If I hadn’t killed 52 flies as a child, how many descendants would they have had by now?
Assuming that the world fly population is roughly constant, year on year, and the flies killed were neither unusually fit or unfit, then the question is about the speed of transfer of genetic information through the local fly population.
If the childhood home were on a small, isolated island, entirely cut off from all other flies, able to sustain a population of only 100 flies, then by now that entire population would have been descended from one of the original victims.
If, on the other extreme, flies typically breed promiscuously with any other flies in a 10 mile radius, never the same partner twice, and can be blown by high altitude winds across major bodies of water, then by now every living fly in the world would be a descendent.
So the answer is somewhere in between. Where exactly, I will leave to Cecil.
I suspect Cecil meant to say kiloparsecs. One parsec is, off the top of my head, 3-point-something light years; the Milky way is about 100,000 light years across, give or take.
When I was a child (age eleven, I think) I inadvertently left the door to the food cupboard open and my step-father made me read an article on flies which I haven’t forgotten. I don’t recall the publication but I remember it being a reputable one. (We lived in Scotland at the time, which is where I’m from.)
**The article stated that if all the flies in the world were collected in any one year they would fill up Germany to a depth of forty feet. ** Ugh! I go on a ‘search and destroy’ mission (odd for a pacifist, I know) if there’s even one fly in my house - I hate germs. I don’t believe I’ve left another food cupboard open since 1967.