The concept of 'de-extinction'—bringing extinct species back to life through genetic engineering—has gained significant attention in recent years. Proponents argue that this technology could restore lost biodiversity and repair damaged ecosystems. However, a more careful examination reveals that de-extinction is not only impractical but also ethically and ecologically problematic. First, the genetic material required for de-extinction is often incomplete or degraded. For species like the woolly mammoth, DNA recovered from permafrost is fragmented, making it impossible to reconstruct a full, viable genome. Even with advanced gene-editing tools like CRISPR, scientists would need to fill gaps using DNA from close living relatives, such as the Asian elephant, resulting in a hybrid organism rather than a true mammoth. Second, de-extinction diverts critical funding and research efforts away from conserving species that are still alive. With limited resources, investing millions in resurrecting a few individuals of an extinct species does little to address the ongoing threats of habitat loss, climate change, and poaching that endanger thousands of existing species. Finally, reintroducing de-extinct species into modern ecosystems poses unpredictable risks. These animals would be ecological 'aliens' in environments that have changed significantly since their extinction, potentially disrupting food chains or introducing diseases. For example, a revived passenger pigeon might compete with existing bird species for resources, causing unintended declines.
🎧 听力讲座
🎯 模拟考试环境：先点「播放讲座」听完内容，再作答。听力原文默认隐藏。
The reading presents a pessimistic view of de-extinction, but its arguments are flawed. First, while it is true that ancient DNA is often degraded, recent advances in sequencing and synthetic biology have made it possible to reconstruct genomes with increasing accuracy. For example, the 2022 sequencing of the thylacine genome achieved near-complete coverage using RNA from museum specimens. Moreover, techniques like base editing allow us to correct errors, and the resulting organism need not be a 'perfect' clone—it could still serve the ecological role of the original species. Second, the claim that de-extinction diverts funds from existing conservation is misleading. In reality, de-extinction projects often generate public interest and attract new funding sources, such as private investors and tourism, which can be channeled into broader conservation efforts. For instance, the 'Great Passenger Pigeon Comeback' project has partnered with conservation groups to protect habitats, creating a win-win situation. Third, the ecological risks are overstated. Scientists conduct rigorous risk assessments before any reintroduction, and de-extinct species could actually fill vacant ecological niches, enhancing ecosystem resilience. The passenger pigeon, for instance, once shaped forest dynamics by creating gaps through nesting; its return could restore that process, which is currently missing. Therefore, de-extinction deserves serious consideration as a conservation tool.
📝 Instrucciones de escritura 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).
