A. The field of ancient DNA (aDNA) analysis has revolutionised our understanding of the past, allowing scientists to study the genetic material of long-dead organisms, including our own ancestors. By extracting and sequencing DNA from ancient remains such as bones, teeth, and hair, researchers can directly investigate questions about evolution, migration, and the history of diseases that were previously only answerable through the indirect evidence of archaeology and palaeontology.
B. The process of aDNA analysis is extremely delicate. Over time, DNA degrades into short, fragmented pieces, and samples are often heavily contaminated with modern DNA from bacteria or the researchers handling them. To overcome this, scientists work in ultra-clean laboratories and use advanced sequencing technologies and sophisticated computational methods to piece together the ancient genetic code and filter out contamination.
C. The insights gained from aDNA have been transformative. Studies of Neanderthal DNA have shown that early modern humans interbred with them, and that traces of Neanderthal DNA are still present in the genomes of most non-African people today. aDNA has been used to trace the massive prehistoric migrations that shaped the genetic landscape of modern Europe and Asia, and to understand the spread of agriculture. It has also allowed scientists to identify the pathogens responsible for historical plagues, such as the Black Death.
D. Beyond human history, aDNA is being used to study the evolution and extinction of other species, such as the woolly mammoth. It provides a powerful tool for understanding how ecosystems and biodiversity have changed over time in response to climate shifts. Despite the technical challenges, the field of ancient DNA continues to push the boundaries of what we can know about the deep past, providing a direct window into the genetic history of life on Earth.
IELTS Practice Tests Practice Test / Part 1 #169
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