US Edition 
Porridge was eaten 100,000 years ago
Humans may have been tucking into porridge and making bread 100,000 years ago, far earlier than had been thought.
Tools and plant remains from a cave in Mozambique suggest that the ancestors of modern humans were grinding and processing wild grass grains at the start of the last ice age.
Use of cereals was previously not thought to have developed until some 90,000 years later, when modern human behaviour began to emerge.
Prior to that time early hunter gatherers were believed to have relied on easily harvested fruits, roots and nuts.
Processing cereals is believed to mark a critical step in human evolution, since it called for a high degree of technical knowledge and improved nutrition.
The limestone cave at Ngalue in north-west Mozambique, was used intermittently by ancient stone age foragers for more than 60,000 years.
Deep inside the cave scientists unearthed dozens of stone tools, animal bones and plant remains providing clues about prehistoric diets.
Starch grains found on grinding and scraping tools indicated that wild sorghum had been brought to the cave for processing.
Sorghum is still the chief cereal consumed today in sub-Saharan Africa. The grain is crushed to produce coarse flours used to prepare porridges, breads and alcoholic beverages.
Dr Julio Mercader, from the University of Calgary in Canada, whose team made the discovery, said: ''This broadens the timeline for the use of grass seeds by our species, and is proof of an expanded and sophisticated diet much earlier than we believed.
''This happened during the Middle Stone Age, a time when the collecting of wild grains has conventionally been perceived as an irrelevant activity and not as important as that of roots, fruits and nuts.''
Dr Mercader, whose findings are published today in the journal Science, added: ''It has been hypothesised that starch use represents a critical step in human evolution by improving the quality of the diet in the African savannahs and woodlands where the modern human line first evolved. This could be considered one of the earliest examples of this dietary transformation.
''The inclusion of cereals in our diet is considered an important step in human evolution because of the technical complexity and the culinary manipulation that are required to turn grains into staples.''