Kevin O'BriantAgronomists are currently interested in an obscure Eurasian grass. How does this relate to archaeology? Aegilops, or goatgrass, as it’s commonly known, has “saved our bread” in the ancient past. A brief thread on the origins of agriculture or the “Neolithic” in western Eurasia 1/ https://phys.org/news/2022-03-hardy-wild-grass-bread.html
Around 23,000 years ago, at a site in Israel called Ohalo II, people started living sedentary lives. They harvested numerous wild plant seeds, among them grasses like Aegilops as well as wild wheat, barley and rye. 2/
The development of microlith technology, which are small, sharp, chipped rocks that can be set into a larger tool, allowed people to harvest plants like grasses into sheafs, but they had to be harvested before they were fully ripened. 3/
Wild grasses are different from domesticated grasses; their ears shatter when fully ripened. Domesticated grasses have a “rachis” which holds the seed to the ear that is less brittle than that of a wild grass. This is why wheat has to be threshed off the ear. 4/
Wheat that has been threshed leaves behind the chaff. Sometimes this chaff falls into a fire, becomes carbonized, and is preserved in the soil for thousands of years. This chaff from Syria is about 11,000 years old, preserving the tell-tale rachis. 5/
Over time, the act of harvesting wheat with a sickle into sheaves and carrying them home has selected for ears of grain that do not shatter, allowing them to be transported to sedentary houses for threshing, saving, and re-planting. 6/
Between 10,700 and 10,200 years ago, Neolithic people in the Near East were mostly harvesting wild grasses (the darker shade indicates the wild type). Image source: https://doi.org/10.1073/pnas.1612797113 7/
By 8,000 years ago, domesticated grains were becoming more and more common. Barley and wheat with large seeds that cling to the ear and with characteristics like sprouting easily when irrigated were becoming widespread. 8/
Genetic & archaeological evidence point to the movement of these crops & their cultivators into places like northwestern Europe. This is called the Neolithic Expansion. But how does a grass from a warm arid region thrive in a cool, wet environment? 9/
Modern wheat, like many domesticated crops, is “polyploid”. People generally have two sets of chromosomes inherited from each parent. A polyploid organism has multiple sets. Einkorn wheat has two. Emmer wheat has four. 10/
The extra set of chromosomes in emmer wheat has been traced back to a cross with a goatgrass, Aegilops speltoides, creating a tetraploid grass with a set of wheat (Triticum) chromosomes and a set of goatgrass chromosomes. 11/
About 8,000 years ago, this tetraploid wheat crossed again with another goatgrass species, Aegilops tauschii, creating the hexaploid (6 sets of chromosomes) wheat most commonly grown today. Having two extra sets of chromosomes has consequences. 12/
That consequence is mutability. Combining with goatgrass has allowed wheat to mutate easily and therefore adapt to environments that are as different from the arid Near East as Poland and Canada. This adaptability helped make the Neolithic Expansion possible. For more on this, and how it relates to beer, see this essay: https://www.academia.edu/38105231/The_Hymn_of_Ninkasi_Originally_published_as_a_3_part_series_on_the_archaeology_of_beer_ END/
