How dogs keep fit

Chris Smith put James' question to animal behaviour scientist Eleanor Drinkwater...

Eleanor - Well if you think about it a lot of breeds of dogs are built for speed, so something like a Greyhound can hit about 45 miles an hour. So even an unfit Greyhound can still be much more speedy than the average or relatively fit human. And like humans with more exercise dogs become more fit and with less exercise they can also become more fat. But on a wider level how do animals in general stay fit? There are some amazing adaptations out there. Two of my favorite examples are something like barnacled geese when they're preparing to fly really long distances, they only need a couple of minutes of flight a day to build up enough muscle in order to become fit enough to migrate which I just find crazy and so unfair. And then on the other hand you have some animals that do this amazing trade off in how fat they are vs. how thin they are depending on predators. A good example of this is porpoises around the UK. If they're in areas in which they are at risk of being killed by dolphins they tend to be much more sleek and much able to get away from dolphins than in areas in which there are less dolphins. So basically the animal kingdom is brilliant and there are loads of interesting adaptations to fitness.

Chris - So they basically evolved in order to give themselves the ability to do that because it's beneficial to them to do that and were it not beneficial for them to maintain this, you know I guess that's probably because we keep opening the carton of dog food isn't it? I mean if we didn't keep feeding them they would lose condition and the fact that they can afford to maintain all this muscle bulk which is energetically very costly to maintain all those muscles and things that they're not using. We on the other hand as humans we just run to fat if we don’t take regular exercise.

Eleanor - Yeah we we have quite a sedentary lifestyle compared to most of the animal kingdom.

Ljiljana - I just said to Patrick, “Blame it on DNA”.

Chris -  So, Patrick, you’re being made the butt of this.

Patrick - Well I was going to say that we humans probably spend most our energy keeping our brain intact, right? We don't have to do much to train it and it will still do most of the essential functions so maybe the dogs are spending less time training its brain and more on the muscles.

Chris - It's an energetically very costly organ the brain isn't it? You think it's running at roughly 20 Watts because it's about 20 percent of your oxygen consumption and your average person is running at about 100 watts it's about 1 or 2 watt per kilo in the average person. So your brain is burning a lot of energy.

Eleanor - Yeah in some cases like for example sponges, people thought that there's some evidence to suggest that they had a neural system or even kind of a brain-like structure, but because it's too energetically costly so they've got rid of it, so you know we don't need a brain!