Humans lack the ability to control their most simple thoughts.

"Every species needs natural controls, and humans have lacked one far too long."

In addition, humans lack a way to make choices that balance innovation and reality.

Or maybe all those other Earths had something that only the humans lacked.

Perhaps humans lack the glands or whatever is necessary for telepathy.

Yet all new departures now come from such, since humans lack the corpus of information to discern what has already been done.

I think humans may lack a sense of proportion.

Humans will simply lack the time to consume even a fraction of the very best of it.

We pondered why humans lacked useful things like tails.

And those fallen humans had not lacked either in courage or in resourcefulness.