Jitter-Legs     

 I have another theory to post, just for the record.  I got yelled at all my childhood for jiggling my legs up and down when seated.  Admittedly, any co-occupant of a picnic table seat, a church pew, or car seat might rightfully object, but I couldn't help it.  It was unconscious, and only temporarily suppressed by a glare from Mom, or a smack from a sister.  And I am not unique, nor even unusual.  So what genetic code controls for this, and what evolutionary purpose could it serve?  Well the specific code is unknown to me, as most behavioral traits handed down through the generations remain unknown as to mechanism.  But I do have a theory to explain why it happens, and what survival benefit it confers.  That movement makes it harder for biting insects to fly low, land on our legs, and bite us.  We benefit from fewer exposures to insect-borne diseases, including many very serious ones, such as Malaria, Dengue, Leishmaniasis, Viral Encephalitis, Zika, and others.  This is no small benefit, and would confer significant survival advantage.  So there, Mom.  I CAN'T help it, and it helps me, and the whole species.  Let me jiggle in peace.