検索キーワード： 制作 "Charles River Editors" 地球科学

The early history of Earth covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead, paleontologists and scientists who study geochronology divide time into periods and eras. What humans commonly refer to as the “Ice Age” is actually a series of fluctuating climate events that have occurred throughout the planet’s history. These ongoing historical phenomena are difficult to conceptualize because of both the time frame involved and the natural process by which they cyclically unfold.

As soon as man discovered writing, he began engaging in historiography (historical writing and philosophy), but paleoanthropology only really began in the late 1800s. As archaeologists began finding bones in European caves of a human race that was very different than any race in the modern world, the study of paleoanthropology was born. The race of those early humans who were found in the European caves were later termed Neanderthals, and for quite some time, they were believed to have been the race from which many modern humans were directly descended.

Scientists have long attempted to understand Earth’s past, and in service to that effort, they have divided the world’s history into eons, eras, periods, epochs, and ages. For example, the current eon is called the Phanerozoic Eon, which means “visible life”. This is the eon in which multicellular life has evolved and thrived. Before this, life was microscopic (single cells).

They say that one is subjected to a sobering sample of what can only be described as an existential crisis when traversing the golden and seemingly infinite terrain of the Sahara Desert. If one climbed any of the countless sand dunes and twirled around in a place, particularly under the starlit sky, they would scarcely be able to tell east from west without a compass, for there would be nothing but dizzying carpets of indistinguishable sand hills unfurling into the distant horizon.