Famine, while it may not wipe out all of humanity it will destroy the developing world. The populations in the developing world are soaring out of control and even today they can't feed all their people- in just a few years to a decade your going to see a major historic problem.
And in honor of this problem, I shall tonight fill my stomach with food, and rejoice: for I will not be famished!
Of course, if humanity produces non-biodegradable toxins fast enough we could gradually poison the whole planet. We would have to genetically engineer life to be able to break it down or engineer ourselves to be able to cope with it.
From a wild imagination: How about: A sudden overflow of weiners from a weiner delivery truck falls into the ocean, causing massive earth tremors due to the strange chemicals in the weiners. Years later, by some twisted chance (evolution, *wink*), the weiners gain sentience and combine themselves with koalas to produce the ultimate symbiotic killing machine. These weiner-controlled koalas will eventually take hold of all the world's major countries, and using penguin shock troops, will gain the insanity of every living human being through mind control. These weiner-controlled koalas and penguins will see that humans are no longer necessary, for they produce neither good meat and are unable to be subjected to harsh labour. Thus, the species we all know as Man will be vanquished from the face of the earth. The end. Please Register or Log in to view the hidden image!
All righty, I'd like to forward the name "Bob". We will all become the race of BOB. All hail Bob. Please Register or Log in to view the hidden image!
Wow, asteroid is in the lead. Do you think, if a major asteroid wipes out 99% of surface life for 2 million years and next life evolves, there will be any sign of us buried somewhere? just two planes destroyed 100% of all copy machines and coffee makers and computers at ground zero. Add another 2 million years for all the papers and steel to disolve and eaten away by bacterias... I wonder....
There's no chance in hell all evidence of human life would be wiped away by an asteroid, unless it was like the size of the moon or something. That might create another asteroid FIELD.
Earth has a number of life forms that are nealy as intelligent as us. Most great apes, the elephant, and cetaciens could develop intelligence in a million year period. This shows that it is not very hard to do so. Sadly these are all evolutionary specialists and would die before us in an extinction.
humans are quite resiliant--i believe that if we can get into space with self-sufficient colonies, we could survive just about anything, unless God wills against it. Yes, I'm a Christian, but don't worry, I'm an evolutionist, too. hehe