Dogs experience 'runner's high' because their brains produce the same chemicals found in cannabis, claims study Study found that dogs get a 'runner's high' similar to those experienced by humans Running creates a drug in the brain that is also found in cannabis Dogs and humans love to run because it gives them a natural high similar to that of cannabis, according to the University of Arizona. Researchers wanted to see why some animals evolved to be better at running, such as humans and dogs, while others, including ferrets, aren't. Their findings suggests that this may be because after running, the levels of endocannabinoids - chemicals found in marijuana that give you a feeling of euphoria - are higher in human's and dogs and this encourages them to run again. Dogs and humans are known as cursorial animals, which means they have evolved specifically to be good at running long distances. Researchers from the University of Arizona have discovered that dogs get the same 'runner's high' as humans, and that we may have both evolved because our brains produce feel-good chemicals, similar to those found in cannabis Chart showing the changes in the level of feel-good chemicals in the animals' blood before and after treadmill exercise. Pre-exercise levels are shown in white, post-exercise levels are shown in black Anthropologist David A. Raichlen from the University of Arizona lead the research. He said: 'Maybe runner's high is not some peculiar thing with humans. Maybe it's an evolutionary payoff for doing something hard and painful that also helps them survive better, be healthier, hunt better or have more offspring.' Raichlen continued that as we evolved, we continued to run because our brains became hard-wired to like it. During the research a human, dog and ferret were put on a treadmill for 30 minutes. The researchers drew blood from each animal and compared the levels of chemicals of each. They also measured the dogs and humans as they walked, while the ferrets rested. Raichlen found that blood samples for both humans and dogs showed a significant increase in levels of endocannabinoids. Endocannabinoids are chemicals produced in the body. They can give people a natural 'high' including feelings of happiness and euphoria. Ferrets are non-cursorial animals, which means they have not evolved to be good at running. During the study from the University of Arizona ferrets were found not to produce feel-good chemicals when they exercise. This suggests that they didn't evolve to be good at running because their brains weren't hard-wired to enjoy it, as is the case with humans and dogs Humans and animals naturally create endocannabinoids. These are chemical compounds that activate the same receptors as delta-9-tetrahydrocannabinol (THC). THC is an active component in marijuana. The cannabis plant, pictured, has been found to relieve chronic pain, increase appetite, alleviate nausea, and ease anxiety. In humans and other animals this chemical compound can boost the feeling of happiness and euphoria. The levels of this chemical increase after exercise. These chemicals are also found in cannabis plants. During the study the humans reported being much happier after the exercise. The researchers concluded that was the first indication that dogs - and possibly other distance-running mammals - experience a naturally induced runner's high. There was no spike in the level of endocannabinoids in the humans or the dogs after walking. And the ferrets saw no increase in the levels of the 'happy' chemicals throughout the whole study. This research suggests that Raichlen's 'reward response' theory shows that intense aerobic activity appears to be part of our evolutionary history. Humans and dogs are known as cursorial animals. This means we have evolved specifically to be able to run long distances and have longer legs that help us stride more easily. By comparing how we have developed from apes, Raichlen discovered that the fitter the primate, the bigger its brain. His findings suggest that exercise helps the brain to grow, and boosts the body's production of neurotrophins - chemicals that build and maintain brain cells. Raichlen said: 'Inactive people may not be fit enough to hit the exercise intensity that leads to this sort of rewarding sensation.' Yet they could build up their exercise tolerance to the point that they do cross the threshold and reach the level of intensity that produces the reward of the high.