This is scientific Americans 60 second science. I'm Karen Hoffman. This will just take a minute.

Based on the sheer number of ants that have invaded my home this summer, it seems hard to believe, but a new study finds that the number of invertebrates, which include any animal without a spine, has fallen by nearly half over the past 35 years, the same period of time in which the human population has doubled.

The estimate appears in the journal Science.

When we think of extinction, we usually picture large charismatic creatures, like the saber-toothed

tiger, the woolly mammoth, or even the dodo bird.

Over the past 500 years, more than 300 species of vertebrates like these have disappeared.

But what about critters that fly or crawl under our radar?

Butterflies, beetles, spiders, slugs, and worms are all in the midst of decline.

Much of that die-off is due to habitat loss.

In the UK, for example, scientists have recorded a 30 to 60 percent decrease in areas inhabited by common insects, including bees and wasps.

While fewer flying pests might seem a plus, insects also perform functions that are key to human survival, like

pollinating crops and recycling nutrients. So crowding out our invertebrate allies could turn

out to be a real buzzkill.

Thanks for the minute. For Scientific Americans 60 Second Science, I'm Karen Hopkins.