U.S. researchers have discovered for the first time the female hormone progesterone in a walnut tree, overturning so far the perception of various plants and animals. The new discovery shows that plants and animals have a closer relationship than hitherto thought scientists.

 Until now, scientists thought that only animals could produce progesterone, the hormone secreted by the ovaries and prepares the uterus for pregnancy.

A synthetic form of the hormone, progestin, used in contraceptive pills and other treatments.

The discovery was made by a team of researchers led by Guido Pauli of the University of Illinois and presented in "Journal of Natural Products" (Journal of Natural Products) of the American Chemical Society, according to Live Science.

The Pauli said the discovery of progesterone in the tree is beyond doubt and stressed the importance of.

"While the biological role of progesterone has been studied extensively in mammals, the reason for its existence in plants is less obvious," he said.

Researchers estimate that the hormone, like other steroids, is an ancient bio-regulator that evolved billions of years ago, even before as the first plants and animals.

The new discovery is likely to change throughout the scientific concept on development and function of progesterone on living organisms. Until now scientists had been unable to detect the same hormone in a plant, apart from some substance similar to that which had been put to believe that progesterone itself may exist in plants.

The Pauli and his colleagues used two new techniques, nuclear magnetic resonance and mass spectroscopy, which failed to find progesterone for the first time, as well as five new steroids, progesterone related.