Nathan Collins writes: With climate change and deforestation threatening biodiversity around the world, it’s fair to wonder just how rapidly threatened species have been declining, and when exactly those declines began. The answer is bleak: Among threatened vertebrates, rapid losses began in the late 19th century, and numbers have since declined by about 25 percent per decade, according to a new study.

“Although preservation of biodiversity is vital to a sustainable human society, rapid population decline (RPD) continues to be widespread” across plant and animal populations, Haipeng Li and a team of Chinese and American biologists write in Proceedings of the National Academy of Sciences.

Understanding the severity and origins of these population losses could help conservationists protect endangered species and possibly help promote public awareness of the threat, the researchers argue. But there’s a problem: Good data on plant and animal population sizes only goes back about four decades, and populations surely declined prior to that.

Fortunately, modern biologists have a way to circumvent that: DNA. [Continue reading…]