Answer to Question 1
One of the main issues in development is whether people remain the same, or stable, over time or whether they change. As individuals, we like to believe there is some stability across time because this enables us to predict what we and others might do in the future based on our past acts. However, we also like to assume that we are not set in stone and that change in behavior or personality is attainable. The related continuity-discontinuity issue is concerned with whether development is smooth across time or whether there are abrupt shifts in development. For example, young children can have periods of almost undetectable physical growth and then seem to grow practically overnight. Their physical development can happen in spurts. This particular example argues for both change and discontinuity.
Answer to Question 2
You would want to understand more about how the study was conducted in order to evaluate whether or not the findings are generalizable to the larger population. You would want to know how many people were studied (10 individuals or thousands of people?) and for how long (1 day or over a period of years?) Was the sample representative in terms of the distribution of the subjects' ages, sexes, races, ethnicities, socioeconomic statuses, weights, health levels, and types of diet? How was longevity and mental stamina defined? What type of research design was used (experimental or correlational)? Finally, you would want to know who funded the research. Was it a well-respected medical hospital, or was it a group that has stock in a company that makes trans fat products?
Nursing Interventions and Prochaska's Stages of Change
Desertification and Climate Change
Hares and Lynx population change "الأرانب البرية و الوشق"
Climate Change: Timescale decades to centuries
The change in the net of an irradiance, in Wm-2, at the tropopause
Consistency and Change in Personality Over the Lifespan