first created the creatures, not their
reproductive apparatus. The Victorian Samuel
Butler awarded the egg overall priority when
he said that a chicken is just an egg’s way of
making another egg. About one point,
however, there is no dispute: eggs existed
long before chickens did. Ultimately, we owe
our soufflés and sunny-sides-up to the
invention of sex.
The Evolution of the Egg
Sharing DNA Defined broadly, the egg is a
kind of cell that is specialized for the process
of sexual reproduction, in which two parents
contribute genes to the making of a new
individual. The first living things were single
cells and reproduced on their own, each cell
simply making a copy of its DNA and then
dividing itself into two cells. The first sexual
organisms, probably single-celled algae,
paired up and exchanged DNA with each other