Editor’s note: This article is from our Science for Kids series, aimed at children in grades 4-8.
Dogs are called “man’s best friend.” You probably know that. But do you know when dogs came into being (and became man’s best friend)?
Some scientists recently tried to figure that out and found that wolves changed into the dogs we know and love less than 15,000 years ago. Wait, what? Let’s back up.
First of all, dogs have not been around forever, even though it might seem like that. No animal (and people are a kind of animal too!) or plant has been around forever. Plants and animals have changed slowly but surely over millions of years, and ended up looking the way they look now! The way in which this change happens is called evolution.
How do we know this? The remains or traces of long-ago dead animals and plants – called fossils – can still be found in rocks. By looking at fossils, we know that the animals and plants that live today are different from the ones that lived (and died) so long ago.
Some scientists think that some wolves changed into dogs over a long period of time, starting almost 30,000 years ago. They believe that the wolves that lived around humans started eating the dead animal bodies and bones that humans left behind. (Back then, we used to get food mainly by hunting animals!). Slowly, the wolves that were friendlier with humans lived longer and had more cubs than wolves that were aggressive toward humans. More friendly and social wolves were born in every new generation, becoming the dogs we know today.
Some other scientists think wolves changed into dogs more recently than that. They say that wolves started hanging around people when we started to grow crops and live in one place, about 10,000 to 15,000 years ago. They say that wolves ate from piles of food and human waste and over time got friendlier and changed into dogs.
To know which one of these theories is true, we have to actually find some evidence for either one, right? Some scientists recently studied two 32,000-year-old skulls that were found as fossils in Russia and Belgium. The scientists wanted to know if these skulls were from dogs or wolves. If these turned out to be dog skulls, we could tell that wolves had changed into dogs at least 32,000 years ago. But how to tell which skulls they were?
Abby Drake is one of the scientists who did that study. She said they used a special kind of light called X-rays to take pictures of the skulls. They measured their shape, size and structure. Remember that there are many differences between the skulls of wolves and dogs.
For example, wolf skulls are generally larger compared to their body size than dog skulls. Wolf skulls also generally have more length, width and height in general than dog skulls. Wolves also have a bigger sagittal crest, which is a raised area or bump on the top and back of the skull.
By comparing the measurements from these skulls to those taken from dogs and wolves that live today, Drake and other scientists found that the skulls were of wolves, not dogs. They concluded that wolves changed into dogs only around 15,000 years ago.
But not all scientists agree. Olaf Thalmann, a scientist who worked on a study which analyzed a skull found in the Altai mountains of Siberia from around 33,000 years ago found the animal was more like a dog than a wolf. Another study concluded that dogs were domesticated between 18,800 to 32,100 years ago.
Thalmann said that even if the skulls that Drake studied were of wolves, there is other evidence that dogs lived more than 30,000 years ago.
That’s how it is with science sometimes. Different studies can lead to different results on the same subject. Usually that means scientists will just study it more and try to reach a conclusion.
For now, whatever the verdict is, can we all agree that dogs are cute, especially when they wake up people like this?