Excess Baggage

Once our genes were our own,

or we were theirs,

horses they selfishly rode

into a Mendelian future,

but centuries ago we learned

the truth: the so-called human genome

was 90% bacterial. Who knew

we were carrying hitchhikers

in such intimate places?

When we reached 95%

it was time to do something.

Some of that stuff

was not pulling its weight, not

facilitating gene propagation—

actually it was slowing us down,

doing things we didn't need,

or doing nothing at all. So we

jettisoned that worthless 5%,

co-opted and improved

an inefficient metabolism

(we already catalyzed

many of its essential functions),

took over the remaining organ systems

(basically, we cut out the middleman),

and now we are really going places!