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Letter from the editor | 108

Evolutionary processes

Endangered species are frequently on the lists of environmental organizations. Just as commonplace to them are the criticisms of man’s action, who occupies and devastates without ceremony the animals’ habitats that should be preserved. This edition’s front cover story (page 32), brought to us by our special reporter, Marcos Pivetta, shows that man has in fact contributed to extinctions, but cannot be made responsible for all of Mother Nature’s blemishes.

The text in questions deals with the sloth, a sympathetic and slow moving animal found only in the Americas. By way of a DNA (deoxyribonucleic acid) analysis, researchers from the University of São Paulo (USP) and the Federal University of Minas Gerais (UFMG) have discovered that the genetic diversity of these animals is very low. Or that is to say, there are individuals with DNA almost identical at the center of each population and, at the same time, there are large DNA differences in the members of distant groups. Specialists says that the evolutionary process could well have led each region to give origin to sloths of specific genetic lineages.

In other words, the low genetic variability means one more threat for those who have to flea from natural predators, from illegal hunting and from the shrinking of their territory. For example, in the Atlantic Rainforest, one of the spaces in the country inhabited by sloths, only 7% of their original vegetation coverage area remains. The warning that comes from the researchers? analysis signals danger: the consanguinity in small populations of different regions could make the species infeasible by bringing about recessive illnesses and infertility. The studies do not expressly state that these animals will become extinct as a result of this peculiarity. Only add on yet another element to be considered when studying preservation strategies. This time man’s action is not the only reasonable cause for the situation.

Other actions have taken us further – more precisely to Saturn. The assistant science editor, Ricardo Zorzetto, gives us details, of the as yet little understood missions of the spacecraft Cassini and Huygens (page 46). Editor Zorzetto explains how a cooperative piece of work between a Brazilian physicist and an Irish astronomer was the first to indicate important modifications in the planet’s F-ring, confirmed by Cassini. This ring is the most intriguing to specialists, who now have the opportunity not only to confirm old and new theories, but also to see images of Titan, Saturn’s largest moon. The Huygens spacecraft sent back photos that suggest the existence of clouds and rivers of methane. The interest in this lunar satellite occurs because of the fact that it brings together, theoretical conditions similar to those that could have given origin to life on Earth, billions of years ago.

Another piece of work, which also monitors the sky, not as ambitious as the Cassini-Huygens mission, but one that could save lives. In the summer of 2006, the inhabitants of Greater Sao Paulo should be able to count upon an efficient system of rain forecasting that will help to avoid flooding and deaths such as those that occurred last month (page 66). Our technology editor, Marcos de Oliveira, the author of the article, explains that the objective is to identify and analyze the formation and the movements of clouds in the region, previewing the intensity of the rains and emitting alerts via the Civil Defense with more than three hours of warning for all of the population via the media. The Hydro Meteorological Integrated System of the State of Sao Paulo (Sihesp) is part of a science and technological innovation program financed by FAPESP in partnership with the Hydro Meteorological Board of the Secretary of Science and Technology.

And to finish, our humanities editor, Carlos Haag, tells us about the time in which some 19th century books sold tens of thousands of copies in Rio de Janeiro, during the period of a high level of illiteracy in the population (page 82). It is worthwhile reading about this little know chapter in the history of Brazilian culture.