The sweet, juicy peaches we love today may have been a popular snack long before modern humans arrived on the scene, according to scientists who have found fossilised peaches in China dating back to 2.5 million years.

Scientists have found eight well-preserved fossilised peach endocarps, or pits, in southwest China. Despite their age, the fossils appear nearly identical to modern peach pits.

The findings suggest that peaches evolved through natural selection well before humans domesticated the fruit.

It is the first discovery of fossilised peaches, and it sheds new light on the evolutionary history of the fruit, which has not been well understood.

"The peach is an important part of human history, and it's important to understand how it became what it is today," said co-author Peter Wilf, a professor of paleobotany at Pennsylvania State University in US.

"If we know the origins of our resources we can make better use of them," Wilf said.

Tao Su, lead author on the paper and associate professor at Xishuangbanna Tropical Garden in China, discovered the fossils near his home in Kunming in southwest China when some road construction exposed a rock outcrop from the late Pliocene.

Peaches are widely thought to have originated in China, but the oldest evidence had been archaeological records dating back roughly 8,000 years.

No wild population has ever been found, and its long trade history makes tracing its beginnings difficult.

Animals, perhaps even primates and, eventually, early hominids, snacked on and dispersed the sweet, wild fruit and played a key role in its evolution.

Only much later, after modern humans arrived, was the peach domesticated and bred. Humans have created new varieties and larger sizes ever since and spread the fruit across what is now China, and far beyond.

"Is the peach we see today something that resulted from artificial breeding under agriculture since prehistory, or did it evolve under natural selection? The answer is really both," said Wilf.

The researchers said that the discovery supports China being the home of the peach. The fruit remains culturally significant in the country, where it carries multiple meanings - from immortality in Taoist mythology to good fortune and beauty, Su said.

Several tests confirmed that the fossils are indeed more than 2.5 million years old and not from recent contamination.

In addition to their having been found in the Pliocene rocks along with many other plant fossils, the seeds inside the pits are replaced by iron, and the walls of the pits are recrystallised.

The study was published in the journal Scientific Reports.