Kimiko Hahn reads

Cope’s Rule

According to Edward Drinker Cope,
nineteenth-century paleontologist, fossil records show

lineages become larger over millennia

indicating that bigger is more successful.
Though later scientists offered further support for Cope’s rule,

from mammals to corals,

paleontologists in the last century challenged such evidence.
Gould, in particular, was dismissive

of such a psychological artifact.

Current more rigorous studies suggest
the results are plain to see:

being big provides a big advantage. And yet,
the study continues

Why isn’t Cope’s rule more of a rule?

Laws of physics reveal that insects
cannot grow to the size of Tyrannosaurus rex

because their exoskeleton cannot support
heavy loads of body mass. Furthermore, a small rat

is probably better adapted to a certain niche.
There is also the issue of surviving mass extinction

though not everything can get small enough quick enough.
I am already small so that isn’t a personal concern;

still, each consecutive husband has gotten larger
though I’m not sure why or what that reveals

except it’s easier for Harold to reach for stuff on the top shelf
rather than watch me, at fifty, climb on the kitchen counter,

though last weekend he bought, for us both, a step ladder

ruling out vulgar advantage.