You're confusing smart and intelligent. Smart are the guys who can multiply ten digit numbers in their heads. Intelligence, at its simplest level, is simply the ability think. An animal doesn't have to be dying to know that something was poison. Maybe it recognizes a bitter taste and spits the thing out. Maybe it sees another animal die after eating the thing and makes the connection. Again with the lion. Remember that bit about knowing when to run away from predators? A naked unarmed man who charges a lion head on is a moron and quite frankly deserves to die. He has failed at natural selection, so his genes won't get passed on. The human doesn't need to kill the lion. He just needs to survive so he can get laid. He can use his intelligence to his advantage by, say, climbing a tree or picking up a heavy rock. Maybe he urinates somewhere to spread his scent around and confuse the lion. Maybe he knows that lions sleep a lot, so he waits for that before running away. Still don't how intelligence can be an advantage? Now, knowledge isn't hereditary, but it can still be passed from parent to child. Children can learn by observing their parents. Thus, the knowledge obtained by the parent during its lifetime is passed on to the next generation. The instinct to observe and imitate a parent is a trait that could affect natural selection.