The concept of 'de-extinction'—bringing extinct species back to life through genetic engineering—has gained considerable attention in recent years. Proponents argue that this technology could restore biodiversity, correct past human mistakes, and even benefit modern ecosystems. Three key arguments support this idea. First, de-extinction could revive keystone species that once played crucial roles in their habitats. For example, the woolly mammoth is thought to have maintained grassland ecosystems by trampling trees and fertilizing soil, and its return to Arctic tundra could help combat permafrost thaw and carbon release. Second, advances in CRISPR gene editing make the process feasible. Scientists have already sequenced the genomes of several extinct species, including the passenger pigeon and the mammoth, and could potentially splice their DNA into the genomes of closely related living species, such as the Asian elephant, to create functional hybrids. Third, de-extinction has significant scientific value. Studying resurrected species could reveal insights into evolution, genetics, and adaptation, and the biotechnological innovations developed for this purpose could advance medical and agricultural research.
🎧 听力讲座
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The lecture challenges the optimism of the reading passage, arguing that de-extinction is neither practical, nor ecologically sound, nor scientifically beneficial. First, the ecological rationale is flawed. While woolly mammoths may have influenced ancient grasslands, current Arctic ecosystems have evolved without them for thousands of years. Introducing them now could disrupt existing food webs and introduce diseases or parasites, potentially harming native species. Moreover, the idea that mammoths could slow permafrost thaw is speculative and unproven at any meaningful scale. Second, the technological feasibility is overstated. Even with CRISPR, scientists cannot yet synthesize an entire genome from scratch; they must use the DNA of a living relative, which is imperfect. The resulting hybrid would not be a true mammoth or passenger pigeon, but a modified version with unpredictable traits. Furthermore, the success rate of cloning and gene editing in animals is extremely low, and many engineered embryos die or suffer severe health problems. Third, the claimed scientific value is questionable. The resources—both financial and human—required for de-extinction could be far better spent on conserving currently endangered species and habitats, which face immediate threats. Studying extinct genes, while interesting, offers limited new insights because we cannot observe their behavior or interactions in real time. In short, the lecture concludes that de-extinction distracts from practical conservation and is an unrealistic fantasy.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
