Models of Aging: Definitions & Types

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  • 0:06 Aging
  • 0:57 Individual Models
  • 2:57 Non-Individual Models
  • 4:44 Lesson Summary
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Lesson Transcript
Instructor: Devin Kowalczyk

Devin has taught psychology and has a master's degree in clinical forensic psychology. He is working on his PhD.

There are different ways to describe how old someone is other than revolutions around the sun. We will explore a few of them and how they focus on either the individual or the individual's place in society.


There are many ways we can look at aging and many ways we can define it.

I am going to divide this into two parts, although this doesn't appear to be supported by the literature. I am going to divide it into individual aging and non-individual aging. I am splitting this up by the different models of aging based on the focus. With individual, we focus on you, your cells, and your body. With non-individual, we will focus on your age and what it means to society.

Individual Models

With individual models of aging, we focus on the individual person. Mechanistic aging, sometimes referred to as the biological model, is broadly defined as damage at the cellular level or DNA level results in accumulation of mutations or incompetent cells. I say broadly defined because biologists have focused on specifics in different areas, like DNA, mitochondria, and free radicals. We, however, are looking at it broadly.

Mechanistic aging states that as you get older your cells run into problems - maybe as one was dividing the DNA got all jumbled, and now the cells that divided from it don't work as well as before; or something got into the cell's mitochondria, which helps power the cell, and damaged that. Now the cell is working on half the juice it should. These accumulate and result in inefficient areas in the body, like the skin not being as elastic or the heart growing weaker.

Think of it like what happens when you break something and you need to repair it. It just is never as good.

Organismal aging is defined as a holistic view of an individual based on cellular aging. With mechanistic, we look at the specific cells and how they work. With organismal, we are seeing how they come together. So mechanistic is sort of subsumed by organismal because organismal focuses on the whole organism rather than the individual parts.

One idea behind organismal aging is that there is a limit on the number of times a cell can divide. Every organ is made up of cells, and many of them are repaired by dividing cells. If they reach that limit, then they can no longer divide, and now the organ is working with fewer and fewer cells. This is kind of like running a big fleet of cars, and in the beginning you have 100 mechanics, and by the end, you have one or two.

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