TOEFL統合ライティング

📖 読解文章

The extinction of the woolly mammoth (Mammuthus primigenius) at the end of the Pleistocene has long been attributed to human overhunting. Proponents of this 'Pleistocene overkill' hypothesis argue that the arrival of human hunters in North America and Eurasia coincided with a rapid decline in mammoth populations. First, archaeological sites frequently contain mammoth bones with cut marks and embedded projectile points, providing direct evidence of hunting. Second, the timing of extinction aligns with human migration patterns; as humans spread, mammoth populations disappeared region by region. Third, mammoths, being large and slow-reproducing, would have been particularly vulnerable to even modest levels of hunting, as their low birth rates could not compensate for additional mortality. Thus, the overkill hypothesis offers a straightforward explanation for their demise.

🎧 リスニング講義

The lecture challenges the overkill hypothesis, arguing that climate change and other factors were more critical. First, the cut marks on mammoth bones are rare and often ambiguous; many could result from scavenging, not active hunting. Moreover, some bones show signs of healing around projectile wounds, indicating that mammoths sometimes survived attacks, so hunting was not always effective. Second, the purported correlation between human arrival and mammoth extinction is flawed. In some regions, humans coexisted with mammoths for thousands of years before extinction, while in others, mammoths vanished before humans arrived. This inconsistent pattern weakens the link to hunting. Third, the vulnerability argument ignores that other large herbivores, such as bison and elk, also had low reproductive rates but survived human hunting. Instead, the lecture points to rapid climate warming and vegetation shifts that reduced mammoth habitats, leading to population fragmentation and decline. These environmental changes, not human predation, were the primary drivers of extinction.