  We show that in some SU(N) type GUTs with the complementary pairs of the
conjugated fermion multiplets there naturally appear the relatively light
($M\ll M_{GUT}$) vectorlike fermions which considerably modify the desert
physics. In the non-SUSY case they can provide for the unification of the
standard coupling constant $\alpha_1$, $\alpha_2$ and $\alpha_S$ whereas in the
SUSY case they can increase the unification point up to the string unification
limit and decrease $\alpha_S(M_Z)$ down to the value predicted from the low
energy physics.
