Why are men so protective over women?

Men seem naturally protective of women and I'm curious whether you think this is a biological instinct thing or something that society encourages and teaches them to be. Biological, i cant say but it just feels like the right thing for guys, but why?

Also this makes we question how much we treasure our women, wife or GF, I mean your friend steals your money and you scream and tell people he is a bad friend, but you hear that your friend is sleeping with your wife and you are looking for your gun or cutlass!!!! No Mercy 

Why are men like this?

What if you had 5 wise friends available 24/7 who actually listen? → drux.space/village