Academic Reading — Test 23

Reading passage

For much of the twentieth century, archaeologists held a remarkably tidy view of how human beings first reached the Americas. According to what became known as the "Clovis-first" model, named after distinctive stone spear points discovered near Clovis, New Mexico, the earliest settlers crossed from Siberia into Alaska around 13,000 years ago. These pioneers were thought to have walked across a broad land bridge called Beringia, a region exposed when sea levels fell during the last Ice Age, and then to have moved southwards through an ice-free corridor that opened between two great Canadian ice sheets. For decades, almost every textbook repeated this sequence as settled fact, and sites claiming greater antiquity were treated with deep suspicion. The Bluefish Caves, a cluster of three small limestone cavities in the northern Yukon close to the border with Alaska, have become central to the gradual unravelling of that consensus. The caves were first excavated by the archaeologist Jacques Cinq-Mars during a series of field seasons that began in the late 1970s. Inside, he and his team recovered the bones of horses, mammoths, bison and caribou, alongside a modest scattering of stone tools. Cinq-Mars argued that some of the animal remains bore cut marks made by human implements, and that radiocarbon dating placed a number of them well before the supposed Clovis threshold. His most striking claims suggested a human presence stretching back perhaps 24,000 years or more, a figure that many of his contemporaries found impossible to accept. The reception of these findings was, for a long time, distinctly cool. Critics pointed out that the bones could have been gnawed and broken by carnivores rather than people, and that natural processes such as the trampling of herds or the pressure of sediment might mimic the marks left by butchery. Because the caves contained no hearths, no human skeletons and only a sparse assemblage of artefacts, sceptics felt that the case for very early occupation remained unproven. Cinq-Mars himself grew frustrated, later remarking that his interpretations had been quietly ignored rather than openly refuted. For much of the 1980s and 1990s, the site languished on the margins of scholarly debate. The picture began to change in 2017, when a team led by Lauriane Bourgeon re-examined the animal bones using modern microscopic techniques. By studying the surfaces under high magnification, the researchers distinguished cut marks produced by stone tools from the grooves left by the teeth of predators. They concluded that at least some of the marks were genuinely the work of humans, and fresh radiocarbon dating indicated that the oldest of these butchered bones was roughly 24,000 years old. If correct, this made Bluefish Caves one of the oldest known archaeological sites in the Americas, and pushed the human arrival in the region back several thousand years beyond the Clovis horizon. These conclusions fit neatly with a broader idea that has gained ground in recent years, sometimes called the "Beringian standstill" hypothesis. Genetic studies of living Indigenous populations and of ancient DNA suggest that the ancestors of Native Americans were isolated for thousands of years before they spread across the continents. According to this view, a founding population became stranded in Beringia during the coldest part of the Ice Age, when ice sheets to the east blocked any easy passage southwards. The people of Bluefish Caves may represent precisely such a stranded community, surviving on the cold steppe of eastern Beringia while the route into the heart of the Americas remained closed. Only when the climate warmed and the ice retreated could their descendants finally move south. Not every scholar is convinced, and a cautious minority continues to question whether the marks on the Bluefish bones can bear the weight placed upon them. Even so, the site illustrates how scientific understanding advances, not through a single dramatic discovery, but through the patient re-analysis of old material with sharper tools. Evidence once dismissed as marginal can, decades later, move to the centre of the story. The peopling of the Americas is no longer regarded as a simple, single migration, and the modest caves of the Yukon have played a surprisingly large part in overturning a once-unquestioned account.