Whether farming and agriculture evolved from an exclusive, homogeneous origin or grew from multiple sources has long been a subject of debate between scientists.

About 12,000 years ago, prehistoric humans began to practice farming, growing wild varieties of crops such as lentils, barley and peas while herding goats, wild oxen and other animals.

Over time, these ancient hunter-gatherers switched to full-time farming and bred both plants and animals, producing new breeds and varieties.

Our ancestors eventually migrated and spread the practice of farming to Asia and Europe.

Experts believe farming may have been started by only one group of ancient humans.

The world's first farmers resided in the Fertile Crescent, which used to be a region in the Middle East that now encompasses modern-day Jordan, Israel, Iraq, Syria, southeastern Turkey, Palestine and western Iran.

It has long been believed that these early farmers were a homogeneous group that intermingled and traded goods, swapping tricks on farming and tools, as well as having interrelationships.

But this longstanding theory is being challenged by a new study. Its findings suggest that instead of originating from a single group, farming may have been invented by multiple people in the Fertile Crescent.

The diverse groups were genetically distinct from one another and did not intermingle at that time. By this, anthropologist Joachim Burger explains that the diverse groups of humans lived more or less in the same area but they remained isolated from one another at least for a few thousand years.

Burger is the co-author of the study along with several international scientists, and they performed a DNA analysis on the remains of four ancient individuals.

These prehistoric humans lived about 10,000 years ago on the eastern edges of the Fertile Crescent. More specifically, they resided on the Zagros Mountains on the border between Iran and Iraq, researchers say.

The research team compared the DNA of the four individuals with that of several skeletons that were younger by a couple of thousands of years. The latter were discovered on the region of the Fertile Crescent that now includes modern Turkey.

Scientists say the two groups "could not have been more genetically different."

Mark Thomas, an evolutionary biologist from University College, London and Burger's study co-author, says they would not expect huge genetic differences from opposite ends of the Fertile Crescent.

But the genetic signatures of both groups indicate that the Zagros population and the Anatolian population diverged from one common ancestor about 46,000 to 77,000 years ago. Farming wasn't even invented back then.

"That's a surprise," says Thomas. "That's the real big surprise of the study."

In the end, the new research concludes that the first farmers of the eastern Fertile Crescent did not move westward. This meant that they were not responsible for spreading farming and agriculture to Western Europe. Additionally, scientists did not find a trace of similarity between the DNA of ancient farmers from this part of the Fertile Crescent and present-day Europeans.

On the other hand, early farmers from Zagros appeared to have genetic resemblance to modern-day humans in South Asia, particularly Afghanistan and Pakistan. Researchers suggest that ancient Zagros farmers may have traveled east and spread their farming techniques to this region of the world.

Meanwhile, the findings of this new study are published in the journal Science.

Photo: Richard Masoner | Flickr