“The privilege of a lifetime is being who you are.” -Joseph Campbell
When you think about dark matter, you probably think of a few things: how mass and gravity don't appear to line up, how there isn't enough normal matter to account for the motions we see on scales of galaxies and up, and how it's necessary to form the structure we see on the largest scales, from the early times of the cosmic microwave background to the cosmic web spanning billions of light years we see today.
But what you might not realize is that without dark matter -- a substance that doesn't interact in any (yet) measurable, non-gravitational way with anything else (or even itself) in the Universe -- life as we know it would be unable to exist. The gravitation from dark matter is the only thing keeping supernova ejecta from escaping from our galaxy, and enabling heavy elements to participate in later generations of stars, planets, and biochemical reactions.
Sounds crazy, I know, but it's true. Here's the science behind why.
Can dark matter have antigravity?
The Giver of Life -- The God Particle is jealous... for he is a jealous particle, The Giver of Gravity. :)
My comment actually is that it is not so absolute, that is, without Dark Matter, Super Novae heavy metals would escape but not all. Some expelled material would collide with other Super Novae shells and with quiescent clouds of H & He, and in both cases, decelerating and seeding gas clouds with the metals that form rocky bodies. I would agree that life as we know it would be more rare but heavy metals would lead to rocky worlds to form life with bilateral symmetry, etc. etc. I hope I have not offended the Dark Matter.