TOEFL統合ライティング

📖 読解文章

The discovery of ancient human remains in the Americas has long been a subject of debate. One prominent theory, known as the Clovis-first model, posits that the first humans to enter the Americas were the Clovis people, who crossed the Bering Land Bridge from Asia around 13,000 years ago. This theory is supported by three main arguments. First, the distinctive Clovis spear points, characterized by their fluted design, have been found across North America and date to roughly 11,500 years ago, making them the oldest widely accepted human artifacts on the continent. Second, the timing of the Clovis culture aligns with a brief window when the ice-free corridor through Canada was open, providing a viable migration route for hunter-gatherers following large game. Third, genetic studies of modern Native Americans show a strong affinity with populations from Siberia, suggesting a single, late migration event that matches the Clovis timeline. Together, these points have led many archaeologists to conclude that Clovis people were the ancestors of all later Indigenous Americans.

🎧 リスニング講義

The lecture challenges the Clovis-first model, arguing that recent evidence undermines each of its key claims. First, while Clovis points are indeed widespread, older artifacts have been discovered at sites such as Monte Verde in Chile, which dates to approximately 14,500 years ago—predating Clovis by over 1,000 years. These sites contain non-Clovis tools, including simple flakes and bone implements, indicating that humans were present in South America before Clovis culture emerged in the north. Second, the ice-free corridor hypothesis is problematic because geological evidence shows that the corridor was not biologically viable—lacking vegetation and animal life—until around 12,600 years ago, after Clovis points appear. This suggests that early migrants must have used a coastal route along the Pacific, which would have been ice-free earlier and rich in marine resources. Third, recent genetic analyses of ancient DNA from remains older than Clovis, such as those from the Spirit Cave mummy in Nevada, reveal a more complex picture. These individuals show genetic links not only to Siberian populations but also to ancient populations from Southeast Asia and Oceania, implying multiple migration waves or a single earlier migration with diverse origins. Therefore, the lecture concludes that the Clovis-first model is no longer tenable, and the peopling of the Americas was likely far more ancient and multifaceted.