What reproduction is
A living thing does not last forever. What lasts is the line it belongs to, and it lasts only because each generation produces the next before it goes.
The biological process by which one generation of living things gives rise to a new generation is called reproduction. It is the one process on this list that a living thing does not do for its own sake — an organism that never reproduces is not harmed by it. The line it belongs to simply ends.
Only living things do it
Reproduction is a characteristic inherited by living things alone. Crystals grow, fires spread and rivers branch, but none of them makes a new one of itself carrying its own instructions. This is what keeps the continuity of life going.
Reproduction happens in two main ways, and the whole of the rest of this chapter divides along that line:
- Asexual reproduction — one parent, no gametes.
- Sexual reproduction — two parents, gametes that fuse.