Superfood — Alles bleibt anders

High hopes are once again being placed in millet. Not only is it able to withstand drought, it also easy to grow, store and prepare. These qualities made it a real superfood even in the Bronze Age. The cultivation of millet, camelina and oats testifies to a new degree of variety in the Bronze Age diet.

Why Bronze Age people suddenly developed a taste for so many new flavours is a question of interest to us in the CRC 1266 — and we’ll be taking a particularly close look at millet.

Far Eastern innovation

An early superfood, broomcorn millet found its way into the central European diet 3,500 years ago — millennia after Neolithic farmers had begun to plant emmer and einkorn. We were able to establish this fact by means of our large-scale dating programme and its analysis of tiny grains of millet.

Unlike emmer and einkorn — archaic forms of wheat originating in the area north of the Arabian Peninsula known as the fertile crescent — the origins of millet lie in the Far East, in modern China. Via the Caucasus, it reached the Black Sea and the Mediterranean in the Bronze Age, with the earliest finds in the region dating from around 1600 BCE. By 1200 BCE it had been introduced to central and northern European.

Broomcorn millet came, saw and conquered

What was it about the Bronze Age that made possible the emergence of broomcorn millet as a superfood? It was a time when many people were moving about and when the human population was growing. And as it grew, it grew together, learning to deal with conflicts and crises. The Bronze Age was an age of proto-globalisation. People had learned to work with copper and tin and developed new technologies. They traded amber from Baltic to Mycenaean Greece, and this fossilised resin has been found as far afield as Egypt, in King Tutankhamen’s tomb.

Millet too was traded over long distances and became a prized export, aided by the vagaries of the climate. Volcanic eruptions and climate shifts brought sometimes heavy rainfall, sometimes drought. This presented farmers with a challenge. In order to feed their families, they tried growing new crops, camelina, oats and millet. Their boldness paid off — millet in particular can thrive in dry conditions.

The name millet refers to a variety of grasses with small round grains.
Ripening broomcorn millet.
Ripening foxtail millet.

Broomcorn millet

Excursion

Why is millet better at surviving drought than wheat and barley?
Unlike wheat and barley, broomcorn millet is a C4 plant and as such particularly well adapted to hot climates. When temperatures rise, plants usually close their stomatal pores in order to retain water. This, however, makes it difficult for them to absorb the carbon dioxide required for photosynthesis.
To cope with this problem, C4 plants have developed a mechanism that allows them to use even the tiniest quantities of carbon dioxide. They do so by means of a particular leaf anatomy, in which the vascular bundles (which supply leaves with water and nutrients) are surrounded by bundle sheath cells. This means that biomass is produced in two steps and in two isolated compartments.
Carbon dioxide is initially fixed in the mesophyll cells, producing large C4 molecules which are then diffused to the bundle sheath cells. In the bundle sheath cells, the carbon is extracted from the C4 molecules and fed into the Calvin cycle, which produces the carbohydrates that allow the plant to grow.
Although the diffusion of molecules requires additional energy, it allows C4 plants to be productive even in the hottest part of the day, when their stomatal pores are closed to avoid water loss.
This makes millet eminently suited to provide people with their daily bread – or, more accurately, their daily gruel – even in times of extreme drought. It did so in the Bronze Age, and its ability to withstand dry conditions has made it ripe for rediscovery as harvests are threatened by climate change.

Broomcorn millet in the wind just before flowering, with a small foxtail millet growing in its midst.
Panicle overhanging to one side during “earing”, 6—8 weeks after sowing (depending on weather).
Golden broomcorn millet. Depending on weather conditions, broomcorn millet is ready for harvest 8—12 weeks after sowing.

Fast (growing) food

The north and central European Neolithic was fairly predictable in terms of the cereals on offer, the most widespread being einkorn, emmer and barley. Not until the Bronze Age did people’s diet become both more varied and more secure. A new crop introduced from Asia made European societies better able to cope with times of scarcity. Broomcorn millet is truly versatile and fast-growing, needing only sixty to ninety days from sowing to harvest. Central European farmers could thus plant millet to compensate for the destruction of other crops by late frosts.

In southern Europe, the combination of a short growth cycle and longer growing season allowed for two harvests a year. Moreover, millet is easy to store, ripening in hard golden husks that protect the grains form pests and fungi. Yet broomcorn millet is also easily prepared: it does not require boiling; soaking will usually suffice. A leather pouch, some hot water, and a few minutes’ patience are all it takes to make a sweet, nutritious gruel. Quickly grown, quickly prepared — truly a Bronze Age superfood!

Excursion

How do archaeologists date their findings?
Radiocarbon dating is an archaeological method for determining the age of organic material. There are three naturally occurring carbon isotopes, 12C, 13C and 14C.
14C is formed largely in the upper reaches of the earth’s atmosphere, in the stratosphere, when the neutrons in cosmic radiation collide with nitrogen atoms (14N) in the air to form 14C. 14C is then oxidised to CO2, is absorbed by plants through photosynthesis and then by animals through the food chain. This means that the proportion of 14C, in spite of radioactive decay, remains nearly constant while an organism is alive.
When an organism dies, however, it ceases to exchange 14C with the atmosphere and the 14C stored within it decays with a half-life of 5,730 years. Adjusting for the fluctuating concentration of atmospheric 14C, this allows organic material to be dated with some precision.
The method used today for measuring the remaining concentration of 14C and thereby the age of organic material is accelerator mass spectrometry (AMS), which measures the ratio of 14C to 12C by detecting the isotopes themselves.

This proved invaluable to our large-scale project for dating broomcorn millet grains, for only AMS allows even tiny samples containing less than one milligram of carbon to be dated.

How can archaeologists even identify millet?

Plant remains may be preserved for millennia in fireplaces, storage pits and rubbish tips — usually in a charred state, which keeps them from being turned into compost by microorganisms. Such remains are often left by burning during cooking or by smouldering fires within settlements. Charred broomcorn millet grains can be found in soil samples from archaeological digs, often baked to charred gruel.

Aside from these macroscopic remains, broomcorn millet can also be identified in microscopic form. The cells forming the grain husks contain minute, distinctively shaped particles of a glass-like substance known as phytoliths. Since these minute silicates are inorganic, they do not decompose and can remain traceable in the soil for thousands of years.

Black diamonds

Bucket flotation

Yet even smaller particles can be identified, down to the molecular level. Miliacin is a molecule specific to broomcorn millet. Geochemists are able to identify it by means of gas chromatography. While it is more often found in soil samples, we were able for the first time to identify miliacin in pottery sherds from Bruszczewo, a Bronze Age settlement in modern Poland. Miliacin was absorbed by the ceramic pots during cooking and remains detectable even several thousand years later.

But our investigations do not stop in the kitchen. Carbon isotopic signatures in bones and teeth tells us what humans and animals were eating. A diet reliant on C4 plants (such as broomcorn millet) leaves an isotopic signature with a higher δ13C value than that left by C3 plants (such as wheat and barley). One place where millet eaters were found was the Tollense valley battlefield in what is now the German state of Mecklenburg-West Pomerania. They were killed around 1250 BCE in the first large-scale armed conflict of Bronze Age northern Europe.

Excavation

Excavating the Late Bronze Age settlement of Dobbin, Mecklenburg-West Pomerania. Archaeobotanical samples are secured in white lidded buckets.
Flotation station at a former peat ditch near the Late Bronze Age settlement of Dobbin, Mecklenburg-West Pomerania, 2019. Tools include a bilge pump powered by a car battery, weatherboard, crates, buckets and a garden hose.
The archaeobotanical samples taken from the Late Bronze Age settlement of Dobbin, Mecklenburg-West Pomerania, are floated.
Wet above, wet below: the archaeobotanical samples taken from the Late Bronze Age settlement of Dobbin, Mecklenburg-Vorpommern, are floated even in rainy weather.
Archaeobotanical work at the Late Bronze Age settlement of Dobbin, Mecklenburg-West Pomerania, continued in 2020.
Archaeobotanical samples are floated near water, giving the task a romantic framing.

Millet today

A new hope

The United Nations General Assembly has declared 2023 the “International Year of Millets”, a measure intended to support indigenous populations. In such places as Nagaland, millets formed a part of people’s traditional diet before being displaced by rice, a cash crop. Millet is now being rediscovered and its cultivation supported by organisations including North East Network Nagaland, a women’s rights charity.

More generally, the UN resolution is meant to raise public awareness of millet’s many advantages. Millet is nutritious and versatile, needing seventy per cent less water than rice and growing in half the time of wheat — and using forty per cent less energy in processing. Millets are an all-round solution in times of climate change, sinking water levels and drought. They are gluten free, easily digested, strengthen the body’s immune system and can help to prevent malnutrition in children and anaemia caused by iron deficiency.

Wiebke Kirleis is an archaeobotanist at the Institute of Pre- and Protohistoric Archaeology, Kiel University. Her research focus on the interplay of humans and plants in the past. She is thrilled to have learnt so much about the many ways in which plants were used and how their use opens up an understanding of how people lived in times past, including specific horizons of social meaning.

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