Passing on Stress to Multiple Future Generations

It has been demonstrated before the effects stress can have on future generations in many animals, including humans. One animal that finds itself under the magnifying glass quite often for this study is the snowshoe hare. This species experiences many population booms and busts that can affect many generations in the future. Scientists have shown that during periods of low stress for the hares, their population doubles every year. In response to this, populations of predators of the snowshoe hares also increase. This causes the population of snowshoe hares to plummet. This cycle lasts about 8 to 10 years. What scientists have found the most intriguing about this cycle is the fact that the hare population does not increase right away following a plummet. The population of snowshoe hares remain low for another 2 to 5 years. An ecologist from Pennsylvania State University, Michael Sheriff, examined this cycle and believed there to be an epigenetic explanation. Sheriff says that although the genes themselves have not been altered, the way in which these genes express themselves can be affect by the level of stress snowshoe hares experience during a population crash. Sheriff and his coauthors analyzed data regarding snowshoe hare population cycles and found that the sharper the population declined, the longer it took the population to increase. Sheriff says that during the periods in which the hares are more viciously being hunted, mothers are under very high levels of stress. This caused the mothers to give birth to smaller and fewer babies. The offspring of the stressed mothers have a higher stress hormone, causing their stress reaction system to be more reactive. Although a snowshoe hare may not have directly experienced these traumatic events, the stress is in a way imprinted in their body.

This article is kind of frightening considering that it shows that high levels of stress can have effects on many generations. While the effects of stress on multiple generations has been observed in humans, scientists have yet to study how the severity of stress can affect multiple generations. This research on the snowshoe hare may be a stepping stone to understanding the same phenomenon in humans.

The link to the original article can be found here.