Recent development of economics has spawned new branches within it, behavioral economics and neuroeconomics. To investigate the problem of how humans cooperate and conform to norms, economics has also extended its scope to interdisciplinary research into human “ultrasociality.” These new trends have today come to urge us to review the traditional conception of humans in economics, homo economicus. Neuroeconomics has brought to the fore the naturalistic conception of humans, while the research into human cooperation has brought to the light the conception of humans that create social/institutional facts (homo instituens). This paper tries to characterize these newly emerging conceptions of humans and examine their impact on how we understand and design social institutions.