"It preserves a tremendous amount of detail," Poinar said. "You can even find a fly inside a spider web inside of amber. It entombs very fragile organisms, including microbes."
Poinar, who took an early retirement from the University of California, Berkeley, to join colleagues at Oregon State, is one of the world's leading experts on ancient life forms preserved in amber, but even he is astounded at the discoveries he is making these days.
Scientists would love to find ancient forms of human pathogens, so they would have a better understanding of how modern diseases evolved, but fossils that are not entombed in amber consist mostly of bones, and possibly a little skin and hair.
"You can't really tell much from bones," Poinar said. "You can't grind them up and see pathogens, or anything like that."
So Poinar took his research in another direction. Instead of looking for pathogens specifically, he decided to look at well-preserved animals, called vectors, that carry pathogens. And he made an astonishing discovery when he looked inside an ancient mosquito.
The mosquito was from a 20-million-year-old chunk of Dominican amber. For the first time, the researchers found a fossilized human malaria pathogen, and they found it inside that well-preserved mosquito. So the pathogen that claims so many human lives every year was around long before the beginning of the human era.
And that's not all. Inside a mosquito from a 100-million-year-old piece of amber from Burma they found a precursor to the human malaria pathogen, which Poinar believes was probably a reptilian pathogen. So the deadly pathogen that causes so many human deaths began evolving more than 100 million years ago.
"It was a shock," Poinar said. "Most people didn't think these pathogens were around back then."
No wonder malaria has proven so hard to eradicate. It outlived the dinosaurs.
We know that now because of a hard, brownish, unassuming substance that began as tree sap and ended up as a remarkable window into the past.
Lee Dye is a former science writer for the Los Angeles Times. He now lives in Juneau, Alaska.