For decades the mystery persisted among the scientific community. What was the determining factor that wiped out mastodons and other mammals during the Ice Age? Now a new study from California appears to have solved the puzzle. It was the effect of man, combined with climate change, that wiped out 70% of large mammals who once roamed what is now Los Angeles for millennia. They suddenly ceased to exist.
From the La Brea Tar Pits, a science museum in downtown Los Angeles, they have managed to analyze what happened about 12,700 years ago, when the Earth underwent the last significant climate change. The findings, made possible by a new radiocarbon chronology of fossils from the La Brea tar pits, provide insight into the dynamics that contributed to the Pleistocene extinctions and modern ecological change, research published in the journal Science.
“The conditions that led to the late Pleistocene change of state in southern California are recurrent today in the western United States and in many other ecosystems around the world,” write the authors of the study, led by Robin O. ‘Keefe, Professor of Biological Sciences at Marshall University. “The event may be useful in mitigating future biodiversity loss in the face of similar pressures.”
Until now it was known that at the end of the last Ice Age about two-thirds of the large mammals on Earth are extinct in most regions of the world. The disappearance of these large species coincided with the climatic changes of the late Quaternary and the expansion of the human population in different parts of the planet, unleashing wildfires that contributed to the end of these large species, mammoths and mastodons among them.
O’Keefe and his research colleagues drew on the wealth of the La Brea (Rancho La Brea) tar pits, a scientific treasure trove located in the heart of Los Angeles and just yards from the Los Angeles County Museum of Art and the Hollywood Academy Film Museum. The site contains a nearly continuous record of Pleistocene megafaunal occupation of the Los Angeles Basin from more than 55,0000 years ago to the Holocene. Until now what was known was based on fragmentary paleontological records that lacked the necessary chronological precision.