Others point out that while the conceit that our human species could be preserved forever is as absurd as the hope of individual immortality, those facts provide no reason to accelerate either senescence or evolution (Robert and Baylis, 2003; Agar 2013). Even in the face of the inevitability of a post-human species, they argue, we are justified in protecting our (admittedly) “species-relativist” values by rejecting enhancements that would serve to alienate their recipients from their former selves, their families, and their communities. Normal evolutionary processes provide the luxury of time for human populations to “negotiate” their adaptations with the environments that provoke them. Leaving evolution to these normal processes can thus ensure that our evolution is both as deliberate and as tentative as our species’ technological history—and also that it is like technological history in that key “threshold” changes can only be seen retrospectively. From this perspective, the danger is the abrupt provocation of biological speciation which radical enhancements might provoke, if they created reproductive barriers between the enhanced and the unenhanced. However, given that almost none of the single capacity enhancement interventions under discussion—cognitive, physical, moral, etc. —are likely to immediately produce biological reproductive barriers in otherwise species-typical enhanced humans, it is not clear whether the introduction of even the most “alienating” enhancements would create this risk. 