What’s more, we did literally descend from the trees. And according to the discoverers of the latest addition to our ancestral tree, Ardipithecus ramidus, our upright posture — something traditionally seen as distinctly modern — had already begun to evolve when we were still mainly arboreal. The knuckle-walking associated with our closest relatives, chimpanzees and gorillas, appears to be a more recent adaptation, which has two implications:

• The popular graphic representation of human evolution, showing an apelike figure gradually straightening up, is completely wrong.
• Though evolution does not represent progress, some lineages have undergone more of it than others. By this standard, gorillas and chimpanzees seem now to be more highly evolved than humans.

These findings make me ridiculously happy. The oldest australopithecine fossils had already suggested that arboreal habits persisted far longer than had previously been thought; we were creatures of the forest until just a few million years ago. Even if Ardipithecus ramidus ultimately turns out not to have been a direct ancestor of our particular branch, it does further bolster the case for a relatively recent Descent of Man. And it puts me in mind of one of my favorite passages from William Carlos Williams’ great poem Paterson:

The descent beckons
as the ascent beckoned.
Memory is a kind
of accomplishment,
a sort of renewal
even
an initiation, since the spaces it opens are new places
inhabited by hordes
heretofore unrealized,
of new kinds—
since their movements
are toward new objectives
(even though formerly they were abandoned). …

*

For more on human connections with trees, visit the latest Festival of the Trees, the blog carnival for all things arboreal, at local ecologist.