Plant cultivation 11,000 years earlier

The site of a 23,000-year-old camp of hunter gatherers on the shores of the Sea of Gallilee in Israel suggest that wheat was being cultivated there 11,000 years earlier than previous evidence of organised agriculture.

Archaeologists, botanists, and ecologists from Bar-Ilan University, Haifa University, Tel Aviv University, and Harvard University published the findings this week in the journal PLOS One.

They base their conclusions on a higher-than-usual presence at the site of domestic-type, rather than wild-type, wheat and barley; a high concentration of proto-weeds – plants of the type known to flourish in fields planted with domesticated crops; and an analysis of the tools found at the site that reveals blades used for cutting and harvesting cereal plants.

The site, known as Ohalo II, nine kilometres south of the modern city of Tiberias, was discovered in 1989 when the level of the lake plummeted.

It was then excavated for six seasons, exposing six brush hut dwellings, a human grave, copious and well-preserved remains of both animal and plant foods, beads from the Mediterranean Sea, as well as evidence of flint tool manufacture and use.

According to the study’s lead researcher, Ehud Weiss of Bar-Ilan University, the study represents the earliest example of small-scale cultivation found anywhere in the world.

“The plant remains from the site were unusually well-preserved because of being charred and then covered by sediment and water which sealed them in low-oxygen conditions,” Weiss explains.

“Due to this, it was possible to recover an extensive amount of information on the site and its inhabitants – which made this a uniquely preserved site, and therefore one of the best archaeological examples worldwide of hunter-gatherers’ way of life. Here we see evidence of repeated sowing and harvesting of later domesticated cereals.”

Some 150,000 plant remains show that the site’s residents gathered more than 140 different plant species from the surrounding environment.

Among these, Weiss’s team identified edible cereals – such as wild emmer, wild barley, and wild oats. These cereals were mixed with 13 species of “proto-weeds” – ancient ancestors of the current weeds known to flourish in cultivated, single-crop fields – indicating that they grew and were subsequently unintentionally gathered together.

A grinding slab set on a brush hut floor provided samples of microscopic cereal starch granules show that cereal grains were processed there.

More importantly the grains showed signs of being domesticated rather than wild.

“The ears of cereals like wheat and barley – in their wild form – are built from separate units that break off and are easily dispersed, allowing the seeds to reach the ground, germinate, and grow into a new plant without any human intervention,” Weiss says.

“When humans cultivate these grains over a number of successive seasons, however, a change occurs. They develop a rough scar that locks the seed dispersal units together. Such plants cannot sow themselves. This is the hallmark of domesticated, rather than wild-type plants.”