The idea of whether rats with exciting lives would indeed be less likely to become addicted to cocaine &#x2F; morphine is quite controversial, and there have been some failures to replicate that original study (references here: 1. <a href="https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;9148292?dopt=Abstract" rel="nofollow">https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;9148292?dopt=Abstract</a> and 2. <a href="https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;2616610?dopt=Abstract" rel="nofollow">https:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;2616610?dopt=Abstract</a>).  I think the argument is that social isolation can and probably does make animals and humans more prone to drug addiction, but it&#x27;s definitely not the only factor, and both animals and humans with good lives can still become hooked.