Read the following two passages regarding the extinction of Pleistocene megafauna.
Passage A
The late Pleistocene epoch witnessed a dramatic loss of large mammalian species (megafauna) across the globe, an extinction event that closely tracks the global expansion of anatomically modern humans. The "overkill" hypothesis posits that human hunters, armed with advanced projectile technology and arriving in environments where prey animals lacked co-evolved defensive behaviors, rapidly decimated these populations. Proponents of overkill point to the stark chronological correlation: in Australia, the Americas, and Madagascar, the arrival of humans is closely followed by abrupt megafaunal collapse. Furthermore, mathematical models of predator-prey dynamics demonstrate that even a small, slowly growing population of human hunters could hunt a slow-reproducing megafauna population to extinction within a few centuries. The sheer unprecedented speed of these extinctions, coupled with their occurrence across diverse climatic zones—from the arctic tundra to tropical rainforests—strongly implicates the sudden introduction of a novel super-predator rather than gradual ecological shifts. While climate fluctuations certainly occurred, they had been a regular feature of the Pleistocene for hundreds of thousands of years without causing mass extinctions; it is the unique variable of human expansion that distinguishes this final extinction event.
Passage B
For decades, the narrative allure of the overkill hypothesis has overshadowed significant deficiencies in its archaeological foundation. If human predation were the primary driver of Pleistocene megafaunal extinctions, one would expect the archaeological record to be replete with "kill sites" demonstrating the systematic slaughter of these animals. Yet, definitive evidence of human hunting in the Americas, for example, is restricted to a handful of species, primarily mammoths and mastodons, leaving the extinction of dozens of other megafaunal species—such as giant ground sloths and saber-toothed cats—archaeologically unlinked to human activity. Instead, a more robust explanation lies in the severe and rapid climate oscillations that characterized the Pleistocene-Holocene transition. As the last glacial period ended, profound shifts in temperature and precipitation drastically altered vegetation patterns, stripping away the mosaic environments and shrinking the specialized habitats upon which megafauna relied. This ecological fragmentation would have placed severe nutritional stress on large herbivores, collapsing food webs and driving extinctions regardless of human presence. The relatively sparse evidence of hunting more likely reflects opportunistic scavenging or the localized hunting of populations already fatally compromised by environmental collapse.
Based on the passages, how would the author of Passage A most likely respond to the assertion in Passage B that ecological fragmentation would have driven extinctions "regardless of human presence"?
- ABy suggesting that the climate change hypothesis fundamentally relies on the false assumption that early humans lacked advanced projectile technology.
- BBy arguing that human hunters actively accelerated the process of ecological fragmentation through the destruction of specialized habitats.
- By pointing out that similar climate fluctuations occurred frequently in the past without resulting in mass extinctions, indicating that climate alone is an insufficient explanation.Answer
- DBy agreeing that the collapse of food webs was the primary driver of extinction, but arguing that this collapse was initiated by the sudden introduction of a super-predator.
- EBy countering that the archaeological record actually contains abundant kill sites for almost every species of extinct megafauna.