The abundance of these molecules depends on the heavy elements produced
in the previous generation of stars. So the mass spectrum influences the
production of heavy elements and the production of heavy elements influences the
mass spectrum. In the Early Universe, when heavy elements were not abundant,
the gas of the clouds should have been much warmer; the Jeans Mass (§ 3) much
higher; therefore stars much more massive than those we have nowadays should
have been produced (Stahler, 1986). These first generations of massive stars have
rapidly increased the abundance of the heavy elements of the Early Universe.