Q. Tell me about some of the ivory seizures you've worked on.

Samuel Wasser has helped to track down the source of many ivory hauls.

A. There was a seizure in 2002 in Singapore of 6,500 kilograms of ivory — 531 tusks, many of which were huge. The authorities knew that poachers were carrying tusks across Zambia and into Malawi. One day they got a tip it was on the move. They went on a truck and then travelled by ship to Singapore. Hong Kong authorities got to the dock just hours before they arrived. The strong smell suggested that at least some of the ivory was fresh.

The ivory was high quality and going to an infrastructure that could get it to wealthy buyers. This is not your small-time village poacher. Everyone thought the ivory had come from multiple locations. We showed it was all from Zambia.

In May 2006, we got another seizure, in Hong Kong. It was 3,900 kg. The tusks were found when officials x-rayed a container from Cameroon. We analysed the tusks and the pieces and found that they were all from elephants in southern Gabon and maybe a bit of the southern part of the Republic of Congo. Everyone thought the poachers were a bunch of little guys operating all over. That's not what seems to be happening here. This is highly organized.

Q. Has it always been this way?

A. Before 1989 there was a period of massive killing of elephants. The population went from 1.3 million to 600,000 in 10 years. That comes out to about 7% annual mortality. It was so bad that CITES — the Convention on International Trade in Endangered Species of Wild Flora and Fauna — banned the ivory trade, and the ban stopped poaching across the whole continent. It was probably the most effective international wildlife legislation in history.

The legislation was so effective that by 1993, western countries withdrew a lot of their aid for law enforcement. Meanwhile, people started to log the forests of central Africa, which created unprecedented access to its forest elephants, which are almost a different species and have desirable harder ivory with a pinkish hue. It was really easy for the poaching to get really bad really fast. Those elephants are getting creamed.

Q. Are things worse now than before 1989?

A. Between August 2005 and August 2006, 25,000 kilograms of ivory were seized. If you estimate that customs catches 10% of what goes through, we are talking almost 37,000 elephants. So now we are at 7.8% annual mortality, higher than the 7% pre-ban.

Q. What's driving the trade?

A. You've got a dramatic increase in the price of high-quality ivory, from US$200 a kilogram in 2004 to $850 now. In China and Japan, the rising middle class has created a tremendous new demand for ivory carvings and signature stamps — hankos. Plus, the CITES rules against illegal trade just apply between nations. Once you get the ivory into the destination country, there are no laws or no enforcement. So it is a formula for disaster.

There is heavy involvement of organized crime. There may also be a strong connection between the ivory trade and gun-runners.

Q. How does determining the origin of ivory through DNA help?

A. When you identify the place of origin you show where the poaching hotspots are and how these guys are actually operating. They seem to be focusing on an area and working it hard. It also forces these countries to take responsibility for the poaching going on inside their borders, because right now few of them do.

Q. How does it work?

A. The secret is to pulverize the ivory without heating it up, which denatures the DNA. We use a freezer mill. It submerges a tube containing a small piece of ivory and a magnet into liquid nitrogen. This freezes the ivory and makes it brittle. We rapidly switch the magnetic field back and forth, causing the magnet to act as a battering ram, smashing the ivory. It's fantastic. I got the idea from this marvellous Canadian dental forensics scientist named David Sweet.

We amplify and sequence the genes of interest in the standard way. The hardest part of the whole project is assembling the reference map of DNA from all over the continent. I am still working on that. Whenever I am at a meeting like this, I work the crowd to fill in any gaps we have in our map.

My genius collaborator Matthew Stephens, a professor of statistics at the University of Chicago, Illinois, developed a new statistical method to assign the ivory. Taking advantage of the fact that two populations close together are much more likely to share genes than are two farther apart, he could generate the probable gene frequencies for areas we don't have data for. That allowed us to ask "where in Africa did this tusk come from", as opposed to "which of our reference samples is this most like?"

Q. Have your studies made a difference?

A. In the Singapore seizure, practically nobody was prosecuted, including customs officials who stamped the shipment identifying the ivory as soapstone. They only prosecuted one guy in Singapore. There are so many wildlife officials and high-level government officials that are getting filthy rich on poaching. Organized crime can afford to bribe everyone.

Q. So what can be done?

A. We need a major infusion of law enforcement in Africa. What you are talking about is a bunch of Land Rovers, guns and ammunition and a little bit of a salary hike. We are not talking about a lot of money here. And legalized ivory trades aren't helping. We need to cool this market down.

Q. And if governments decide to cull certain elephant populations, what should they do with the ivory?

A. Burn it.

Visit our tuskdetective.html">newsblog to read and post comments about this story.