I don't know much about this, only looked into it a bit yesterday. If you know more or can find out something, please contribute. Abraham Loeb (eminent Harvard astroph.) says, if I understand him correctly, that light from stars richer in heavy elements than the sun has been observed at redshift z ≥ 6. More specifically, these are stars in the central regions of galaxies which host quasars. That was in 2006: it may have been found more generally, not limited to cores of quasar-host galaxies. http://arxiv.org/abs/astro-ph/0604242 See page 3, top of right column. "For example, the cores of quasar host galaxies are known to possess super-solar metallicities at z ≥ 6." z=6 means the light has been traveling 12.8 billion years, so was emitted only 0.9 billion years after start of expansion. So simply on that basis, rocky planets and carbon chemistry could have existed quite a long time ago. The star-forming clouds of gas were rich enough in heavy elements. Loeb points out that this could make sense because the giant stars that cook heavy atoms and blow them out into the surrounding clouds have short lifetimes. You could have several generations of supernovae successively enrich the chemistry of the clouds within a few hundred million years. Loeb points out that the environment was denser back then, by a factor of (z+1)3, which would tend to speed up star-formation. He didn't spell it out but one can imagine a supernova chain reaction where one SN makes shockwaves in the gas which nucleate contraction and trigger formation of other giant stars, that then go SN themselves, repeating the process. At redshift z = 9 we are talking about conditions that are 1000 times denser on average. So it kind of makes sense that there could have been at least some regions in some galaxies back then that had metal-rich stars. Maybe only certain parts of certain galaxies, but still... So carbon chemistry on rocky worlds is not so new? You mean something could have been playing the violin 12.8 billion years ago? We aren't the first to make instruments that cause the local atmosphere to vibrate at definite frequencies? Something else could have plucked a string or blown a flute so long ago?