I recently posted an observation of an osage-orange, and as I always try to do with observations, I followed up with reading the Wikipedia article on it. I noted this passage, "the fruit is typically not eaten by humans and rarely by animals, giving it distinction as an [anachronistic] “ghost of evolution,” which caught my attention. I wasn’t certain what the phrasing meant, so I followed the footnoted source. Judging from a quick skim of some material, I gather that the fruit was a food source for an extinct animal? Do I have that correct? If I do, are there other examples out there? I mean how does one know when something may have outlived the thing that used it? I thought of purchasing the book, but it’s older, and I was wondering if there is a newer source? I just found it intriguing and was hoping someone might know more about it.
Yes, megafauna used to eat the fruit and spread their seeds, but now that they are extinct, the tree has lost its symbiotic relationship. Another wonderful example is the Pronghorn. It is much faster than any modern predator in North America. It may be a now useless relic of evolving alongside the American Cheetah, which is also now extinct.
https://en.wikipedia.org/wiki/Evolutionary_anachronism explains it pretty well. I hadn’t heard of it before, but horse apples are pretty much nailed by the “Common megafaunal dispersal traits”. They also follows “Ecological indicators of missing dispersal partners” pretty closely.
I suspect many human foods fall under such categories. Coconuts and Pineapples leap to my mind.
Some such foods might have actually been changed by humans over time. Humans being the “megafauna” that caused the change, or their domesticated animals. Not sure if such an idea is pursued in the concept or not.
Thank you–that’s fascinating. iNat. sometimes sends me down some great rabbit holes.
Thanks, I appreciate the link. I missed that article somehow–it has an interesting list of examples. I really am going to have to read up more on this.
I heard the avocado evolved to be eaten by now-extinct giant sloths. I don’t have any sources, but maybe we can look that up too.
The wiki article mentions:
(
e.g. the absence of gomphotheres to eat avocados doesn’t make the avocado’s pulp in any way vestigial, rudimentary or intrinsically incapable of playing its original function of helping disperse the avocado’s seeds through zoochory, were a new suitable ecological partner to appear; while a true vestigial organ like the python’s pelvic spurs cannot in any way be used to walk again).
And upon reading further, notice there are tons of examples, by region, at the bottom of the article. Bottom meaning about 90% that I hadn’t browsed through yet. :)
The avocado thing is a commonly told story but it’s largely a myth. The avocado most people are familiar with is a cultivated product that’s undergone a lot of human modification.
There are still a lot of different kinds of wild avocados from Central America and South America that still grow and are dispersed just fine in the wild. They’re smaller and have an oily, bitter flesh, but lots of animals and birds like them just fine.
I’d find them all the time when I was working on bear conservation in Ecuador.
So, if the food source can sometimes survive without the animal that ate it, could the reverse ever be true? An animal that survives even though its primary food source goes extinct? I would imagine that would be more difficult --I’m mostly just thinking out loud, so pardon me if the question is just silly.
OK, never mind–I see the article also addresses such animals–it is long. :)
Also topical: their current prevalence in our area, and in eastern North America in general, is a reflection of old farming practices. They were planted as living hedgerows before the advent of barbed wire to keep cattle in the pastures and out of the roads.
Cool. I never saw an osage-orange until I moved to DE, but I do see they are up as far as NY, just less frequent. I assume the climate is too cold after that?
I’ve always thought avocado is the most unappetising of fruits. Now I know why 
On a side note: Who heard of the name Osage-Orange before joining iNat? If yes, what part of the world are you from? I knew Horse Apple and what I thought was Beau d’Arc. Knew it was French. :)
On clay_s’s side note – I’ve heard them called Osage-Orange. Not sure exactly where I picked that up, whether it was a field guide or just when I was down in Texas.
Regarding the idea of Coconuts falling under this category – I think it’s unlikely. We don’t eat Coconut fruits. Rather, we eat the seeds. The fruits are truly fibrous – the Polynesians used the stuff for rope! And there’s no pulp to speak of. They’re apparently dispersed by wind and wave along coastlines, and the fruit serves as flotation and short-term protection against saltwater.
I guess mother nature is the megamegafauna that distributes coconuts then. I like what Wikipedia says about coconut seeds.
Unlike other drupes, the coconut seed is unlikely to be dispersed by being swallowed by fauna, due to its large size. It can, however, float extremely long distances across oceans.
I’m from the western U.S., but first heard this name while living briefly in the southeastern U.S. in the early 1980s, and have seen it in many different floristic references ever since.
Osage-orange is what someone told me it was when I ran across the fruit the first time years back. The folds and creases on the fruit always remind me of a brain.
I have heard the name before. I am from South Africa