A Zebra Finch
© RedOrbit.comA Zebra Finch
In an experiment that examines genetics in the development of culture, biologists at The City College of New York (CCNY) and Cold Spring Harbor Laboratory (CSHL) have discovered that zebra finches raised in isolation will, over several generations, produce a song very similar to that sung by the species in the wild.

Young zebra finches learn to sing by imitating adult male songbirds. But when raised in isolation, they produce an unrefined, off-beat song quite different from anything heard in the wild. In order to understand what would happen to this "isolate song" through generations, the scientists designed experiments in which these isolated singers would pass the song to their progeny, which was repeated in following generations. The birds were either paired one-on-one with their offspring, or placed in a more natural social setting with a colony of non-singing females to breed for a few generations.

The study is a product of the collaboration between Professor Partha Mitra and Haibin Wang of Cold Spring Harbor Laboratory and Olga Feher, Sigal Saar and Ofer Tchernichovski at City College New York (CCNY).

According to Dr. Olga Fehér, who conducted the experiment for her dissertation at CCNY, the study confirms that the songbirds raised in complete isolation do not sing the same song as they would if raised in the wild among other members of their species. The study provides the surprising fact that the offspring of the isolated birds eventually introduce improvisations that have a likeness to those raised in the wild over several generations.

"We were surprised the song reverted back to the "wild-type" song so fast," she said.

"What is remarkable about this result is that even though we started out with an isolated bird that had never heard the wild-type, cultured song, that's what we ended up with after generations," explains Professor Mitra. "So in a sense, the cultured song was already there in the genome of the bird. It just took multiple generations for it to be shaped and come about."

"People have theorized long and hard about how the evolutionary process applies to culture," he says. "This experiment takes culture and puts it into a laboratory setting. We've tested some questions, asked by others over many years, in a mathematically and experimentally crisp manner and come up with a concrete answer."

"Culture appears to be encoded in the birds. It just needed a few generations to emerge," said Dr. Ofer Tchernichovski, CCNY Professor of Biology and Dr. Fehér's thesis adviser. He noted that the same pattern of evolution in the song occurred regardless of whether the subsequent generations were raised with the non-singing female birds or alongside fellow isolated males.

Dr. Fehér concluded the experiment identified some encoded traits of culture.

"This finding could be used to explain why different species develop different song cultures," Professor Tchernichovski added.

According to Mitra, the results mean that the cultured song that is heard in the wild is a product of both genes and learning. This combination of both innate song learned in isolation and the effects of a learning process taking place over multiple generations is an insight initially hypothesized by Mitra to address a problem scientists commonly face when studying songbirds.

It has been long understood by scientists that the "innate" song of the isolated songbird is different from the "learned" song of a songbird that has been tutored by an adult, however the origin of the adult tutor's song has been unknown. Mitra refers to this as the classic "chicken-and-egg" problem.

Future research could show whether "changes in gene expression, neuronal reorganization or neurogenesis associated with song development show orderly multigenerational progression during the evolution of song culture."