今年我学到的一些有趣事实： 全球约 33% 的人口（约 22 亿人）从未使用过互联网。 38% 的斯坦福大学学生登记为“有残疾”（其中相当一部分很可能是在利用制度，以获得考试延时等便利）。 HIV 在 20 世纪初就开始在非洲传播，但直到 1980 年代才引起广泛关注，因为其致死症状与农村地区常见的其他传染病相似。 如今的曼哈顿人口比 1910 年 少了大约 65 万。 人类和章鱼的眼睛是独立进化出来的：人类的视神经连接在视网膜前方，造成“盲点”；章鱼的视神经连接在视网膜后方，因此没有盲点。 自 2000 年 以来，全球自杀率下降了约 36%。 印度是主要的皮革出口国，尽管牛被视为神圣；大多数皮革来自水牛，而水牛并不被视为神圣动物。 韩国检疫机构使用的工作犬中，约 82% 是克隆犬。由于只克隆表现最优秀的个体，其训练成本不到随机选犬的一半。 美国劳动力中，每月约 1% 的人会被裁员；而在德国，这一比例低于 0.1%。 光污染导致全球鸟类每天鸣唱时间变长，平均每天延长约 50 分钟。 直到 20 世纪 80 年代末，医生常常在不给婴儿麻醉的情况下进行手术，因为当时普遍认为婴儿感觉不到疼痛。 唐氏综合征患者罹患实体癌症的比例约为普通人群的一半，可能与 21 号染色体上的抗癌基因有关。 SpaceX 的星舰（Starship）在发射瞬间产生的功率，约相当于整个美国电网的 10%。 自 1949 年 以来，中国平均下来几乎是每天建成一座大型水坝。 Some interesting things I learned this year: • 33% of the world’s population (= about 2.2 billion people) have never used the internet. • 38% of Stanford students are registered as having a disability (likely many of these are gaming the system to get extra time on exams). • HIV began spreading in the early 1900s in Africa but went largely unnoticed until the 1980s, as its deaths resembled other infectious diseases common in rural areas. • Manhattan today has about 650,000 fewer residents than it did in 1910. • Humans and octopuses evolved eyes independently, but in humans the optic nerve attaches in front of the retina, creating a blind spot, while in octopuses it attaches behind the retina, so they don’t have one. • Global suicide rates have declined by about 36% since 2000. • India is a major leather exporter, despite cows being considered sacred. Most hides come from water buffalo, which are not considered holy. • About 82% of dogs used by South Korea’s quarantine agency are cloned. Training costs are less than half those of randomly selected dogs, since only top performers are cloned. • Roughly 1% of the U.S. workforce is laid off each month, whereas in Germany it’s less than 0.1%. • Light pollution is causing birds worldwide to sing longer each day, extending their vocalizations by an average of 50 minutes. • Until the late 1980s, doctors often performed surgery on babies without anesthesia, due to the belief that infants did not feel pain. • People with Down syndrome have about half the rate of solid cancers compared to the general population, likely due to anti-cancer genes on chromosome 21. • At launch, SpaceX’s Starship produces instantaneous power equivalent to roughly 10% of the entire U.S. electricity grid. • China has built, on average, roughly one large dam per day since 1949.