Complex sentence: Humans and primates use the sudomotor response to thermoregulate, or control their body temperature, mainly via the sympathetic nervous system with negligible influences from the parasympathetic nervous system.
Split into simpler sentences: Humans and primates use the sudomotor response to thermoregulate body temperature. The sudomotor function is mainly a result of the sympathetic nervous system with negligible influences from the parasympathetic nervous system.