 The biologists Stuart A. Newman and Gerd B. Müller have suggested that organisms early in the history of multicellular life were more susceptible to this second category of epigenetic determination than are modern organisms, providing a basis for early macroevolutionary changes.Development in specific lineages can be biased either positively, towards a given trajectory or phenotype, or negatively, away from producing certain types of change; either may be absolute (the change is always or never produced) or relative.Evidence for any such direction in evolution is however hard to acquire.