Dogscoff writes: "...as you look back in time towards the Big Bang the amount of heavy elements in the universe dwindles down to nothing. Since these heavy elements are needed for life, shouldn't the probablilty of life dwindle away with it?"
Absolutely. Note, however, that we're dealing with averages and probabilities here. In regions of unusually rapid star formation (galactic cores, globular clusters) the interstellar medium could be sufficiently enriched with "metals" (atomic number 3 and above) in a billion years (the most massive stars are thought to go supernova in under a hundred million years). Such regions are also pretty hostile to life (black holes, sterilizing radiation), but given the vast number of galaxies in the universe, it seems likely that suitable combinations of conditions would exist in many of them. If so, even after 4-5 billion years of evolution, life forms in these regions would have a 7 billion year head start on us.
While researching this post I came across an interesting article from 1996:
http://hubblesite.org/newscenter/new...eases/1996/37/
Judging from Hubble images of distant galaxies, it appears that the rate of star formation in the universe peaked about 3 billion years after the Big Bang (BB), at about 10-15 times the current rate. By the time our sun was formed, some 8-9 billion years post-BB, most of the stars the universe will ever have had already been born. That means we've also already had most of our supernovas, so Dogscoff's curve (lovely diagram, BTW) should probably be skewed to the left.