The children in Chiapas seem a lot older than normal children. They already have the weary weight of responsibility in their eyes. From as young as three they wander the streets of San Cristóbal till the early hours, selling bracelets and flowers and any number of miscellaneous objects. One girl heads straight for me in the wine bar where I sit with the evidence of privilege spread around me; my digital appliances charging on the table, my Harris Tweed wallet, my resounding European laugh. She must be about six years old. She can smell my oestrogen levels from the other end of the street and uses just one calculated expression to send me into broody fits of moisten-eyed sympathy. “Una Tortuga. Diez pesos,” she says – that’s about 40p. It’s very difficult to resist as she lines up her selection of little clay animals on the table, and I do buy the tortoise first presented to me. I even exclaim childishly, “dos tortugas!” pointing out the second small tortoise on the back of the first. …