For as long as there have been groups of human beings, there has been a need to keep them safe from a wide range of potential threats.

Setting up shelters, organising guard watches during the night and setting up rudimentary early-warning systems predate civilisation and conceptually resemble the principles behind modern security, which is to provide early warnings of potential threats and the possibility to react to prevent them.

One of the earliest security systems outside of organising watch duties was the guard dog, and even after millennia of developments in security systems, it is notable that security dog units are still a key part of many security systems.

Whilst the domestication of the dog is believed to have taken place over 30,000 years ago, the exact reasons why and when dogs went from being hunting companions to protective watchdogs is something that can only be speculated on.

One prevailing theory is that the role of dogs as guards and protectors is a key reason why they were domesticated in the first place, at least according to the human campfire theory.

Wolves were drawn to the smell of cooked meat, formed a loose affiliation with humans and incidentally formed a prototypically early warning alarm as an incidental consequence of guarding “their” territory.

This relationship between humans and dogs became closer and eventually led to complete domestication, where dogs were explicitly tasked with helping humans with certain roles, including guarding, hunting and sledge pullers.

The first guard dogs were used in agriculture, helping to assist farmers and protect herds of animals, which developed the characteristics seen in modern guard dogs and police dog units.

By the establishment of societies, the role of dogs was well-established, to the point that Roman homes even had early “beware of the dog” signs, most notably the mosaic found in the House of the Tragic Poet.

Much like security dogs used today, there are various different suitable breeds of guard dogs that each have a useful purpose.

Some are most useful as watchdogs and early warning alarms, having loud barks and the intuition to see potential threats and intruders from further away, making enough noise to either scare away the intruder or alert the owners of a property to handle the situation.

However, other dogs, particularly those that had been bred to protect livestock, were significantly larger and were typically trained not only to bark to raise the alarm but also to attack a perceived threat that does not back away, typically as a last resort.

Historically, mastiffs were the most popular breed for guard dogs, but many other larger dog breeds have become useful for the purpose. Shepherd dogs such as Alsatians are used as security dogs, as are many hunting dogs and sport dogs.

Any dog that is protective, loyal, territorial and has an aversion to strangers tends to be good as a guard dog breed, as long as there are clear warnings about their use, they are kept in kennels and otherwise follow the provisions of the Guard Dogs Act 1975.