London-Scientists have discovered the earliest direct evidence of milk consumption by humans.

The team identified milk protein entombed in calcified dental plaque (calculus) on the teeth of prehistoric farmers from Britain.

It shows that humans were consuming dairy products as early as 6,000 years ago - despite being lactose intolerant.

This could suggest they processed the raw milk into cheese, yoghurt or some other fermented product.

The team members scraped samples of plaque off the teeth, separated the different components within it and analysed them using mass spectrometry.

They detected a milk protein called beta-lactoglobulin (BLG) in the tartar of seven individuals spanning early to middle Neolithic times.

“Proteomic analysis of calculus is a fairly recent technique. There have been a few studies before, but they have generally been on historical archaeological material rather than prehistoric material,” co-author Dr Sophy Charlton, from the department of archaeology at the University of York, told BBC News.

Lactose intolerance arises from the inability to digest the lactose sugar contained in milk beyond infancy. This means that consuming milk-based foods can cause uncomfortable symptoms such as abdominal pain, diarrhoea and nausea.