how would it happen - naturally?

while talking about boobs and booties, and getting some new friends in the fraternity of brotherhood and kicks in the geography of bottomhood, i got [ummm... did i] bored. someone did for sure. it was getting repetitive. there was nothing to read except for about girls [which i guess not many girls like]. so in a [not so serious] attempt to write something for girl audience, i failed [anyways that isn't a news when girls are involved].

but then i saw something and thought about something. i mean i thought about girls even than too but i mean i thought more about it than girls. how is human life going to perish from the face of the earth? i mean, firangi writers have thought about seemingly all the ways in which the life can perish, but then what can beat nature; can imagination?

natural calamities - earthquake, volcano are not much in vogue. so are WMDs. space although very vast, fast and undiscovered won't be bothered about relatively little issue such as human life [if at all it is as big]. parasites aren't as big to kill 'everybody' and dinosaurs would sure leave some of them under their fat arses unseen and thus uneaten [if that is a correct grammatical usage].

so what would it be? think think think, burf, think think think. my ideas:-

would it be that from a very unfine day in future, the females would stop giving birth to girls [could be any medical or psychological reason] and there would be only guys on earth and no girls to hump and therefore no new kids.

or would it happen in a very natural way? i mean, with growing tech, all the humans would shift to other planets in other solar system in other galaxies and find alien girls who are less fussy [about everything and sex :D ] and look much more beautiful and desirable [than human females - which is a shuddering thought. and of course, their anatomy can be a hot topic for another comprehensive post such as this ;) ].

what do you think could be the reason?