It depends on what you mean by existing. Pure altruism does not evolve because it means you give away something and get nothing in return. That's not something that goes rewarded. But reciprocal kindness, however, is a great strategy. We both have backs that need scratching at some point in time, we help eachother out. This means that kindness evolves and sometimes, it can look a lot like altruism. Perhaps so much that the two are almost identical.
Let's say you see a starving child on the telly as part of some charity program. Seeing the starving child stirs you to give money to the charity. You could argue that it is an act of altruism because the starving child or the charity will not give you anything in return. But you could also say that it is not altruism because the reason you reacted that way was because we humans have not evolved in a world where there are TVs. When we see people starving on TV, our biology doesn't know these people are not part of our group. So, you subconsciously reacted as if the starving person is part of your community and could reciprocate your kindness in the future.
So we're capable of acts that closely resemble altruism, particularly now that we live in a world which is so far from the sort of environments we've spent most of our evolutionary history as humans in. F.ex many people have strong, compassionate feelings for animals. It's likely not a capability we evolved because it's a great strategy to get emotional about animals, but rather something that happens because we've started treating and viewing animals more like people. So the compassion we've evolved to have for others in our group can f.ex bleed over to pets.
Is it altruism then?
edit :
Sometimes writing on my Nexus 10 these days. Auto correct made a mess a couple of places.
And for the sake of argument, I'll answer the poll with no with the argument that what looks like altruism evolved out of selfishness and thus it is not real altruism .. even though I can think of a couple of weaknesses with that argument.