Book Review: Ghosts of Evolution by Connie Barlow–More Adventures in Co-Evolution

By:  Priscilla Hayes

In December, I had knee replacement surgery.  Since I am a school garden educator, I timed it with the “off-garden” season.  The recuperation involves lying with my leg elevated, heating and icing my knee, so I am catching up on my reading.  I’ve chosen a book called The Ghosts of Evolution, by science writer Connie Barlow, for my first book review.  I learned about the book from my Aunt Dency, who is a member of the Webster Groves Nature Study Society’s book club (  The society was founded in 1920 with the intent of helping its members to better experience nature.

The “ghosts of evolution” that the title refers to are “evolutionary anachronisms.”  This term is mostly used to describe plants which “designed” their seeds over millennia of evolution to be dispersed by a specific animal or type of animals through co-evolution.  Some plants have encased their seeds in fruit, and used that fruit to attract “seed dispersers.”  Some plants encase the seeds in burs, which attach to some passing creature, and fall off in a new location.  Evolutionary anachronisms are plants whose seed dispersers, or at least the primary ones, have disappeared from the face of the earth.  Now the plant may be in danger of dying out, since it cannot get its seeds moved, and they may just pile up under the few remaining trees or plants.

A modern, not-anachronistic example of co-evolved seed dispersal would be the relationship between acorns and squirrels.  Over the course of evolution, the oak tree evolved a fruit—the acorn—that was attractive to squirrels.  Each squirrel would stash a number of acorns in various locations by burying them, and most, not right under the original tree.  Since the squirrel would normally not go back for all the stashed acorns, voila!  Some acorns are planted in new locations to hatch out new little tree seedlings.

So, oak trees are in no danger of going extinct, since there are plenty of squirrels in the world (more on that in a future post).  Picture instead, an ancient forest, an avocado tree and ancient gomphotheres.  No, I could not visualize gomphotheres either, but this link will help you get a better idea (!  Suffice it to say, each is large enough to take an entire avocado into his/her mouth, sort of gum the fruit, eventually digest it (presumably with the skin) and poop out the pit.  As Barlow says: “A parent [avocado] tree could wish for no more desirable fate for its offspring than to have its seeds plopped into the world within steaming heaps of dung.”

Why do I say “gum” the avocado?  Why doesn’t our lovely gomphothere also chew up the nice big pit (which the avocado tree has thoughtfully packed with a year’s worth of nourishment for the little embryo hiding inside)?  Why, because that brilliant avocado tree, through eons of evolution, has packed the pit’s food layer with enough bad-tasting toxins to make the first time the gomphothere bites into the pit its last time.  The toxins aren’t going to kill the creature, but he/she will surely spit out the nasty seed, and recall not to do that again.

Doesn’t this all sound just like those howler monkeys that ate fruit whole and pooped out the seeds, along with lovely poop for dung beetles to work with?  But, tell me, when was the last time you saw a gomphothere—or even the first time?  This is because they have disappeared and have not been replaced in wild avocado forests with any other animals capable of eating the fruits whole and dispersing the seeds in those piles of poop.  There are mostly only us humans, and we have adopted only one or two kinds of avocados to grow.  Unlike our friends the gomphotheres, we remove the seeds and skins before we eat the fruits.  I know they plant seeds at my schoolroom, but those seeds don’t make it back to the forest.  And because we are fixated on only a couple varieties, other varieties of avocado tree are in trouble.  Fruit drops to the ground and either rots or gets ransacked by critters that aren’t good at moving the seeds—animals that eat the pulpy fruit part, and leave the seed, where it may start growing right in the shade of its parent.

The original pairing of avocado and gomphothere was worked out through co-evolution over time, so why can’t the avocado either re-evolve to match a new seed disperser, or get on with it, and just die out?  Turns out that plants, especially perennial plants like the avocado tree, take way longer to evolve than animals.  Animals, on the other hand, may evolve their way out of existence before that tree has a chance to figure out they are gone.  Avocados may be evolving, but that process may be too slow to save most of them.

But, here’s the kicker.  Early humans may be the ones responsible for the disappearance of the gomphotheres, and of other avocado seed dispersers.  And, we are surely the ones driving any number of other creature extinctions since:  what Barlow quotes scientist Paul Martin as calling “much more familiar extinctions of historic time, the dodo of Mauritius, the solitaire of Labrador duck, Carolina parakeet, and Tasmanian wolf, to begin a litany of the names from the Doomsday Book.”  As Barlow’s book warns, we are on the verge of a cascade of extinctions, with each creature or plant we extinguish impacting any co-evolved species, and cascading down.

The book ends with a possible “outrageous proposal:” bring ‘em back!  Bring back the ancient creatures, or their nearest surviving analogs, to the forests that depend on them for seed dispersal.  Or, bring back the plant based habitats that will encourage some of our endangered species to prosper.  Bring them back, both for them, and for us.


A Dung Beetle Obsession

Penny Jones With a Dung Beetle From Her Collection
Penny Jones With a Dung Beetle From Her Collection

By:  Priscilla Hayes

My friend, Penny Jones, has long been a dung beetle fanatic, so much so, that her husband presented her with a mounted dung beetle in a frame.  She even has her own pair of dung earrings!  As a recycling professional, she particularly appreciates that dung beetles are the ultimate recyclers, fashioning dung—not even a waste they are responsible for producing—into balls bigger than they are, and then rolling the balls off for their own use.  In contrast, we humans are notoriously poor at recycling our own waste, let alone that of some other organism or planetary force.  It is clear we could take a lesson from these creatures.

Unlike Penny, I still had a rather rudimentary knowledge of dung beetle activities, when I got a seminar announcement via email, as I sat at my desk at Rutgers University.  I invited Penny down to the dung beetle seminar, which was to be given by a National Geographic researcher, Dr. Kevina Vulinec.  Once Penny had indicated she and her husband would attend, I realized I would, of course, need to join her.

Dr. Vulinec had been studying the interactions of monkeys, dung beetles and trees in various rain forests across the world, to see if there was proof of co-evolution.  I know she described observations of various kinds of monkeys in various different rain settings, but the ones that took my fancy were the howler monkeys.

Howler monkeys are apparently more social than some other monkeys, and more prone to group activities.  These monkeys get up in the morning, and gather on a branch to eat fruit—whole, with the seeds inside—and then have a “group poop.”  The poop, naturally enough, falls down from the tree into a pile on the ground below, where dung beetles form balls of poop, then roll them away to bury and inject eggs into.  By doing so, each beetle assures its hatchlings a ready supply of food, before they must venture out to find their own food (poop) and risk being eaten.

But, remember that the howler monkeys ate the fruit whole!  So, when the dung beetles roll away with poop, they also carry the tree’s embryos, its seeds.  The tree gets its seeds planted in a location where the offspring won’t directly compete with the parent tree, and the baby trees, as with the baby beetles, have a ready supply of food for their initial development.

Here I must confess that, although I don’t have dung earrings like Penny’s, the seminar started my own love affair with dung beetles.  For a while I collected stories:  someone had brought a dung beetle home from Florida, and fed it baby poop (it didn’t last too long).  Our department chair had observed the extreme level of care—complete with forced detours—taken in Africa to make sure that trucks didn’t drive over the beetles that are so essential to cleaning up cow manure there.  My student interns collected dung beetle photos and humor for me.  Perhaps the most fun fact I learned was from one of my favorite books, Dirt, the Ecstatic Skin of the Earth by William Bryant Logan, which has an entire chapter on dung beetles.  There I learned that dung beetles actually fly up to the branches where the monkeys are busily eating fruit, and hang out waiting to attach to a piece of dung as it leaves a monkey’s butt and begins to descend to the forest floor.  Dung is in too hot demand there to take chances that it won’t be scooped up by some other beetle or other organism from the ground.  So, the beetles actually takes their lives in their own wings (since there is not only a hot demand for the poop, but for the beetles, which many animals find to be a tasty treat) to gather poop on the fly.

Dung beetles have become a go to lesson for many presentations I do, since they so clearly typify symbiosis, benefitting all the organisms along the chain.  They present such a clear challenge and inspiration for us humans to make sure that we at least cycle the natural resources that are the stuff of our everyday life.

Love Those Lichens

By:  Priscilla Hayes

A lichen I photographed during my program at Eagle Hill Institute
A lichen I photographed during my program at Eagle Hill Institute

I have loved lichens for as long as I can remember. I have always found the large and colorful rosette shapes they form on rocks beautiful. Thirty or so years ago, I wowed a group of teachers while taking a Project Learning Tree training course. For my introductory science question, I asked them to identify the entity composed of a symbiotic relationship between a fungus and an alga.

So, when I started designing an after school schoolyard habitat series for young students, I naturally included a session on lichens. Along with the bird books which were meant to make me an expert for the birding session, I bought two normal size lichen books (this is meant to distinguish the books from Lichens of North America, a massive volume, which I finally bought this month).

I realized almost immediately that I wouldn’t be able to be enough of an expert on birds to do any kind of session, partly because birds move. You might not find any at all! What you do find may be moving too fast to see with binoculars, let alone to see long enough to identify with beginning birding skills. It’s better not to be embarrassed in front of my little third and fourth grade students!

So I concentrated on creating a lesson about lichens. Lichens don’t move, and I could theoretically scout my lichen hunting sites out in advance, make identifications, and be prepared to wow my students into loving them as I did.

Of course it didn’t happen that way (there’s a Steve Forbert song, “It Isn’t Gonna Be That Way” playing in my head as I recount this)! I never found the time to do the advance scouting. I made sure I knew a place that had lichens, but I didn’t do any ID. Of course, I needn’t have worried. Not only was I miles beyond my third and fourth graders, so they didn’t notice any lack of expertise, but really, what they wanted to do was make little movies in the garden with the iPads again. And not even movies about habitat or plants, but featuring little stuffed animals! It was an after school program after all.

This teaching experience had taught me that my lichen ID skills were rudimentary, so for my next student lesson, I persuaded a local lichen expert to come out to one of the schools that I work with to do a lichen walk in our “community forest.” He even brought a microscope, and gave each student a look at several different lichens.

It was on his recommendation that I headed off to Maine for a week in June, to an intensive course on lichens at the Eagle Hill Institute (link and a description, below). It was on the first day, I finally had to face the supremely underestimated profundity of my ignorance.

I didn’t even have a clue about good naturalist hand lenses, and had to go to the office to buy one immediately (they didn’t have the lighted ones the instructors recommended). I had not used a microscope myself since 9th grade biology, and had never dreamed how much skill that required. Out in the field, I collected lichen specimens in small brown bags as feverishly as any of my colleagues (none of whom were the rank beginner I proved to be), but my notations on each bag were sketchy, since I figured I would do identifications back in the lab. After the first night, when I found I couldn’t understand the difference between isidia and soredia and other lichen structures, or apply the dichotomous key well enough to identify my specimens from scratch, I made sure to carefully write down whatever name the instructors said in the field as we were collecting. That made it somewhat easier to make correct identifications back in the lab and let me play around with looking for whatever structures the book said that kind of lichen was supposed to have.

This experience not only challenged me to sharpen my lichen identifying skills, but also left me with another positive end result. My preconceived notions about symbiosis were upended, leaving me with a whole new understanding of and appreciation for what I thought I already knew. I’ll explain more in a future post!

Eagle Hill Institute, in Steuben, Maine, offers weeklong and shorter courses/seminars on lichens, birds, bryophytes, and a host of other nature topics. See My week was intense but thoroughly enjoyable, the food is great and the accommodations are rustic but fine. During my lichen week, there was also a group of people studying bryophytes, including a 12 or 13 year old prodigy who had already been volunteering at a natural history museum in Chicago. He was always the first one to head back to the lab for specimen identification after dinner.

Human Symbiosis: Positive or Negative?

By:  Priscilla Hayes

I have been teaching symbiosis for a number of years. In presentations to recycling professionals, sustainability experts and others, I described the recycling behavior of the dung beetle in moving dung into holes in the ground, where it served as food for both dung beetle babies and the seeds that had been pooped out by whichever animal the dung was from. My next slides were of our own waste—from home or business to garbage truck to landfill was no way to practice the symbiosis of the dung beetle. Recycling, which took bottles, cans, paper and cardboard to a MRF where they were baled and sent in huge cubes to places like China to be made into new products seemed a better approximation. If you ever get a chance to visit a MRF, put on your hardhat and go—it is like a giant game of chutes and ladders.

But it was in an intensive lichen course in Summer 2014 that I discovered that we humans were actually in a symbiotic relationship with the earth, despite what seem our best efforts to totally separate ourselves from it and all of its organisms.  We pride ourselves on being the smartest and most innovative organisms on the planet, and increasingly seem to feel that things like food, come from the equivalent of a replicator, as on the Starship Enterprise, and waste simply disappears.

No, actually we are in symbiosis with the earth. But it is not the mutualistic symbiosis of the dung beetle, where every organism in the chain, including a host of soil organisms, derive a benefit from what the dung beetle does. Instead, our symbiosis is of one of the other two basic varieties, parasitism, where one organism benefits and the other is harmed.

I think our symbiosis is most akin to that of the tick. The tick settles onto a living host, begins to suck blood into its body, and as it disengages, injects or regurgitates disease organisms into the host. The host gets sick, the tick goes off to reproduce.  This blog is meant to help me and all of us achieve a more positive symbiosis with the Earth and each other.