Author: Self-Control
Reviewer: Guanfu Juntian

  P.S. First, an apology. In the article from two issues ago, “The Sapiens Flood, Part I,” I overlooked an error. Homo sapiens left Africa about 70,000 years ago, but I wrote that this happened when the species first appeared, 150,000 years ago. That date is itself uncertain: estimates of 160,000 or 200,000 years also appear, partly because some classifications treat Neanderthals as early Homo sapiens. Here, we will follow the view taken in the book. Fortunately, a friend on Qzone pointed out the mistake. My apologies.

  Two issues ago, we saw how Homo sapiens entered the Australian “level” and, in only a few thousand years, effortlessly swept away most of the continent’s medium-sized and large animals. Only the boxing kangaroos just managed to hang on ԅ(✧_✧ԅ). But questions remain about exactly how humans cleared the level. After all, they were still living in the Paleolithic, so conquering Australia could hardly have been easy.

(Image sourced from the internet)

  In Sapiens: A Brief History of Humankind, the author broadly offers three explanations. First, large animals—the chief victims of the Australian level—reproduce very slowly: their gestation periods are long, and they bear few young at a time. Living elephants, for example, have a gestation period of roughly 20–22 months and usually produce only one calf. Thus, even with an animal as large as Diprotodon, Homo sapiens needed to kill only one every few months for deaths to outnumber births. Over time, Diprotodon disappeared from Australia. Second, the humans who reached Australia had probably mastered fire-stick farming. These “fire mages” could start a blaze at the slightest excuse and clear a tract of land in no time—an area-of-effect ability in their arsenal. Third, the climate was exceptionally harsh. About 45,000 years ago, climatic changes in Australia dealt the animals the final blow. Under ordinary circumstances, Australia’s large animals might have survived such changes, but they struck just as Homo sapiens arrived. That was well and truly game over. Without further evidence, we cannot decide which explanation is the most convincing; in reality, all three probably operated together.

(Image sourced from the internet)

  With Australia behind us, we can turn to the journey into the Americas, across the ocean from China. Most of us know the outline: during the Ice Age, several tribes of Homo sapiens crossed the frozen Bering Strait and reached the Americas. On the surface, this may seem much easier than reaching Australia, but it was not. Crossing the Bering Strait posed a formidable challenge. Siberia’s extreme cold and the polar days and nights at high latitudes alike presented mortal dangers.

  Homo sapiens first reached the Americas about 16,000 years ago, or around 14,000 BCE. (Look at that—dozens of easy filler words, including this sentence. (◦˙▽˙◦)) The earliest human tribes there were mammoth hunters. Some pressure may have forced them to seek a living farther north, but they soon learned to make snowshoes and warm clothing. This made life considerably more comfortable, because hunting mammoths paid handsomely: the meat was food, the bones became weapons and tools, the hide became warm clothing, and even the ivory could be fashioned into ornaments. Mammoth hunters therefore lived rather well, although they often had to keep migrating in pursuit of the herds. It was the Ice Age, and water levels were low across much of the Bering Strait, leaving a land bridge between the two sides. The first Homo sapiens unwittingly followed the mammoth herds from Siberia into Alaska.

  Humans were still few in number, however, and their range remained confined to Alaska. Around 12,000 BCE, the global climate warmed and easier routes opened to the south. Only then did Homo sapiens begin migrating south on a large scale. The “Sapiens flood,” held back for two thousand years, burst through the gates once more and poured across the Americas from north to south. In less than two thousand years, humans spread from Alaska all the way to Tierra del Fuego at the southern tip of the Americas. Countless species across the continents disappeared in their wake.