On the basis of quantum Monte Carlo results the evolution of the spect
ral weight A(k, omega) of the two-dimensional Hubbard model is studied
from insulating to metallic behavior. As observed in recent photoemis
sion experiments for cuprates, the electronic excitations display esse
ntially doping-independent features; a quasiparticlelike dispersive na
rrow band of width of the order of the exchange interaction J and a br
oad valence- and conduction-band background. The continuous evolution
is traced back to one and the same many-body origin: the doping-depend
ent antiferromagnetic spin-spin correlation.