Losing weight, where does the weight go
Mostly we breathe it out funnily enough, also sweat contains fats, and of course yes in urine too.
@Eckhart Yes, language is changing so much faster these days, with communication being so much freer than it was even just a few years ago.
Not only that, the world is so much "smaller" as a result and people are communicating with others who speak other languages more than ever before I'm sure.
I started compiling a list of things we don't have a word for in English
Somehow missed this earlier I think
It would be a VERY long list because most words we use in "English" are actually french/Italian/German/Dutch/Hindustani/Swahili/Japanese...
Much shorter list - Anglo Saxon words we still use! 
@honeylulu there's been whole threads on 'post apocalyptic survival skills which do you have?' - not a real thread title not sure how you'd find them. I'm fairly good as had practical and outdoorsy parents plus I was involved in guiding and scouting for a LONG time from the age of 7 until mid 30's and learnt a lot there too. A lot of people have skills but a shocking amount wouldn't know so much as how to start a fire without a match or a lighter! 

Re walking as humans and teaching babies to walk. I've looked after a LOT of babies and I don't think we do teach them, I think they teach themselves at different stages. I certainly didn't bother with dd as I didn't need to! The little bugger was off and into everything at 9 months!! She never crawled though she side rolled to get places before that and not for very long and then just one day only a short while after pulling to standing she just walked clear across the living room floor with no warning! Pleased that day...not so pleased in the days and weeks following as she really did find her way into everything! She was a right "climber" too. Never mind just regular baby proofing we had to make chairs, boxes, toys that could be stood on etc inaccessible too as she'd use them to climb.
Building whole cities on areas prone to earthquakes - why?! Surely the humans living in those areas KNEW there were loads of earthquakes there?!
LOVING this thread!