biologists Samuel Wasser (left) and Benezeth Mutayoba remove
a piece of elephant tusk for DNA extraction. Photo
by Wendy Schackwitz.
Despite a long-standing
international ban on ivory trade, African elephants continue to
be killed in large numbers for their prized tusks. But a team headed
by UW biologist Sam Wasser has devised a new means of determining
the geographic origin of ivory, which could prove a potent tool
in slowing elephant poaching and the illegal ivory trade.
It is relatively easy to monitor elephant populations with flights
over the open savannas of eastern, central, and southern Africa,
but much harder to do the same in the dense forests of central and
western Africa. Those forests are where elephants are currently
being slaughtered wholesale, says Wasser, who holds the UW’s
endowed chair of conservation biology and is director of the Center
for Conservation Biology.
“My colleagues working in the forests are saying, ‘There
are no elephants left here,’” he says. “That’s
the problem—in the forest you don’t notice the change
in population until it’s so dramatic that it’s almost
too late to do anything about it.”
The African elephant population plummeted by 60 percent—from
1.3 million to just 500,000—between 1979 and 1987, largely
because of ivory poachers. An international agreement banning ivory
trade was enacted in 1989, but still three of the largest ivory
seizures have occurred since 2002.
In June 2002, authorities in Singapore seized a shipment of about
6.5 metric tons of ivory bound for the Far East. The shipment included
532 whole tusks, many more than six feet long, and 41,000 small
carved ivory cylinders about the size of hanko stamps, used for
document signatures. The cylinders alone were worth more than $6
The new methods developed
by Wasser’s team are being used to show generally where such
ivory came from, alerting authorities to specific areas where added
enforcement is needed to curb poaching.
Wasser and his colleagues extracted DNA from elephant droppings
and skin biopsy samples collected from numerous locations in 16
African nations. They used that information to build a DNA-based
reference map to assign tusk origin. They noted genetic differences
in populations from one location to another, and used a statistical
method to extrapolate genetic signatures to fill in gaps between
Matthew Stephens, UW associate professor of statistics, developed
a model allowing the researchers to build genetic profiles for elephant
populations from which they do not have genetic samples. The model
is weighted toward genetic information obtained from populations
nearest those for which information is unavailable.
The method allows a DNA sample to be assigned to a fairly specific
location, with a relatively high confidence that the assignment
is correct. The study indicated that 50 percent of the samples tested
were accurately located within 300 miles and 80 percent were accurate
to within less than 600 miles. Accuracy was much greater among forest
populations, which are more clearly defined because of terrain.
The new method allows for speedy determination of where a particular
ivory sample came from, Wasser explains. That is important because
mounting pressure to lift the 1989 ivory trade ban enacted under
the Convention on International Trade in Endangered Species. But
many experts believe any legalization of ivory trade will only increase
poaching. The new sampling method can help determine quickly whether
that is true in time for exemptions to be altered before elephant
populations suffer catastrophic damage.
Two years ago, five African nations sought, and three received,
an exemption from the ban so that they could conduct one-time ivory
sales. Now numerous other countries are considering seeking exemptions,
and some hope to obtain permanent exemptions.
“Once the door is cracked open, they try to force it open
all the way,” says Wasser, who notes that a number of countries
have kept ivory stockpiles since the 1989 ban. The small central-African
nation of Burundi has a stockpile of 80 tons despite the fact that
it had only one elephant at the time of the ban. Some observers
believe ivory has been sold from that stockpile and replenished
from poached ivory. “This method could detect such restocking
in the future,” Wasser says.
The research was supported by the U.S. Fish and Wildlife Service,
the Gordon and Betty Moore Foundation, the Bosack Kruger Charitable
Trust, the National
Institutes of Health, the International Elephant Foundation and
the Woodland Park Zoo in Seattle. The entire ivory seizure investigation
is being funded by the International Fund for Animal Welfare.
[Winter-Spring 2005 - Table of Contents]