[Javik could only guess at Hiro's age, but even as young as he looked, he sounded like Shepard. That sharp, never-give-up attitude was exhausting, and it had killed more people than it had saved. At least, in his time it had. Shepard had a way of pulling people out of the fire.]

Our galaxy is slave to a cycle. The Reapers, machines, would return to the stars every fifty thousand years to harvest the space-faring organic races, and wipe their culture and civilization out entirely. We have yet to divine a reason, but once they are done, they retreat to dark space, and wait for the next cycle to begin.

Organic life is never eradicated, though. Only those that have achieved spaceflight are culled, and the rest are left to continue their own evolution or demise.