Early farming's beginnings are rewritten by ancient climatic maps.

According to reconstructed maps, 12,000 years ago, the wild ancestors of wheat, barley, and rye roamed much smaller areas in West Asia than previously thought.

The early farming landscape is redrawn by that constricted geography, which also casts doubt on archaeologists' interpretations of the earliest sites of domestication.

Constructing the historical maps

Instead of dispersing into the interior uplands, the modelled ranges of 65 wild plant species are concentrated within a coastal corridor along the Mediterranean boundary of West Asia.

Joe Roe of the University of Copenhagen (UCPH) showed by analysing those predicted habitats that a large number of grain and legume ancestors were centred in the Levant in the late Ice Age.

Large portions of Anatolia, northern Mesopotamia, and the Zagros deviate from the projected ranges that appear to be vast now beyond that corridor.

A closer examination of how those old distributions were reconstructed is necessary because of this contraction, which suggests that long-used maps of agricultural origins may have exaggerated how extensively available these species were.

Emergence of coastal refuges

The models packed a wide variety of edible grasses into a narrow band along the seaward edge of West Asia. Crops may have been protected from the effects of the Ice Age in that region by a refugium, an area where plants can withstand harsh weather.

Additionally noteworthy were Cyprus and portions of western Turkey, indicating multiple cold-weather safe havens for cereal origins. Early tribes' ability to settle would have been influenced by this coastal concentration because dependable crops were not dispersed equally.

Cold still influenced decisions.

These plants did not just move southward with cooler, drier swings, and they did not reappear in large numbers when temperatures warmed up early. Rather, a wetter climate does not necessarily result in more suitable habitat because many species were already able to survive with little rainfall.

As the area got closer to early agriculture, the average modelled range for those plants decreased by almost 25%. Because there would have been fewer dependable stands for people to return to each season, that squeeze would have concentrated the strain on the gathering.

Data-driven models

Computer models can examine where a plant could live in a particular climate, but they cannot go through time. Using contemporary observations as a model, Roe employed ecological niche modelling at UCPH to identify the climatic ranges of potential species' habitats.

The Global Biodiversity Information Facility (GBIF) provided the researchers with contemporary occurrence spots, which allowed them to begin with actual places rather than conjectures.

The team used those layers, which were taken from a dataset, to roll models backward and compare the results with plant remains found at digs.

When the proof disappears

The entire plant community in the area is rarely revealed by charred seeds at excavations, but they do illustrate what people handled.

According to Roe, "we don't know exactly where the Neolithic peoples found the plants that they eventually domesticated because we don't know much about the natural background vegetation in these areas."

The new maps provide a separate line of evidence that is independent of what survived because that record is inconsistent. However, a climate-based map can only depict areas where plants may reasonably grow, not which hillsides humans favoured.

Where maps diverge

The model performed well on contemporary data, but comparisons with plant remnants from archaeological locations frequently revealed weaker similarities. Predictions can be pulled in diverse directions away from reality by both uneven current sample and sparse excavation records.

When a machine learns too limitedly from botanists' searches, particularly in remote areas, underestimates may result.

The UCPH team does not yet consider their reconstructions to be a definitive map of historical ranges, but rather conservative minimum estimations that serve as a baseline.

Old presumptions are put to the test.

For many years, a lot of theories about the origins of farming were predicated on the idea that the ranges of the wild plants that exist now were the same as those that were thousands of years ago.

Cultivation is gradual and region-wide, allowing for several local experimentation, according to a 2011 assessment.

According to our new findings, it appears that the progenitors of some of the most significant plants in modern agriculture—such as wheat, rye, barley, etc.—did not grow where we anticipated and were far less common than we once believed, Roe said.

A plant discovered far from its current range ceased to be proof that people were growing it after that shortcut was compromised.

Hints for upcoming excavations

These kinds of map overlays can help archaeologists find the coasts and valleys that formerly had the most abundant wild grain stands. Researchers can now determine whether the climate map forecasts a nearby habitat when a site provides an unexpected species.

Since the model gets better with more accurate dates and places, better archaeological information could make the test more rigorous. Where people took plants and where nature deposited them should become clear through frequent comparisons between maps and excavations over time.

The research's wider ramifications

Because natural ancestors carry genes for disease and drought resilience, modern breeding still uses them. Additionally, identifying former refuges provides clues as to where genetic diversity—the range of genes within a species—may have remained high.

Losing those landscapes now could eliminate opportunities for future agricultural improvement if important ancestors used to reside in tiny places. By separating human selection from the constraints already imposed by climate, understanding the prehistoric distribution also helps to clarify what domestication changed.

These reconstructions provide a climate-based check on archaeological narratives and reduce the probable gathering areas for early cereals.

Instead of remaining a scholarly curiosity, the approach should develop into a useful tool as archaeologists find more plant records and investigate more sites.