If one looks back on the history of man which, so far as it is known has covered a period of perhaps a million years, it will be apparent that for some 99 per cent of this time he has been a hunter and gatherer of food. That is, he has collected edible fruits and vegetation, larvae and other small invertebrate animals. At an early period in his history, man also learned to hunt larger animals with increasingly improved weapons and methods. The provision of food for the family or group depended upon what the surrounding countryside had to offer, and there was no knowledge on how to store foods in any quantity.
True pests of stored goods were therefore unknown to these ancestors, who must however have had problems with blowfly maggots infesting their game and other pests destroying their hides and skins.
Nor would they have been spared by the true parasites. Lice must have infested their hair and bed bugs and fleas must have multiplied, generation after generation, over thousands of years. Sleep must have been disturbed by mosquitoes, with their ceaseless buzzing, and also by the numerous small invertebrates which lived in their dwellings. These would include swarms of flies and other insects which would be attracted by domestic waste.
About 10,000 years ago came a significant change. Man began to plant and harvest crops and to keep domestic animals. This new life form brought many advantages, for it provided a more secure existence and the soil could feed far more people when it was used this way. But it also brought problems. Animals which had hitherto fed on scattered wild grass seeds now had the opportunity, when their food plants were sown in whole fields, to multiply as never before. Food specialists among the invertebrates, which had previously survived winters with stores they collected during summer and autumn, could now enter and exploit the enormous food stores collected by man.
As man started to establish permanent dwellings, these provided excellent living quarters for many animal species, whether in the house itself or in the outhouses used by the domestic animals. There was also woodwork to gnaw and textiles and furs to eat.
The buildings provided new hunting grounds for animals such as spiders, and also places for nesting and spending the winter for many animals which had previously used hollow trees and rock crevices. Throughout the ages these man-made facilities increased, and even today, with all our technical aids, we are far from being alone in our houses and stores.