Group Behaviors Can Change the Course of Evolution

A team of researchers studied huddling behaviors in mice and made a new discovery. They found that when animals are under less evolutionary pressure, evolution processes actually speed up. This goes against previous beliefs that stress leads to faster adaptation through evolution. The research team specifically studied the phenomenon of self-organization and how it affects gene mutations. The details are in a paper that was just published in the journal Royal Society Open Science.

Huddling is considered a form of “self-organization” in which complex, coordinated behaviors can arise even when each individual is acting on their own without any instruction. When huddling, animals group together to stay safe and warm. The behavior is seen in penguins, rodents, and even insects. A flock of birds is another example of self-organization in animals. These types of behaviors may affect evolution but there had been little formal research on the topic.

A research team developed a complex computer model to study the effects of self-organization and harsh environments on the process of evolution. The model could track gene mutations and changes in laboratory mice. When the animals were exposed to cold temperatures, the scientists expected their temperature regulating genes to evolve quickly. If the animals huddled, staying warm, there might be less evolutionary pressure to adapt.

Interestingly, the huddling mice actually evolved better thermoregulation genes faster than mice that were exposed to cold temperatures without huddling. The research team attributes this to a process called relaxed selection. In relaxed selection, animals can actually evolve faster. This is because they’re under less stress and gene mutations become less costly. Since there’s less pressure to adapt, the genes can “experiment”. Huddling is an unusual case where a performed behavior can change the direction and speed of natural selection.

The findings point to a new driver of evolution that can take priority over environmental conditions: group behaviors. The research team found that mice that stayed warm in group huddles actually evolved faster because of a phenomenon called relaxed selection. The team believes further research is needed to fully understand how self-organizing behaviors affect evolution.


Glancy J, Stone JV, Wilson SP. How self-organization can guide evolution. Royal Society Open Science (2016).

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