  We consider the process $\gamma\gamma\to H_1\bar H_2$ where $H_1$ and $H_2$
are either mesons or baryons. The experimental findings for such quantities as
the $p\bar p$ and $K_SK_S$ differential cross sections, in the energy range
currently probed, are found often to be in disparity with the scaling behaviour
expected from hard constituent scattering. We discuss the long-distance
pole--resonance contribution in understanding the origin of these phenomena, as
well as the amplitude relations governing the short-distance contribution which
we model as a scaling contribution. When considering the latter, we argue that
the difference found for the $K_SK_S$ and the $K^+K^-$ integrated cross
sections can be attributed to the s-channel isovector component. This
corresponds to the $\rho\omega\to a$ subprocess in the VMD
(vector-meson-dominance) language. The ratio of the two cross sections is
enhanced by the suppression of the $\phi$ component, and is hence constrained.
We give similar constraints to a number of other hadron pair production
channels. After writing down the scaling and pole--resonance contributions
accordingly, the direct summation of the two contributions is found to
reproduce some salient features of the $p\bar p$ and $K^+K^-$ data.
