The titular ghosts here are the long extinct mega-fauna species that once roamed the continents for millions of years shaping the plant species in question here and, in their interactions, shaped the landscapes themselves. Now absent their animal partners, these plants still retain the characteristic structures that evolved in their long dance together, the genetic inertia contained within their DNA. These plants remain today as anachronisms, seemingly misplaced curiosities with no existing, obvious, reason for ever being, mysteries of form and function, that only begin to make sense when we look far enough back.
I only recently came across this book while doing research into my continuing interest and focus on what exactly is ‘life’ and what is it that distinguishes living organisms from other matter. This book is a little outside of this topic, but not by much. Barlow here is concerned with the process of natural selection and how species have come to acquire and retain their physical and functional characteristics, how they’ve retained them long after the shaping forces have disappeared. While there is a somewhat random element in the process of evolution, organic forms follow patterns and particular patterns are ‘selected’ over time through the ‘working’ of shaping forces. Forms are supported or not, Once acquired they remain disappearing with a particular species when it is no longer supported enough and goes extinct. This ‘opens’ a niche for possible other species to fill. Each species is time limited. Each is a process or event that continues so long as it is adequately supported. It in turn fills roles in the lives of other organisms, other species. Natural selection is not some process relegated to the past, but an active, ongoing, one, though we tend to fail to see it around us. We have a tendency to expand the ‘now’ and attribute to it a precedence and persistence that it doesn’t have and so we also fail to see our own role in the continuing ‘work’ of evolution. We all know something of the concept of the ‘survival of the fittest’, a process that suggests that today’s species are the ‘best’ fit given the conditions in the world today. Barlow, and the scientists who support this idea, argue instead that today’s species are the best fit for the past as a result of thousands, even millions of years of evolution. Today is just a moment in time. Our imagining of it as something broader and more stable is a problem.
Ecologists study those relationships between species, the biotic players, as well as the abiotic, the non-living factors, at play in an organism’s survival, its success. Evolutionary biologists study the long line of change in the evolution of an organism, from what it was before to what it is today. Geneticist attempt to link these in their study of an organism’s chromosomes and genes, the extremely complex molecules which ‘encode’ the thousands of proteins that comprise a species and an individual as well as catalyze the complex chemical reactions essential to its life. Chromosomes are ‘impossibly’ stable passing these ‘codes’ from one generation to the next as they slowly evolve, over millions, and in some cases 2 or more billion years, with a fidelity that we could never produce in a laboratory. This stability is behind the topic of this book, namely relict or anachronistic forms which seem strangely out of step in today’s world.
Barlow performs a thorough examination of the phenomenon of biological anachronisms, primarily, through a plant’s fruit, which seem over ‘engineered’ given todays available ‘dispersers’. Fruit serve to both protect a plant’s seeds from predation and rot, which result in damage to a seed which can cause it to fail to germinate, while also serving as an attractant to appropriate consumers, who by ingesting it increase the chances that it will successfully germinate and be spread to appropriate sites away from the mother plant where it will have a better chance to survive and mature. The ‘pulp’ of the fruits themselves provide nutrition and fiber to its consumer, which is in these cases, not digestible by many modern day potential dispersers. Alternatively the pulp of some of these fruits, or the seeds themselves, contain toxins that have come to prohibit their consumption. In addition to seed dispersers, Barlow looks at seed ‘predators’ like many rodents who may strip away the pulp to chew up and consume the seed, thus destroying its capacity to germinate. There are also ‘pulp thieves’ that leave the seeds unconsumed, so unscarified and not subjected to the acids and microorganisms of a true disperser’s gut, leaving them unprepared for germination; and then the seed hoarders which cache large amounts of seeds for later consumption…though are sometimes left to germinate or rot.
Opponents of this idea often accuse supporters of concocting a theory that is untestable, the needed species gone forever. They also accuse them of ‘over reach’ including far too many plants up in to this group of anachronistic plants. In response the idea has been clarified and proponents now argue that anachronistic plants exist on a scale from those that are so to an extreme, their extinct primary dispersers having been their only effective option, all of the way down to those which may be moderately or minimally anachronistic, dispersal ‘duties’ filled in by other animal species. The extinction or local extirpation of a disperser species shape the resultant plant community and landscape in new, probably reduced patterns.
Paul Martin and Dan Jantzen, who first put this idea formally to paper, were drawn initially to this by the ‘riddle of the rotting fruit’, the entire season’s fruit production lying untouched on the ground beneath mother trees which Jantzen first came to recognize over his years of study in Costa Rica. The idea has since been ‘picked up’ by others and expanded to plants and regions around the world. Supporters argue that anachronistic fruits were once consumed by now long extinct species, dispersers, which aided the plant’s survival. Specifically, or primarily, the supporters of this theory argue that the Megafauna, those animals over 100lbs which once roamed around much of North and South America, the Caribbean, Europe and Australia, died out roughly between 3-18,000 years ago, some much earlier. 3/4 of North Americas mammalian megafauna were lost over this period. The continents of Africa and Asia still retain many of the species of their megafauna, though in much reduced numbers, and thus provide examples of what might have been in North America and those other places which have lost theirs. With many of these headed toward extinction scientists expect that those plant species that share some or total dependence upon them for dispersal, will begin to decrease as well while the physical form of many trees and a species density will change as well. These have been primary actors in these landscapes for several millions of years.
Some scientists have focused on the loss of pollinating species in the decline of various plants species, especially those not served by generalists like the European Honeybee, but the dispersers, at the other end of a seed’s story, are also essential. Since then, it has been found that the survival of a plant species’ can be dependent on these dispersers, their ranges are shrunken drastically, often limited to scattered sites on floodplains where water can float seed away, when these decline or go extinct. In the case of extinction, these plants must then depend upon secondary dispersers, if any, and whatever other survival strategies they may have. Those anachronistic species that remain relatively common have such strategies that have enabled them to survive, such as being very long lived, producing seeds apomictically, without pollination, which aids a plant when they become widely separated and others that are more suckering, ‘extending’ their lives through clones hundreds if not thousands of years.
Barlow looks specifically into the Honey Locusts, Kentucky Coffee Tree, Osage Orange, Persimmon, Pawpaw, Avocado, the Desert Gourd and Gingko in some depth, focusing on those native primarily to temperate, North America, giving more cursory looks to fruits like Papaya, Mango and other tropical fruits of which there are far more than are found in North America. Anachronistic plants tend to be over engineered given today’s dispersers, having fruits and/or seeds being too large to swallow whole, containing toxins that available dispersers cannot detoxify, have a taste that is repellant or skin or husk that potential dispersers cannot get through or spiny armament which ward them off. Many candidates cannot digest the often fibrous, though often sweet pulp. Others while eating the pulp grind and damage the seeds before they swallow and later expel them destroying their chances for successful germination.
North and South America had its own species of mammalian megafauna including species of horse, Mastadon and Wooly Mammoth as well as other elephant and rhino relatives, bovids, Camels, Giant Tapirs and Ground Sloths which died out over the last 13,000+ years, some as recent as 3,000 years ago. Other places like Australia lost its giant Kangaroos and Wombats while New Zealand lost its several giant Moa birds, it had no giant mammals, far more recently. Yet these plant species persist with their anachronistic traits, but in very differently composed communities. In some cases researchers have found that non-native, present day, species such as horses and cows, due to their guts, teeth or even the size of their ‘gape’, their throats, can consume the fruit and ‘ready’ the seed for germination aiding in the spread and survival of these relict, anachronistic, plants. In these cases these plants have ‘expanded’ their ranges beyond their recent more isolated and limited populations on flood plains. In other cases it is us, through our practice of horticulture and agriculture, selectively planting these away from their mothers and their shrunken ranges, responsible for their return to vacated regions and in so doing may be saving them. These anachronisms, having ‘returned’ to previously occupied regions, may not then in a ‘longer’ historical sense, be out of place, but simply repatriated. Without their original megafaunal species, their continuation in their expanded range will be dependent on other dispersers…like us.
In one notable chapter Barlow looks into the architecture and armaments brandished by many plants, that served in their defense long ago in vanished mega-herbivores. This group of mega-fauna members browsed and grazed, not always there for the fruit. She begins with a focus on the SW desert region of the US and Mexico looking into plants like Mesquite, Opuntia and Devil’s Claw, plants which Martin ascribes some degree of anachronism to. These were well ‘armed’ plants capable of fending off many of today’s modern and reduced browsers, their fruits going unconsumed. In other cases, like the Devil’s Claw, North America’s largest burr, the dry fruits cling weakly, if at all, to animals as they move through and so are not moved far away from the ‘mother’. Here she spends more time discussing the practice of such land owners as the National Park Service with active programs to control/eradicate ‘non-native’ browsers, animals which Martins, Jantzen and others are coming to believe may fill part of the role of extinct megafauna and thus be important in maintaining a healthy landscape. On the other hand are the ranchers who would prefer pristine grasslands, absent the Opuntia and woody, well armed legumes, which are now often dominating them. Both sides fail to see the effects of their decisions and have unrealistic expectations given the species and forces at play across the landscapes. When asked whether one range or another was over grazed by cattle, Martin has responded, ‘It’s under browsed’, meaning that while the cattle were consuming the soft, more desirable, undergrowth, the woody plants were being left uncontrolled and were then crowding out the remaining grasses and forbes, ‘robbing’ them of the available water, sun and nutrients. Healthy landscapes require both to keep them in dynamic balance. She and others speculate about the possibility of introducing Asian Camels to our arid West to provide the needed browsing pressure to stop our loss of grasslands, even suggesting that camel could become a beef substitute that would require far less water while they ate back the spreading Cacti, shrubs and mesquite. It is becoming ever more obvious that by favoring one over the other, or eliminating both, that the plant communities are left in a dysfunctional relationship with one another, the dominant one threatening to push a landscape into an unmanageable and undesirable extreme.
In this same chapter she covers such adaptations as spines, thorns and prickles which have proven more than adequate to fend off today’s reduced population of grazers, browsers and frugivores, but were much less of a deterrent to those now lost. Ample evidence is suggested by surviving cousins in Africa and Asia. Such armament on these plants often is abandoned by plants above the reach of even these now long non-existent herbivores, an unnecessary investment. She also covers the isolated case of New Zealand with its high proportion of divaricating plants, those growing in a zig-zag pattern which often doubles back into itself with relatively sparse, small, evergreen leaves…at least until the grow beyond the reach of the several species of giant Moa which the Polynesians hunted into extinction some 600 years or so ago. This particular strategy is thought to have resulted from the large, hard beaked birds, who would have been much less effected by thorns and such which would ward off the hungry and soft muzzled mammals. There much ‘food’ for thought here.
For me as a horticulturist I found her treatment of the teeth, guts and digestive systems of the various herbivores, graziers, browsers, frugivores and carnivores interesting without overwhelming me with too much detail. Understanding the whys of particular animal groups needs and tendencies concerning their food choices was helpful, giving me just enough detail to open my eyes to things I hadn’t had cause to consider, but are essential to ‘solving’ this particular evolutionary puzzle.
Barlow is not a ‘scientist’ though she is clearly invested in this subject. Her examination of Martin and Jantzen’s theory is thorough, interviewing scientists who support this idea as well as those who caution others acceptance of it. She reviews the literature, goes out into the ‘field’, whether that be the Parks and streets of NYC, the deserts of New Mexico and the SW or the woodlands of the Mid-West and Florida, visiting specialists at New York’s Natural History Museum, even doing simple ‘studies’ of her own, tasting fruit, examining ‘scat’ for seed after feeding subjects fruit and testing its viability all to ground her own experience from which she writes. This book expanded my understanding of ‘natural selection’, brought it ‘forward’ from something relegated to the past into present day. Ongoing….In my mind natural selection was more ‘active’ on animal species than on the more passive plants. The story of anachronistic plants, and the animals they evolved with, particular the loss of nearly all of our earlier species of non-ruminant mega-fauna, places an emphasis on the biotic community as a whole, the interdependence and necessity of plant and animal communities upon which the other’s survival depends, its future shaped…and emphasizes our own role in the loss and survival of both. As active agents in the living world, we play an important role, whether we take it on or not.
This book helps ‘explain’, “Where did that come from?” when we consider some of the botanical ‘solutions’ that surround us today, seemingly disconnected inventions of the plant world. There is value here for those working, or interested, in conservation ecology as well as those interested in ‘novel’ landscapes, those trying to build into our modern, drastically disrupted landscapes, the kind of dynamic stability that characterize those that evolved naturally, but today have such altered conditions that they are in decline. There is much of interest here to the seed propagator and anyone simply interested in the plants growing around us. This is for those who embrace our role as responsible actors and stewards of this ‘new’ and much changed world…a call for new thinking and a request to challenge long held ideas. There are many books out there with the potential to teach us about the countless relationships between all living things and the landscapes they evolved with. We are at a tipping point.
Many argue we have already passed it and change is already on its way, accelerating beyond our capacity to rein it in. But that is a loser’s argument, there is much that can and must be done. Within the world of western jurisprudence it is often stated to offenders that ignorance of the law is no excuse, no defense. Consequences, will inevitably follow the determination of guilt and complicity. In the case of life, the ‘laws’ of nature are not abstractions of our own making, they are woven into the very fabric of being and like a defiant act against the limits of gravity, we will fall. In this case, the fate of the guilty and innocent are inexorably bound together, so it behooves us all to educate ourselves so that we might act ‘rightly’, to correct our individual and societal ‘wrongs’. There are no accommodations that will be made to those who insist that there was nothing they could do, that the needed changes were beyond them.
One thing that life, evolution and nature demonstrates most emphatically, is that none of us matter, ultimately, as individuals. Life itself, as a process, is what matters…its continuation. Each individual exists for a mere moment in time. At birth, we are a set of limited potentialities, ‘best’ attempts at advancing the whole, that will ultimately fail, in the never ending process of life’s unfolding, laying the way for the next generation, the next attempt. Anyone generation, in a very real sense, is set and limited at birth and must give way to the next. We are in a very real sense, not living ‘things’, but events, dynamic expressions, reformulations, of what came before, which play out over time in an inclusive process, continuously ‘recycling’ itself, each moment ‘informed’ by those that preceded it. While “I” am “me” and therefore possess inherent value, “I” am also so much more than that limited to the boundary of my own skin. No species, no generation, no individual, can ever be said to be the ultimate expression of life…unless, perhaps it is the last….. We could not be more wrong when in our lives we choose to focus entirely upon ourselves and the limited world around us we choose to acknowledge. What does it matter how much wealth we accumulate, power we wield or ‘monuments’ we erect to ourselves, if by doing so we decrease the richness and diversity of life in the world from which we and all things of value spring? In a living process that goes on for literally billions of years, how little does my comfort and ego matter in this brief moment? We all serve a greater purpose beyond our own immediate desires. We are all intricately enmeshed in the unfolding of life all around us. Inseparable. None of us stand alone or even ever could. To deny this essential aspect of our lives is to doom ourselves and all around us.
Books such as this teach us to again look at the world with a sense of wonder and encourage us to assign to it the limitless value inherent to it when we rediscover our sense of awe at its miraculousness, beauty and relatedness. It is evident in Barlow’s writing that she sees this, as do ecological researchers like Jantzen and Martin. This wonder and awe undergirds the study of the biological sciences. Those who choose such work for their careers have not done so simply as a means to make a living. Each of them has discovered in the living world something of value that drives them. Ultimately their most significant accomplishment will be found in their ability to awaken the same in the rest of us, those of us more caught up today in the economic ‘game’ of survival, a game largely divorced from the world and values inherent in nature. When the rest of us begin to recognize those values we can move passed the abstractions of the economy, of marketers, branders and manufacturers, of politicians intent on gaining or retaining power. What the world most needs right now is for us to rediscover this for ourselves and to recognize that the so called ‘invisible hand’ of commerce seeks only the value that can be converted into ready profit. Business it is often argued, bears no responsibility to the health of the whole, that such protections undermine the efficiencies of the economy. That the ‘best’ decisions will be made collectively as we as individuals pursue our own individual well being….The community, the future, will be assured, they argue, by the essentially selfish choices of the individual. There is little discussion of the ‘quality’ of the discussion, of the information available to consumers, which ‘inform’ their decisions. All is left to the ‘invisible hand’ while promoters and sellers pour countless dollars into the media to increase the sales of their product or service. Consumers, individuals, are left on their own, with this ‘information’, to decide whether it is in fact in their, or their community’s, best interest to so choose. Government, free-marketers claim, should have no role to play in this process. Such an economy recognizes only that individual needs can and will be met by consuming more and more at the expense to an environment with limited resources and capacities. But such an economy does not recognize the requirements of the wider environment or its capacity to maintain its own healthy functioning. Free-marketers fail, by doing this, to recognize that the ongoing health or vitality of the economy, its capacity to provide for the society’s needs that we purportedly require, itself requires a healthy environment, that a world of compromised and collapsing biotic communities and cycles, cannot long support such a society and its economy. Our economy is after all a human abstraction, an invention, and in order to continue, it too must recognize the reality and value of the landscape and living world in which it exists. Human ideas and understanding have had to change through history to meet the requirements of both people and the surrounding environment. The failure to do so historically has lead to the collapse of civilizations and empires. Blind insistence on an idea that stands in opposition to life and its supportive forces, cannot be sustained. Life and health are not an endlessly extractable resource. Life cannot simply be an opportunity to profit. When we fail to recognize our responsibility to the health of the whole, when our leaders and our economy seek only to minimize costs in the pursuit of ever greater profits, if everything is treated as if it can be reduced to a dollar cost, we should expect the decline in the quality of life to continue slipping and the ‘carrying’ capacity of the world to continue diminishing. When we recognize the complex relationships and feedback loops inherent in any living system, we can begin to understand what we are risking. This is not some abstract topic suitable only for academic discussion, it is one essential to the survival of all of us. When we are asked what is of value to us, we must be able to think beyond our own current financial wellbeing. As long as our own valuing of life is out of line with the ‘reality’ of nature, we put ourselves and much of the living world around us, at risk. As the Earth’s systems begin to falter, our financial security will as well, because it is not the vitality of this particular economy upon which everything else depends, it is those direct relationships between the untold species of the world itself. Economy and ecology must be consistent and supportive of one another…it is not today.