Flash interactive Produced by the American Museum of Natural History, April 2006.
Nearly 16 lemur species have disappeared in the last 2,300 years. Scientists are studying Madagascar's natural history to find out why. This interactive reveals the paleontological, historical, and other evidence scientists have unearthed in Madagascar to understand how its human and lemur populations have coexisted.
Visual: Photographs of a man standing next to the skeleton of a bird even larger than an ostrich, and the skull of a mammal with a long snout.
Key Evidence: Elephant bird skeleton and giant lemur bones
Analysis: Paleontologists have found no sign of humans on Madagascar predating 417 BC. But they have unearthed plenty of bones of unusually large animals dating from the late Pleistocene through the last millennium. These megafauna include 4 meter tall birds with 8 liter eggs and about 20 species of large lemurs. No animal species heftier than 10 kilograms lives on Madagascar today.
Visual: A microscope photograph of a fungus spore with four round lobes in a long shape, a close-up photograph of a bone with slash marks in it, a photograph with an animal leg bone chopped in four pieces, and a scanning electron microscope super-closeup image of a spherical pollen spore.
Key Evidence: Decrease in fossil fungus spores of the genus Sporormiella, slashed arm bones of giant lemur, chopped leg bones of pygmy hippopotamus, fossil pollen of hemp of genus Cannabis.
Analysis: Many cut marks on a bone signal the animal was hunted and butchered with tools: a sign of human presence. Another sign is 2,250-year-old fossil pollen of a non-native plant, hemp, found in lake sediment. Since early mariners used hemp for sails and ropes, the pollen suggests that visiting sailors cultivated hemp on Madagascar at that time. Also, the number of spores of Sporormiella fungus in sediment dropped sharply about 1,720 years ago. This fungus grows only on the dung of large animals. Less of it suggests that large lemurs declined as hunting and agriculture increased.
Visual: Sections of clay pots and a microscopic photograph of a burned grass blade.
Key Evidence: Early pot fragments and charcoal particles
Analysis: Paleontologists found 1,500-year-old fragments of ceramic under a rock overhang on Madagascar's northern coast: the earliest human artifacts. The amount of microscopic charcoal particles—burned organic material—also increased during this time. The findings suggest that natural fires set by lightning burned wide areas during this period, and that humans were increasingly burning forests to clear land for agriculture. This deforestation continued to reduce lemur habitat.
Visual: Black-and-white engravings of animal species with French writing on them, a photo of stone structures in an excavated pit of earth, and a long jawbone.
Key Evidence: Étienne de Flacourt's Histoire de la Grand Isle Madagascar, 1661 first written account of Madagascar's biodiversity, archaeological dig of Mahilaka City, and a cattle jawbone.
Analysis: Europeans began to explore Madagascar in the 1500's. They wrote the first Western accounts of the now-extinct large lemurs and other oversize animals there. Written and oral records suggest that some of these species survived in small numbers into the 20th century. Remnants of walls, glass, pottery, and other artifacts reveal that Madagascar's first city, Mahilaka, thrived from 1150 to about 1400. Counts of fossilized Sporormiella fungus spores also increased during this time. This fungus grows only on the dung of large animals. Since large native animals were dwindling, the increase suggests a rise in domesticated animals.
Visual: Photograph of a white, fuzzy lemur with a black face in a tree, photo of agricultural fields, a satellite image of Madagascar, fire burning grassland
Key Evidence: Lemur observation, widespread agriculture, satellite observation, visible deforestation
Analysis: Today, scientists using ground-surveying and satellites estimate that Madagascar is deforested at a rate of 1 percent a year. There are about 16 fewer lemur species than when humans first arrived. Scientists monitor remaining lemur populations carefully. Forty-six protected reserves now exist, and the government vowed to triple that area by 2008. As scientific techniques improve and evidence mounts, scientists hope their work will help curb future extinction of lemurs on this ever-changing island.