(1)Unlike any other known species, humans have developed the ability to record thought. Millennia ago, cave people carved symbols into cave walls to communicate with each other. These messages allowed any person who came into the space to understand information that someone else discovered. As transportation developed, distribution of information became possible. Though we spend a lot of time studying the works of others, this tool allows us to access and learn material in weeks or days that took its discoverers years to grasp.
(2)Humans rely on time to conduct many experiments in their research. We discovered time by noticing solar and lunar patterns which, when examined closely enough, ultimately yielded time about as specific to hours. With advancing technology, humans developed sundials and clocks. Continuing on this trend, we began specifying smaller and smaller quantities of time and now put second hands on our watches and cell phone clocks. This understanding of time drives our existence because we always consider time when we do anything.
(3) Humans are conscious of mortality.