How many species are there? My latest for the New York Times

By CARL ZIMMER - THE LOOM
Added: Thu, 25 Aug 2011 00:49:57 UTC

In 1833, John Obadiah Westwood, a British entomologist, tried to guess how many species of insects there are on Earth. He extrapolated from England to Earth as a whole. “If we say 400,000, we shall, perhaps, not be very wide of the truth,” he wrote. Today, scientists have found over a million species of insects and keep finding more every year.

The question of how many species there are on Earth has been a tricky one ever since Westwood’s day. I’ve written a story for the New York Times about a new estimate that was published today: 8.7 million.

What makes the paper particularly interesting is that it introduces a new method for estimating biodiversity. The method is based on Linnean taxonomy. While we have lots of new species left to find, we may have found most of the classes, orders, and phyla. It turns out that for a number of groups–mammals, birds, and so on–the numbers of each of these rankings rise as you descend the hierarchy.

Here’s a diagram that summarizes this striking pattern (courtesy of the Census of Marine Life). I couldn’t fit it into the story, so I thought I’d show it here:

RELATED CONTENT

The Descent of Edward Wilson

Richard Dawkins - Prospect 10 Comments

Richard Dawkins's review of The Social Conquest of Earth, by Edward O Wilson (WW Norton, £18.99, May)

Ancient walking mystery deepens

Helen Briggs - BBC News - Science &... 7 Comments

One of the first creatures to step on land could not have walked on four legs, 3D computer models show.

Rare neurons found in monkeys’ brains

Laura Sanders - Science News 4 Comments

Cells linked to empathy and consciousness in primates may offer clues to human self-awareness

Rewritable memory encoded into DNA

Erika Check Hayden - Nature 5 Comments

Researchers have encoded a form of rewritable memory into DNA.

Live Slow, Die Old

Ed Yong - TheScientist 12 Comments

Live Slow, Die Old
Ancient bacteria living in deep-sea sediments are alive—but with metabolisms so slow that it’s hard to tell.

Group finds circadian clock common to...

Bob Yirka - PhysOrg.com 6 Comments

Group finds circadian clock common to almost all life forms
- A group of biology researchers, led by Akhilesh Reddy from Cambridge University have found an enzyme that they believe serves as a circadian clock that operates in virtually all forms of life. In a paper published in the journal Nature, they describe a class of enzymes known as peroxiredoxins which are present in almost all plants and other organisms and which appear to serve as a basic ingredient in non-feedback loop biological clocks.