When do your memories start?

How far back do you remember? Surely you remember being 10. Most likely you remember being 5 - at least a few events. Farther than that? 3? I have some impressions that I think are memories from that age.

Things start to get murky here though because it's hard to be sure you aren't transcoding what people have told you later in life about that time into pseudo-memories. It's been shown people can be made to "remember" things that never happened, by hypnosis, by psychotherapy, even by leading questions asked by researchers.

So when does long-term memory actually begin? More to the point, why don't we remember back all the way to birth? Is there some advantage in forgetting those first few years?

Of course, we forget millions of things every minute - only a tiny contingent of the vast armada of information assaulting our senses makes it into consciousness, and then only a small fraction of that gets transfered into long term memory.

Even long term memory goes away for one reason or another. But what I'm talking about is the seeming wall that exists before which we remember nothing. Is there a reason for this?