Introduction
​
 

Common wheat, also known as bread wheat and botanically known as Triticum aestivum, is the most widely cultivated and consumed cereal grains in the world. It can also be considered the cereal that fed the humanity through the last 1000 years. About 95% of wheat produced worldwide is common wheat; it is the most widely grown of all crops and the cereal with the highest monetary yield.

In this article we will examine the genetic history of common wheat, a cereal that has always been domesticated since the first day it appeared in the fertile crescent. We will see how this cereal could be born spontaneously in its farmed form and how the evolution of humans and wheat were influenced by each other through the history. 

s

The origins

​

• The origins of modern wheat

The story of common wheat has very deep roots that plunge in the middle Pleasitocene, between 500'000 and 300'000 years ago, when homo sapiens still had not appeared.
Two different grasses, Triticum urartu [diploid species with 14 chromosomes organized in 7 sets of 2 chromosomes each] and Aegilops speltoides [dipoloid species with 14 chromosomes organized in 7 sets of 2 chromosomes each]  sexually reproduced and generated a new species: Triticum turgidum. The reproduction of the two different species presented a double anomaly from both sides: the gametes (the pollen of urartu and the ovule of Aegilops) presented a full set of chromosomes in pairs, 14 in total, instead of a single set of 7 chromosomes each as it should have been: In both cases the meiosis didn't happen and as result of this double anomaly, the new species generated, Triticum turgidum presents 28 chromosomes organized into 7 sets of 4 chromosomes each; therefore Triticum turgidum is a tetraploid species.
The occurrence of spontaneous hybridization in plants is considered a rare event. In the specific case of wheat evolution, the hybridization event between Triticum urartu and Aegilops speltoides was pivotal in shaping the history of wheat domestication. 

About 12'000 years ago in the fertile crescent humans invented agriculture and domesticated Triticum turgidum, selecting the useful traits for farming and that lead to the subspecies Triticum dicoccum, also known as emmer wheat, the wheat farmed by ancient Egyptians and Romans. Another subspecies that came from the domestication  of Triticum turgidum, is Triticum durum, the wheat used nowadays to make pasta. 

​

The invention of agriculture

​

• When did the humans start to eat wheat?

Homo sapiens appeared about 300'ooo years ago and according to new evidence, eating grass seeds is much older than we thought. Plant domestication, most scientists think, made its debut some 10,000 years ago, with grain storage cropping up about 11,000 years ago. But a

 large assemblage of starch granules has been retrieved from the surfaces of Middle Stone Age tools from Mozambique, showing that early Homo sapiens relied on grass seeds starting at least 105,000 years ago, including those of sorghum grasses.  [1]. The inclusion of cereals in our diet is considered an important step in human evolution because of the technical complexity and the culinary manipulation that are required to turn grains into staples. Crushing grains taken from wild plants with mortar and pistil and then mixing them with water and cooking the primordial dough it is considered to be the first processed with food consumed, excluding cooking meat on fire that is much older. That led through thousands years to different forms of flat breads. The inclusion of cereals in our diet is considered an important step in human evolution because of the technical complexity and the culinary manipulation that are required to turn grains into staples.

​

• What changes did the invention of agriculture bring in human evolution?

As the human population grew, so did the demand for food. The realization that wheat was a much more convenient source of nutrients than hunting brought humans to invent agriculture.​

Agriculture was a huge turning point for human evolution.  Before agriculture, humans were nomadic groups of hunters and gatherers. Some plants like legumes, could be farmed beside a nomadic camp, but not wheat. Wheat requires fields, irrigation systems and advanced techniques that couldn't match with a nomadic lifestyle. That's how about 12'000 years ago, in the Middle East area known as fertile crescent, humans started to settle into villages to adopt a sedentary life style that gave us the social structures we still have nowadays. J.J. Rousseau suggested that the invention of the agriculture implemented the private property as the dwellings and the fields were among the first important forms of private property[2]. The private property requires laws, laws requires institutions and the protection of the fields from nomadic groups required an army. Trivially we can follow the syllogism suggested and affirm that wheat created all this.

​

• What was the first type of wheat to be farmed?

The first type​ of wheat to be farmed was not Triticum turgidum, the tetraploid species coming from a spontaneous hybridization 500'000 years earlier, but it was Triticum boeoticum, a diploid species (2 x 7 chromosomes)  that was not subjected to any spontaneous hybridization and became in its domesticated form Triticum monococcum, aslo known as einkorn wheat. The main difference between the domesticated Einkorn and its wild version is the seeds dispersion that in the wild form tend to fall after maturation, while they stay attached to the spike in the domesticated form, making it ideal for picking and crushing. Einkorn, that is still farmed, has bigger overall content of proteins than common wheat, but it less gluten comes out when mixed with water and that affects the bread-making process. The difficulties in kneading and processing a dough made with einkorn led humans to prefer the tetraploid species, Triticum turgidum that has much better bread-making properties and it became Triticum dicoccum, commonly known as emmer wheat in its domesticated form. Emmer was also preferred over einkorn due to its larger grain size and potentially higher yields.

​

​

​​