Do fermions and bosons produce the same gravitational field?

We examine some cosmological consequences of gravity coupling with different strength to fermions and bosons. We show that this leads to a different perturbation of the standard picture of primordial nucleosynthesis than the addition of extra neutrino types or overall scaling of the value of G. Observed abundances of deuterium and ⁴He place bounds on the ratio of the bosonic gravitational constant (G_B) to the fermionic gravitational constant (G_F) of 0.45<G_B/G_F<0.92 at 1σ and 0.33<G_B/G_F<1.10 at 2σ. A value of G_B<G_F can reconcile the current “tension” between the abundances of deuterium and ⁴He predicted by primordial nucleosynthesis. We comment briefly on other cosmological effects.