Google's drive into robotics should concern us all

You may not have noticed it, but over the past year Google has bought eight robotics companies. Its most recent acquisition is an outfit called Boston Dynamics, which makes the nearest thing to a mechanical mule that you are ever likely to see. It's called Big Dog and it walks, runs, climbs and carries heavy loads. It's the size of a large dog or small mule – about 3ft long, 2ft 6in tall, weighs 240lbs, has four legs that are articulated like an animal's, runs at 4mph, climbs slopes up to 35 degrees, walks across rubble, climbs muddy hiking trails, walks in snow and water, carries a 340lb load, can toss breeze blocks and can recover its balance when walking on ice after absorbing a hefty sideways kick. There, you will find not only a fascinating video of Big Dog in action, but also confirmation that its maker has a menagerie of mechanical beasts, some of them humanoid in form, others resembling predatory animals.