METHODS AND LIMITATIONS IN STUDIES OF 

 HUMAN ORGAN SYSTEM FUNCTION 



Milton Landowne 



Gerontology Branch, National Heart Institute, PHS, D.H.E. & W., Bethesda, 

 and the Baltimore City Hospitals, Baltimore, Maryland 



Experiments where time is a variable are so essential to 

 most researches that one could fairly include all scientific 

 disciplines and methods in a discussion of the methodology of 

 ageing. When the primary focus is upon ageing or age changes 

 in human biology, where studies may extend from cytological 

 to anthropological areas, certain modes of approach appear to 

 be more inviting or fruitful, and others appear formidable or 

 limited. Rather than essay a categorical review of methods 

 which have been used in the study of age changes in man, I 

 should like to discuss some of the approaches and share some 

 of the limitations of methodology with which we have been 

 concerned in our studies of physiological function in contem- 

 porary adults. The word "contemporary" emphasizes not only 

 that we lack longitudinal studies for the most part, but also 

 that the samples of the species which we study yield us data 

 about how man today has aged and not whether man ages 

 apart from his present environment. This, then, is a pragmatic 

 view of ageing; and, in this, all things which alter structure and 

 function with time are relevant and are to be counted. While 

 our task is certainly to describe the changes, it is important 

 that we do so in a manner which attempts to identify the 

 nature and the cause of change, or to learn how change is 

 avoided. 



Paramount to our undertaking is the method of sampling. 

 Although we measure individuals, our results and conclusions 

 have tended to describe the group rather than the individual. 

 If it were at all possible to have a "pure" sample of entirely 



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