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Letter from the Editor | 227

Important developments

A group of biologists and zoologists are carrying out extensive fieldwork with the ambitious goal of mapping the geographic distribution of Brazilian snakes in the past and the present. Contrary to what you might expect, the researchers’ efforts to discover where some types of snakes live is of interest to all of us, even if indirectly. Preliminary results indicate that some species have lost up to 80% of the forest area or fields that they occupied three decades ago. The shrinking of the population of snakes creates an ecological imbalance between animal communities and makes the production of snake venom antidotes difficult.

Brazil has the greatest diversity of snakes in the world. There are 380 species, from the inoffensive blind snake to the frightening anaconda. Based on the maps already completed, we know that 22 species are endemic to the Caatinga and another 80 to the Atlantic Forest, and these biomes are contracting. In total, there are 25 Brazilian and two Argentine specialists working on the mapping, and they are surprised by what they have found. Since the mapping began, in 2010, they have noted that deforestation caused by agriculture and the growth of cities has reached the boundaries of the Xingu Indigenous Reserve, in the states of Mato Grosso do Sul and Pará, Emas National Park in the state of Goiás, and conservation areas in the state of Alagoas. The researchers’ warnings with respect to native forests is already familiar to Brazilians: if we do not act now, in a few years there will be nothing left to preserve, only much to lament. Special Editor Carlos Fioravanti tells this story starting on page 14.

Archaeologist Niède Guidon, of the Museum of the American Man Foundation, has also been making breakthroughs since the 1970s, when she began to work systematically at the archaeological sites in the Serra da Capivara, in the state of Piauí. Her studies show that the dating of fire remains and stone artifacts attributed to Homo sapiens suggest the presence of man in the region between 30,000 and 100,000 years ago by means of a maritime route over the Atlantic Ocean. The traditional theory, mainly advocated by researchers in the United States, argues that the arrival of the first H. sapiens group on the mainland was about 13,000 years ago, via the Bering Strait. In recent decades, new research has pushed this date back, closer to Guidon’s conclusions.

Recently, two deer teeth unearthed in the same geological layer as human bones near the Serra da Capivara National Park were analyzed. The estimated age of the teeth—dated by two different laboratories, one in Brazil and another in the United States—was 29,000 to 24,000 years ago, respectively. Thus, the researchers have gathered a set of indirect evidence of the presence of humans in the semi-arid Northeast at least 20,000 years ago. This new chapter in the search for the approximate date in which the first humans reached the Americas is described by Special Editor Marcos Pivetta (page 40).