What is the current understanding as to why organisms age and die? In the following explanation on Ask an Engineer, entropy is not even considered (despite it being answered by an engineer). Unless you consider

accumulation of damage to an organism over time

as a result of entropy ?

In the end, is the eventual death of any organism a result of how the laws of universe? In the paper Aging of the brain, entropy, and Alzheimer disease, the author states that

Increasing entropy, manifest through a complex network of interacting ARCs, is seen as the fundamental driving cause of neural and cognitive decline in the elderly

where the abbreviation ARC stands for age-related changes.

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    $\begingroup$ Living organisms are not closed systems, and as far as I am aware, the laws of thermodynamics only apply to closed systems. $\endgroup$
    – AMR
    Dec 29 '15 at 3:58

Second law of thermodynamic and ageing

The second law of thermodynamic applies to closed system. Organisms are not closed system. The second law of thermodynamic is a fundamental principle of our universe and any biological processes do follow the principles of physics. However, stating that biological ageing is (partially) caused by the second law of thermodynamic suggests a big misunderstanding of what the second law of thermodynamic is.

To have a better understanding of the second law of thermodynamic, check up the wikipedia article or one of the many other sources of information on the subject and ask questions on Physics.SE if needed.

Ageing and its evolution

The evolution of ageing (or senescence) is a big subject and has already been subject of a large number of questions on Biology.SE. Have a look at the questions tagged . Below are two examples of post that will interest you:

There is also a wikipedia page on the evolution of ageing.

Note btw that biological immortality and negligible senescence do exist.

