Somewhere, in the endless blue ocean, a gigantic mammal shudders as it takes its last breath. Thanks to science, we know that all dogs go to heaven, but all whales descend through the murky depths until their carcasses litter the seabed. Imagine a giant dying. You can’t. They are huge and endless. A towering presence which, so it seems, has always been part of our world. They dominate and are…