Why don't we remember before the age of three?

Somewhere around the age of one, a baby begins to develop short-term memory. He or she becomes clearly aware of certain objects, such as toys or clothes, and can remeber where they have been put away.
Up to about the age of three, remembered scenes seem mostly to be like isolated snapshots - full of colour and detail, but lacking a context. The explanation may be that the baby's brain is still growing and has not formed a sufficient network of nerve pathways and connections, the synapses between brain cells, to file new experiences in an organized way.
Normally at about age three, as the child's familiarity with language increases, the brain begins to be capable of recalling long-term memories. Interestingly, the word infancy comes from the Latin infans, meaning "incapable of speech." Thus the end of infancy literally means the beginning of speech, and there seems to be little doubt that the power of speech has much to do with the capacity for log-term memory, if only as an unmistakable sign that the child's nerve pathways are now ready to handle grown-up challenges.