Cientificamente falando...

[Sumudica by Night]

Alguém abriu o rolo depois de tirar a foto.

[Ghelthon]

A Ciência é mesmo maravilhosa. Um passo de gigante para estudar os buracos negros, que são das coisas mais impressionantes que há na Física/Astronomia.

Curioso ver, agora, este vídeo gravado há dois anos atrás:

 

Editado 13 Abril 2019 por Ghelthon

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Citação

 

"THREE DISCRETE groups of giant tortoises survived at the start of the sixteenth century. The three groups together accounted for more than a half-dozen species. They all grew as big as bears and they were all closely related, assignable to the genus Geochelone. In addition to those three sets of giants, the same genus also encompassed a number of smaller tortoises native to the South American mainland, Africa, Madagascar, and southern Asia. The giants, by no coincidence, were entirely confined to small islands.

One group inhabited the Galápagos. Another group lived on the Mascarene Islands of the Indian Ocean, the cluster of forested volcanic nubs that includes Mauritius, Rodrigues, and Réunion. The third group occurred in the Indian Ocean too, but remote and distinct from the Mascarene animals. This third group was scattered across seven hundred miles of oceanic wilderness, from the granitic Seychelles southwestward, beyond Farquhar, beyond Cosmoledo, to the tiny coral atoll known as Aldabra. Aldabra sat lost in its own singularity, far off the coast of Tanzania.

Aldabra was nowhere, hundreds of miles from anywhere. It was not a destination or even a stopover point on any preferred sailing route. It consisted of a low ring of limestone, a corona of coralline sand, and some scrub vegetation, all surrounding a shallow lagoon. The noon sun was blistering and the dry season was longish and grim. Not many kinds of animal could live there. With no high land, no decent harbor, hardly any food or fresh water or timber that might attract human voyagers, it was the most desolate and unapproachable of all tortoise islands. Unlike some other small oceanic outcrops, it didn’t even contain guano resources worth harvesting. Scarcely anyone coveted Aldabra, scarcely anyone visited. So its tortoises survived. By the start of this century, all other giant tortoises of the Indian Ocean were virtually extinct. Some of those other populations may have left a few hybrid offspring, in translocated meat herds or as mascots held captive at botanical gardens, but they were gone from the wild. On Aldabra, meanwhile, a real population of giant tortoises persisted.

The Aldabran population belongs to the species that taxonomists now call Geochelone gigantea. It’s probably the same species as those lost populations from the granitic Seychelles. Down in the Mascarenes, by contrast, each island seems to have harbored a distinct species, and in some cases there were two distinct species coexisting on the same island.

Mauritius had Geochelone inepta and Geochelone triserrata. The anatomical differences between these two species were subtle; the ecological differences can only be guessed at. G. inepta may have been more tolerant of dry coastal habitat, while G. triserrata may have favored the wetter zones of the island’s interior. Both species seem descended from the same ancestral species, possibly having arrived on Mauritius in two separate episodes of colonization. Each colonization may have been accomplished by just a tiny number of individuals, maybe only one—a single pregnant female who found herself washed off a beach in Rodrigues, say, and floated passively across to the neighboring island. Giant tortoises are capable of oceanic crossings, riding the waves like an inflatable raft, head up, patient, enduring days or even weeks adrift. Maybe the Rodrigues population was itself descended from colonists who, centuries earlier, had been washed off a beach in Mauritius. Such back-and-forth colonization is what makes the patterns of evolution on archipelagos so complicated.

 

Still, it’s safe to say that the tortoises of Mauritius, Rodrigues, and Réunion were all closely related. Taxonomists now lump them within a single subgenus, Cylindraspis, but I prefer to think of them simply as the Mascarene cousins. Various factors contributed to their evolutionary history on the Mascarene Islands, of which one was crucial: absence of humanity. Each of those three volcanic nubs was spared the presence of Homo sapiens until just a few hundred years ago. By some quirk of chance (probably related to distance and to the prevailing currents of water and wind), no ocean-voyaging humans had arrived there during earlier millennia. While the islands of Polynesia and Melanesia were harboring rich Neolithic cultures, while places as remote as New Zealand and Hawaii and Easter Island were being colonized by adventurous men and women in canoes, the Mascarene Islands (like the Galápagos) remained uninhabited. That lack of two-legged predators allowed the tortoises to survive and evolve.

But it couldn’t last. Portuguese ships touched at Mauritius as early as 1507. In 1598 a Dutch expedition landed, beginning an era of frequent contact, and by 1638 there was a Dutch settlement on the island. Eighty years later Mauritius was taken over by the French. The French, the Dutch, and the Portuguese all seem to have used the place as a resting point during long voyages, and as a larder. The Portuguese introduced goats, pigs, and chickens, presumably hoping those meat animals would go feral and multiply; they or the Dutch, by accident, also introduced rats; cats too were introduced, probably by the Dutch during their settlement period in a misguided attempt to control the rats. Nobody knows who introduced monkeys, and nobody can fathom why. In addition, the Dutch slaughtered native animals, most notably dodos and tortoises. Seagoing explorers in those days spread ecological mayhem without dreaming it made any difference, and they ate what they found.

A visiting Englishman in 1630 was impressed by the size of the tortoises, “so great that they will creepe with two mens burthen,” but he was less impressed by their culinary appeal. He called them “odious food,” and in light of English cuisine he presumably knew odious when he tasted it. The Dutch seem to have found tortoise meat tolerable as expeditionary fare. The French, of course, found ways to make delicacies of what the Dutch took for granted and the English despised. French settlers on Mauritius butchered thousands of tortoises, salting the flesh or rendering it for fat. This was before the world’s navies and whaling fleets had made a discovery that doomed Geochelone further: Giant tortoises could be stored alive. Their reptile metabolism and their behemoth endurance allowed the animals to linger for months, without food or water, in the hold of a ship. To prevent wandering and induce stoic surrender, they could be turned upside down. Their physiological dormancy made up for the lack of meat freezers.

That phase of exploitation came later. A more immediate style of butchery prevailed during the seventeenth century and into the eighteenth on Réunion and Rodrigues as well as Mauritius. One traveler reported from Réunion: “The Land Turtles are also some of the Riches of the Island. There are vast Numbers of them: Their Flesh is very delicate; the Fat better than Butter or the best Oil, for all sorts of Sawces.” Another witness, a Frenchman who spent perhaps too many weeks on Rodrigues in the course of an expedition, remembered “soupe de tortue, tortue en fricassée, tortues en daube, tortues en godiveau, oeufs de tortue, foie de tortue,” and grumbled that everything he ate seemed to be only more tortoise stew. By about 1780, the tortoises of Rodrigues, Réunion, and Mauritius were reduced to the point of extreme rarity, most of them having been eaten. Within another generation they were extinct in the wild, possibly extinct altogether. No one knows the fate of the last purebred Geochelone triserrata, or of the last ghost of the species preserved in a translocated hybrid. In 1836 Charles Darwin himself visited Mauritius, on his homeward journey aboard the Beagle. With his Galápagos experience so recent, giant tortoises must have been fresh in his mind. If he had spotted any in Mauritius, presumably he would have said so. But there’s no mention of a Mauritian tortoise in his Journal.

The Aldabra-Seychelles species, Geochelone gigantea, was not quite so closely related to the Mascarene cousins as the cousins were related to each other. Probably G. gigantea had descended from a separate branch of the genus, and taxonomists now place it within its own subgenus, Aldabrachelys, another piece of expendable nomenclature that you have my blessing to forget instantly. The subgenus also includes some giant tortoises that once lived on the great island to the southwest, Madagascar. Those Madagascan species have been extinct for some time, possibly several millennia, and are known today only from shell remains, which look very similar to the shell of G. gigantea. So it may be that this species originally colonized Aldabra along sea currents from the north coast of Madagascar. Its distinctness from the Mascarene group shows in a few curious traits of skull structure. G. gigantea has a more pointed snout. It has a peculiar arrangement of nasal passages, in which a flaplike ridge seems to stand in defense of the olfactory chamber, leaving a clear channel from the nostrils to the esophagus. The ridge could support a fleshy valve (though apparently no scientist has dissected an Aldabran tortoise to find out), which might seal off the olfactory chamber at will. Those structural traits, combined with the field observation that G. gigantea sometimes draws water in through its nostrils, suggest an interesting possibility: Maybe the species is adapted to survive droughts by quenching its thirst in deep narrow potholes—stretching its neck down, drinking through its nose. The compacted coral rock of Aldabra happens to be pitted with deep narrow potholes.

Droughts were part of its evolutionary experience, but nothing prepared G. gigantea to survive the arrival of humans. Aldabra was protected by its remoteness; the other sites were more accessible, so the other populations were more vulnerable. In 1609 an expedition discovered the granitic Seychelles and their most conspicuous species. A participant in that expedition, one William Revett, recorded “lande turtles of so huge a bignes which men will think incredible; of which our company had small luste to eat of, being such huge defourmed creatures and footed with five claws lyke a beare.” He meant that the tortoises, not the members of his company, were “huge defourmed creatures,” I think. Revett was another squeamish Englishman whose distaste for reptile meat wasn’t shared by the people who came later. Although the Seychelles didn’t support a permanent settlement until 1778, by the end of that century the colony’s biggest export was tortoises. G. gigantea turned out to be just as toothsome as the Mascarene species. In fact, a large portion of the exported animals went to Mauritius, where folks maintained a traditional hunger for tortoise but had nearly exhausted their own supply. Customs records from Mauritius testify to shiploads of tortoises brought in from the Seychelles during the peak of the trade, totaling five thousand animals or more. Additional thousands were taken off the Seychelles by naval ships. Making matters worse, cats and rats had come ashore with the humans, and those animals preyed on tortoise eggs and hatchlings. G. gigantea soon disappeared (at least as a wild and unhybridized species) from the granitic Seychelles. Big shipments of tortoises were still passing from the Seychelles to Mauritius in the early nineteenth century, but by then the Seychellois tortoise mongers were just middlemen. The granitic Seychelles had become an import destination, and the imported tortoises must have come from Aldabra; they could only have come from Aldabra. In this ocean, there was no other remaining source.

A further threat arose around 1870, when someone got the notion to lease Aldabra for woodcutting. Severe habitat loss, combined with direct harvest of animals, probably would have extinguished the Aldabran population. Even without the woodcutting, that population was already badly depleted—as indicated by the fact that in 1878 a party of sailors spent three days hunting and found only one tortoise. Scientists back in England grew so concerned over what they were hearing that an illustrious group, including Charles Darwin and Joseph Hooker, signed a letter to the governor of Mauritius asking that Aldabra be protected. Some protective measures were put into force, but the tortoise population continued its decline. Rats and cats had infested the atoll by now, raising the mortality rates of tortoise hatchlings and eggs, and those rates had been naturally high under even the prior conditions. A naturalist who visited just before World War I, spending four months camped there, found the tortoises scarce and concluded that “it would be possible to live for years on Aldabra and never see a specimen.” The reason, he felt, was simply that they were shy and retiring. The governor of the Seychelles was less upbeat: “No plan will effectively prevent the final extinction of these curious survivals in a wild state in their natural habitats.” Not long afterward, as though to prove the governor wrong, the tortoise population began a comeback.

That trend has continued during this century. From its historic low, the tortoise population on Aldabra has increased dramatically. Why? Well, they were left mostly alone, protected from the meat harvesters, their scrub-vegetation habitat still intact. Probably they were also helped by the arid, severe conditions of the atoll, which discouraged a population explosion of cats or rats. After a passing threat in the 1960s that the British government might put an air base on Aldabra, and a public outcry against that bad idea much like the outcry that Darwin had joined earlier, the Royal Society of London assumed protectorship of the atoll. An Aldabra Research Station was built; other developments were kept out. In 1976 Aldabra was incorporated within the Republic of Seychelles, which had emerged as an independent nation, and in 1981 the Seychelles government designated Aldabra a special reserve. According to recent reports, the population of G. gigantea is doing well.

Possibly it’s doing too well. About 150,000 tortoises now live on Aldabra, and they may be destined for a natural crash in the near future, when they have succeeded in disastrously overeating their own resources.

The story of G. gigantea is complicated, but at its core is one simple fact: geographical isolation. In the case of Aldabra, that isolation is extreme. And it isn’t measured only in mileage. In the era of the shrinking planet, Aldabra’s margins of isolation haven’t shrunk. Its remoteness is uncompromised. Today you can board an airliner in Miami and step off within hours in the central Amazon; you can fly out to the Galápagos, connect with a cruise ship, and wander the individual islands on the coattails of a licensed guide; you can book an “adventure travel package,” that oxymoronic commodity, to Antarctica; you can even reach Krakatau, cinderlike Krakatau, for a handful of rupiahs paid to a Javanese fishing-boat captain. Aldabra, no. Not so easily attained. Aldabra stands in a different category. It’s the place you can’t get to from here.

If you’re a scientist—or even just a plausible scientific journalist, so I’m told—you might talk your way onto the biennial Aldabra expedition of the Smithsonian Institution, and have the privilege of spending a sun-stricken month watching serious people collect polychaete worms from the potholes. Alternatively, you might charter a somewhat reliable boat in the granitic Seychelles and venture out on the seven-hundred-mile sea journey toward Aldabra, which your compass-guided Seychellois captain might succeed in finding, with luck, though perhaps not on the first try. That charter would cost about ten thousand dollars, I’m told; and when you did reach the atoll, if you did, you might not be legally entitled to step ashore. Having heard all these things, I elect not to test my own plausibility or my own luck.

The published record is obscure but it’s substantial, and this one I’ll take on faith. I can content myself with having seen G. gigantea in a botanical garden in Mauritius. The wild tortoises of the Indian Ocean have been harried enough. Let them have their refuge, their privacy, on that one little desolate atoll. If Aldabra is the epitome of isolation, I figure, then what better way to highlight that fact than by staying the hell away from it myself?"

"The Song of the Dodo" (1996),  David Quammen

 

 

Editado 9 Maio 2019 por bmfpcdm

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Citação

"THE FLIGHTLESS beetles of the Madeiras play a curious role in The Origin of Species. They show Darwin at both his best and his worst. The power of Darwin’s intellectual method derived from marshaling many small obscure facts toward a great singular argument, and that’s how he used the Madeiran beetles. They were certainly small and obscure, and they seemed to have large implications. Whether they proved what Darwin claimed they proved is another question.

Rising in the eastern Atlantic, four hundred miles west of Morocco, the Madeiras are a pair of tiny islands, Porto Santo and the namesake Madeira, of which the larger and ecologically more rich is the latter. Madeira is a steep hump of volcanic rock that rises to six thousand feet, with a high central crest standing exposed to tropical breezes and storms, and a series of ridges dropping transversely from the crest, like ribs from the backbone of an emaciated horse. This partitioning topography probably helps to account for the fact that such a small island harbors so much species diversity, at least among certain insect groups. Lying as it does in the path of the trade winds, Madeira was one of the last stops for European sailing ships headed westward across the Atlantic. Relatively accessible for an oceanic island, it attracted early attention from scientists. I’ve already mentioned the visit by Charles Lyell in 1854, and the fact that Lyell noticed a high degree of endemism among Madeiran beetles. Another colleague of Darwin’s, a quiet man named T. Vernon Wollaston, did a more thorough study of Madeiran entomology and in 1856 published some of his findings in a book that was dedicated to Darwin.

Wollaston had made the remarkable discovery that 200 beetle species, of the 550 native to Madeira, were flightless. The wings of those 200 species were undersized to the point of uselessness. In the more extreme cases, Wollaston found, they were no more than dinky little nubs. The ratio of flightlessness was higher still at the level of genus. Among the twenty-nine beetle genera endemic to Madeira, twenty-three genera contained only flightless species. Wollaston also noticed that certain large groups of beetles, common on the main lands but especially dependent upon flight, were absent entirely from Madeira.

His friend Darwin seized on these facts and invoked them in connection with two separate arguments: for evolution by natural selection and for the evolutionary effects of use and disuse. In one of those arguments (use and disuse) Darwin proved to be broadly wrong. In the other (natural selection), it seems he was wrong only narrowly.

Chapter 5 of The Origin, devoted to “Laws of Variation,” contains Darwin’s mistaken assertion: “I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited.” His study of dogs, captive-bred pigeons, and racehorses had convinced him that characteristics acquired in one generation—by laborious training, for example, or by muscle-building exercise—could be passed on biologically to the next generation. And if that were true for domestic animals, why not for beetles on a wind-swept island? Darwin’s logic entailed three reasonable premises: that the Madeiran beetles tend toward concealing themselves on the ground, so as to avoid being blown out to sea; that this habit of concealment leads to the atrophy of their wings; and that a female with wings atrophied by disuse would produce progeny with wings stunted by birthright. The shrunken-winged beetles of Madeira, Darwin felt, helped to prove that acquired characteristics can be inherited.

Today we know otherwise. The notion that one individual can acquire some trait during the course of its life, and then pass that trait to its offspring as an inherent biological attribute, contravenes the holiest tenets of modern genetics. If a woman’s arm is severed in a car accident, will she give birth to one-armed babies? No. Will the children of a body-builder have bulging biceps? No. Yet if acquired characteristics were heritable, those phenomena would occur. Some contemporary biologists, who take Charles Darwin as their true prophet, refer to this notion as “the Lamarckian heresy”—blaming it on that earlier and somewhat confused evolutionist Jean Baptiste Lamarck. But you can find the same notion in Chapter 5 of The Origin of Species. If it’s heresy, it’s also Darwin’s heresy against Darwinism.

Still, Darwin didn’t claim that disuse and its heritable effects were the sole factor accounting for Wollaston’s data. Even more important, he thought, was natural selection.

In a typical mainland situation, natural selection will favor robustness, and one standard of robustness is the proficiency of flight. Assuming that flight is useful toward finding food, mates, and protection from predators, individual beetles that are good flyers will leave more offspring than poor flyers, and the flying ability of a species will gradually improve. But on an island like Madeira, natural selection might instead punish the big-winged, strong-flying individuals. How so? Because those strong flyers face a higher probability of being swept out to sea by winds. If they are swept out to sea, their genes disappear from the island’s gene pool. Consequently the genes for strong flight will be winnowed away from the insular population. Only the weaker flyers, and the occasional mutants that are totally flightless, will be left on the island to breed. Embracing this hypothesis, along with the more dubious one about acquired characteristics, Darwin concluded that “the wingless condition of so many Madeira beetles is mainly due to the action of natural selection,”—on which point he was right—“but combined probably with disuse”—on which point he was wrong.

Darwin set the notion of disuse to one side and focused more confidently on his main subject, natural selection. He described how it might lead to flightlessness among an insular population of insects: “For during thousands of successive generations each individual beetle which flew least, either from its wings having been ever so little less perfectly developed or from indolent habit, will have had the best chance of surviving from not being blown out to sea; and, on the other hand, those beetles which most readily took to flight will oftenest have been blown to sea and thus have been destroyed.” With or without corroborative evidence, coming from Darwin it sounds good enough to be true. Certainly it seems more plausible than the explanation by disuse. But the plausibility of a hypothesis and the high authority of the man offering it don’t guarantee its correctness.

The Origin of Species is a book of encyclopedic richness and inexhaustible tendentiousness, a great potpourri of argument and fact in which a reader can find almost anything a reader might want: Lamarckism, animal husbandry, geology, ethology, experimental botany, the kitchen sink, island biogeography. But Darwin didn’t answer every question, and every answer he gave wasn’t infallible. Evolutionary biologists of the twentieth century have rejected his general idea about the heritable effects of disuse. And one modern researcher, Philip Darlington, has challenged his view of flightlessness among Madeiran beetles."

"The Song of the Dodo" (1996), David Quammen

 

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Citação

"THE UNGAINLY and gigantized species of pigeonlike bird that eventually received the name Raphus cucullatus, more familiar to us as the dodo, had lived on Mauritius a long time. No one knows how long. Probably the lineage had been there many thousands of years. It was an evolutionary success; it had adapted itself well to the local conditions. It existed nowhere else.

Most likely it ate fallen fruit. It may also have fed, at least occasionally, on seeds and bulbs. It grew big and husky, storing fat to a degree that true pigeons could not, and it ran through the forest on stout legs. Probably it wasn’t a fast runner, not what we’d call graceful, but competent within its context. As its body had evolved toward greater size, its wings hadn’t, and at some point it dispensed with flying. This was a well-measured compromise that yielded more advantage than disadvantage. A bird so hefty, with such a big head and such a wide gape, could swallow sizable fruits whole—pounding down big meals quickly and thereby stockpiling nutriment efficiently during the seasons of bounty. Bulked up, it could survive through the seasons of scarcity. The smaller species of fruit-eating birds, mincing and tentative by comparison, less able to gain and lose weight, would have been hard-pressed to compete. On the negative side, flightlessness meant surrendering one means of escape from enemies. But that was an easy sacrifice, since the dodo had evolved in an ecosystem impoverished of predators. Mauritius in its primordial state contained no terrestrial mammals—no rodents, no carnivores, no humans. There were some large reptiles, but none that could intimidate a thirty-pound bird with a beak like a claw hammer. Flightlessness dictated that the dodo put its nests on the ground. That too was no problem, since ground nesting in this ecosystem was safe and economical. The big bird may have gathered grass into an eggholding basket, as claimed by one historical source. The same source suggests that a dodo clutch consisted of a single white egg, approximately the size of a pear. The dodo seems to have carried pebbles in its crop to help grind its food. Its sharply hooked beak may have been used for ripping morsels away from large fruits held on the ground with its claws. A recent historian has deduced that, unafraid of water, it drank and bathed freely but was unable to swim.

This much is all we really know about the ecology, behavior, and biogeography of Raphus cucullatus. Everything else is rumor.

The song of the dodo, if it had one, has been lost to human memory. A visitor on the island in 1638 recalled later that it made a squeak like a gosling. Another historical report, from a Dutch mariner shipwrecked on Mauritius in 1662, said: “When we held one by the leg he let out a cry, others came running forward to help the prisoner, and were themselves caught.” But a scream of distress is not to be confused with the natural call of a species. More recently Errol Fuller declared in his book Extinct Birds: “The call was never clearly described but one school of thought inclines to the opinion that the word ‘dodo’—probably coined by Portuguese sailors—is simply a rendering of it.” From there Fuller digressed into etymological speculation about its name, without saying more about the bird’s voice. Other modern sources on Raphus cucullatus generally don’t go into the subject of vocalization at all. The song of the dodo, if it had one, is forever unknowable because no human from whom we have testimony ever took the trouble to sit in the Mauritian forest and listen.

As for the dodo’s anatomy, we have three or four cobbled-together skeletons preserved in museums, a scattered assortment of other bones, one severed and dried foot, a few written records of the bird’s appearance, and an array of paintings and engravings dating back to the year 1600. The three-dimensional reconstructions displayed in some museums, suggesting taxidermy, are only dummies made of plaster and wire and glued-on plumage from expendable poultry. The paintings and engravings form a chain of derivation and distortion, later artists having loosely copied earlier ones. What the images commonly show is a homely animal with an oversized, knob-ended beak and a bare face, behind which the feathered part of its head looks like the hood of a sweatshirt. The nakedness of the face, the gawkiness of the feathery hood, the knobbed beak, and the gross body have contributed toward making the dodo seem unreal. But it wasn’t unreal, of course. Beyond the reconstructions and the half-fantasy portraits lay a real bird whose face, we can reasonably assume, was featherless. If the paintings can be trusted at all, the dodo’s body plumage was gray and the ineffectual little wing feathers were either yellowish white or, alternatively, black. A few of the engravings and paintings are persuasive, evoking a flesh-and-blood animal, but others are cartoons. None of the images, it seems, was done by an artist who had ever seen Raphus cucullatus in the wild.

So the story of the dodo is obscured by a fog of uncertainties. We can be sure that it lived. That it was confined to Mauritius. That its shape was consistent with the remnant skeletons. That it thrived for a long time and then met disaster. That the disaster was caused, directly or indirectly, by Homo sapiens. Isn’t this a fair bit of knowledge about an animal that’s been gone for centuries? Well, no. For an instructive comparison, think of the hadrosaurian dinosaur Maiasaura peeblesorum, which died out about seventy million years ago. Paleontologists possess better data on that species than ornithologists possess on the dodo. There are fossilized eggs and embryos of Maiasaura peeblesorum. But there is no verified egg and no embryo of a dodo in any of the world’s museums. We know that it was a bird. Warm-blooded. Earthbound. Conspicuously meaty and, as matters developed, vulnerable. We know that, beginning around 1600, it faced a struggle for survival in the presence of humans and pigs and monkeys. We know very little else. The main certainty about Raphus cucullatus is that by about 1690, if not earlier, it was extinct."

"The Song of the Dodo" (1996), David Quammen

 

 

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Citação

"PORTUGUESE sailors first reached Mauritius in 1507, during the era when Portuguese sailors were going everywhere. The expedition, under command of Alfonso Albuquerque, probably touched also at Réunion and Rodrigues. This counts as the European discovery of the Mascarene Islands, though seafaring Arab traders from the lands around the perimeter of the Indian Ocean already knew of them. There were no human inhabitants of the Mascarenes at the time Albuquerque’s group visited. In 1512 came another Portuguese navigator, Pedro Mascarenhas, who left behind his name and apparently little else. Throughout the rest of the sixteenth century, the Portuguese manifested no very keen interest in Mauritius, although by one account they did introduce some domestic animals. Still, they came and went more lightly than later European visitors. And if the Portuguese ever caught sight of a dodo, they don’t seem to have mentioned it to posterity.

With the Dutch, who arrived at the end of the century, it was different. An expedition commanded by Jacob Cornelius van Neck reached Mauritius in 1598. Beginning that year, Dutch sailors making transits across the Indian Ocean treated the island as a pasturing and breeding ground for livestock and as a source of wild native meat. I’ve already noted that they ate up a share of the native tortoises. They also ate dodos.

The earliest record of dodophagy comes from a narrative of the van Neck voyage, published in 1601. Since the dodo at that time was still an unheard-of beast, the van Neck account introduced it visually before offering a culinary critique:

Grey Parrots are also common there, and other birds, besides a large kind, bigger than our swans, with large heads, half of which is covered with skin like a hood. These birds want wings, in place of which are three or four blackish feathers. The tail consists of a few slender, curved feathers, of a grey color. We called them Walckvögel, for this reason, that the longer they were boiled, the tougher and more uneatable they became.

 

It was probably the first European report of the dodo’s existence, but the pattern of contumely was already set, walckvögel being Dutch for “disgusting bird.”

In various spellings, that epithet recurs throughout later accounts as a conventionalized insult: Walgh-voghel, walg-vogel, waldtvögel, wallighvogel, walyvogel. A typical complaint was that “even long boiling would scarcely make them tender, but they remained tough and hard, with the exception of the breast and belly, which were very good.” In the same spirit, a titled English visitor observed snottily that the dodo “is reputed more for wonder than for food, greasie stomaches may seeke after them, but to the delicate they are offensive and of no nourishment.” No nourishment to his rarefied sensibility, anyway; but most early travelers to Mauritius couldn’t afford such choosiness. Tough or tender, the dodo was never quite disgusting enough for its own good.

Several years after van Neck’s expedition another ship reached Mauritius. The journal of its captain reported that a foraging party returned from shore with some impressively fat dodos, and “the whole crew made an ample meal from three or four of them, and a portion remained over.” Ten days later, the foragers brought back another two dozen dodos, enough to suggest either that dodo hunting had quickly progressed to a fine art or that the birds weren’t hard to kill. They were so big and heavy that a pair of them more than fed the crew, “and all that remained over was salted.” Still later, five men went ashore “provided with sticks, nets, muskets, and other necessaries for hunting. They climbed up mountain and hill, roamed through forest and valley, and during the three days that they were out they captured another half hundred of birds, including a matter of 20 Dodos, all which they brought on board and salted.” Easy pickings, like the tortoises.

This journal mentioned three different names for the big flightless bird: dronten and dod-aarsen as well as wallich-vogel. The names are significant insofar as they reflect fresh early impressions, later to be replaced by a received caricature. But the etymology of those names is controversial. One scholar declared that dronten isn’t traceable to the Dutch language; another scholar claimed that it’s an obsolete form of a Dutch verb meaning “to be swollen.” The second scholar asserted that dod-aarsen, too, alludes to the bird’s bulbous shape: dod from the Dutch for “round heavy lump” and aarsen as cognate to the venerable English “arse.” Round-ass. Fat-ass. The swollen, lump-assed bird. But our first scholar argued that dod-aarsen derives rather from the Dutch word dodoor, meaning “sluggard.” Centuries were passing as the debate went back and forth, and whole dictionaries were becoming obsolete. To confuse matters further, dod-aarsen (like walckvögel) has a number of variants, appearing in some of the early sources as dodaersen, dottaerssen, dodderse, dodars, even totersten. What can I tell you? The Gutenberg revolution was young and nobody gave a shit about spelling. Dodoor became dodars, according to our first scholar, and dodars in turn became dodo. The sluggardly bird. The slow, lazy bird. There is a third opinion, offered by the snotty Englishman of the delicate stomach, to the effect that dodo comes from a Portuguese word, doudo, meaning “foolish” or “simple.” The Englishman was Sir Thomas Herbert, whose travel narrative was published in 1634. Herbert might merit some credence on this point, since he was reputedly the first person to use “dodo” in print. And there is a fourth opinion, mentioned by Fuller in his Extinct Birds and traceable to earlier sources: that “dodo” was an onomatopoeic approximation of the bird’s own call, a two-note pigeony sound like “doo-doo.”

The various conjectures all converge on a common notion: the foolish, swollen, sluggardly bird with the big butt. It may not be ornithologically accurate, it may not be fair, but it’s recognizable as the dodo of legend.

What the European witnesses saw as stupidity and laziness we can take to have been only a certain inherent ingenuousness, reflecting the bird’s long-term adaptation to a benign environment. In the terminology I proposed earlier, the dodo was ecologically naïve. Further testimony comes from a Dutch sailor who saw dodos in 1631: “They are very serene or majestic, they showed themselves to us with an extremely dark face with open beak, very dapper and bold in their walk, would hardly move out of our way.” It’s a nice sympathetic observation, “serene” and “bold” having greater biological validity (“dapper” is another matter, admittedly) than those invidious adjectives associated with the name. The dodo was no more foolish or simple or sluggardly than the marine iguanas, the giant tortoises, the mockingbird that perched on Charles Darwin’s water pitcher, or the other tame-seeming animals of the Galápagos and other islands.

Even on Mauritius, the dodo wasn’t unique in its ecological naïveté. Some other native birds were also disastrously trusting—including some of the small, agile species with unimpaired powers of flight. Van Neck’s chronicler reports that scouts sent ashore found no human inhabitants but “only Turtle-doves and other birds in great abundance, which we took and killed, for as there was no one to scare them, they had no fear of us, but kept their places and allowed us to kill them.” Another narrative, from a 1607 voyage, says that the men of that party “lived on Tortoises, Dodos, Pigeons, Turtle-doves, grey Parrots and other game, which they caught by hand in the woods.” In 1611 the chronicler of still another voyage was impressed by both the quantity of wild game and the ease with which it could be killed. This witness focused especially on the dodo: “In colour they are grey; men call them Totersten or Walckvögel; they occur there in great plenty, insomuch that the Dutch daily caught and ate many of them. For not only these, but in general all the birds there are so tame that they killed the Turtle-doves as well as the other wild Pigeons and Parrots with sticks, and caught them by hand. They also captured the Totersten or Walckvögel with their hands, but were obliged to take good care that these birds did not bite them on the arms or legs with their beaks, which are very strong, thick and hooked; for they are wont to bite desperately hard.” It’s good to know that dodos weren’t utterly docile and defenseless, despite their caricatured reputation. But the biting didn’t save their lives.

Summarizing the historical records, Errol Fuller wrote: “Dodos were hunted mercilessly during the short time in which Europeans came into contact with them and for a period of upwards of half a century they proved a very useful source of fresh meat for travellers in the Indian Ocean.” Unlike the giant tortoises, they weren’t stockpiled alive on shipboard, passing weeks and months in a state of stoical dormancy. Instead, when the supply was excessive, some dodos were salted or smoked; others were eaten fresh, sating whole boatloads of men and supplying leftovers. We can imagine the shipboard menu—boiled dodo, roast dodo, pickled dodo, kippered dodo, dodo hash. The birds may have seemed disgusting because of the sheer surfeit of dodo meat.

Although the heavy harvest went on for decades, it couldn’t continue indefinitely. It was insupportable for a species of bird that grew huge and laid one egg per clutch. So the direct slaughter by humans no doubt hurt the dodo population, maybe badly. Still, that’s only part of the story.

Another part of the story is more subtle and indirect. Sometime during the early years of their acquaintance with Mauritius, the Portuguese had introduced pigs. And not many decades later, by a route that remains obscure, the island became infested with monkeys."

"The Song of the Dodo" (1996), David Quammen

 

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Citação

"PIGS AND monkeys presented a bigger threat to Raphus cucullatus than the goats, chickens, cattle, deer, cats, and dogs that also came ashore with the Portuguese and, later, the Dutch. Goats competed for food, cats caused trouble, but pigs and monkeys were capable of deadly efficient predation upon the flightless dodo—or at least upon its juveniles and its nests. Having arrived in small numbers, those new enemies took hold in the forest and proliferated nightmarishly.

They were omnivorous, so their population levels weren’t limited by a single food supply. Reports from the late 1600s tell of pigs putting an end to tortoise and sea turtle reproduction by eating the eggs. In 1709, feral pigs were so numerous, causing “great destruction,” that a posse of eighty men killed more than a thousand in one day. Probably that slaughter had no lasting effect on the pig population, and by then it was too late for the dodo anyway.

The case of the monkeys is more puzzling. The particular monkeys that haunt the forest remnants and the roadsides of Mauritius belong to the species Macaca fascicularis, commonly called the crabeating macaque, a notoriously adaptable primate whose original native range stretched from upper Burma down through Indochina and Malaysia to some of the less remote islands of the Philippines and Indonesia. Macaca fascicularis is capable of spreading across a tropical continent like a tribe of Visigoths but not of invading an oceanic island without help; unlike the monkeys of Oz, it doesn’t fly. How it first reached Mauritius, and why, nobody knows. At one time the species was thought to have been introduced by the Portuguese during the sixteenth century. The only evidence for such a supposition seems to be that, first, the presence of monkeys was mentioned in at least one of the earliest Dutch accounts and that, second, Portuguese sailors were allegedly fond of monkey meat. But the monkeymeat allegation could have been just a slander invented by the Dutch. Besides, the Portuguese favored Réunion over Mauritius as a way station in the Mascarenes, yet Réunion didn’t end up cursed with a permanent infestation of monkeys. And there seems to be no record that the Portuguese ever transplanted crabeating macaques onto any other island. Why would they? It’s a wild species, skinny and smart, not a tractable, fat-bearing domestic beast that could be conveniently harvested on demand. Lack of evidence against the Portuguese tends to point the blame back toward the Dutch. Furthermore, the strain of M. fascicularis that persists on Mauritius has recently been traced to Javanese ancestry, and Java was a Dutch point of contact as early as 1596.

What motivated the Dutch is anyone’s guess. Maybe they themselves had a secret monkey-eating vice. Or possibly some Dutch ship stopped at Mauritius with a pair of mascots, which escaped. Or the female alone escaped, but she was pregnant. Or maybe a few macaques were intentionally discarded onto Mauritius (like those pet alligators of legend, discarded into the sewers of New York) because they had become a nuisance on shipboard. In any case, the conditions of this new island were highly agreeable to M. fascicularis. The population exploded. The same traveler who reported the pig eradication effort in 1709 also mentioned that he “had the pleasure to see more than 4,000 monkeys in a near-by garden.”

Four thousand monkeys is a passel. Although the spectacle was a pleasure for him, it suggests a plague of frantic and clever omnivores that may have made life (or at least procreation) impossible for a species of ground-nesting birds. So my own notion, as unencumbered by evidence as the other hypotheses I’ve described, is that whoever did introduce the crab-eating macaque, for whatever inscrutably stupid reason, committed a very consequential act. Those monkeys have been much underestimated, I suspect, as a contributing factor in the extinction of the dodo."

"The Song of the Dodo" (1996), David Quammen

 

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Citação

"THE LAST credible eyewitness account of living dodos dates from 1662. A Dutchman named Volquard Iversen was marooned on Mauritius that year, after his ship was wrecked in a storm. Though a lifetime had passed since the first Dutch arrival, a tenuous colony had failed several years earlier, and the island was uninhabited when Iversen and his shipmates straggled ashore. We can safely assume that, hungry and desperate, they scoured the vicinity for food. Despite the incentive for thoroughness, Iversen evidently found no dodos at all on the Mauritian mainland. But he did see some dodos on a small islet just off the coast, near enough that he and the others could walk to it at low tide. “Amongst other birds,” Iversen reported, “were those which men in the Indies call doddaerssen; they were larger than geese but not able to fly. Instead of wings they had small flaps; but they could run very fast.” Iversen’s account, though short on detail, makes good ecological sense. The small water gap must have been just enough to protect the islet from pigs and monkeys.

At least some of those islet dodos were captured by Iversen’s party. It was his testimony that I quoted earlier: “When we held one by the leg he let out a cry, others came running forward to help the prisoner, and were themselves caught.” Of course the Dutchmen weren’t wrestling with these birds for entertainment. A knife, a campfire, a stout green stick to serve as a roasting spit—the details are imaginary, but without doubt Volquard Iversen helped to butcher and eat a few dodos, which may or may not have been the last of the species. Probably the walckvögel, to this party of shipwreck survivors, didn’t seem quite so walck. I’m reminded here of some lines of old doggerel about cannibalism by a group of castaways, among which the last victim to be sacrificed—by the poem’s narrator—was the cook himself:

And I et that cook in a week or less
And as I eating be
The last of his chops, why, I almost drops
When a vessel in sight I see.

 

Iversen and his mates were lucky. After just five days, they were rescued by a passing ship. No living dodo was ever seen again.

 

THE VIVIDNESS of the Iversen episode is somewhat misleading. The crux of the matter of extinction—the extinction of Raphus cucullatus or any species—is not who or what kills the last individual. That final death reflects only a proximate cause. The ultimate cause, or causes, may be quite different. By the time the death of its last individual becomes imminent, a species has already lost too many battles in the war for survival. It has been swept into a vortex of compounded woes. Its evolutionary adaptability is largely gone. Ecologically, it has become moribund. Sheer chance, among other factors, is working against it. The toilet of its destiny has been flushed.

The causes of extinction are usually multiple and linked to one another in complicated synergy. But the precondition to extinction can be put in a single word: rarity. Obviously, common species become rare as a prelude to vanishing totally; and species that are naturally rare carry an extra, inherent jeopardy of extinction. This dictum—that rarity leads to extinction—might sound like a truism, but the truism has content. The scientific study of the extinction phenomenon addresses three basic questions: (1) why some species are inherently rare, (2) why others become rare, and (3) what particular sorts of trouble afflict rarities.

To be rare is to have a lower threshold of collective catastrophe. Any misfortune, even one that would seem small by an absolute standard, is liable to be a total misfortune. A modest-sized disaster can push a rare species immodestly close to oblivion. At the end, the last individual’s death might turn out to be accidental, independent of the factors that shoved the species into the foyer of extinction.

Imagine, for instance, that the last dodo didn’t perish on Iversen’s islet. Imagine a single survivor, a lonely fugitive at large on mainland Mauritius at the end of the seventeenth century. Imagine this fugitive as a female. She would have been bulky and flightless and befuddled—but resourceful enough to have escaped and endured when the other birds didn’t. Or else she was lucky.

Maybe she had spent all her years in the Bambous Mountains along the southeastern coast, where the various forms of human-brought menace were slow to penetrate. Or she might have lurked in a creek drainage of the Black River Gorges. Time and trouble had finally caught up with her. Imagine that her last hatchling had been snarfed by a feral pig. That her last fertile egg had been eaten by a monkey. That her mate was dead, clubbed by a hungry Dutch sailor, and that she had no hope of finding another. During the past half-dozen years, longer than a bird could remember, she had not even set eyes on a member of her own species.

Raphus cucullatus had become rare unto death. But this one flesh-and-blood individual still lived. Imagine that she was thirty years old, or thirty-five, an ancient age for most sorts of bird but not impossible for a member of such a large-bodied species. She no longer ran, she waddled. Lately she was going blind. Her digestive system was balky. In the dark of an early morning in 1667, say, during a rainstorm, she took cover beneath a cold stone ledge at the base of one of the Black River cliffs. She drew her head down against her body, fluffed her feathers for warmth, squinted in patient misery. She waited. She didn’t know it, nor did anyone else, but she was the only dodo on Earth. When the storm passed, she never opened her eyes. This is extinction."

"The Song of the Dodo" (1996), David Quammen

 

[Hammerfall]

 

[Lebohang]

O eclipse com que Einstein derrubou Newton passou por território português

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[Ghelthon]

Li agora uma frase, num comentário de um vídeo no YouTube, que faz todo o sentido e me deixou espantando:

Citação

Time doesn't exist - when you measure time you just measure repeated events, like the ticks of a clock. That is why it is called space-time.

Isto porque ando numa "obsessão" de saber mais sobre buracos negros.

[Jpa]

Há uns tempos quis informar-me mais sobre a teoria da relatividade e essa questão do espaço-tempo e fritei o cérebro todo. Ainda para mais quando a física clássica não segue certos princípios da física moderna (fiquei com esta ideia, correct me if im wrong).

[Ghelthon]

Eu também não percebo muito, como é evidente. Estou a tentar moldar o meu cérebro para tentar compreender o mínimo dos mínimos em relação a isso.

O que tenho compreendido é que, nos buracos negros, a física que temos não funciona muito bem.

[Pan]

No horizonte de um buraco negro há uma chamada singularidade, em que as leis da física conhecidas deixam de se aplicar.

Quanto ao teorema da relatividade, é simples: diferentes referenciais (ou pontos de referência do espaço) oferecem duas medidas diferentes, mas verdadeiras do tempo. A velocidade com que te deslocas afeta a tua relação com o espaço e, daí, o tempo também se altera como consequência direta. De uma forma prosaica, imagina que tu estás dentro de um comboio a jogar ténis de mesa com o Ghelton, e que eu estou junto à linha de comboio a ver-vos passar. Se tu largares a bola, ela cai da tua mão com velocidade horizontal 0, mas com velocidade vertical. Contudo, para mim, a bola tem a mesma velocidade vertical, e ganha alguma velocidade horizontal, igual à do comboio.

Se transportares a metáfora para o tempo, dependendo da velocidade com que te moves, da gravidade associada e do teu ponto de observação, o tempo passa mais devagar ou mais depressa. Lê sobre o paradoxo dos gémeos.

O tempo é uma dimensão, assim como a altura, largura e comprimento. Dependendo da tua velocidade, podes andar nesta quarta dimensão mais rápido ou mais devagar. O interessante disto é que quem está de fora vê uma velocidade diferente da que tu vês, porque no teu caso, como o teu referencial é o sítio exato onde estás, todas as dimensões se relacionam de forma igual de forma relativa, includindo o tempo. Eu sei que é confuso...mas não sei explicar melhor eheh

[Dominator]

Por acaso até explicaste bem. Esse exemplo foi bom.

[Ghelthon]

Eu percebo a parte da relatividade, e o exemplo dos gémeos é bastante útil nisso. Mas depois toda a questão do "space-time fabric", ondas gravitacionais e o diabo a quatro, mexe completamente com o cérebro porque é todo um novo olhar sobre a forma como achamos que as coisas funcionam.

[Rōnin]

Recomendo a verem.

[Black Hawk]

Citação de Ghelthon, há 5 minutos:

Eu percebo a parte da relatividade, e o exemplo dos gémeos é bastante útil nisso. Mas depois toda a questão do "space-time fabric", ondas gravitacionais e o diabo a quatro, mexe completamente com o cérebro porque é todo um novo olhar sobre a forma como achamos que as coisas funcionam.

Rule of thumb: a forma como interpretamos o tempo é uma invenção humana, advém da nossa percepção do mundo que nos rodeia e da necessidade de controlamos as variáveis sobre as quais não temos influência.

Basta ver que as medidas básicas de controlo do tempo - o dia, o mês, o ano - foram definidas com base em acontecimentos recorrentes facilmente observáveis e que apenas se aplicam ao nosso contexto.

A partir do momento em que analisamos, estudamos e criamos teorias para temas mais abrangentes além da nossa realidade observável, as regras definidas são obsoletas. A "nossa" passagem do tempo, conforme convencionada por nós, não se replica no resto do Universo. Os segundos, minutos, etc, não são medidas universais, mas sim medidas aplicáveis à nossa percepção.

"Percepção" é a palavra chave. O Pan deu um excelente exemplo de como a percepção muda conforme as referências. Só depois de se entender isto é que se consegue abrir a mente para a complexidade que é o espaço-tempo.

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[John Bonifácio]

Isso é fascinante, mas hoje dava-me jeito adormecer. 😳

[Ghelthon]

Tardígrados são os bichos mais badass de sempre.

[Dominator]

Brutal

[Hououin Kyouma]

Satellite Images Show Vast Swaths of the Arctic On Fire.

Citação

 

The remote nature of many of the fires there means they're burning out of control, often, through swaths of peatland that's normally frozen or soggy (...). That's worrisome since peat is rich in carbon, and fires can release it into the atmosphere as carbon dioxide.

(...)

All told, northern fires released as much carbon dioxide in June as the entire country of Sweden does in a year, according to data crunched by the European Union’s Copernicus program. All that carbon dioxide released by fires represents one of the scarier feedback loops of climate change as hot weather ensures more fires, which releases carbon dioxide and makes climate change worse. The boreal forest that rings the northern portion of the world is witnessing a period of wildfire activity unseen in at least 10,000 years, and this summer is another worrying datapoint.

 

 

Editado 20 Julho 2019 por Hououin Kyouma

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Citação de Ghelthon, Em 16/07/2019 at 10:37:

Tardígrados são os bichos mais badass de sempre.