In a talk Tuesday afternoon at the Peabody Museum of Natural History, Yale ornithology professor Richard Prum defended beauty.

Prum’s talk, entitled “The Evolution of Beauty,” claimed that sexual selection is a separate entity from natural selection and plays a significant role in shaping the evolution of a species. The audience featured over 100 OC Marsh Fellows, Peabody donors who provide significant funding support to the Peabody in return for opportunities to hear from experts like Prum, said Melanie Brigockas, public relations and marketing manager for the Peabody.

“There are a myriad of ways to have desire, to be seduced, to express and to attract” Prum said. “Darwin had [the theory of evolution] right, but Darwinism has it wrong.”

Prum explained that Darwin, although certain in his thoughts on fitness and natural selection, was confounded by the ornamental quality of the peacock’s feathers, as they seemed to serve no physically beneficial purpose. Darwin proposed the concept of sexual selection — that beauty exists as its own end. Other scientists tried to redefine the meaning of sexual selection as a mere subset of natural selection, arguing that seemingly superfluous qualities such as brilliant color indicated the underlying physical fitness of an individual.

In 1975, the biologist Amotz Zahavi proposed the handicap principle, which states that some ornamental features indicate overabundance of physical resources. Peacocks signal their surplus of energy by squandering this excess of resources on the ostentatious ornamentation of feathers.

However, Prum said he rejects the handicap principle because advertising an overuse of resources communicates weakness. Many of his colleagues find his idea deeply controversial because it upsets a century of scientific consensus, Prum said.

“Subjective experiences, like beauty, are the unquantifiable, immeasurable responses to cognitive stimuli,” Prum said. “Scientists have now said ‘Okay, these ideas cannot be studied’ and then they flee, but just because they are hard for us to study doesn’t mean they don’t exist and have an impact.”

According to Prum, evolutionary biologists fear the words “beauty” and “aesthetic” because they do not fit the molds of natural selection expressed in Darwinism. He added that he will continue advocating for his theory to try to advance and change the scientific debate on evolution.

Shelly Albino, a nine-year OC Marsh fellow, said she was excited to hear Prum talk after previously hearing him speak on dinosaur feathers.

“By going to these events and funding the museum, I feel like I am keeping the Peabody going for the next generation,” Albino said. “It’s a real treasure that a lot of people don’t know we have.”

Kristof Zyskowski, Peabody collections manager of vertebrate zoology, said he loves that Prum’s theory presents the new idea that not every external appearance of an animal has to be guided by rationality: sometimes beauty happens for no purposeful reason except the drive of desire.

Prum won the MacArthur “Genius” grant in 2009 for his work on bird development, behavior and evolution.