马达加斯加菊石化石 Ammonite fossil from Madagascar (© ThomasLENNE/Shutterstock)

马达加斯加菊石化石 Ammonite fossil from Madagascar (© ThomasLENNE/Shutterstock)

大自然的秘密代码 Nature's secret code

斐波那契日

仔细观察这块菊石化石。它那优雅盘旋的螺壳，曾是史前海洋生物的家，如今却蕴藏着一个数学的秘密：螺旋结构。每一个新的壳室都比前一个按比例增大，保持着恒定的生长比，这种规律常被认为与斐波那契数列密切相关。

每年的11月23日，人们都会庆祝斐波那契日，以纪念这位13世纪的意大利数学家。然而，这一数列的最早记载可追溯至公元前200年，由古印度诗人兼数学家品迦拉首次提出。他描述了这样的序列：1、1、2、3、5、8……每个数字都是前两个数字之和。斐波那契数列广泛存在于自然界之中，从菠萝、洋蓟、松果到植物茎上的排序，都能看到它的影子。

菊石是一类生活在距今约4亿年至6600万年前的软体动物，它们在远古海洋中滑行，螺旋壳保护柔软的身体。死亡后，壳体被沉积物掩埋，矿物质在漫长岁月中渗入其中，将这份自然的几何美永久定格。如今，菊石化石静静提醒着我们：数学与自然，其实说着同一种语言。

Fibonacci Day

Look closely at this ammonite fossil. Its swirling shell, once home to a prehistoric sea creature, holds a mathematical secret—a spiral pattern. Each new chamber is proportionally larger than the previous one, maintaining a consistent growth ratio, often associated with the Fibonacci sequence.

Each November 23, we celebrate Fibonacci Day, named after the 13th-century Italian mathematician Leonardo Bonacci (Fibonacci), who introduced the concept to Europe. The pattern 1, 1, 2, 3, 5, 8…—where each number is the sum of the two before it—was, however, first described in India as early as 200 BCE by the ancient poet-mathematician Pingala. The Fibonacci sequence appears widely in nature, including pineapples, artichokes, pinecones, and the arrangement of leaves on a stem.

Ammonites were mollusks that lived between 400 and 66 million years ago, gliding through ancient seas inside coiled shells that protected their soft bodies. When ammonites perished, sediment buried their shells, and minerals slowly turned them to stone, preserving this natural geometry for millions of years. Today, the ammonite fossil is a striking reminder that math and nature speak the same language.