A new name was added to the extinction list last week: the Yangtze river dolphin. According to the Guardian, the Yangtze dolphin 'is the first large vertebrate forced to extinction by human activity in 50 years, and only the fourth time an entire evolutionary line of mammals has vanished from the face of the Earth since the year 1500.'

The freshwater mammal's demise raises pressing questions about the impacts of unsustainable fishing and mass shipping. But it also raises more -- for lack of a better term -- existential questions: How do scientists track these deaths? And what do such losses mean to us? To answer the first query, scientists rely on a careful, analytical process. As reported by BBC News, exactly which creatures get put on the death list are determined by the World Conservation Union (IUCN) after a thorough surveying process that is reviewed every four to five years. Currently, there are more than 800 species listed as extinct, some 60 of which can be found in captivity, but not in the wild. 

The question of what these losses actually mean to us, however, is a far murkier one to answer. There are no commemorative services for the recently extinct, no mock burials. Instead, we have gloomy news reports that read like obituaries.

In National Wildlife, Mark Jerome Walters grapples with the quandaries posed by extinction. 'Each extinction,' he writes, 'is a unique voice silenced in a universal conversation of which we ourselves are only one participant. When the tiny wings of the last Xerces blue butterfly ceased to flutter, our world grew quieter by a whisper and duller by a hue. Our world grew dumber still when the last raspy call of the dusky seaside sparrow rose and fell within the straw-and-emerald marshes of Florida's east coast.' These are frustrating losses, especially because they are accelerated by human activity and disregard. 'Of our own choice,' Walters goes on, 'the community of life becomes less intelligent -- in the broadest sense of the word.'