Biologists recognize two elephant species in Africa, and both are larger than their Asian counterpart. But the forest elephants (orage area) of Central and West Africa are smaller than elephants on the savanna. They also have smaller ears and straighter tusks.
Savanna elephants (green area) range over a greater region than forest elephants (purple area shows where hybrids of the two species occur). A 1999 report estimated that at the peak of the ivory trade poachers took 1,000 tons of ivory from Africa each year.
While Georgiadis assembled his samples in Kenya, Wasser laid the groundwork for the next breakthrough in neighboring Tanzania. Wasser hadn’t come to Africa to work on elephants; he was there studying how female baboons curtail their reproduction when resources grow scarce, and he was interested in measuring changes in the hormones that regulate stress and reproduction. To chart this process, Wasser and his colleagues devised a new, noninvasive method—tallying hormone metabolites in feces.
Extracting information from fecal samples is now an important conservation tool, but it was new ground in early 1985. Using drug-sniffing dogs retrained to sniff out scat, Wasser tracked grizzly bears in Washington’s Cascade Range, pumas and jaguars in Brazil’s Central Highlands, and even right whales in the North Atlantic. Dogs can distinguish the scat of 18 different species, detect samples from great distances on land and sea, and search much faster and more thoroughly than humans. Once he gets the scat, Wasser says, he “can tell you if it was a female via DNA, and from hormones how stressed the animal was, and if it was a female, whether she was pregnant—all without ever seeing her.”
While chasing baboon scat, Wasser stumbled upon elephant poaching. “I spent years in one of the most heavily poached regions of Africa,” he says. “I became totally disgusted with the ivory trade.” And he realized how the methods he’d developed might help combat it. Forest elephants, which travel in smaller groups in dense foliage, are much harder to track and dart than their brazen savanna cousins. Fecal sampling and DNA analysis might provide much-needed information on their numbers and movements.
Eventually, by drawing on Georgiadis’s tissue collection, Lori Eggert’s West African samples, and the gleanings of other on-site collectors, Wasser’s team at the Center for Conservation Biology at the University of Washington assembled a bank of 354 tissue samples and 491 fecal samples, collected from 45 locations in 23 countries, that together account for over 85 percent of Africa’s surviving elephants. They extracted and amplified DNA from these samples, concentrating on microsatellites, repetitive noncoding DNA sections that rapidly accumulate genetic changes. Where the mitochondrial DNA that Georgiadis analyzed provides just a single locus for comparison, Wasser’s team compared up to 16 loci in each microsatellite sample—and the regional differences they found did not evaporate upon closer inspection.
By comparing the frequency of markers in samples taken from known locations, they managed to assemble a map of elephant gene flow across the continent. They tested this map by using it to deduce the origins of samples from undisclosed locations—and found they could place half these samples within 300 miles of their points of origin and 80 percent within 600 miles.
Last fall Wasser’s team began analyzing tusks from the Singapore seizure. Figuring out the origins of 75 randomly selected tusk samples would prove the first real-world test of the genetic detection method. To get to this point, the sleuths had managed to succeed where other investigators had failed; they had figured out how to successfully extract high-quality DNA from ivory, and they had done so by picking up a few tips from orthodontists and forensic scientists. Wasser surmised that because tusks are just massively overgrown teeth, they should harbor DNA in remnants of the odontoblastic cells that form dentin. And when he consulted a forensic dental laboratory in British Columbia, he found that superfreezing would avoid the DNA-wrecking heat of ordinary drilling and pulverizing. When Wasser and collaborator Kenine Comstock pulverized tusk samples in their nitrogen-cooled device, they found them shot through with DNA.