We measure the morphology–density relation of galaxies at z { = } 1 
across the full three orders of magnitude in projected galaxy density available in low–redshift studies .
Our study adopts techniques that are comparable with those applied at lower redshifts , allowing a direct investigation of how the morphological segregation of galaxies has evolved over the last 8 Gyr .
Although the morphology–density relation , as described by the fraction of early–type ( E { + } S0 ) galaxies , was in place at z { = } 1 , its form differs from that observed at both z { = } 0 and z { = } 0.5 .
In the highest density regions the early–type fraction has increased steadily with time from { \mathrel { f _ { E { + } S 0 } } } { = } 0.7 { \pm } 0.1 at z { = } 1 to { \mathrel { f _ { E { + } S 0 } } } { = } 0.9 { \pm } 0.1 at the present epoch .
However , in intermediate density regions corresponding to groups and the accretion regions of rich clusters , significant evolution appears to begin only after z { = } 0.5 .
Finally , at the lowest densities , no evolution is observed for the early type fraction of field galaxies which remains constant at { \mathrel { f _ { E { + } S 0 } } } { = } 0.4 { \pm } 0.1 at all epochs .
We examine a simple picture consistent with these observations where the early–type population at z { = } 1 is comprised largely of elliptical galaxies .
Subsequent evolution in both intermediate and dense regions is attributed to the transformation of spirals into lenticulars .
Further progress in verifying our hypothesis may be achieved through distinguishing ellipticals and lenticulars at these redshifts through resolved dynamical studies of representative systems .