The dog who sniffed 5000-year-old bones

Dog helps archaeologists in archaeology

  On a clear and cloudless afternoon in Croatia in southeastern Europe, a hot wind called “Pola” passed through the Velebit Mountains in Croatia and passed over the Adriatic Sea. When hurricane levels are reached, this cold and dry air currents will cause steep, arid terrain-porous rock formations called karsts-to freeze at noon.
  Despite the difficult conditions in the region, humans have lived here for thousands of years.
  Archaeologist Vedrana Gravas of Zadar University in Croatia grew up on this land. In 2014, when she and her team were working on the Velebit Mountains, they discovered a 3000-year-old tomb—a new archeological work began.
  In 2015, Gravas found dog trainer Andrea Pintal. The dog trained by Pintal can sniff out the corpse of many years ago. For more than 30 years, her dog has assisted the local police in solving a large number of strange cases that have been sealed for many years. “I want to know how long ago her dog could smell something from the past.” Gravas said, “Unexpectedly, it smelled the corpse buried in the 8th century BC.” So Pintal’s dog became Gravas. Good helper for archaeology.
  Compared with modern archeological techniques such as aerial photography, infrared satellite imaging, and ground penetrating radar, the role of these dogs cannot be replaced. They have unique search capabilities and can sniff out the remains buried centuries ago.
  These dogs eventually helped Gravas discover six peculiar graves, one of which was about 50 meters away from the others. From these tombs, she unearthed stone boxes, artifacts, and bones of the fingers and toes of the dead.
  For a long time, dogs have been man’s best friends-brave protectors, loyal partners, excellent grippers, and now it seems that they are also ideal archaeological assistants. More archaeologists are now using the ability of dogs to find debris to unearth more and more ancient cemeteries. In northwestern Canada, archaeologists use dogs to find mammoth tusks.
How dogs are trained to archaeology

  The German Shepherd is ideal for accepting archaeological missions. The Swedish female archaeologist Sophie Valuli has a seven-year-old black purebred German shepherd “Fabel”. It is a typical dog who likes to play and is also a trained archeological dog. It has a keen eye and a keen eye, and once entered into archaeological work with its owner Valuli, it will become focused.
  When Valuli started training Faber in 2013, it was only five months old. She devised a set of methods to test Faber-prepared four bone samples for Faber to identify, of which only one is human. Valuli himself didn’t know which of the bones in the jar was human, to avoid revealing clues to Faber unknowingly.
  A total of 120 such tests were carried out. As a result, Valuli found that Faber had an accuracy of 94.2% in distinguishing human remains.
  Then Faber went to archaeology with Valuli. One of its most outstanding missions was an ancient human settlement on the Aland Islands on the east coast of Sweden. This settlement has a history of more than 1,000 years. There, Faber discovered human remains buried 1.5 meters deep underground with a history of 1600 years.

  In North America, there is another project that is using dogs to search for older remains.
  In 2018, Hannah Decker, a junior at Carroll College in Montana, USA, under the guidance of her teacher, studied whether it is possible to train a 12-week-old “Dax”-it is a border collie and an Australian A hybrid of shepherd dogs-to search for the bones of mammals that humans hunted in the past.
  Her training started indoors and then gradually turned to the outdoors. When appropriate, Dekker will use the real bones of mammals. She is very cautious in every operation. In some cases, she wears gloves when handling samples to avoid contamination caused by direct contact.
  At first, Decker grinds the bones into powder (because it can emit more odor and is more conducive to the smell of the dog), and put these powders and toys on the ground together, so that the dog can distinguish; next, she will The powder was simply hidden and let the dog look for it; finally, she buried the whole bone about 10 centimeters underground and let the dog sniff.
  By the end of the training, Dax was able to sniff out the bones buried 10 months ago from 10 centimeters underground. In a similar experiment, it discovered animal bones more than 3,500 years old. In August 2019, the dog found a complete mammalian skeleton underground. This bone has a history of 5,000 years. Buried more than 30 cm deep.
  Now, Dax is a full-time archaeologist. It has identified archaeological sites with archaeologists. At these sites, it has discovered the bones of many ancient mammals, such as bison, deer, elk or rabbits— -These animals should be part of the food of the aboriginal people at that time.
What the dog sniffs

  Dog noses are at least ten thousand times better than our human noses.
  Specifically, dogs can recognize low-molecular-weight compounds, which evaporate easily at room temperature and often have odors, which scientists call “volatile organic compounds.” Dogs can accurately identify any one of these trillions of compounds-this is an incredible ability to smell. Dogs can sniff out some information based on the smell of objects. For example, you can sniff out melanoma skin cancer in humans, you can find pregnant cows from a herd, and so on.
  So, what exactly did the dog sniff out in the archaeological excavation? “Our dogs are not actually looking for bones,” Gravas explained, “but looking for molecules broken down from human remains.” In
  terms of human remains, dogs can smell one of several unique molecules.
  One possibility is that dogs have discovered fatty acids in fat-a substance that scientists have paid attention to for centuries, sometimes called “corpse wax” or “cemetery fat.” It is a by-product of natural decomposition. Human fat is converted into free fatty acids by bacteria, and then hardened into cadaver wax that can effectively turn the dead into mummies. Corpse wax can help scientists determine the age of a corpse. This substance can be preserved in the remains for a long time. For example, in 2009, scientists reported that corpse wax was found in the remains of a 1,600-year-old German child.
  Another possibility is that dogs can sniff out a compound called “ester” in animal fat (a study in 2015 found that humans have five unique esters). Moisture, sunlight, temperature, and soil composition all affect the odor emitted by bones, and odors immersed in rocks and soil may be effectively stored for thousands of years.
  Exactly how old a dog can smell is currently unknown. Matthew Collins, an archaeologist at the University of Cambridge in the United Kingdom, studied how long ancient proteins can remain, and found that some of them have a lifespan of more than 1 million years. However, these proteins only exist in well-preserved, non-decayed remains, and the molecules that dogs sniff are produced by decomposition, so can dogs sniff these truly ancient specimens? This requires more experiments and analysis to draw conclusions.