This cycle follows a pattern every 3 -4 years that starts with a very low population density that increases with time. Once it reaches its peak density the population dramatically crashes and the whole cycle commences again. This cycle is clearly amplified by the harsh arctic conditions.
Why study cycles like this?
While the population density is increasing, social behaviour is amicable and the animals are relatively timid; however, once it enters the crash phase, there is disruption of social structures, aggression, and increased territoriality. This cyclical process must be driven by epigenetic changes, the process by which the activity of our genes is modified in real time. By studying the epigenetic changes driving this process we can learn how genetic changes control different behaviours in mammals. There is very strong evidence that human civilisations have longer but similar lemming/vole cycles. Understanding the mechanism driving cycles in small animals will provide new insights into human behaviour and how changes in behaviour cause cycles in human populations.
To learn more about this topic, check out our paper which includes a model that shows how stress can cause genetic and behavioural changes across generations:
