Dinosaurs of the Lost Continent

In my last post, I addressed the hypothesis of dinosaur provincialism—that is, isolated communities of giant dinosaurs—on North America during the Late Cretaceous. Specifically, I discussed a recent paper by Vavrek and Larsson (1), who concluded on the basis of a rigorous statistical analysis that Maastrichtian dinosaurs (i.e., those living in the final 6 million years of the Mesozoic immediately prior to the K-T extinction) were not split into isolated provinces, as argued previously, but rather formed a single community. I cautiously agreed with their findings and noted a few caveats. For example, their study was restricted geographically—limited to the four most dinosaur-rich geologic units in the northern part of the Western Interior—leaving plenty of terrain for possible dinosaur provinces elsewhere.

Today I want to focus on another of my caveats: dinosaur provincialism in the preceding Campanian Stage (83.5 – 70.6 million years ago). If your goal is to understand large scale patterns and processes in the Mesozoic world of dinosaurs, the best place and time to look for answers is Campanian-aged rocks from the Western Interior on North America. Period. Nowhere else on Earth do we have continent-scale sampling of fossiliferous formations from the Mesozoic that have been intensively worked for more than a century. Literally dozens of different kinds of dinosaurs, many of them exceptionally preserved, have been recovered from as far north as Alaska and as far south as Mexico. And the great bulk of these occur in a 2 million year window of time, between about 77 and 75 million years ago.

The importance of this particular slice of Mesozoic time and space is heightened by the geographic context of the fossils. The Mesozoic was a hothouse world virtually devoid of polar ice caps. As a result, sea levels tended to be much higher than they are today, often flooding low-lying regions of continents with shallow seas. In North America, the Cretaceous Western Interior Seaway, extended from the Arctic Ocean in the north to the Gulf of Mexico in the south. For almost 30 million years (~95-67 million years ago), this so-called “epeiric” sea subdivided the continent into eastern and western landmasses, known as Appalachia and Laramidia, respectively. We know little of the dinosaurs of Appalachia, but geologic activity in the west has exposed an abundance of Campanian rocks along the eastern margin of the “lost continent” of Laramidia. Key geologic units that have yielded dinosaurs include the Dinosaur Park Formation of Alberta, the Two Medicine and Judith River formations of Montana, the Kaiparowits Formation of Utah, the Kirtland and Fruitland formations of New Mexico, and the Aguja Formation of Texas.

Campanian Laramidia was home to arguably the greatest known fluorescence of dinosaurs, and the emerging diversity patterns are stunning. On the one hand, wherever we look, the same groups of dinosaurs tend to show up. Bird-hipped herbivores include horned dinosaurs (ceratopsids), duck-billed dinosaurs (hadrosaurs), smaller ornithopod dinosaurs (hypsilophodonts), armored ankylosaurs (nodosaurids and ankylosaurids), and dome-headed dinosaurs (pachycephalosaurs). Lizard-hipped theropods are also very diverse, including ostrich-like ornithomimids, beaked oviraptorosaurs, and sickle-clawed dromaeosaurs and troodonts, with giant tyrannosaurs invariably filling the role of top predator. (Although poorly known, a great diversity of smaller-bodied theropods, such as feathered microraptorines and birds were almost certainly present.) On the other hand, the species-level representatives of these groups appear to be limited to small ranges. In particular, as first argued by Dale Russell (2), and later by Thomas Lehman (3), we find different genera and species in the north (Alberta and Montana) than we do in the south (Utah, New Mexico, and Texas). So, for example, Chasmosaurus is a horned dinosaur known only from the north, whereas Pentaceratops is limited to the south. Similarly, some species of Gryposaurus are known only from the north, whereas at least one species is restricted to the south.

Until recently, a relative dearth of identifiable dinosaurs from southern Laramidia made it difficult to test the provincialism hypothesis. This “southern gap” has now been partially remedied by a decade of fieldwork in the Kaiparowits Formation, abundantly exposed in Grand Staircase-Escalante National Monument, southern Utah. Working in close collaboration with the Bureau of Land Management, our interdisciplinary team—based out of the University of Utah, but including researchers from multiple institutions—has unearthed an entirely “new” assemblage of dinosaurs in the Kaiparowits,16 different dinosaur varieties so far, 11 of which can now be identified to the level of species (4). Several of these animals are represented by exceptionally preserved skulls and partial skeletons, often with skin impressions. Some of these species have been named and described, including the oviraptorosaur Hagryphus giganteus (5) and the hadrosaur Gryposaurus monumentensis (6). Other studies are nearing completion or well under way. I am happy to say that the discoveries keep on coming; the most recent field season yielded a plethora of amazing finds from a single quarry. First to be found was a hadrosaur about the size of T.rex; excavation of this specimen, which includes a nearly complete skull, yielded one skull and skeleton of a crocodilian and another of a turtle, as well as an ankylosaur with what appears to be an intact skull, and a possible pterosaur! All this from a single (albeit very large) site.

Remarkably, of the dozens of dinosaur species now identified from the Campanian of Laramidia, none can be confidently placed in both the north and the south—strong support for the notion of dinosaur provincialism. Sullivan and Lucas (7) argued previously that this provincialism is illusory, the result of animals arrayed in time rather than space. But recent advances in both the number and precision of radiometric dates (8) conclusively demonstrate temporal overlap of key formations (e.g., Dinosaur Park and Kaiparowits), as well as species belonging to particular groups (e.g., horned dinosaurs, hadrosaurs, and tyrannosaurs). A recent faunal review and statistical analysis by our working group (9) supports earlier claims from Lehman, showing that the late Campanian provincialism extends well beyond dinosaurs to encompass a variety of vertebrates.

These findings have profound implications for our understanding of dinosaur ecology and evolution. The “island continent” of Laramidia was less than 20% the size of present day North America. Much of this landmass was covered with rising mountain ranges (primarily the Cordilleran Overthrust Belt, but perhaps the Laramide orogeny as well), sandwiching known Laramidian dinosaurs between a restless seaway to east and rising mountains to the west. So it’s remarkable to contemplate the notion of one diverse assemblage of dinosaurs—many with body masses in the rhino-to-elephant range—let alone multiple assemblages of such animals. To add insult to injury, some of these dinosaurs, especially among the hadrosaurs and ceratopsids, appear to have lived in large herds numbering at least in the hundreds of animals. How could so many giants make a living and persist over geologic time spans on such a diminutive landmass. Likely answers involve greater volumes of available plant food (primary productivity) and/or decreased dietary needs relative to modern-day warm-blooded mammals.

Given that most northern and southern dinosaur species within a given group appear closely similar, differing primarily in features associated with reproductive success (horns, frills, crests, etc.), they may well have played similar ecological roles. For example, the long-frilled horned dinosaurs (chasmosaurines) in the north and south, although distinct species, may well have consumed very similar kinds of plants. If so, the ecological niches filled by dinosaurs might have changed very little for millions of years during the Late Cretaceous. Behind this apparent ecological stasis, however, a variety of factors—perhaps including seaway migrations and other environmental changes—appear to have resulted in rapid evolutionary turnover of species (10). Like a long-running Broadway show, the players changed while the same story played out endlessly.

We have only begun to plumb the depths of knowledge relating to Laramidian dinosaurs. And we can count on many surprises to come. I will use this blog as an outlet to update readers on new discoveries as they are announced.

References
1) Vavrek, M. J. and Larsson, H.C. E. 2010. Low beta diversity of Maastrichtian dinosaurs of North America. Proceedings of the National Academy of Sciences,
2) Russell, D. A. 1967. A census of dinosaur specimens collected in western Canada, National Museum of Canada Natural History Papers, 36:1-13.
3) Lehman, T. M. 1997. Late Campanian dinosaur biogeography in the western interior of North America. Dinofest International Symposium Volume, pp. 223-24.
4) Sampson, S. D., Gates, T. A., Roberts, E. M., Getty, M. A., Zanno, L. E., Loewen, M. A., Smith, J. A., Lund, E. K., Sertich, J., and Titus, A. L. in press. Grand Staircase-Escalante National Monument: A new and critical window into the world of dinosaurs. Learning from the Land Symposium Symposium Proceedings.
5) Zanno, L. E. and Sampson, S. D. 2005. A new oviraptorosaur (Theropoda: Maniraptora) from the late Campanian of Utah and the status of the North American Oviraptorosauria. Journal of Vertebrate Paleontology, 25(4): 897-904.
6) Gates, T. A. and Sampson, S. D. 2007. A new species of Gryposaurus (Dinosauria: Hadrosauridae) from the Upper Campanian Kaiparowits Formation of Utah. Zoological Journal of the Linnean Society, 151:351-376.
7) Sullivan, R. M. & Lucas, S. G. 2006. The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America. New Mexico Museum of Natural History Science Bulletin 35, 7-29.
8) Roberts, E.M., Deino, A.D., and Chan, M.A. 2005a. 40Ar/39Ar age of the Kaiparowits Formation, southern Utah, and correlation of coeval strata and faunas along the margin of the Western Interior Basin: Cretaceous Research, 26:307-318.
9) Gates, T.A., Sampson, S.D., Zanno, L.E., Roberts, E.M., Eaton, J.G., Nydam, R.L., Hutchison, J.H., Smith, J.A., Loewen, M.A., and Getty, M.A. in press. Biogeography of terrestrial and freshwater vertebrates from the Late Cretaceous (Campanian) Western Interior of North America: new information from the Kaiparowits Formation, south-central Utah. Palaeogeography, Palaeoclimatology, Palaeoecology.
10) Sampson, S. D. 2009. Dinosaur Odyssey: Fossil Threads in the Web of Life. University of California Press), 332 pp.
(Note: One of the book's chapters is dedicated to the story of Laramidian dinosaurs.)

Images (from top to bottom)
1) Late Cretaceous (Campanian) North America, showing the Cretaceous Western Interior Seaway subdividing North America into Laramidia (western landmass) and Appalachia (eastern landmass). Image credit: Ron Blakey http://jan.ucc.nau.edu/~rcb7/
2) The Kaiparowits Formation, Grand Staircase-Escalante National Monument, southern Utah. Image credit: Rebecca Hunt-Foster.
3) Reconstruction of the oviraptorosaur Hagryphus giganteus. Image credit: Michael Skrepnick.
4) The skull of Gryposaurus monumentensis, a new duck-billed dinosaur from the Kaiparowits Formation.
5) The skull of an unnamed horned dinosaur from the Kaiparowits Formation.

Provincial Dinosaurs

This week, a pair of authors from McGill University, Matthew Vavrek and Hans Larsson, published a paper in the prestigious Proceedings of the National Academy of Sciences in which they argued that dinosaurs living in North America during the last few million years of the Cretaceous Period were not divided up into distinct, geographically separated communities, or “provinces” (1). These authors plumbed a large storehouse of paleo data known as the Paleobiology Database in order to collect information about which kinds of North American dinosaurs lived in different locales during the Maastrichtian stage, spanning almost 6 million years (~71.3 - 65.5 million years ago). Among the varieties examined were Tyrannosaurus and Triceratops, as well as somewhat lesser known forms like the duck-billed Edmontosaurus, the long-necked Alamosaurus, the dome-headed Pachycephalosaurus, and the bony-armored Ankylosaurus. Vavrek and Larsson subjected these data to a rigorous statistical analysis, focusing in particular on the four most fossiliferous geologic units (i.e., those that have yielded more than 100 dinosaur specimens): the Horseshoe Canyon Formation of Alberta; the Hell Creek Formation of Montana and North Dakota; and the Lance Formation of Wyoming. They concluded that the evidence strongly supports the presence of a single dinosaur community inhabiting western North America during the Maastrichtian.

So what’s the big deal? Given that all of the animals noted above qualify as giants, shouldn’t we expect to find one community of dinosaurs living in Western North America during a single chunk of time? Well, yes, that would be the natural assumption, since bigger animals require more space to find sufficient food. The problem is that, beginning almost 50 years ago (2), paleontologists began noting that different varieties of Late Cretaceous dinosaurs tend to show up in the southern and northern parts of the Western Interior. For example, the giant sauropod Alamosaurus is known only from the south (e.g., New Mexico, Utah, Texas), whereas Triceratops tends to occur further north (e.g., Wyoming, Montana, Alberta, North Dakota). Thomas Lehman of Texas Tech University undertook an in depth study of the matter and concluded that dinosaurs were divided into northern and southern “provinces” during the Maastrichtian and (the preceding) Campanian stages of the Late Cretaceous (3,4,5).

Lehman expanded the scope to investigate the spectrum of vertebrate groups (animals with back bones), and found the same pattern; fishes, amphibians, lizards, turtles, crocodiles, and mammals all occurred in both north and south, but distinct representatives of these groups tended to be clumped latitudinally—that is, distinct genera and species were recovered in Alberta and Montana than in New Mexico and Texas. Even pollen fossils seemed to yield a parallel signal. Lacking any evidence of a physical barrier to north-south dispersal, Lehman hypothesized that some sort of climatic gradient must have caused the formation of unique plant communities, which in turn resulted in semi-isolated vertebrate communities.

Vavrek and Larsson’s study seems to fly in the face of any purported dinosaur provincialism. Their argument focuses attention on problems related to sampling and the vagaries of the fossil record. Based on probabilities alone, paleontologists are bound to recover the most common components of a fauna first. Sample sizes—that is, the number of specimens found—need to get relatively big before many of the rarer species are likely to show up. So any perceived differences between geologic formations and geographic regions may be due to biases in sampling rather than actual differences in the community composition. This is exactly what Vavrek and Larsson argue has occurred with our understanding of the Maastrichtian dinosaurs from North America. The paper’s closing statement sums it up: “These results suggest that dinosaurs were not as restricted in their ranges as once thought and that the fauna as a whole was largely homogenous.”

For the most part, I find these conclusions reasonable. Based on the four best-sampled geologic units of Maastrichtian age, I concur that there is no compelling evidence of geographically separated and biologically distinct dinosaur communities. I also applaud the application of rigorous statistical methods to the study of dinosaur paleobiology, something that has occurred all too infrequently in the past (once again, largely due to small samples).

Is that it then? Is the dinosaur provincialism hypothesis dead? By no means.

First off, Vavrek and Larsson focus their study only on dinosaur genera rather than species (for example, Triceratops versus Triceratops horridus). This strategy makes some sense, given that most Maastrichtian dinosaur genera contain only one species, and that many fossil specimens can only be identified to the genus level. Yet it must not be forgotten that genera are human categories with no biologically reality, and what we are really interested in here is communities of species—that is, populations of animals that are reproductively isolated from their near relatives elsewhere. In the much better sampled Campanian stage, several North American dinosaur genera (e.g., Parasaurolophus, Gryposaurus) include distinct, apparently latitudinally separated species. So it’s certainly conceivable that a similar pattern pertained to the Maastrichtian. Indeed some previous authors have raised the possibility of distinct species of Triceratops north and south within the Western Interior.

Second, the restricted quartet of geologic units (three formations in four places) used by Vavrek and Larsson covers a relatively limited latitudinal span, from southern Alberta in the north to Wyoming in the south (on the order of 10 degrees of latitude). So their study leaves wide open the possibility of distinct communities further south in Western Interior (and elsewhere on the continent). The south-only distribution of Alamosaurus is interesting here, perhaps reflecting a semi-isolated, upland, intermountain community (3,6).

Third and most important, a lack of dinosaur provincialism in the North American Maastrichtian does not negate the growing abundance of evidence documenting distinct dinosaur communities during the preceding Campanian Stage (~83.5 - 71.3 million years ago). The Campanian of the Western Interior of North America is much better sampled than the Maastrichtian, with more dinosaur species known from a 2 million year interval (about 76-74 million years ago) than for the entire 6 million years of the Maastrichtian. Moreover, in stark contrast to the Maastrichtian, most of the key fossil-bearing formations of the Campanian are now well dated, with multiple radiometric age estimated (i.e., absolute dates based on the decay of certain unstable radioactive isotopes found in volcanic ash) (7). So we can now begin to state with confidence which Campanian dinosaur species overlapped in time, but not in space.

Research conducted by our working group points to a very different picture for the Campanian than the Maastrichtian. In particular, a decade of work in the Kaiparowits Formation of Grand Staircase-Escalante National Monument (GSENM), southern Utah, has resulted in an entirely “new” dinosaur fauna (8,9), including the duck-billed Gryposaurus monumentensis (10) and the oviraptor theropod Hagryphus giganteus (11). Most of these new animals are still under study, with publications and announcements forthcoming. A comprehensive statistical analysis by Gates et al. (12), partially based on our GSENM results, finds robust support for Lehman’s hypothesis of vertebrate provincialism in the Western Interior during late Campanian. Remarkably, to date not a single dinosaur species can be confidently placed in both the south (e.g., Texas, New Mexico, Utah) and the north (e.g., Montana, Alberta).

Suffice it to say that the hypothesis of Late Cretaceous dinosaur provincialism in North America remains alive and well—and, in the opinion of our working group, robustly supported—at least for the Campanian. In my next post, I’ll address this topic again, describing some of our recent results in GSENM and probing deeper into the notion of provincial dinosaurs. Along the way, I’ll tell the story of a lost continent with grand implications for our understanding of the Mesozoic world of dinosaurs.

Notes and References
1) Vavrek, M. J. and Larsson, H.C. E. 2010. Low beta diversity of Maastrichtian dinosaurs of North America. Proceedings of the National Academy of Sciences, published ahead of print doi:10.1073/pnas.0913645107.
2) Russell, D. A. 1967. A census of dinosaur specimens collected in western Canada, National Museum of Canada Natural History Papers, 36:1-13.
3) Lehman, T. M. 1987. Late Maastrichtian paleoenvironments and dinosaur biogeography in the western interior of North America, Palaeogeography, Palaeoclimatology, Palaeoecology, 60:189-217.
4) Lehman, T. M. 1997. Late Campanian dinosaur biogeography in the western interior of North America. Dinofest International Symposium Volume, pp. 223-24.
5) Lehman, T. M. 2001. Late Cretaceous dinosaur provinciality. In D. H. Tanke and K. Carpenter (Eds.), Mesozoic Vertebrate Life (pp.310-328) Indiana University Press.
6) Sampson, S. D. and Loewen, M. A. 2005. Tyrannosaurus rex from the Upper Cretaceous (Maastrichtian) North Horn Formation of Utah: biogeographic and paleoecologic implications. Journal of Vertebrate Paleontology, 25(2): 469-472.
7) Roberts, E.M., Deino, A.D., and Chan, M.A. 2005a. 40Ar/39Ar age of the Kaiparowits Formation, southern Utah, and correlation of coeval strata and faunas along the margin of the Western Interior Basin: Cretaceous Research, 26:307-318.
8) Sampson, S. D., Gates, T. A., Roberts, E. M., Getty, M. A., Zanno, L. E., Loewen, M. A., Smith, J. A., Lund, E. K., Sertich, J., and Titus, A. L. in press. Grand Staircase-Escalante National Monument: A new and critical window into the world of dinosaurs. Learning from the Land Symposium Symposium Proceedings.
9) Sampson, S. D. and Loewen, M. A. 2010. Unraveling a radiation: a review of the diversity, stratigraphic distribution, biogeography, and evolution of horned dinosaurs. (Ornithischia:Ceratopsidae). Pp. 405-427 in M. J. Ryan, B. J. Chinnery-Allgeier, and D. A. Eberth (eds.), New Perspectives on Horned Dinosaurs. Indiana University Press.
10) Gates, T. A. and Sampson, S. D. 2007. A new species of Gryposaurus (Dinosauria: Hadrosauridae) from the Upper Campanian Kaiparowits Formation of Utah. Zoological Journal of the Linnean Society, 151:351-376.
11) Zanno, L. E. and Sampson, S. D. 2005. A new oviraptorosaur (Theropoda: Maniraptora) from the late Campanian of Utah and the status of the North American Oviraptorosauria. Journal of Vertebrate Paleontology, 25(4): 897-904.
12) Gates, T.A., Sampson, S.D., Zanno, L.E., Roberts, E.M., Eaton, J.G., Nydam, R.L., Hutchison, J.H., Smith, J.A., Loewen, M.A., and Getty, M.A. in press. Biogeography of terrestrial and freshwater vertebrates from the Late Cretaceous (Campanian) Western Interior of North America: new information from the Kaiparowits Formation, south-central Utah. Palaeogeography, Palaeoclimatology, Palaeoecology.

Images
Top: Tyrannosaurus and Triceratops, by Michael Skrepnick
Upper Middle: Corythosaurus, by Michael Skrepnick
Lower Middle: Albertosaurus and Bambiraptor, by Michael Skrepnick
Bottom: Centrosaurus, Origin of a Mass Death Assemblage, by Michael Skrepnick
For more from Michael Skrepnick, go to: http://www.dinosaursinart.com/

The Illusion of Self

We think of ourselves as separate beings isolated from the rest of the world, with our skin forming the barrier between inside and outside. This sense of separateness runs deep within the human psyche, guiding our thinking about such fundamental issues as being, life, and (particularly) death. Among Westerners, the notion of isolation extends outward to embrace humanity and exclude the nonhuman world; in this conception, humans exist outside, usually above, nature. The end result of all this externalization is billions of “skin-encapsulated egos,” each of us consumed by thoughts of furthering our own ends and protecting ourselves from the outside world.

But what if we are not separate at all? What if we are fully immersed into the ebb and flow of everything around us? Would such knowledge change how we think and act? I’m not certain about the answer to the third question, but there’s now little doubt about the first two. Scientific insights over the past several decades mirror much older insights derived from a variety of wisdom traditions. Despite its near ubiquity, we can state with confidence that the notion of a separate self is largely illusory.

The most obvious challenge to the concept of separateness is our need to consume air, water, and food. At what point did your last breathe, sip, or bite cease to be part of the outside world and become you? The truth is that we constantly exchange matter with the outside world, replacing every atom in our bodies every seven years or so. And your metabolism is intimately linked to Earth’s metabolism. Energized by sunlight, life converts inanimate rock into nutrients, which then pass through plants, plant-eaters, and animal-eaters before being decomposed and returned to the inanimate Earth. Humans fit into this amazing planet-scale metabolic system as major consumers of plants and animals. Isolation from any aspect of this metabolic flow translates to death.

If all that isn’t enough to dampen your sense of separateness, how about the fact that the body you identify with consists not of one lifeform but many? Your mouth alone contains more than 700 distinct kinds of bacteria. Carving out a variety of roles over every square millimeter of tongue, teeth, and gums, many of these microbial partners serve as armed guards, improving health by fighting disease-causing bacteria. Others can cause dental cavities if you don’t brush. Your skin and eyelashes are equally loaded with bacteria (no matter how long you shower) and your gut has a bevy of bacterial sidekicks (on the order of another 500 varieties) that are essential to converting food to useable nutrients. Although this still leaves several bacteria-free regions in a healthy body (e.g., brain, spinal cord, blood stream, etc.), current estimates indicate that, of the 10 trillion cells that compose your physical self, 9 out of 10 are not human cells. This means that your body is home to more lifeforms than there are people on Earth, or stars in the Milky Way galaxy.

If your bias is to count genes instead of cells, the truth of the matter becomes even more stark. You house about 30,000 human genes, versus about 100 times as many bacterial genes. In short, depending on how you make the calculation, you are somewhere around 1-10% human, and 90-99% nonhuman (1). A large-scale, five-year research effort called the human microbiome project (HMP) is currently underway (2). Five main body areas are being targeted in the HMP -- skin, mouth, nasal cavity/lungs, vagina, and gut -- but the goal is to indentify and characterize all the microbes inhabiting the human body. If you’re immediately inclined to regard these multifarious bacterial hitchhikers as freeloaders, or even parasites, keep in mind that these trillions of microbes are indispensible to your health, helping to regulate not only your physical well being—digesting food, processing vitamins, keeping out bad bacteria, etc—but perhaps your mental and emotional vigor as well.

And just in case you attempt to cling to some kind of special status for your human cells, it turns out that even they are likely the result of ancient evolutionary mergers with bacteria. Each of your human cells contains a “mitochondrion,” a membrane-enclosed “organelle” that is responsible for generating most of the cell’s energy, as well as such activities as cell signaling, growth, and death. Hundreds of millions of years ago, mitochondria evolved from certain types of bacteria that were engulfed by other bacterial forms. A mutually beneficial relationship developed between the host cells and the newly incorporated bacteria and this successful partnership was passed on to all animal cells, including our own. A similar merger occurred in the evolution of another cell structure called chloroplasts, which are big players in plants and other photosynthesizing lifeforms.

So, if you continually exchange matter with the outside world, if your body is completely renewed every few years, if you are walking colony of trillions of lifeforms, and if your human cells still incorporate bacterial ancestry, exactly what is this self that you view as separate? You are not an isolated being. You’re an ecosystem, a complex, self-regenerating amalgam of lifeforms that interact communally to form a larger whole. Metaphorically, to think of your body as a machine, as current bias would hold, is inaccurate at best and destructive at worst. You’re far more akin to a whirlpool, a brief, ever-shifting concentration of energy in a vast river that’s been flowing for billions of years.

We’ve only begun to fathom the implications of this profound notion, but it’s one that deserves to be disseminated and discussed widely. I think that the dissolution of our separate selves can help us see the world in new, more accurate, and even sustainable ways. What do you think?

Notes and References
1) A quick search will reveal many sources online that cite similar numbers, but I recommend a wonderful TED talk on bacteria by Princeton University microbiologist Bonnie Bassler: http://www.ted.com/talks/lang/eng/bonnie_bassler_on_how_bacteria_communicate.html

2) http://en.wikipedia.org/wiki/Human_microbiome_project

3) This is called endosymbiosis theory. For more information, check out: http://en.wikipedia.org/wiki/Mitochondrion

All images courtesy of the public commons website Wikimedia.