Potential Impact of Space Environments on Developmental and Maturational Programs Which Evolved to Meet the Boundary Conditions of Earth: Will Maturing Humans Be Able to Establish a Functional Biologic System Set Point under Non-Earth Conditions?

Abstract

Mammalian development and maturation, particularly processes for humans have evolved in the context of the boundary conditions of Earth (i.e. 1 g gravity, geomagnetic field, background radiation) to yield functional individuals, although the process is not perfect and “errors” do occur. With the advent of spaceflight to low Earth orbit (the International Space Station), humans are now exposed to microgravity and increased exposure to radiation. However, thus far, only adult humans have served as astronauts, but this will likely change with plans to explore deep space and colonize planets. Thus, conception, fetal development, post-birth maturation, puberty and skeletal maturity will occur in the context of boundary conditions that did not shape human evolution and influence physiological and biomechanical systems designed to function within the Earth’s boundary conditions. Thus, processes utilizing the 1 g environment (i.e. walking upright) and the geomagnetic field (i.e. the electrical/biomagnetic basis of neural interactions) will have to adapt to new boundary conditions, providing opportunity for additional errors or alterations in processing during development which could impact functional outcomes at multiple levels. This review/perspective will discuss some of these issues and attempt to provide direction for addressing the potential issues to be encountered.