points surrounding its discovery. To wit:</p>
<p>
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<img alt="man with elephant-bird egg" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-03.width-990_HAKJvO1.jpg"/>
<figcaption>An Antandroy tribesman holds the fossil egg of an elephant bird, which stomped through Madagascar until it went extinct about a millennium ago.
        
        <div class="credit">© Frans Lanting/Corbis</div>
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<p>
<strong>Legends often hold some truth.</strong> In the Middle Ages, ivory horns supposedly taken from unicorns were peddled to European royalty for 20 times their weight in gold. Few if any collectors knew that these long, spiraled tusks came from an actual animal, the narwhal, a cetacean that lives in the Arctic. Scholars believe that the remarkably human aspect that the heads of seals and manatees rising above the waves can take on may have given rise to tales of the mermaid, the fabled half-woman, half-fish of the deep.</p>
<p>
	While traveling across Arabia on his return from China in 1294, Marco Polo heard of a bird on Madagascar that was so large it could carry elephants aloft in its talons. Baseless? Nope. Until they went extinct about a thousand years ago, Madagascar's elephant birds were the largest birds that ever lived. Though they couldn't lift an elephant, they did stand ten feet tall and weigh close to half a ton.</p>
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<img alt="pygmy hippo" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-04.width-990_Ilqy4Ot.jpg"/>
<figcaption>The forest-dwelling pygmy hippopotamus is alive and well in West Africa.
        
        <div class="credit">© Dirk Freder/iStockphoto</div>
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<p>
<strong>Local people's tales of fantastic creatures should not be dismissed out of hand. </strong>For centuries, Europeans traveling in remote areas were wont to disregard any legend an indigenous person might have of beasts that they themselves had not seen. This was part paternalism, part justifiable caution in the face of the possibly apocryphal.</p>
<p>
	Yet indigenous people often know whereof they speak. In 1840, for example, outsiders first heard of a dwarf version of the hippopotamus that native Liberians claimed they hunted in the jungle. But since no Europeans had seen a live one, it was not until the early part of this century that biologists finally conceded that the West African pygmy hippo actually exists.</p>
<p>
	In Africa alone, there are myriad instances of animals that foreigners thought fabulous even as locals calmly informed them they were quite real. "Most of these animals were known first from native reports about them," writes the late naturalist Gerald Durrell, adding wryly, "and, of course, primitive tribesmen all over the world spend their time making up stories about animals in order to confuse and delude European zoologists."</p>
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<img alt="Komodo dragon" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-05.width-990_8w8qq6C.jpg"/>
<figcaption>Named for the Indonesian island that is its chief remaining habitat, the Komodo dragon is the world's largest lizard.
        
        <div class="credit">© pius99/iStockphoto</div>
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<strong>Just because a scientist hasn't seen it doesn't mean it doesn't exist. </strong>In 1912, a pilot crash-landed his plane on a small island in the heart of the Indonesian archipelago. "The airman came back with a tale that he had met fierce and monstrous dragons, at least four meters [13 feet] long, which according to the inhabitants ate pigs, goats, and deer, and even attacked horses," writes Bernard Heuvelmans in his classic 1955 work <cite>On the Track of Unknown Animals.</cite> "Needless to say, nobody believed a word of his story." Soon, however, a Dutch botanist based in the region, following up on a story by locals of a <span class="science-term">boeaja darat,</span> or "land crocodile," traveled to the island and "discovered" the Komodo dragon.</p>
<blockquote>
	Surprisingly for many, discoveries of large, previously unknown animals continue to occur.</blockquote>
<p>
	One of the most famous of once-fabulous creatures was first described in 1625. That year, an English adventurer named Andrew Battel published a story about a monster in the heart of Africa known as the <em>pongo</em>.</p>
<p class="article-indent">
	This Pongo is in all proportion like a man, but ... he is more like a Giant in stature, than a man: for he is very tall, [and] hath a man's face, hollow-eyed, with long haire vpon his browes. His face and eares are without haire, and his hands also. His bodie is full of haire, but not very thicke, and it is a dunnish colour... Hee goeth alwaies vpon his legs, and carrieth his hands clasped on the nape of his necke, when he goeth upon the ground... They goe many together, and kill many Negroes that trauaile in the Woods ... Those Pongos are neuer taken aliue, because they are so strong, that ten men cannot hold one of them....</p>
<p>
	Despite such a detailed portrait by a white man, few Europeans believed such a beast existed. A full century-and-a-half after Battel's story appeared, one writer claimed that "the large species, described by Buffon and other authors as of the size of a man, is held by many to be a Chimera." It was not until the mid-19th century that biologists finally described the animal, giving it the scientific name <span class="science-term">Gorilla gorilla.</span></p>
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-06.width-990_uYUTEws.jpg"/>
<figcaption>It took a specimen shot in China by sons of Teddy Roosevelt to finally convince outsiders that the giant panda actually existed.
        
        <div class="credit">© Sam Lee/iStockphoto</div>
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<p>
<strong>Just because it hasn't been seen in a long time doesn't mean it doesn't exist.</strong> In 1869, the French missionary Armand David became the first Westerner to lay eyes on a giant panda, when Chinese hunters brought him a young panda they had killed. David never saw a live panda, and in the ensuing decades, as expedition after expedition failed to turn up the animal, people in the West began to wonder whether the purported black-and-white "bear" even existed. A German expedition to southeast Tibet finally saw one in 1915, but it was not until 1929, when two sons of Theodore Roosevelt shot one in China and placed its stuffed skin in Chicago's Field Museum, that the giant panda finally came into being for many.</p>
<p>
<strong>Even when scientists have specimens in hand, they may remain fantastic.</strong> One of the most famous of the sea serpents in days of yore was the <em>kraken</em>, from the Norwegian word denoting a tree trunk with its roots. Alfred, Lord Tennyson once described the kraken's many arms:</p>
<p class="article-indent">
	And far away into the sickly light,<br/>
	From many a wondrous grot and secret cell<br/>
	Unnumber'd and enormous polypi<br/>
	Winnow with giant arms the slumbering green.</p>
<p>
	Many have felt that the kraken was none other than the giant squid, a tentacled beast with eyes the size of hubcaps and a length that can exceed 60 feet. Yet is the giant squid any less mythical than the kraken? No one has ever seen a giant squid in its natural habitat*; the animal is known only from a few specimens hauled up by fishermen. In 1997, a $5 million expedition funded by the Smithsonian Institution and the National Geographic Society tried to outfit sperm whales with video cameras in order to observe their chief prey in its abode 2,500 feet down. Alas, they saw no giant squid.</p>
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-07.width-990_IQ9WuQy.jpg"/>
<figcaption>Before a fisherman caught one in 1938 off the Comoros Islands, the coelacanth was thought to have been extinct for 90 million years.
        
        <div class="credit">© Hoberman Collection/Corbis</div>
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<p>
<strong>Sometimes animals thought long extinct turn up alive.</strong> The five-foot-long fish known as the coelacanth was thought to have died out a full 25 million years before the dinosaurs vanished, until a fisherman caught one off the African coast in 1938. (The coelacanth has recently turned up in Indonesian waters as well.)</p>
<p>
	Long-lost creatures are still found on land, too. In 1995, the French ethnographer Michel Peissel discovered what appears to be an ancient breed of horse in a remote valley of northeastern Tibet. The Riwoche horse, as his team named the animal for its home region, looks just like horses in cave paintings of the European Stone Age. If an ancient horse can be found in a remote Tibetan valley, is it possible that the fabled giant sloth might one day be found in the remote Amazonian jungle?</p>
<p>
<strong>Despite common wisdom, the world has not been fully explored.</strong> In 1812, the renowned French naturalist Baron Georges Cuvier boldly asserted that "there is little hope of discovering new species of large quadrupeds." Alas, Cuvier was off the mark. A short list of large mammals that have been identified since 1812 might include, in addition to all those mentioned above, the mountain gorilla, Indian tapir, black ape, siamang, gelada, Himalayan takin, Père David's deer, Przewalski's horse, white rhinoceros, pygmy chimpanzee, and Kodiak brown bear.</p>
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/fantastic-creatures-08.width-990_sOavWAA.jpg"/>
<figcaption>Przewalski's horse, a wild horse native to the steppes of Central Asia, was first described by a Russian colonel as late as 1881.
        
        <div class="credit">© Laurent Rozier/iStockphoto</div>
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<p>
	Surprisingly for many, discoveries of large, previously unknown animals continue to occur. Since 1986, several new species of primate have turned up in Madagascar. In the past few years, in a single, mountainous region on the border between Vietnam and Laos, scientists have identified a new species of giant barking deer, a new kind of pig, and a 200-pound bovid, or cow-like animal, known as the pseudo oryx. The seas, in particular, continue to reveal secret beasts, some of them quite sizeable. Marine biologists have identified three new species of beaked whale off Japan in 1958, off California in 1966, and off Peru in 1991, respectively. And in 1976, fishermen near Hawaii hauled up a 15-foot shark weighing just under a ton. Never before seen, this monster plankton-feeder has since been dubbed "megamouth."</p>
<p>
	The great 19th-century American naturalist Louis Agassiz once held that "[e]ach time that a new and surprising fact is revealed by science, people say first that 'it is not true,' then, that it 'disagrees with religion,' and, finally, that 'everyone has always known it.'" Those who hold no truck with local tales of strange creatures off in the forest may do well to consider these words, just as they may do well to remember the story of that fantastic antelope-donkey-anteater-giraffe, the okapi.</p>
<p class="article-footnote">
	*Editor's note: Since this article was written, Japanese scientists have observed and photographed a giant squid in its natural habitat (see Further Reading).</p>

Trace the discovery of animals once thought mythical, including the okapi, the narwhal, and the elephant bird.

Diamonds in the Sky

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<p>Glittering stars in the night sky aside, scientists have long known that some diamonds hail from the heavens. In 1981, for example, when Smithsonian researchers tried to cut through a large iron meteorite that had crash-landed in the Allen Hills of Antarctica, the sawteeth on their blade got all chewed up. Subsequent X-rays showed that the stone was riddled with microscopic diamonds, the hardest substance known. The scientists theorized that the meteorite's diamonds were born during a cataclysmic collision out in the asteroid belt.</p>
<h3>Cosmic gems</h3><p>Other meteoritic diamonds apparently hail from deep space. In 1987, a team of researchers headed by Edward Anders and Roy Lewis of the University of Chicago reported the discovery of meteorite-embedded diamonds so miniscule that trillions could fit on the head of a pin. Unlike the Smithsonian diamonds, these microscopic crystals contain an isotopic mixture of xenon gas not found on Earth. "It seems necessary to invoke an extra-solar origin for the diamond," the scientists concluded in a paper published in Nature, indicating a birth outside our solar system.</p><p>Indeed, the team proposed that the lucent crystals formed in the atmosphere of a "red giant" or dying star before it collapsed and exploded billions of years ago. The supernova would have sent the diamond-studded material far out into space, where in the fullness of time some pieces eventually fell to Earth. If this scenario is correct, the researchers said, then interstellar dust may be peppered with tiny diamonds.</p>
<figure class="richtext-image full-width">
<img alt="round sky of stars" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-01.width-990_178z20Y.jpg"/>
<figcaption>Scientists have long suspected that at least some diamonds found on Earth hail from the heavens.
        
        <div class="credit">NASA, ESA, and the Hubble Heritage Team (STScI/AURA)</div>
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<p>Still other diamonds are apparently created during the fiery instant when meteors and meteorites slam into Earth. In the 1960s, scientists discovered more microscopic diamonds in the remains of the vast Canyon Diablo meteorite, which formed Meteor Crater in Arizona. The diamonds are sand-grain-sized, only hundredths of an inch across. Other crater-related diamonds are larger. In the 35-mile-wide Popigari crater in Siberia, the result of a huge impact 35 million years ago, Russian researchers unearthed polycrystalline diamond clusters reaching nearly half an inch across.</p><p></p>
<figure class="richtext-image full-width">
<img alt="Meteor Crater" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-02.width-990_gL9ESCg.jpg"/>
<figcaption>Microscopic diamonds appear to have formed in the fiery instant when the meteor that created Arizona's Meteor Crater struck the Earth.
        
        <div class="credit">© Stephan Hoerold/iStockphoto</div>
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<p></p><p>Many of these impact-spawned diamonds bear the cubic structure of ordinary, Earth-grown diamonds. But analysts studying the Canyon Diablo diamonds found that up to a third of them bore a hexagonal atomic structure never before seen in diamond. Mineralogists named the new hexagonal variant of diamond lonsdaleite after the British mineralogist Dame Kathleen Lonsdale, who helped advance the study of natural diamond crystals.</p><h3>Origins unclear</h3><p>Today, more than 30 years after the discovery of the Canyon Diablo diamonds, scientists still debate how such mini-diamonds form. Some suspect they were wrought in the vacuum of space by vapor deposition, a process that specialists can use to make synthetic diamond here on Earth. Others maintain that, within the hurtling meteorite itself, carbon atoms (or, in a minority opinion, grains of meteoritic black graphite) transformed instantly into diamond during the extraordinary heat and shock of impact.</p><p>Even nearby planets may be churning out diamonds.</p><p>Whatever the origin of meteorite diamonds, some scientists believe they have found evidence that the colossal cloud of dust thought to be thrown up into the atmosphere in the wake of such impacts may spread newly formed diamond dust all around the world. In 1991, Canadian geologists David B. Carlisle and Dennis R. Braman reported finding Lilliputian diamonds embedded in a layer of sediment 65 million years old—right at the time when many scientists believe a giant meteor slammed into Earth and precipitated the extinction of the dinosaurs.</p><p>Can these miniature diamonds, which are so fine-grained that the researchers deem them the result of a collision, serve as an indicator of this ancient catastrophe, much as the famous iridium layer has done? Scientists won't be able to say without further study, but the idea holds promise. (In the 1998 book <i>The Nature of Diamonds,</i> the geologist George Harlow and two Russian colleagues wrote simply, "This subject is very new, and many exciting discoveries have yet to be announced.")</p><p></p>
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<img alt="black diamond" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-03.width-990_c8DQiPB.jpg"/>
<figcaption>For scientists, the allure of carbonados, otherwise known as black diamonds, lies not in their look but in their age and origin.
        
        <div class="credit">Steve Haggerty</div>
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<p></p><h3>black diamonds</h3><p>Outer space may also be the birthplace of the mysterious black diamonds known as carbonados. From the Portuguese word for burned or carbonized, carbonados were first found in Brazil in the 1800s and have since turned up elsewhere, most notably in central Africa. Unlike the clear diamonds of engagement rings, which are single crystals, black diamond consists of aggregations of individual crystals, which lend the gem its dark color. The largest diamond ever found was a carbonado from Brazil. Named Sergio, the stone weighed 3,167 carats. (One carat equals one-fifth of a gram.)</p><p>The origins of carbonados have long baffled scientists. Black diamonds don't adhere to the rules of diamond mineralogy, and they don't occur in the usual places where clear diamonds turn up. Even so, scientists initially believed they must have been fashioned in the same conditions under which clear diamonds are thought to form. That is, they were crafted deep within the Earth, 100 to 300 miles down, when intense heat and pressure transformed carbon into diamonds, which volcanic eruptions then lofted to the surface.</p><p>But that theory suffered a blow when scientists examined the carbon isotopes of black diamonds. (Isotopes are species of a chemical element that reside in the same place on the periodic table but have different atomic weights and physical properties.) Unlike clear diamonds, black diamonds feature ratios of the two most common carbon isotopes in the Earth's crust, carbon-12 and carbon-13. These isotopes characterize surface carbons rather than those found in the Earth's depths.</p><p></p>
<figure class="richtext-image full-width">
<img alt="dying star" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-04.width-990_hsJM3wY.jpg"/>
<figcaption>Did carbonados form in the unimaginably explosive shock waves emitted by dying stars, such as the one whose death throes created the Eskimo nebula (seen here)?
        
        <div class="credit">NASA, Andrew Fruchter and the ERO Team, Sylvia Baggett and Zoltan Levay (STScI), Richard Hook (ST-ECF)</div>
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<p></p>
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<h3>Wherefrom?</h3><p>This finding helped lead to a new theory of carbonado formation. In 1985, Joseph Smith of the University of Chicago and J. Barry Dawson of the University of Sheffield in England suggested in an article published in the journal Geology that large meteor impacts in the Precambrian Era (570 million years ago back to Earth's beginning some 4.5 billion years ago) formed the black diamonds we find today. Scientists had long deemed carbonados quite old, because the streams where they are typically uncovered cut through geologic strata dated from one to more than two billion years old. In fact, recent atomic measurements of black diamonds have placed their origins at nearly four billion years ago, a time when a constant barrage of giant meteors battered the Earth.</p><p>In the 1990s, other scientists showed that Brazilian and African carbonados bear similar isotopes of carbon and nitrogen, suggesting a common origin, while still others provided theoretical and physical evidence that black diamonds could have arisen during the extreme shock and heat of a meteor impact. But why, some scientists wondered, had no unambiguous evidence ever been shown for craters associated with carbonados?</p><p>As for tapping the riches of any diamonds from space, don't hold your breath.</p><p>Geologist Stephen Haggerty of the University of Massachusetts at Amherst had an idea why, and he shared it with a dumbfounded audience at a 1996 American Geophysical Union meeting in Baltimore. Carbonados were born not on Earth, either the way regular diamonds are or by meteor impact, he said. Rather, they originated in dying stars, when shock waves from exploding red giants crushed carbon into dense aggregations of black diamond and sent them hurtling into deep space. Eons later, the sun's gravity lured some of this material into our solar system, where blocks of it slammed into our atmosphere, shattering into the fragments we find strewn over select areas today, perhaps billions of years after they formed.</p><p></p>
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-05.width-990_IHe196D.jpg"/>
<figcaption>Neptune, seen here in a composite image from the Voyager 2 mission, may be a veritable diamond factory.
        
        <div class="credit">NASA/JPL</div>
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</figure>
<p></p><h3>Lucid in the sky with diamonds</h3><p>Even nearby planets may be churning out diamonds. In fact, planetary scientists say that Uranus and Neptune, the seventh and eighth planets from the sun, may <i>rain</i> diamonds, which then pile up miles-thick at the planets' cores.</p><p>Uranus and Neptune are each nearly four times the size of Earth. Scientists believe that, beneath an outer layer of hydrogen and helium, the gaseous atmospheres of both planets contain 10 to 15 percent methane, a hydrocarbon. Deep within the extremely dense atmospheres, above a rocky core, these planets are also thought to bear temperatures ranging from 3,000 to 12,000°F and pressures varying from 200,000 to 6,000,000 times the pressure of our own atmosphere.</p><p>In other words, possibly ideal conditions for producing diamonds.</p><p>With this in mind, a team at Lawrence Livermore National Laboratory tested in the early 1980s what would happen to methane under intense pressure. One of the team's leaders, Marvin Ross, had calculated that the gas would separate into hydrogen and carbon at temperatures above 3,000°F and pressures exceeding 200,000 Earth atmospheres. The carbon atoms would be squeezed so tightly together that they would become diamonds, he theorized.</p><p>To find out if he was right, Ross and his team used a gas cannon to severely compress and shock methane samples. Resulting data, they later reported, indicated the fleeting formation of diamonds in the instant before the target material evaporated, and recent experiments at several labs support the predictions.</p><p></p>
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<img alt="Quintuplet cluster" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/diamonds-in-the-sky-06.width-990_rMpFw4e.jpg"/>
<figcaption>For the foreseeable future, the greatest benefit we'll see from diamonds in the sky will be increased scientific knowledge.
        
        <div class="credit">NASA, Don Figer, STScI</div>
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</figure>
<p></p><h3>Reaping the benefits</h3><p>As for tapping the riches of any diamonds from space, don't hold your breath. Earth-hitting meteorites that either bear or engender diamonds are few and far between, and unlike diamonds you're likely used to, their associated diamonds often cannot be seen, much less admired, with the naked eye. Black diamonds, for their part, are rare and are primarily used for industrial purposes. And the challenges of harvesting any diamonds on Uranus and Neptune, which are roughly 1,700 and 2,720 million miles away from Earth, respectively, are as clear as the Koh-i-Noor diamond. Alas, scientific understanding is the primary beneficiary of diamonds from the heavens.</p>
<div class="newsletter"></div>

<p data-block-key="s768i">Meteorites, the outer planets, even interstellar dust—all may possess our favorite sparkling gem.</p>

Albert Einstein in 1921, the year he won the Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect."

Putting Relativity to the Test

<p data-block-key="1rhuw">Nearly a century after Einstein published his general theory, experiments continue to confirm its every prediction.</p>

This photograph does a pretty good job of "describing" ripples. But a mathematician could do it with greater precision and predictive power. Image credit: andressolo, Flickr, CC BY 2.0

Describing Nature With Math

<p data-block-key="qsbm2">How do scientists use mathematics to define reality? And why?</p>

Secrets of Ancient Navigators

<p>
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<img alt="stormy sea" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/secrets-of-ancient-navigators-01.width-990_koTDchN.jpg"/>
<figcaption>How did mariners of old navigate their way around the open ocean?
        
        <div class="credit">© Felix Mí¶ckel/iStockphoto.com</div>
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</p>
<h3>
	Land and air</h3>
<p>
	The first seafarers kept in sight of land. That was the first trick of navigation—follow the coast. To find an old fishing ground or the way through a shoal, one could line up landmarks, such as a near rock against a distant point on land; doing that in two directions at once gave a more or less precise geometric location on the surface of the sea. Sounding using a lead and line also helped. "When you get 11 fathoms and ooze on the lead, you are a day's journey out from Alexandria," wrote Herodotus in the fourth century B.C. The Greeks even learned to navigate from one island to the next in their archipelago, a Greek word meaning "preëminent sea." They may have followed clouds, which form over land, or odors, which can carry far out to sea.</p>
<p>
	But what if land were nowhere nearby? The Phoenicians looked to the heavens. The sun moving across the commonly cloudless Mediterranean sky gave them their direction and quarter. The quarters we know today as east and west the Phoenicians knew as <em>Asu</em> (sunrise) and <em>Ereb</em> (sunset), labels that live today in the names Asia and Europe. At night, they steered by the stars. At any one time in the year at any one point on the globe, the sun and stars are found above the horizon at certain fixed "heights"—a distance that mariners can measure with as simple an instrument as one's fingers, laid horizontally atop one another and held at arm's length. The philosopher Thales of Miletos, as the Alexandrian poet Kallimachos recorded, taught Ionian sailors to navigate by the Little Bear constellation fully 600 years before the birth of Christ:</p>
<p class="article-quote article-indent">
	Now to Miletos he steered his course<br/>
	That was the teaching of old Thales<br/>
	Who in bygone days gauged the stars<br/>
	Of the Little Bear by which the Phoenicians<br/>
	Steered across the seas.</p>
<p>
<figure class="richtext-image full-width">
<img alt="bird with fish" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/secrets-of-ancient-navigators-02.width-990_K7gqTru.jpg"/>
<figcaption>Watching the direction a seabird traveled with food for its young was one reliable method to find the nearest land.
        
        <div class="credit">© Ken Canning/iStockphoto.com</div>
</figcaption>
</figure>
</p>
<h3>
	Bird and wave</h3>
<p>
	The Norsemen had to have other navigational means at their disposal, for in summer the stars effectively do not appear for months on end in the high latitudes. One method they relied on was watching the behavior of birds. A sailor wondering which way land lay could do worse than spying an auk flying past. If the beak of this seabird is full, sea dogs know, it's heading towards its rookery; if empty, it's heading out to sea to fill that beak. One of the first Norwegian sailors to hazard the voyage to Iceland was a man known as Raven-Floki for his habit of keeping ravens aboard his vessel. When he thought he was nearing land, Raven-Floki released the ravens, which he had deliberately starved. Often as not, they flew "as the crow flies" directly toward land, which Raven-Floki would reach simply by following their lead.</p>
<blockquote>
	Like Eskimos study the snow, the Polynesians watched the waves.</blockquote>
<p>
	Heeding the flightpaths of birds was just one of numerous haven-finding methods employed by the Polynesians, whose navigational feats arguably have never been surpassed. The Polynesians traveled over thousands of miles of trackless ocean to people remote islands throughout the southern Pacific. Modern navigators still scratch their heads in amazement at their accomplishment.</p>
<p>
	Like Eskimos study the snow, the Polynesians watched the waves, whose direction and type relinquished useful navigational secrets. They followed the faint gleam cast on the horizon by tiny islets still out of sight below the rim of the world. Seafarers of the Marshall Islands built elaborate maps out of palm twigs and cowrie shells. These ingenious charts, which exist today only in museums, denoted everything from the position of islands to the prevailing direction of the swell.</p>
<p>
<figure class="richtext-image full-width">
<img alt="compass with map" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/secrets-of-ancient-navigators-03.width-990_8d51WKJ.jpg"/>
<figcaption>The chart and the compass were two early technological breakthroughs that benefited seafarers.
        
        <div class="credit">© DNY59/iStockphoto.com</div>
</figcaption>
</figure>
</p>
<h3>
	Chart and compass</h3>
<p>
	Charts have aided mariners ever since the Alexandrian astronomer Ptolemy created the first world atlas in the second century A.D. The redoubtable Ptolemy even plotted latitude and longitude lines on his atlas's 27 maps, though the farther one got from the known world centered on the Mediterranean, the dangerously less reliable they became. Even before Ptolemy, there were sailing directions—the Greeks called them periplus or "circumnavigation"—that were compiled from information collected from sailors far and wide. One of these, <cite>The Periplus of the Erythraean Sea</cite>, a document written in the first century by a Greek merchant living in Alexandria, described trading routes as far east as India. By the 10th century, Italian-made portolans supplied detailed directions, distances, depths, and coastal descriptions, and by the 13th century, sea maps with scale and bearings began to appear.</p>
<p>
	The greatest advance in navigation came with the compass. The Chinese apparently knew about the powers of magnetism as early as the third millennium B.C., when, historians tell us, one army defeated another after the battlefield had become enveloped in dense fog by using a device known as a "point-south carriage." This was a standard carriage for carrying royalty with a small, rotating figure mounted on the front, which by magnetism always pointed south. (The Chinese chose to have the arrow point south rather than north.)</p>
<p>
	But no one seems to have manipulated the lodestone for sea navigation until early in the present millennium. The first mention of the compass in the West comes from the Englishman Alexander Neckham, who wrote in 1187 that "sailors use a magnetic needle which swings on a point and shows the direction of the north when the weather is overcast." Despite its usefulness, the compass took a long time to come into wide use, as many seamen thought it operated by black magic. (Hence the invention of the binnacle, in which sea captains could hide their recondite instrument from the suspicious eyes of the crew.) In the meantime, sailors relied on natural forces they could readily comprehend.</p>
<p>
<figure class="richtext-image full-width">
<img alt="calm sea" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/secrets-of-ancient-navigators-04.width-990_9awnzVV.jpg"/>
<figcaption>Currents may be invisible to the untrained, but not to seasoned mariners.
        
        <div class="credit">© Clicks/iStockphoto.com</div>
</figcaption>
</figure>
</p>
<h3>
	Current and wind</h3>
<p>
	One of these was currents. From time immemorial, journeys have been made or broken by these undersea winds. The western-trending currents of the Indian Ocean, for one, are likely responsible for the Indonesian-based race of Madagascar, an African island more than 3,500 miles from the nearest bit of Indonesia. Similarly, the clockwise currents in the North Atlantic helped doom one of the greatest land scams in history: Erik the Red's colonization scheme for the island he cleverly dubbed "Greenland." Of the 25 ships that sailed west from Norway in the year 990, only 14 arrived.</p>
<p>
	The father of those North Atlantic currents—the Gulf Stream—was named by none other than Benjamin Franklin. While deputy Postmaster-General of Great Britain in the 18th century, Franklin noticed that his mail ships to the American colonies took longer than whaling ships. Questioning whalers, he learned of a powerful current originating from the Gulf of Mexico—hence his name for it—and sweeping northeast into the North Atlantic (and, incidentally, giving the British Isles a climate positively balmy for such a northern latitude).</p>
<blockquote>
	The sextant allowed users to determine their latitude to within a sea mile or two, even from a swaying deck.</blockquote>
<p>
	Like currents, trade winds have always been important to mariners. Those blowing heads on yellowed old maps were not mere decoration. In the Indian Ocean, for example, Indian traders over the ages have ridden the northeast monsoon to Africa in the cool, dry winter and taken the southwest monsoon back to the subcontinent in the hot, wet summer. To make their annual voyages from Tahiti to Hawaii, a journey of several thousand miles, the Polynesians hitched a ride on the prevailing south-easterly wind, setting a starboard tack and sailing northeast.</p>
<p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/secrets-of-ancient-navigators-05.width-990_twpYNDs.jpg"/>
<figcaption>With the sextant for determining latitude and the chronometer for longitude, sailors by the 1800s were able to navigate the high seas with great precision.
        
        <div class="credit">© Bruno Buongiorno Nardelli/iStockphoto.com</div>
</figcaption>
</figure>
</p>
<h3>
	Sun and star</h3>
<p>
	For millennia, as sailors from the Phoenicians to the Polynesians knew, the heavens remained the best way to find one's north-south position. Increasingly sophisticated devices were designed over the centuries to measure the height of the sun and stars over the horizon. The gnomon or sun-shadow disk operated like a sundial, enabling the user to determine his latitude by the length of the sun's shadow cast on a disk floating level in water. The Arabian <em>kamal</em> was a rectangular plate that one moved closer or farther from one's face until the distance between the North star and the horizon exactly corresponded to the plate's upper and lower edges. The distance the plate lay away from the face—measured by a string tied to the center of the plate and held at the other end to the tip of the nose—determined the latitude.</p>
<p>
	In the Middle Ages, sailors relied on the astrolabe, a disc of metal that one held suspended by a small ring. The disc had a scale with degrees and a ruler for measuring the height of an astronomical body. Other medieval mariners preferred the cross-staff, a T-shaped device whose base was held up to the eye. One measured the sun's height by pulling the slidable top of the T toward one's eye until the sun lay at the top and the horizon at the bottom. Since blindness resulted from frequent use, the explorer John Davis invented the back-staff in 1595, which enabled one to get the same measurement with one's back to the sun. The sextant was the most advanced of these devices, allowing users to determine their latitude to within a sea mile or two, even from a swaying deck.</p>
<h3>
	Time</h3>
<p>
	In the years after the sextant was invented in 1731, many held out hope that it would aid in east-west navigation as well—that is, in finding longitude. Sailors could employ the sextant to figure longitude using the lunar-distance method, but with the astronomical tables of the 18th century, the process could take several hours to work out one's position—not remotely good enough for sea travel. In the end, it was the dogged clockmaker, John Harrison, who solved the longitude problem with his chronometers. And today, the precocious step-child of these highly accurate clocks, the Global Positioning System, has finally proved the Roman dramatist Seneca right, when he wrote in the first century:</p>
<p class="article-quote article-indent">
	There will come an age in the far-off years<br/>
	When Ocean shall unloose the bonds of things,<br/>
	When the whole broad earth shall be revealed....</p>

From following seabirds to watching the stars, early seafarers developed a host of ingenious ways to find their way.

Mysteries of Great Zimbabwe

<p>
	De Barros thought the edifice, which he never saw, was Axuma, one of the cities of the Queen of Sheba. Other Portuguese chroniclers of the day linked the rumored fortress with the region's gold trade and decided it must be the biblical Ophir, from which the Queen of Sheba procured gold for the Temple of Solomon.</p>
<p>
<figure class="richtext-image full-width">
<img alt="view from Great Zimbabwe" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-01.width-990_Xvu5L3Y.jpg"/>
<figcaption>The view from Great Zimbabwe, which Europeans didn't "discover" until the 1870s
        
        <div class="credit">© Karen Graham/iStockphoto</div>
</figcaption>
</figure>
</p>
<h3>
	A city of stone</h3>
<p>
	This notion persisted for centuries, right up until the monument's 19th-century European "discovery." That distinction fell to a young German named Carl Mauch. In 1871, Mauch, eager to seek for the fabled ruins of Ophir, penetrated deep into what is today southern Zimbabwe. In August, he reached the home of a lone German trader, who told him of "quite large ruins which could never have been built by blacks." On September 5, local Karanga tribesmen led Mauch to the site.</p>
<p>
	In the midst of a wooded savanna backed by bare granite hills stood a city of stone. Its beautifully coursed walls curved and undulated sinuously over the landscape, blending into the boulder-strewn terrain as if having arisen there naturally. Bearing no mortar, as de Barros had correctly heard, the walls nevertheless reached enormous height, standing as high as 32 feet over the surrounding savanna. Of fully 100 acres of these granite enclosures, not a single one was straight.</p>
<p>
	Mauch was looking at the greatest pre-Portuguese ruins of sub-Saharan Africa.</p>
<p>
<figure class="richtext-image full-width">
<img alt="modern hut by ancient wall" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-02.width-990_Dld5nNb.jpg"/>
<figcaption>A modern-day thatch dwelling sits amid ancient walls on the site, which lies in southeastern Zimbabwe.
        
        <div class="credit">© Darren Patterson/iStockphoto</div>
</figcaption>
</figure>
</p>
<h3>
	Dim view</h3>
<p>
	Unfortunately, Mauch, for all his tenacity, was "no thinker," as Peter Garlake, author of the definitive archeological text on Great Zimbabwe, deemed him. And Mauch only boosted the Portuguese theories of three centuries before. The soapstone and iron relics he uncovered told him that a "civilized [read: white] nation must once have lived there." From a lintel, he cut some wood that he described as reddish, scented, and very like the wood of his pencil. Therefore, he concluded, the wood must be cedar from Lebanon and must have been brought by Phoenicians. And <i>therefore,</i> the Great Enclosure—the edifice's most impressive structure, which local Karanga called <i>Mumbahuru,</i> "the house of the great woman"—must have been built by the Queen of Sheba.</p>
<blockquote>
	Mauch was looking at the greatest pre-Portuguese ruins of sub-Saharan Africa.</blockquote>
<p>
	As it turns out, Mauch's description of the wood aptly characterizes the African sandalwood, a local hardwood that later visitors also found in the walls of the Great Enclosure. But no one would know that for years.</p>
<p>
	In the meantime, Mauch's line of reasoning, distinguished as it was by the most purblind logic, perfectly suited Cecil Rhodes, whose British South Africa Company (BSA) occupied Mashonaland in 1890. (Mashonaland lies just to the north of Great Zimbabwe.) Inextricably steeped in his native country's racist views, Rhodes bought into Mauch's take without a second thought. Indeed, on Rhodes' first visit to the site, local Karanga chiefs were told that "the Great Master" had come to see "the ancient temple which once upon a time belonged to white men."</p>
<p>
<figure class="richtext-image full-width">
<img alt="wall height" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-03.width-990_GlCh9uB.jpg"/>
<figcaption>The highest of Great Zimbabwe's walls stand three stories tall.
        
        <div class="credit">Cicada Films</div>
</figcaption>
</figure>
</p>
<h3>
	Ignoring the obvious</h3>
<p>
	Eager to nail down the edifice's exotic origins once and for all, Rhodes and his BSA quickly sponsored an investigation of Great Zimbabwe. They hired one J. Theodore Bent, whose only claim to expertise lay in an antiquarian interest born of travels through the eastern Mediterranean and Persian Gulf. Bent adhered just as tenaciously as Rhodes to the notion of the city's non-black origin, though to his credit he didn't automatically swallow the link to the Queen of Sheba. (As he set to work at Great Zimbabwe, he later recalled, "the names of King Solomon and the Queen of Sheba were on everybody's lips, and have become so distasteful to us that we never expect to hear them again without an involuntary shudder.")</p>
<p>
	All the artifacts Bent subsequently uncovered screamed "indigenous." Pottery sherds and spindle whorls; spearheads of iron, bronze, and copper; axes, adzes, and hoes; and gold-working equipment such as tuyères and crucibles—all were very similar to household objects used by the local Karanga. Yet Bent, clearly incapable of following where the evidence might lead him, concluded ("a little lamely and nebulously," notes Garlake) that "a prehistoric race built the ruins ... a northern race coming from Arabia ... closely akin to the Phoenician and Egyptian ... and eventually developing into the more civilized races of the ancient world."</p>
<p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-04.width-990_XZxCvd3.jpg"/>
<figcaption>All artifacts that Bent turned up pointed to an indigenous origin of Great Zimbabwe and its builders, but he would have none of it.
        
        <div class="credit">Cicada Films</div>
</figcaption>
</figure>
</p>
<h3>
	"Reckless blundering"</h3>
<p>
	Bent was amateurish and narrow-minded but not utterly incompetent. The same could not be said of Richard Nicklin Hall, a local journalist and author of <cite>The Ancient Ruins of Rhodesia</cite>. In what would prove to be one of the most sickeningly misguided assignments in the history of archeological preservation, the BSA appointed Hall Curator of Great Zimbabwe, with a mandate to undertake "not scientific research but the preservation of the building."</p>
<p>
	Instead, Hall, hell-bent on finally settling the issue of its origins, launched into a full-scale "archeological" investigation. Claiming he was removing the "filth and decadence of the Kaffir occupation," he scoured the site for signs of its white builders, discarding from three to 12 feet of stratified archeological deposits throughout Great Zimbabwe. An archeologist who visited the site shortly after Hall left deemed his fieldwork "reckless blundering ... worse than anything I have ever seen."</p>
<blockquote>
	Great Zimbabwe was home in its heyday to some 12,000 to 20,000 people.</blockquote>
<p>
	Word eventually got back to the BSA of Hall's desecration of southern Africa's greatest archeological treasure, and he was dismissed. But the damage had been done. "Hall's disastrous activities left only vestiges of archeological deposits within the walls," wrote Garlake in his book <cite>Great Zimbabwe</cite>, "a paucity that was to inhibit all future scientific work."</p>
<p>
<figure class="richtext-image full-width">
<img alt="eroded wall" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-05.width-990_pCSWlER.jpg"/>
<figcaption>David Randall-MacIver, the first archeologist to study Great Zimbabwe, declared it unequivocally of African origin.
        
        <div class="credit">Cicada Films</div>
</figcaption>
</figure>
</p>
<h3>
	Archeology begins</h3>
<p>
	Contrite, the BSA hired archeologist David Randall-MacIver, protégé of the great Egyptologist Flinders Petrie, to investigate the site. Hall's polar opposite in almost every way, Randall-MacIver quickly concluded that former mud dwellings within the stone enclosures "are unquestionably African in every detail and belong to a period which is fixed by foreign imports as, in general, medieval."</p>
<p>
	While MacIver's careful work set the stage for the sound archeological inquiry of Great Zimbabwe, racial prejudice surrounded the monument until quite recently. In the 1960s and 1970s, as the edifice grew into a potent symbol of the African Nationalist movement, the white government of Rhodesia set about suppressing the findings of prehistorians who claimed that Africans had built Great Zimbabwe. (Garlake, for one, was forced out of the country.) But those problems went away when Zimbabwe, as the country is known today, achieved majority rule two decades ago, and now we can look at Great Zimbabwe free of racial overtones.</p>
<p>
</p>
<h3>
	"Venerated houses"</h3>
<p>
	Many believe that "Zimbabwe" is a contraction of the Shona phrase <em>dzimba dza mabwe</em>, "houses of stone." (The Shona are Bantu people of Zimbabwe and southern Mozambique.) Garlake, for his part, feels the word more likely derives from <em>dzimba woye</em>, "venerated houses," a term usually reserved for chiefs' houses or graves.</p>
<p>
	Either way, archeological investigation has shown that the edifice's monumental walls did once enclose houses. Great Zimbabwe was a city, home in its heyday to some 12,000 to 20,000 people. To this day, <em>daga</em>, a clayey conglomerate of gravel that is Africa's most common indigenous building material, still stains the soil within Great Zimbabwe a robust red color.</p>
<p>
	While few traces of the mud houses remain, the towering stone walls stand in mute testimony to the city's former greatness. Quarried from the nearby granite hills, the rock used in the walls' construction easily split along fracture planes, giving the stones a cuboidal shape that lent itself to stacking without need of mortar. Ranging from four to 17 feet thick, Great Zimbabwe's walls are about twice as high as they are wide. This results in a very sturdy structure, which spreads its pressure evenly over the ground and adjusts well to subsidence. When two walls meet, they abut eachother with unbroken vertical joints; there are no interlocking stones. In the finest walls, workers knapped and dressed the stones so well that the coursing is as smooth as a modern brick wall.</p>
<blockquote>
	Whites did not build Great Zimbabwe, blacks did, and this fact only deepens the sense of mystery.</blockquote>
<p>
	The Great Enclosure is the largest single prehistoric structure south of the Sahara. Looking from the air like a giant gray bracelet, its elliptical Outer Wall is more than 800 feet long and contains an estimated 182,000 cubic feet of stone, more than in all the site's other ruins combined. Garlake believes the Great Enclosure, which encircles a series of smaller stone walls and a Conical Tower shaped like a stone beehive, was likely a royal residence.</p>
<p>
<figure class="richtext-image full-width">
<img alt="Conical Tower" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-07.width-990_G0vjKYX.jpg"/>
<figcaption>Archeologists have determined that the Conical Tower is completely solid. Its original purpose remains unknown.
        
        <div class="credit">Cicada Films</div>
</figcaption>
</figure>
</p>
<h3>
	Rise and fall</h3>
<p>
	While the site was occupied in ancient times—iron was in use there by the third century A.D.—its rise to prominence, and the advent of the finest walls, occurred in the 14th and 15th centuries during a florescence in trade. Great Zimbabwe happened to lie right on the route between the region's gold-producing regions and ports such as Sofala on the Mozambique coast, where merchants traded African gold and ivory for beads, cloth, and other goods from Arabia and farther east. The site may also have been a religious center, as evidenced by stone monoliths and "altars" found throughout the site, along with enigmatic soapstone birds and figures that, says Garlake, "point to the important role of ritual and symbol in the art and architecture of Great Zimbabwe."</p>
<p>
	By the mid-15th century, however, the balance of trade had shifted to the north. Local resources had also apparently dwindled to dangerously low levels from overuse, and salt was scarce. Whatever the cause, Great Zimbabwe's people abandoned their once-glorious stone city, leaving the site a ruin that Mauch found 400 years later inhabited by local Karanga people who had no idea of its history.</p>
<p>
<figure class="richtext-image full-width">
<img alt="Professor Mathiva" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/mysteries-of-great-zimbabwe-08.width-990_Tqsgg0l.jpg"/>
<figcaption>The Lemba, including their spiritual leader Professor Matshaya Mathiva (seen here), believe their ancestors erected Great Zimbabwe.
        
        <div class="credit">Cicada Films</div>
</figcaption>
</figure>
</p>
<h3>
	Unsolved mysteries</h3>
<p>
	Despite decades of study, mysteries still cling to Great Zimbabwe like ivy. How did its residents manage to monopolize trade in the area? To what degree was it a religious center? Why was it abandoned? Even the question that, as Garlake said about the site itself, "has given rise to such strong, widespread, and often bizarre emotional responses"—who built it?—has been only partly answered.</p>
<p>
	To wit: <em>Which</em> Africans built it? Many tribes, including the Shona and Venda, maintain that their ancestors were responsible for Great Zimbabwe, but the Lemba are "particularly insistent," says University of London scholar Tudor Parfitt. "They claim that one of their clans, the Tovakare, were the actual builders of Zimbabwe," Parfitt says. "They even call them Tovakare Muzimbabwe, which means 'the ones that built Zimbabwe.'"</p>
<p>
	Certain evidence appears to support the Lemba claim. For instance, unlike other Bantu tribes, who bury their dead in a crouched posture, the Lemba bury theirs in an extended position, as did the ancient Zimbabweans. One of the strongest pieces of evidence concerns trade, Parfitt says. "Great Zimbabwe was a civilization that was constructed very largely on wealth generated from cattle and trade. And given that for hundreds of years we know the Lemba were the great traders of southern Africa, it seems almost certain that their ancestors would have been involved in this trading nexus between Great Zimbabwe and the Indian Ocean."</p>
<blockquote>
	"The mystery of Zimbabwe is the mystery which lies in the still pulsating heart of native Africa."</blockquote>
<p>
	If the Lemba contention is true, does this mean that outsiders—that is, not native Africans—built Great Zimbabwe? After all, the Lemba have Semitic origins (see <a href="/--RESOURCEID=7357--/">Tudor Parfitt's Remarkable Quest</a>). The answer is no, because by the time Great Zimbabwe was built in medieval times, the Lemba had become decidedly African, having so thoroughly intermixed with Bantu Africans over many hundreds of years that today, among other African traits, the Lemba have dark skin and speak a Bantu language.</p>
<p>
	Indeed, the more contentious part of that question "who built it?" has finally been put to rest almost 450 years after Joí£o de Barros and others first propounded it. Whites did not build Great Zimbabwe, blacks did, and this fact only deepens the sense of mystery enveloping the site. As archeologist Gertrude Caton-Thompson declared back in 1931:</p>
<p class="article-indent article-quote">
	Examination of all the existing evidence, gathered from every quarter, still can produce not one single item that is not in accordance with the claim of Bantu origin and medieval date. The interest in Zimbabwe and the allied ruins should, on this account, to all educated people be enhanced a hundred-fold; it enriches, not impoverishes, our wonderment at their remarkable achievement ... for the mystery of Zimbabwe is the mystery which lies in the still pulsating heart of native Africa.</p>

Who built sub-Saharan Africa's greatest ancient wonder, and why did they abandon it?

Life in the Abyss

<p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-01.width-990_UviwV10.jpg"/>
<figcaption>A fish hovers by a forest of tubeworms at a hydrothermal vent on the ocean floor.
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<p>
	Yet amazing communities of life exist at hydrothermal vents and the so-called "black smoker" chimneys that, given the right conditions, rise above them like erupting stalagmites. Blind shrimp, giant white crabs, and a variety of tubeworms are just some of the more than 300 species of vent life that biologists have identified since scientists first blundered upon this otherworldly community two decades ago. More than 95 percent of these species are new to science.</p>
<p>
	It's hard to say which is more remarkable to scientists studying this bizarre world thousands of feet beneath the sea: what these animals have to cope with, or what they have come up with to do that coping.</p>
<p>
<figure class="richtext-image full-width">
<img alt="black smoker chimney" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-02.width-990_6TOkywv.jpg"/>
<figcaption>A black smoker chimney belches scalding, mineral-laden water from the subsurface.
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<h3>
	Dark as night</h3>
<p>
	For starters, it's pitch black at such depths. Sunlight penetrates no farther than a few hundred feet down, leaving the deep-sea floor as dark as the deepest cave. With no sunlight, there are no plants; all vent life belongs to the animal kingdom. And with no plants, there is no photosynthesis. Biologists were flabbergasted when they first learned that creatures lived in total darkness at the seafloor. All other life ever identified, on land or in the sea, derives its energy either directly or indirectly from the sun. How, they wondered, did these animals manage without?</p>
<blockquote>
	Surprisingly enough considering the vastness of the ocean floor, space is extremely limited.</blockquote>
<p>
	Through chemosynthesis, it turns out. Vent species rely not on photons from the sun but on chemicals from the Earth's interior. Tiny microbes oxidize the hydrogen sulfide that diffuses out of the vents, providing nutrients for animals higher up the food chain. Some creatures, such as the mollusks known as gastropod snails, feast on the bacteria directly; others, including predatory fish, dine on animals that have eaten or otherwise made use of the microbes; still others, like tubeworms, host the microorganisms in their tissues in exchange for organic compounds that the bacteria fashion from the vent chemicals and seawater. (The only element from above that these microbes require for their artistry is oxygen, which is abundant in seawater and was originally produced, of course, by plants. So when it comes right down to it, even these life forms ultimately rely on sunlight. Which may have made those flabbergasted biologists breathe a little easier.)</p>
<p>
<figure class="richtext-image full-width">
<img alt="smoker &amp; crab" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-03.width-990_fKTd6Ok.jpg"/>
<figcaption>A crab within steps of a toxicant-spewing hydrothermal vent
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<h3>
	Acid rock and heavy metal</h3>
<p>
	As if utter darkness were not enough, vent animals must contend with a witch's cauldron of deadly toxicants. Foremost among them is hydrogen sulfide, one of the principal ingredients of the broiling water spewing from vents and black smokers. While vent microbes thrive on the stuff, this gas is lethal to most other organisms, including the creatures that live within wafting distance. Yet not only do those animals survive it, they depend on it as intrinsically as they do on the microbes. Hydrogen sulfide reacts spontaneously with oxygen, so as soon as vent fluids come into contact with seawater, a swift reaction occurs, releasing energy. All that energy would go to waste if it were it not for the microbes. They harness that reaction and use carbon dioxide to make organic compounds that tubeworms, for example, need to live.</p>
<p>
	Vents and smokers also release a bevy of heavy metals. Besides being toxic substances, these particles can clog mouthparts and gills. Biologists are still trying to figure out exactly how vent animals cope with these. Several animals have metal-binding proteins in their systems, while others, like some polychaete tubeworms, appear to expel these toxics in mucus. Beyond the toxic gas and particles, vent water can also be extremely acidic. The pH of waters coming out of black smokers can be as low as 2.8, making it more acidic than vinegar. Biologists have seen "naked" snails around hydrothermal vents that could not form their calcium carbonate shells because the water was too acidic.</p>
<p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-04.width-990_mmMWk81.jpg"/>
<figcaption>The pressure on every part of this octopus's bone-white body is over 3,000 pounds per square inch.
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<h3>
	Pressure's on</h3>
<p>
	Another factor these creatures have evolved to live with is the pressure. With every 32.8 feet of descent, the weight of the water above increases by 14.7 pounds per square inch. At 7,500 feet, the pressure animals feel over every square inch of their bodies is over 3,350 pounds. At such pressures, any air pockets, such as lungs, would be crushed flat as a deflated balloon. Vent animals have evolved bodies with no such air spaces.</p>
<blockquote>
	Vent life appears to be more closely related to ancient animals than anything alive today.</blockquote>
<p>
	Perhaps the most startling condition these animals cope with is unusual temperatures. For they must deal with both extremes—icy and scalding, often simultaneously. Water at the bottom of the ocean is about 35°F, while vent fluids released from chimneys can reach 750°F. Tubeworms and other vent creatures often live right on the flanks of black smokers, within mere inches of the scorching brew, which only the pressure keeps from boiling. Currents constantly stir up the hot and cold, meaning tubeworms and the like have to deal with ever changing temperatures. Even without currents, the extremes are sobering. Biologists have determined that the difference in temperature between a tubeworm's plumed tip and its base anchored in the side of a vent can be more than 50°F. Vent microbes themselves can take temperatures up to 230°F.</p>
<p>
<figure class="richtext-image full-width">
<img alt="crab clinging to tubeworm" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-05.width-990_72fKyS1.jpg"/>
<figcaption>Space is dear—grab what you can.
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<h3>
	Location, location, location</h3>
<p>
	To compound problems, the physical environment of the vent itself has limitations. Surprisingly enough considering the vastness of the ocean floor, space is extremely limited. Talk about the value of location: A tubeworm, for one, must live close enough to a vent to get hydrogen sulfide but not close enough to get burned. To make matters worse, due to geophysical changes taking place beneath them, hydrothermal vents and black smokers can turn off suddenly, choking off the life that depended on them. Even healthy black smokers, though they're made of stone, are fragile structures that eventually crumble beneath their own weight. So vent creatures have to have a means for detecting, traveling to, and colonizing new habitat. Yet vents are spread far and wide throughout the world's seas. How newborn vents acquire new residents is a mystery that continues to keep scientists up at night.</p>
<p>
	But clearly vent creatures manage to do it. Biologists have discovered these animals at sites right around the mid-ocean ridge that circles the globe. Indeed, they have found that vent animals more closely resemble vent creatures on the other side of the planet than they do animals living even a few feet away from them on the ocean floor.</p>
<p>
<figure class="richtext-image full-width">
<img alt="fish and tubeworms" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/life-in-the-abyss-06.width-990_60WIrLY.jpg"/>
<figcaption>Did life on Earth get its start at a hydrothermal vent on the seafloor?
        
        <div class="credit">© WGBH Educational Foundation</div>
</figcaption>
</figure>
</p>
<h3>
	First life?</h3>
<p>
	The irony of vent communities is that, despite the harshness of their home, they appear to have survived for many millions of years, having apparently changed little in that time. Vent life, for one thing, appears to be more closely related to ancient animals than anything alive today. What's more, even during times when all hell was breaking loose on the surface, such as during the periodic mass extinctions that have swept the Earth, vent creatures have calmly gone about their lives, probably little affected. This tenacity, evinced albeit through the most exceptional isolation, bodes well for them in the current mass extinction event.</p>
<p>
	Some biologists have gone so far as to suggest that a vent-like environment was the place where life on Earth likely got its start. And if such a miracle could have occurred here on Earth, why not on other planets that have the necessary ingredients, including heat, water, and the right mix of chemicals? In the end, there may indeed be a harsher place to live than hydrothermal vents. But again, it hasn't been found. Yet.</p>

Pitch darkness, poison gas, pounding pressure, water both frigid and searing&mdash;how do hydrothermal vent animals cope?

Peter Tyson

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