Cavemen’s taste for milk revealed: ‘The image of our cavemen ancestors as wild hunters who enjoyed no better meal than flesh torn from their latest kill has been dented by new archaeological research. Chemical analysis of 6000-year-old pottery shards shows ancient Britons also had a taste for cow’s milk and goat’s cheese.

“This is the first direct evidence for widespread dairying at prehistoric sites anywhere in the world,” says Richard Evershed, professor of biogeochemistry at the University of Bristol, UK. Archaeologists had previously uncovered a few objects that suggested dairying, such as suspected cheese strainers, but nothing unambiguous.’ New Scientist

Yes, but did they enjoy their dairy products this way? Also from New Scientist, this time the delightful ‘Last Word’ column, which solicits erudite explanations of scientific stumpers from readers:

One of the recommended ways of drinking the liqueur Tia Maria is to sip it through a thin layer of cream. If the cream is poured onto the surface of the drink, to a depth of about 2 millimetres, and left to stand for about two minutes, the surface begins to break up into a number of toroidal cells. These cells develop a rapid circulation pattern which continues even if some of the Tia Maria is sipped through the cream. How and why do these cells develop and what is the energy source?

— Geoffrey Sherlock, Amersham Buckinghamshire

Answers

This is a truly astonishing effect for which not a single reader has produced an explanation. “Rapid circulation pattern” does not do justice to the series of eruptions that convulse the surface of the cream as the liqueur bursts through from beneath.

Reach for a bottle and be amazed. Then sit back and work out why it happens. Extra toroidal cells can be generated by puncturing the surface of the cream with a skewer. Drinking off a little of the cream can also regenerate activity.

Additional data gathered in the New Scientist office may help. What is needed for the effect? The liquid must be dense enough to support a layer of cream. Substitute water or neat gin and the cream simply sinks to the bottom of the glass. The liquid must also contain alcohol. Substitute blackcurrant cordial for Tia Maria and the cream just floats there motionless and no cells form.

Provided the liquid is strongly alcoholic and dense, almost any mix will do. Gin and soy sauce is particularly effective–pour on the cream and the toroidal cells appear in seconds, even though the taste leaves much to be desired.

Could it be that the molecules of fat in the cream and those of the alcohol in the liqueur are immiscible and fighting a fierce battle at the surface of the glass? Do doughnut-shaped cells appear because toroids minimise the surface area around a hole? What exactly is happening between the fat and the alcohol? And how can the circulation be sustained for so long? Any answers we print will win their authors a bottle of Tia Maria.