We were sitting around a table yakking over beer
When Jim said accidents happen, that’s why we’re here

You mean our car stalled in front of this bar?
So we didn’t have to end up driving much too far?

No dummy, he sneered, what I said was profound
We’re pretty much just what mother nature found

Ah, he’s back on evolution, Al correctly pointed out
He didn’t need instruction, he was right beyond a doubt

Tom and I still hadn’t gleaned what Jim had really meant
So he grinned and sipped his beer and on and on he went

Our ancestors a million years ago varied much as now
But none of them had thumbs then, I think you will allow

Consider how opposable thumbs began with a genetic accident
That was simply a slightly difference in a finger bone that bent

His oddity remained in the gene pool because it wasn’t any problem
Then in some later generation a further accident occurred with them

Through thousands of these tiny accidents an ancestor of Tom or Jim
Ended up with a finger bone that helped to grab a hanging limb

When tigers came prowling he was quickest up the tree
And gradually that advantage was handed down to you and me

If there hadn’t been some trees around it wouldn’t have evolved
As it was that odd bone growth matched a problem to be solved

So if all had been low desert or grassland with no trees
None of us here would have opposing thumbs like these

So evolution depended on the environment there had been
Which determined what new trait were out and which were in

Accidents and their consequences take many generations
Before some old guys appear holding beer mugs on vacations