A scientist cracks cases of wildlife crime
The crime scene: a New York City airport. A government officer has just seized handbags and shoes made from reptile skins. He believes the skins came from a threatened type of caiman, a crocodile-like animal. It's illegal to bring products made from threatened animals into the United States without a permit.
But the shipper claims the officer has it all wrong. He says the products were made from an unprotected type of croc.
The officer doesn't buy it. But there's not enough evidence to prove which type of animal is the victim. Will the shipper get away with a possible wildlife crime?
A Call for Help
For help determining the animal victim, the officer calls the American Museum of Natural History in New York City. There, conservation geneticist George Amato studies endangered animals. But when law enforcement officers call, Amato turns his genetics equipment into a crime-fighting forensics lab. Could he crack the case?
The evidence—the reptile-skin handbags—arrived at Amato's lab. Croc skins from different species may look alike, but that doesn't confuse Amato. His evidence is microscopic. Skin cells, like all the body's cells, contain an animal's DNA. DNA is made of four different chemicals that can string together in billions of different sequences. Every species has a unique DNA sequence for certain genes. If Amato can read the DNA, he could prove which kind of croc was bagged.
A croc's DNA sequence contains 2.5 billion chemicals. Fortunately, Amato wouldn't need to look at them all. The mystery's solution lies in a short section of DNA called the barcode region. This section works like universal product codes (UPCs) that are stamped on items at the grocery store. Depending on how a few bars are arranged, UPCs can identify billions of different products. Likewise, says Amato, "A small piece of DNA from a particular region has enough differences that it acts like a barcode for [animal] species."
Cracking the Code
Amato removes DNA from the croc's cells. Then he makes chemical copies of the barcode region. Having many copies makes it easier for a machine to read the code.
Since scientists can duplicate DNA in this way, they can read a DNA barcode even if they have only a tiny piece of the animal. "Theoretically, all I need is one cell," Amato says.
Now Amato can read the barcode. He enters the information into a computer database of DNA barcodes and finds a perfect match—South America's Yacare caiman, a threatened species! Thanks to Amato's detective work, the officer can arrest the suspicious importer.
Amato's lab has identified illegal products made from seal skins, shark fins, and whale and monkey meat. When those results come in, Amato's sad to learn that a rare animal has been killed. "On the other hand," he says, "it is rewarding to play a role in closing down that illegal activity."
Words to Know
Geneticist—a scientist who studies heredity.
Forensics—the study of crime-scene evidence for use in court.
DNA—a chemical code that carries hereditary information.
Sequence—the order in which chemicals line up to form DNA.
Barcode region—a small section of DNA that can be used to identify a species.