Scientists Use Chickens to Study New Theory of Multi-Level Evolution

Oct 8, 2018

In the 19th century, Charles Darwin presented a theory of evolution that is still widely accepted and taught today. Natural selection and "survival of the fittest" categorizes species into 'weak' and 'strong' groups, with the latter carrying over into following generations and the former dying out. Michael Bordieri, professor of psychology at Murray State University, visits Sounds Good to discuss a new evolutionary theory that promotes collaboration and harmony between all 'strength' levels of species.

Natural selection, a key part of Darwin's theory of evolution, is the preservation of desired, advantageous, or otherwise preferred traits through reproduction, which allows species to survive more easily in the wild. This theory borrowed from widely practiced animal breeding techniques. Domestic dogs, for example, have undergone wildly dramatic shifts in physicality and temperament due to a long history of selective breeding. Purposeful breeding of 'stronger' or 'genetically superior' individuals gradually removes undesired traits from the species altogether. By Darwin's theory, inferior species are similarly eliminated for their less preferred or advantageous qualities. 

Although this theory has been widely accepted as an evolutionary fact, new studies suggest that evolution is affected equally, if not more so, by intergroup dynamics within the same species. David Sloan Wilson and other scientists have researched the idea of multi-level selection, in which survival of a species relies on the quality of the entire group, as opposed to the individual. Professor of Animal Sciences at Purdue University, William Muir, tested this theory with an experiment involving hen houses in the 1990s. The goal of this experiment was to create the highest egg-producing hen house through evolutionary techniques. 

Hens were separated into groups based on different characteristics. The first group was selected based on individual egg production levels. The hens who individually produced the most eggs were placed in the same group and observed through multiple generations for changes in productivity. What came of this 'top' hen house was an increase in aggression, lower egg production, and fewer chickens overall due to hyper-aggressive hens plucking the others to death. Hens with higher productivity were 'bullies' who suppressed the egg production of the other chickens. According to Muir, "bullying behavior is a heritable trait, and several generations were sufficient to produce a strain of psychopaths."

The second group of hens were picked based on group productivity levels. Not every hen in this group had been the most prolific egg layer, but they had shared the same environment as those that were. The parallel experiment showed completely opposite results, with all the hens surviving the experiment and a 160% increase in egg production. This is an almost unheard of response to artificial selection in animal breeding experiments. 

William Muir's experiment revealed the inaccuracies of thinking that creating a good society is merely a matter of picking the "best" individuals and breeding them for their hereditary traits. Rather, adaptive traits like cooperation, promoting harmony, and community building play a far larger role in evolutionary survival than Charles Darwin might have thought. In the case of the chicken experiment, laying more eggs was the end goal. By focusing only on the increased egg production, other tasks essential to the maintenance of the environment, often performed by weaker members, were ignored and the environment was damaged. The inclusion of individuals who contribute or promote cooperation and consensus building proved to be far more beneficial to the domain, regardless of the number of "top" genetic examples. 

Bordieri places Muir's experiment in more human contexts, such as workplace or academic environments. While not every employee or student might be considered the most successful, strongest, etc., every member is crucial to the upkeep of the organization regardless of their place on the genetic totem pole. Weaker members make up for what they lack in skill, success, or power through cooperative behavior and the promotion of a harmonious environment, which has been proven to be indescribably valuable to the species' or organizations' overall prosperity. Borderi concludes the interview by explaining the importance of Wilson and Muir's research in regards to "[fostering] communities that collaborate together to accomplish things that are important to them."