Dogs (Canis lupus subspecies domesticus) have lived alongside humans for over 33,000 years. We have selectively bred these animals to shepherd, hunt, sniff out and retrieve our targets for us upon demand. Human-directed selection has 'evolved' working dogs that can be trained to recognise around 200 human words. Commands, or proxies for them such as whistled signals, are tools use to coordinate their activity with ours (Image: Wikimedia Commons)