I have a teeny tiny obsession with giant ground sloths, which has been made ever so much worse by moving to California, which is sloth ground zero. The sloths haven’t been extinct for long – 10,000 years is pocket change in evolutionary terms – so many of the plant species that knew the sloths still exist. The Joshua tree, for example, is unable to travel without sloths to poop out intact seeds. There is also the theory that avocados evolved for sloth poopage, since nothing else is big enough to pass the giant pits.
Joshua trees aren’t alone. NPR recently had a story on the thorns of honey locust trees, which live in Manhattan (among other places.) A paleoecologist is theorizing that the big thorns were evolved to protect against a big grazer – the mastodon. The story totally captures the pain of a tree that is all gussied up with no predator to pierce:
[Said in a mournful tone] There hasn’t been a mastodon in New York for at least 13,000 years, but the thorns are still there, waiting for the mastodons that will never come.
Fortunately for the honey locust, researchers proposed a solution back in 2005. Bring the Pleistocene megafauna back to America! The Pleistocene wasn’t just about sloths & mastodons – there were also lions and cheetahs and camels and dire wolves, and those have living modern analogues. So the idea is to let African lions and elephants and such loose on the Great Plains. Wouldn’t you like to go on a safari in Oklahoma?
Of course this idea is completely mad (especially since we can’t seem to deal with the wolves that are already here) but it’s the kind of madness I love. Maybe one day we can clone the sloths, too. If you want more info, the official rewilding page is here.
Also, now I really want this book on ecological ghosts by the author of the honey locust NPR piece.