Is shadow a necesity for one to live on earth?

Well, when it is 98 degrees and 100% humididty, I don't think I would want to spend too much time in the direct sun here in Fl. So, yes I would say that shadow is very important here. When I lived in southern Spain, and it got up to 115 degrees with very little humidity, it was also important to stay in the shade because you dehydrated so quickly in the sun. I do not know if it is the basic criteria for existence, but in the summertime in the hotter climates it is very necessary, especially in the middle of the day. Shalom~Adoniah

I am not sure how you came up with "criteria that qualifies" you to live on earth. You can have a shado on the moon too, but you cannot live there. I guess, you have to have the sun to have a shadow outside, so then since the sun is needed, the shadow is inevitable. Unless of course one resides only inside and never ventures out except after dark. Then it would appear that they have no shadow when indeed they do.... but just not seen!