Here's a breakdown:
* Size and Structure: They have a larger olfactory bulb (the part of the brain responsible for smell) than humans, and a nasal cavity with a larger surface area and more olfactory receptors.
* Sensitivity: They can detect odors at much lower concentrations than humans. It's often said they can smell a single drop of blood in a swimming pool.
* Training: While naturally gifted, their smell abilities can be honed through specialized training. This allows them to perform tasks like drug detection, bomb detection, and tracking missing people.
However, it's important to note that the exact number (100,000 to 1 million times stronger) is an estimate and not a precise scientific measure.
Regardless, German Shepherds are renowned for their exceptional olfactory capabilities, making them valuable assets in many fields.