Hi everyone! This is my first post on this forum so please, if I have missed something please let me know! I have a lot of questions to ask but this is the main/first question in my mind right now! As I understand things, everything in the universe has mass (or anti-mass) and everything that has mass exerts gravity (depending on density). Every human has mass and a very low level of density meaning they exert a small amount of gravity and they have a small amount of weight. So with all that in mind, as the population of humans increases exponentially, does the earth either weigh more, less and does it shrink or contract due to humans? The way I see it, although we can't have any more material mass on earth, what about biological? Please start my education and stop my ignorance! Thank you for reading and I hope you can reply!