蜜蜂化石揭示气候变化

LOS ANGELES — Fossils from California’s La Brea Tar Pits keep supplying scientists with excellent material for studying the region’s past. Ancient animals, from mammoths to tiny insects, reveal facts about climate changes during the last Ice Age and help scientists understand the modern climate.

For millennia, natural tar that seeped from the ground in what is now southern California trapped large and small animals, preserving their fossils and providing scientists with a trove of specimens suitable for study.

Anna Holden, a researcher at the Page Museum in Los Angeles, is analyzing fossilized bees to learn about the ancient environment of the tar pits.

In trying to reconstruct what the climate and local habitat were like, she said, “this bee offered kind of uNPRecedented information."

By exposing the fossils to a micro CT scanner, scientists discovered that the bee’s habitat was warmer than expected. They concluded that at the end of the Ice Age, about 11,500 years ago, this area was not covered with snow and ice, as previously thought.

Insects’ limited range – unlike that of the large mammals that came to La Brea from South America or across the land bridge now covered by the Bering Strait – allows the collection of detailed information about their immediate environment, Holden said.

“Insects have very specific life cycles, so they're just really good paleoecological indicators,” she said. “In other words, they're just very specific in their behavior, their habitats.”

Whoever collected the specimens in the 1970s did a good job of keeping records, Holden said. Comparing that data with current findings can reveal something about our future.

“Understanding past climate change is understanding current climate change,” she said. “Climate change is a big issue right now and insects are often really good indicators.”

Holden said her work may help today’s farmers fight the problem of collapsing bee populations, by switching over to bee species better adapted for the changing climate.