&gt; It&#x27;s a bit like the Army. In theory anyone of any age and background can join up.<p>this is patently false. There are very strict requirements for enlisting&#x2F;being commissioned [0], including minimum and maximum age for new members, minimum aptitude tests, and either be a us citizen or a resident alien. Also many people are disqualified for having a criminal record.<p>&gt; but the physical requirements and &quot;culture fit&quot; does a very good job of selecting for young males.<p>yes, this makes sense. &quot;Culture fit&quot; must be the reason that every single military in the history of the world from every culture ever has been heavily male dominated.<p>&#x2F;s<p>[0] <a href="http:&#x2F;&#x2F;www.military.com&#x2F;join-armed-forces&#x2F;join-the-military-basic-eligibility.html" rel="nofollow">http:&#x2F;&#x2F;www.military.com&#x2F;join-armed-forces&#x2F;join-the-military-...</a>