Arkansas River Pleistocene Dreamtime
North America Sacred Site of the Epic of Evolution

report by Connie Barlow, March 2009

      The first week of March 2009, my husband (Michael Dowd) and I stayed for four days with a friend who lives right along a high bank of the Arkansas River, about 10 miles west of Tulsa, Oklahoma. For me, this riverine area has become a Sacred Site of the Epic of Evolution because of the juxtaposition of two species of life — one living, and the other extinct.

Upon arrival, I instantly noticed the large pods of Gymnocladus dioca, a "rare but locally abundant" legume species of tree native to North America (with sister species in eastern Asia). Many of the pods had already fallen (left), but some were still hanging on the female trees (below), as the male trees bear only pollen. The extinct species was my discovery in the river sand on day 2 of a fossil bone of a large Pleistocene mammal (below left). That's me stretching my walking stick up to the pods in the photo below right.

   Since 2/3 of all mammal species deer-size or larger went extinct on my home continent 13,000 years ago, there is a good chance that this particular bone is from the "wrist" or "ankle" area of a large extinct herbivore: maybe a North American camel, or maybe even an American mastodon! (Our hosts told us that a mastodon skull was recently found eroding out of the river bank a few hundred yards downstream.)


Gymnocladus dioca (a.k.a, Kentucky Coffee Tree) is now "rare but locally abundant" because it co-evolved with mastodons and with American rhinos (the latter, millions of years before any elephants trooped into North America from Asia). Its large pods, lined with sugary green pulp would have been immensely attractive to big herbiovores in late winter, early spring. (Pods on riverbank tree above.) Indeed, now the pods simply rot on the ground (below right), or if the seeds do work their way into the soil, perhaps carried downstream by a flood, they may never germinate. Why?       An immensely tough seed coat evolved to survive mashing by mastodon teeth and then etching by stomach acids. So now the seed actually requires manual etching by horticulturalists who intentionally plant the seed. You have to carve down hard until the beige underlying flesh becomes visible. After that, water will swell the seed and germination occurs rapidly. How do I know? Because I've tried it, and I wrote a whole book on this topic: The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms.


How do I know that American rhinos (extinct here 5 million years ago) might have helped shaped how the pod and seeds evolved? Because a few years ago I tested the idea on an Indian black rhino in The Wilds of southeastern Ohio. Zoos use this 10,000 acre reserve of reclaimed coal mine for breeding endangered large herbivores. (Below) A curator drove my colleague and me out into rhino pasture, enticed the male rhino to approach my open front window of the truck, and then my colleague (sitting behind me) offered the rhino its first taste of this American species!


After a moment sensing the pod with its nearly prehensile upper lip, the rhino took the pod right from his hand, as I snapped the photos below. Then I did the same, and I had one of the greatest experiences of my life. Tears welled as I fed the rhino all 25 pods I had with me. I told the curator, "For the first time in 5 million years, Kentucky Coffee Tree is reunited with its ancient seed dispersal partner!"


Two VIDEOS Connie posted on YouTube provide the background science:

BELOW LEFT is a fun and fast-paced 5-minute MUSIC VIDEO about anachronistic fruit (and which includes some of the photos you saw here). RIGHT is Connie using a chart and other illustrations to teach the scientific understanding of the Ice Age extinctions of big mammals.




Other observations onsite contributed to the sense of taking a pilgrimage back in time. First, a lot of brown chert (two rows up) is along the river and eroding from the ancient Pleistocene deposited bank. Notice the conchoidal fractures on broken edges, whose sharpness would have given the Indians excellent material for arrow heads. I imagined paleoIndians wintering on this tall, south-facing bank, watching for opportunities to hunt migrating herds of large herbivores — perhaps some attracted by the tasty pods.


Because Kentucky Coffee Tree readily resprouts from its roots when the trunk is damaged or consumed by fire, perhaps the trees I was enjoying in 2009 had been resprouting from their roots for 13,000 or more years — with the original seed haviing been scarred by the teeth of a mastodon and deposited in fertile dung. How wondrous is an awareness of deep time! How much more one's communion with nature when one approaches an area such as this with deep-time eyes!


Along the river, I came upon the corpse of a large possum (above). What chances did this possum have of becoming a fossil? Slim, I guessed, on this eroding, high-banked side of the river. Now, across the river (above right) would be another story. That's the depositional side of the river. The precious little bone I had found on my pilgrimage might have been deposited precisely in that kind of environment. So long as the river cuts down to a lower level after deposition, and before it shifts and begins eroding that side again, the skeleton might eventually become a fossil.


I also came upon the thick scaly skin of large gar that had washed up on shore, remarkably resistant to further decomposition. My hosts told me about another ancient species of fish, a paddlefish (below), that they had come upon one day: hopelessly tangled in debris and dying as the fast-fluctuating river level (a dam is just upstream) had left it stranded out of water. Try as they might, they were unable to save this strange, spectacular fish.

Also during my four days of living alongside the mighty Arkansas River I witnessed vast shifts in temperature and great winds characteristic of interior America in early spring. During the coldest times (into the 20s at night) bird life was especially abundant along the river: pelicans, gulls, geese, ducks, and bald eagles. How did the flock of lovely western bluebirds survive those chilly insectless days? Now, as I pack to leave, the birds have mostly vanished, heading north I presume on a 70-degree F day!

One final image comes to memory that I shall cherish: Dawn on the coldest morning I walked out to the river bank and then heard a slight commotion a hundred feet downstream, on a low branch. There sat two predatory birds, bird-eating birds, the size of a merlin falcon or a Swainson's hawk. They watched the sun-rise together, snug against one another. And I watched silently with them.

EPILOGUE: The following Sunday I presented the guest sermon at the Unitarian Universalist Church of Stillwater, OK. For the "Story for All Ages" that preceded the sermon, I told the story of my spiritual experience with Kentucky Coffee Tree and the ghosts of evolution along the Arkansas River. I gave each of the children a pod to take home with them. After the service, several adults told me excitedly of their own childhood experiences with this fascinating seed pod, and some took home pods to prepare the seeds for planting.


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