Dogs 101—your canine companion – ABC Radio National
Hello, Dr. Karl here.
They’re supposed to be our best friends, they have teeth that can cut like scissors, and they might even cry emotional tears – they’re dogs, and besides love, we give them seat belts, cute rubber boots and therapists.
The current thinking is that dogs started being wolves – after some mutations in their DNA. These mutations reduced their tendency to be aggressive in a kind of flight and increased their ability to process their emotions. These changes started happening around 23,000 years ago in Siberia and made dogs ideal companions for us humans. The first definitive evidence of the connection between humans and dogs is a 15,000-year-old grave in Germany containing a dog, a man, and a woman.
Beginning around 200 years ago, intensive breeding began to give us most of the approximately 450 breeds we have today. These dog breeds are distinguished by three major characteristics. The first is morphology, which relates to the type of fur and its color, the size and shape of their body and skull, and their tail. The second characteristic is their behavior, which includes their tendency to hunt or herd, guard and protect, or retrieve prey. Finally, their personalities can range from loving humans to bits, all the way to aggressiveness. These three characteristics combine in different ways to make dogs valuable to humans in their varied roles as working dogs. There are dogs that work with the army and the police (narc dogs); to be companions and protect humans (park dogs); and hunting prey (marking dogs). Dogs have become so close to humans, that they have evolved from their strictly carnivorous or carnivorous diet, to be able to digest carbohydrates. They do this by having high levels of enzymes such as amylase.
Today, there are almost a billion dogs in the world. But about three quarters of them are village dogs, community dogs or wild dogs. Strangely, there are relatively few companion dogs on the planet. When dogs are closely related to humans, they bond. When a female dog and the owner look at each other for a moment, they both get an increase in blood levels of the so-called love hormone, oxytocin. We don’t know why this only happens with females, but not with males.
We already knew from previous studies that humans who spend a lot of time with dogs simultaneously have lower stress indicators (such as blood pressure, heart rate, and cortisol levels), as well as lower levels. higher levels of beneficial binding and affiliating neurochemicals, such as beta-endorphin, prolactin and, again, oxytocin.
A recent study took this emotional search a step further. They took humans through several stages of increasing involvement with dogs. They started with no involvement (just staring at a white wall), then started looking at a dog, touching the dog with a still hand, then ending with a full pat on the dog. As people became more involved, the areas of the human brain involved in social and emotional responses became much more active.
Humans see the world a little differently than dogs. It’s more than just the fact that we have three color receptors in our retina: red, green and blue and dogs only have two color receptors: yellow and blue). No, it turns out that we humans tend to see the world more as collections of objects (a chair or a ball), while dogs tend to see the world more as actions performed on objects (like sitting on a chair or catching a ball)
Some dogs can be very smart. Rico, a Border Collie, knew the names of over 200 different objects. Chaser, another Border Collie, knew over 1000 different words, related to names and activities.
Now, it’s still a bit controversial, but it seems dogs are the only other animal (besides humans) to have emotional tears. Now, these aren’t tears so profuse that they spurt out of the eyes and down the cheeks, but more of a lesser volume, so the eyes look moist as the tears well up. This study involved dogs separated from people for about six hours. The dogs’ eyes filled with tears when they were reunited with their owners, compared to being reunited with someone they knew, but who was not their owner.
Now, we already know that we humans like pictures of dogs with moist eyes more than those with less moist eyes. Perhaps it was part of our evolution from dog to human, where we humans gave more care and food to a pup with wetter eyes than to one with dry eyes – and after a few hundred generations, dogs began to have wetter eyes.
But maybe these dogs are crying crocodile tears to manipulate puppy love and get more treats from their lovesick owners.