NEW YORK (AFP) - A man who lived as a goat in the Alps and a scientist who studied how pants affect the sex drive of rodents are among this year's spoof Nobel prizes.

The 26th edition of the annual Ig Nobel Prizes, which celebrate the silly side of science, were handed out Thursday at Harvard University in Cambridge, Massachusetts.

The prizes aim to "celebrate the unusual, honour the imaginative - and spur people's interest in science, medicine and technology," organisers said of the event, which featured a traditional onstage paper airplane toss.

The top honour in the reproduction category went to the late Ahmed Shafik from Cairo University, who died in 2007, for his work that showed how the sex lives of rats are affected by the fabric of pants they are fitted with.

Published in 1993, the study concluded that rats who wear polyester have less sex than those who don cotton or wool.

The biology prize went jointly to Charles Foster, who lived in the wild several times as animals including a badger, an otter and a bird, and to Thomas Thwaites, who constructed prosthetic legs so he could live three days on all fours and roam the hills with goats.

The winners received a trophy in the likeness of a large clock and US$10 trillion in cash prizes in essentially worthless, inflation-ravaged Zimbabwean money.

Like every year, the awards were presented by real Nobel laureates, with four attending Thursday's ceremony.

Two New Zealanders and a Briton took the economics category for their work on the personalities of rocks, studying "brand personality" by letting students label the stones with human characteristics.

In a twist, Volkswagen - caught for cheating US emissions law - nabbed the chemistry prize for "solving the problem of excessive automobile emissions by automatically, electromechanically producing fewer emissions whenever the cars are being tested."

The prize comes at a massive cost for the German automaker - including a US$14.7 billion settlement the company agreed to help resolve the dispute.