In science, "alive" refers to organisms that perform specific vital functions. While there is no single perfect definition, biologists generally agree on seven key characteristics that distinguish living things from non-living matter:
: The capacity to produce offspring, either sexually or asexually, to ensure the continuation of the species. In science, "alive" refers to organisms that perform
: The ability to maintain a stable internal environment (like body temperature) despite changes in the outside world. : Organisms react to their environment, such as
: Organisms react to their environment, such as a plant growing toward light or an animal fleeing from a loud noise. : Organisms react to their environment
: Living things increase in size or complexity over time throughout their lifespan.
: Over generations, populations of living things change to better survive in their specific environment. 2. The Human Experience: What It Means to "Feel Alive" What Really Makes Us Feel Alive (And Why We've Forgotten)