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📖 Texto de lectura

The extinction of the woolly mammoth has long been attributed to human overhunting. However, a closer examination of the evidence suggests that climate change was the primary driver. First, the timing of mammoth extinctions correlates more closely with major climatic shifts than with human arrival. In Eurasia, mammoths disappeared from most of their range around 12,000 years ago, during the Younger Dryas, a period of abrupt cooling, while humans had been present for over 30,000 years. Second, the habitat required by mammoths—open steppe-tundra—dramatically shrank as the climate warmed and became more humid, leading to the spread of forests and peatlands. This habitat fragmentation would have reduced mammoth populations to isolated pockets, making them vulnerable to stochastic events. Third, genetic evidence from late-surviving populations, such as those on Wrangel Island, shows a lack of genetic diversity, indicating small population sizes that were more susceptible to inbreeding and disease, rather than sustained hunting pressure. Thus, while human hunting may have delivered the final blow in some areas, the overarching cause was environmental change that degraded their ecosystem.

🎧 Conferencia de audio

The professor argues that the reading's emphasis on climate change is misguided; instead, human hunting was the decisive factor. First, the correlation with climate is weak. For example, in North America, mammoths survived until about 10,000 years ago, well after the end of the Younger Dryas, and they coexisted with warming climates for millennia. In contrast, their extinction coincides with the arrival of Clovis hunters, who left abundant spear points at kill sites. Second, the habitat argument overlooks the fact that mammoths were adaptable. Fossil evidence shows they could feed on a variety of vegetation, including grasses and sedges that persisted in post-glacial landscapes. Moreover, similar cold-adapted species, like caribou and musk oxen, survived the same habitat changes, suggesting that habitat loss alone was not fatal. Third, the genetic bottleneck observed on Wrangel Island is not evidence of natural decline; rather, it reflects a small, relict population that survived until about 4,000 years ago, long after humans had occupied the island. However, when humans arrived on Wrangel, the population collapsed quickly, indicating that hunting, not genetic problems, caused their final extinction. Therefore, the pattern of human expansion and hunting technology is the best predictor of mammoth extinction.