Life is stressful, right from birth. That's why babies cry.

  Thumb sucking is a stress response, creating a feedback loop
  that says, ''I'm still here and everything is ok as long as I'm
  still here.''

  (that's my interpretation)

  Studies with rats in cages have shown that stress responses can
  be reduced to zero when they're in what's called ''enriched
  environments'' Plenty of food, water, space, diversions, few
  restrictions on behavior.

  Play.

  There's needs to be more play and less structure. There. That's
  how I'd change the world.

  ...just keep the knives, fire and drainplugs away. Oh and things
  with lids and hinges and heavy things balanced on unstable
  shelves... oh and soften hard surfaces...

  Great.. I've just advocated rubber rooms for all.

  Oh wait - then you have latex allergies... dang it. Hm,
  Plastics! Oh, but the environment... and volitile organic
  compounds...

  Ugh. Just keep a stack of bandaids, an Epipen and some sticks
  and wraps for broken bones. There. Solved. Sort of.... not
  really.