A recent study from the University of Pennsylvania used 60 years of data on the snowshoe hare to identify stress as a major factor in the wildly varying numbers from generation to generation. Freaked-out hare females with high levels of stress hormones give birth to smaller litters, with smaller babies who also possess high stress hormone levels, and subsequent generations then decline in numbers.
In humans, we know stress is a factor in heart disease, diabetes, and obesity. And an increasing body of work suggests we may be able to inherit stress by means other than our DNA.
