The extinction of the megafauna—large animals such as mammoths, giant sloths, and saber-toothed cats—at the end of the Pleistocene epoch has long puzzled scientists. While many factors have been proposed, the most compelling explanation is overhunting by early humans. First, the timing of extinctions correlates strongly with human arrival. In North America, for example, most megafauna disappeared roughly 13,000 years ago, just after the Clovis people, known for their distinctive stone spear points, spread across the continent. In Australia, giant marsupials vanished about 45,000 years ago, soon after humans first arrived. Second, archaeological evidence supports human predation. Clovis spear points have been found embedded in mammoth skeletons, and kill sites with butchered remains indicate that humans actively hunted these animals. Third, the selectivity of extinction points to human hunting rather than climate change. Megafauna species that went extinct were typically large, slow-reproducing, and vulnerable to hunting pressure, while smaller, faster-reproducing species survived. Climate shifts would have affected a broader range of species, not just the large ones. Therefore, human overhunting is the primary cause of the Pleistocene megafauna extinction.
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The reading presents a compelling case for human overhunting, but a closer look at the evidence reveals serious flaws. First, the correlation between human arrival and extinction is not as clear as claimed. In North America, some megafauna species disappeared before the Clovis people appeared, while in other regions, such as Africa and Asia, megafauna coexisted with humans for hundreds of thousands of years without going extinct. This suggests that human presence alone does not drive extinction. Second, the archaeological evidence is problematic. While spear points have been found with mammoth bones, these are rare and often show no clear cut marks. Many such finds could be scavenging events rather than active hunting, as humans may have used tools to strip meat from already dead animals. Third, the selectivity argument is misleading. Climate change at the end of the Pleistocene was drastic, causing rapid shifts in vegetation and habitat. Large animals, which require vast territories and specific food sources, would have been more vulnerable to these changes than smaller, adaptable species. In fact, many extinctions occurred during periods of abrupt climate warming, not just after human arrival. Thus, the evidence supports a more complex scenario where climate change, not overhunting, was the dominant factor.
📝 Hướng dẫn viết Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
