Nucleosynthesis Constraints
There are some fairly strong arguments based on the production of the light
elements in the Big Bang indicating that the majority of the dark matter cannot
be ordinary matter or antimatter (which physicists call "baryonic matter": matter made up of atoms or
molecules or ions having neutrons and protons and related particles in their nuclei), and
thus that the majority of the mass of the Universe is in a form very different
from the matter that makes up us and the world around us (physicists call this
"non-baryonic matter"). If that is true, then the matter that we are made of
(baryonic matter) is but a small impurity compared to the dominant matter in
the universe (non-baryonic matter). As someone has put it, "not only are we
not the center of the Universe, we aren't even made of the right stuff!"