A Lack Of The Mind
All I can say is thank goodness for biological urges and a lack of the mind bulls**t which we humans build up as we age, otherwise the human race would die out in just a generation.
What do I mean? Well just imagine if you had left it solely to your mind to decide whether or not you should go and try and find a partner. 
If you had, the only decision it would have made is, you should stay at home and watch TV!

