I watched a very interesting documentary a few years back when Google video first started. It was about a Daniel Tammet, a semi-autistic savant who learned to speak icelandic in a week, could memorise thousand of items and perform incredible calculations. He "suffered" from synthaesia - a condition where the senses interfere with each other. Some people can "see" sounds or "smell" colours etc. Daniel Tammet could see numbers, they had particular shapes and colours and it was consistent - a week later, the same number would have the same shape and colour.
So what's that got to do with infantile coprophagia? The participants shall remain nameless to protect them but a couple of weeks ago (let the record show that it was Tue March 25th 2009) my youngest child was left alone briefly with a nappy loaded full of my eldest child's poo. When my wife returned, she found that not only had he tucked in to a tasty treat and was smiling a joyous brown smile but he had decorated the floor, the toys, the books and anything else he could get to.
So while I have no reason to believe that he will be an autistic savant, he does know what number 2 tastes like...