By Bruce Bower
Ceramic vessels pocked with holes have pushed the earliest evidence for cheese making back to 7,400 years ago.
Chemical signatures of milk fat in perforated pots used as strainers provide the tell-tale clues to cheese making, says a team led by biogeochemist Richard Evershed of the University of Bristol in England. As with similar-looking cheese strainers today, these devices — previously found at ancient farming villages in Poland — separated fat-rich milk curds from lactose-containing whey, the scientists report in the Dec. 13 Nature.
An earlier pottery analysis led by Evershed placed the origins of cattle milking at around 9,000 years ago in what’s now Turkey, although there is no evidence of specific milk products from that time.
Cheese making played a big part in early dairy farming, Evershed proposes. Aside from providing a reduced-lactose milk product for communities that included many individuals unable to digest lactose easily, cheese could be stored and eaten throughout the year.
“The big surprise was finding dairy fats specifically in sieves from these farming sites,” Evershed says. “We had known about the sieves for years but had been skeptical that they were truly cheese strainers.” Hole-covered pots could have been used, say, as flame covers, honey strainers, or for beer making.
Intriguingly, the ability to produce low-lactose cheese emerged at the same time that a gene enabling lactose digestion, and thus milk drinking, spread among European farming populations. In 2009, geneticist Yuval Itan of University College London and his colleagues used archaeological data and modern prevalence of a gene for lactose tolerance to calculate that the gene initially spread through Central Europe about 7,500 years ago.
It’s unclear why a lactose-tolerance gene caught on so quickly if early farmers could make cheese, remarks bioarchaeologist Oliver Craig of the University of York in England. Perhaps early sieves were relatively ineffective at removing lactose from milk or were applied to cheese making by only a few communities. Lactose tolerance possibly originated in parts of North Europe and Scandinavia where no sieves have been found amid the ruins of ancient farming settlements, Craig speculates.
Evershed’s group tested 50 fragments from 34 sieves for milk-fat residue. Pieces of 44 cooking pots, seven bowls and 15 flasks were also analyzed. The pottery came from eight sites in Poland dating from 6,800 to 7,400 years ago.
Chemical remnants of milk fats were identified on 15 sieve fragments, consistent with the separation of milk curds from whey during cheese making. More than half of the fragments from cooking pots displayed chemical signatures of animal fat, probably a result of cooking meat.
Bowls contained dairy-fat remains and could have served as receptacles for whey strained through sieves, the researchers propose.
Beeswax was detected in most flasks, one cooking pot and three sieves. This substance was probably used to waterproof containers and to line pots used as sieves when straining honey from the comb, Evershed says.
His team plans to probe residue on sieves from other ancient European farming sites. But pottery offers a limited look at early dairying practices, Evershed cautions. “The straining of curds could have been done with textiles or baskets.”
