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The story of life

Posted on: Tuesday, 19 August 2003, 06:00 CDT

INTRODUCTION

Who are we? And where did we come from?

All kinds of theories were offered up in the early days of science, but the story of life really began to unfold in 1859 when Charles Darwin put forth his theory of evolution in the book On the Origin of Species (by Means of Natural Selection). Simply put, the theory states that all organisms on Earth descended from a single, common ancestor. The "book that shook the world" sold out on the day it was published and served to lay the foundation of modern biology. Now, some 144 years later, Darwin's theory of evolution has endured as the most powerful and elegant ever promulgated in the field, and the essence of his hypothesis remains the heart and soul of the story of life.

Our knowledge of how evolution works, however, has come a long way since the British naturalist hypothesized the pattern of common descent. The clues are everywhere . . . buried in rocks and beneath the soil . . . in our DNA and the DNA of other living things on Earth . . . even in molecules in space. Through the years, thousands of researchers from numerous fields have devoted their careers to uncovering the clues and expanding our knowledge of evolutionary mechanisms. In the process, they have augmented and revised evolution dynamics, and sometimes rewritten entire chapters in this life saga.

On October 7 and 8, 2003, a stellar group of those researchers - Nobel laureate and cell biology pioneer Christian de Duve, paleontologists Niles Eldredge and Philip Currie, paleoanthropologist Timothy White, biologists Peter and Rosemary Grant, and molecular biologist Scan Carroll - will gather for Nobel Conference(R) XXXIX at Gustavus Adolphus College in Saint Peter, Minnesota, to discuss the latest findings and theories enhancing the various chapters of "The Story of Life," from the origin of life in the universe to how our vast knowledge of evolutionary theory may influence the course of humanity in the future. Evolutionary theologian John Haught will join these scientists to consider the broader social implications of contemporary evolutionary theory and how God fits into the equation.

I. VITAL DUST

Contemplating the beginning and the end

During the last decade or so, Nobel laureate and cell biology pioneer Christian de Duve, the keynote speaker at Nobel Conference(R) XXXIX, has been examining the "bigger picture" of the origin and the evolution of life. In fact, after ending his radiant career as a biochemist studying the intricate parts and inner workings of the cell, de Duve traded the physical laboratory at his institute to devote all his time and energy to the "wider issues" in the laboratory of life exploring, researching, and contemplating what our ever-increasing knowledge and understanding of evolution, and of mind, can reveal about the structure and meaning of the universe.

In Life Evolving (Oxford University Press, 2002), de Duve presents summaries of the major scientific advances that come to bear on our understanding of the origin and evolution of life, supported with his own deductions and beliefs, bestowing a kind of testament for present and future generations based on his cumulative experiences and research, as well as a lifetime of personal reflection.

Embracing a naturalistic view of the origin of life, devoid of "isms," he favors the view that life arose naturally by the sole enactment of physical and chemical laws. Life, as he suggests in Vital Dust (Basic Books, 1995), is a "cosmic imperative," the inevitable outcome of natural biochemical forces. Moreover, he writes in Life Evolving, "The chemical germs are banal products of space chemistry. There is 'vital dust' everywhere in the universe."

Christian de Duve shared the Nobel Prize in physiology/medicine in 1974 for his discoveries "concerning the structural and functional organization of the cell." A pioneering researcher in the field of subcellular biochemistry, he founded the International Institute of Cellular and Molecular Pathology in Brussels, Belgium, to accelerate the translation of basic knowledge in cellular and molecular biology into useful practical applications. More recently he has turned his attention to what our growing understanding of life and mind can tell us about the structure and meaning of the universe. He is the author of several books, including Vital Dust (1995) - a study of how life on Earth emerged and developed - and Life Evolving (2002).

Through the rules of chemistry, he proposes that this "dust" tends to organize itself, transforming in time into larger macromolecules that are the precursors to life, which, in turn, tend to aggregate into the molecules that eventually become living cells. In other words, protocells spontaneously develop via Darwinian evolution into the living cells with the mechanism being "molecular selection." Or, to put it more simply, life generated itself.

Physicists have long espoused that the physical properties of the universe display evidence of incredible precision that allows life to exist, and specifically to exist on Earth; but de Duve maintains that this process - and hence life - is widespread, noting that many scientists now seriously contemplate the possibility, the probability, that life exists elsewhere. There is "every reason to believe" that the elementary constituents of life form in this spontaneous manner "in every part of the universe," and divine intervention appears unnecessary for life to arise and evolve.

The fact that life formed naturally does not necessarily exclude a belief in a Creator, de Duve reasons, "but scientific findings do call for a revision of the image . . . [to perhaps] a God, who from the start, created a world capable of giving rise to life by the sole unfolding of natural laws of his own devising."

De Duve reconciles chance and necessity in positing that evolution is constrained by the physical, chemical, and environmental factors of the setting - what he calls "constrained contingency" - yet he decries the declaration put forth by Stephen Jay Gould that humanity is simply the embodiment of contingency. He views this "gospel of contingency" as "a fallacy."

There is something more to life, something meaningful that is not addressed by science, de Duve concludes. He does not shy away from broaching the G word. The conflict between science and religions is understandable, but, he opines, a dialogue is more necessary now than ever before. It is time to come to terms with the reality that a number of the teachings of religions are simply incompatible with the discoveries of modern biology. No scientific data to date offers evidence for life after death, but it is a religious belief to which humans cling to devoutly.

It is time, too, he suggests, for humankind to "depersonalize" God. The God of the Bible is rooted in "deceptive imagery of wishful anthropomorphism." God did not create man in his image; rather, man created God in his image, he contends. That is not to say, however, that we do not need "spiritual guides" - we do; therefore, religions "should not be abandoned but safeguarded" for the valuable roles they serve, perhaps most importantly in teaching and encouraging the moral high ground and providing a place for meditation and reflection.

All that written and laid down, de Duve acknowledges the "mystery of life" and admits to having experienced rare feelings of the "ineffable," concluding that the "entity" that will emerge in the end is something he calls "ultimate reality."

II. PUNCTUATED EQUILIBRIA

The impact of environmental and human events

Paleontologist Niles Eldredge, curator of invertebrates at the American Museum of Natural History in New York City, has studied thousands upon thousands of fossils, dedicating his career to meshing evolutionary theory with the imperfect fossil record. In 1972, he and Harvard biologist Stephen Jay Gould published their theory of "punctuated equilibria," challenging Darwin's notion that evolution was a slow, steady, gradual process that occurred over millennia.

According to the Eldredge-Gould hypothesis, evolution has proceeded throughout history in fits and starts with long periods of relative stasis where species show little or no change. While species may remain stable because of the nature of their internal structural organization as other species are integrated into local ecosystems, stasis may also be induced by "habitat tracking," Eldredge wrote later, a phenomenon that takes place when environmental change causes organisms to seek familiar habitats to which they are already adapted. Eventually, however, these long periods of stability are "punctuated" with abrupt extinctions of species, and then are followed by a rapid origin and diversification of new species driven by the organismic void.

Since the "punctuations" appear to be catalyzed by major environmental events, often caused by climate change, evolution is "deeply contingent" on the physical constraints of a given setting, the Eldredge-Gould theory holds. That essentially means, in essence, these extraneous effects are driving the engine of natural selection. In addition to triggering extinction, these dramatic environmental events can also prompt speciation, the process of one species turning into or replacing another species. When a given ecosystem is disrupted, species that have stabilized for millions of years can abruptly disappear at the same time that other species rise by adapting to the changing envi\ronment.

The theory, which emerged from the realization that there is a veritable absence of transitional specimens in the fossil record, created a whirlwind in evolutionary circles and Eldredge and Gould suffered the slings and arrows of criticism and skepticism. As the dust settled, however, the vast majority of evolutionary scientists embraced the theory of punctuated equilibria, conceding it effectively explains the pace of evolutionary change. Significantly, the theory also introduced a sobering reality to public consciousness - extinction is the rule, not the exception.

Niles Eldredge has devoted his career to examining evolutionary theory through the fossil record and exploring the general relationship between extinction and evolution. Widely known as the co-author - with the late Stephen Jay Gould - of the "punctuated equilibrium" theory of evolution, he has centered his research on achieving a better "fit" between stasis and change in the fossil record and evolutionary theory. For nearly 30 years, he has worked at the American Museum of Natural History, New York, where he is now curator of the Department of Invertebrates and heads the team of curators responsible for the museums new Hall of Biodiversity.

In his books Fossils: The Evolution and Extinction of Species (Harry N. Abrams, 1991), The Miner's Canary: Unraveling the Mysteries of Extinction (Prentice Hall Trade, 1991), Dominion (Holt & Co., 1995), and Life in the Balance: Humanity and the Biodiversity Crisis (Princeton University Press, 1998), Eldredge elaborates on the theory of punctuated equilibria, bringing it into the 21st century. While the fossil record shows that abrupt upheavals of the biosphere have occurred only five times in the past 600 million years, we are now in the midst of the sixth "punctuation" - and we are the vector.

It began thousands of years ago, after Homo sapiens began to wander Earth, after they developed agriculture and became the first species whose local populations were no longer living "inside" ecosystems. With this unique accomplishment, which most people have ignored, writes Eldredge, humanity, in effect, halted natural selection for the time being. Not living inside the ecosystem ultimately has led humankind to view itself as not really a part of nature the way everything else is. So far, we have gotten away with it, suffering no real consequences aside from the occasional famine. But we are, in fact, inside a global ecosystem, the biosphere, he points out, and we are altering the environment for every living species. Our sheer numbers and the disproportionate consumption and distribution of wealth are causing a grave disruption of the biosphere; consequently, Earth is now confronting a disaster of major ecological proportions.

"Dino detective" Philip Currie, staff paleontologist and head of dinosaur research at the Royal Tyrrell Museum, Drumheller, Alberta, Canada, is in demand as a lecturer for his ability to explain to general audiences the importance of the fossil record in the study of evolution. His extensive fieldwork in the badlands of Alberta has provided insights into problems with dinosaur growth and variation, the anatomy and relationship of carnivorous dinosaurs, and the origin of birds. he and his colleagues have recently unearthed clues suggesting that large, carnivorous dinosaurs previously thought to be solitary hunters may instead have been social and moved and hunted in packs.

If the current disruption of the biosphere is not resolved, Eldredge warns, this disruption will lead to a mass extinction on the scale of that which wiped out the dinosaurs, only this time we - not a giant asteroid - will be the cause. Despite all our technology and knowledge, we are knowingly guiding ourselves into oblivion. If only in that sense, we may have much more to learn from the dinosaurs than we ever imagined.

III. JURASSIC PARK

Uncovering the past life of dinosaurs

The chapter on dinosaurs in "The Story of Life" is more popular than Harry Potter, having already withstood the tests of time and countless childhoods. No one can vouch for that better than Philip Currie. The tiny, plastic dino he found in a cereal box when he was just six years old set him on his life path to becoming one of the world's dinosaur experts.

As curator of dinosaurs at the Royal Tyrrell Museum in Drumheller, Alberta, Canada, Currie has spent years in the field digging up bones in the badlands that wind from Alberta in south central Canada down into Montana and Wyoming, as well as in the Arctic, Argentina, Mongolia, and China. He has brought many "new" dinosaurs to past life, adding surprising plot twists and revisions to the stories we have long been told about species like the famed Tyrannosaurus rex. Along the way, he has rewritten much of this entire chapter in the "story." From Albertosaurus to the velociraptors that terrified audiences in Steven Spielbergs movie Jurassic Park, from creatures with feathers to the biggest, most fearsome beast ever, Currie - dubbed the "dino detective" - has crossed paths with just about every dinosaur imaginable.

In 1997, at a site in the Patagonian desert, on the eastern slopes of the Argentinean Andes, Currie, along with Rodolfo Coria, dug up a "graveyard" of fossilized remains that contained at least half a dozen dinosaurs, ranging in size from half-grown to full- grown animals. It was an awesome find. The bones belonged to what just may be the largest meat-eating dinosaur species that ever thundered across Earth 100 million years ago. A ferocious species of theropod dinosaur, more monstrous than T. rex and even bigger than the reigning king of carnivores, Giganotosaurus, the male adults of this species measured a whopping 45 feet and featured a long and narrow skull, a jaw shaped like scissors, and mouth filled with razor-sharp teeth. These features, according to Currie, appear to indicate that this theropod, still to be named, could have dissected its prey with almost surgical precision.

The discovery of this graveyard also offered important social and ecological significance, bolstering a notion Currie had for some years (after finding a graveyard of Albertosaurus bones in Alberta) - that these huge carnivorous monsters traveled not as loners as has been long believed, but in packs. The idea that such humongous meat- eaters traveled in packs paints a whole new picture of how these creatures traveled and socially interacted, and how they caught their prey. The fast and furious youngsters may have literally cut prey, such as a vegetarian hadrosaur, out of their herd and drove them into the crushing jaws of waiting adults.

Curries research has also shown that many of the physical distinctions in dinosaur bones, which previously led other scientists to believe they had unearthed a new species, are actually differences associated with growth and variation. Of the 900 species of dinosaurs described, probably only about 500, according to Currie, are actually real, because the bones of juveniles and adults of many species appear so different. At the same time, he has also found remarkable similarities among other species - a baby tyrannosaur leg, for example, is almost indistinguishable to that of an adult ornithomimid.

With geologist Ji Qiang of the National Geological Museum in China, Currie discovered one of the most intriguing dinosaurs that ever lived - Caudipteryx, a reptile that boasted feathers. Caudipteryx, they propose, stood about three feet tall and swanked a sizeable fantail. Most likely, they surmise, the feathers evolved for warmth, because the species featured short arms and long legs so they were probably unable to fly. Nevertheless, the fossils appear to support the ground-to-air theory of flight - that fast-running, bird-like animals eventually developed wings that enabled them to lift up and away from the ground. Currie is convinced that there is an evolutionary link between the dinosaurs and modern birds; from that extinction 65 million years ago rose highly diversified decendants.

IV. OUT OF AFRICA

Unearthing human lineage

Paleoanthropologist Tim White, professor of human evolutionary studies at the University of California, Berkeley, has been charting the evolution of Homo sapiens since his career began at Berkeley in 1978. With renowned anthropologist Donald Johanson - who unearthed, arguably, the most publicly well-known hominid skeleton to date, "Lucy" - he proposed what then was viewed as a controversial addition to human heritage by classifying Lucy as a new species, Australopithecus afarensis. The new classification caused an anthropological uproar initially, but A. afarensis, which lived between 3.6 and 2.9 million years ago, was soon inducted into a new picture of human evolution, a picture that White has continued to reillustrate ever since.

Since 1981, White has codirected the Middle Awash Research Project in eastern Africa with Dr. Berhane Asfaw of Ethiopia's Rift Valley Research Service. This long-term program has expanded our knowledge of early hominid skeletal biology, environment, and behavior. At sites in Ethiopia's Afar Depression, northeast of Addis Ababa, they and their colleagues have produced many of the oldest finds and freshest insights into human past over the last several decades, adding significantly to the chapter on the human lineage. Their research, for example, has completely redrawn the age-old diagram that depicts a linear progression of increasingly modern- looking ancestors, from ape to modern man (and which now graces current editions of Darwin's Origin of Species), by showing that throughout most of our ancestors' history, multiple species of human- like creatures were present on Earth concurrently.

In the early 1990s, for example, the team discovered what was then found to be the oldest known human ancestor, Ardipithecus ramidus. The bones and teeth of this hominid, precisely dated to 4.4 million yearsold, provided the first clue that humans began to walk upright in the forest, not on the savannah as most anthropologists long believed. White and his colleagues are currently analyzing a partial skeleton of this ancient hominid who died more than 1 million years before Lucy was born.

Several years later, White and Asfaw, and their international team announced they had uncovered the remains of yet another previously unknown human ancestor, which they classified as Australopithecus garhi. This hominid, dated to 2.5 million years ago, boasted an ape-like face and small braincase like Lucy, but had long legs and a human gait - and may be the long-sought link connecting more ape-like ancestors to the human family. The remains were found near antelope bones marked by the sharp edges of stone tools and fractured by hammer-stones. This evidence suggests that these ape-men were butchering meat, fracturing the bones, and consuming the nutritious bone marrow inside. As a result, A. garhi fills yet another crucial gap in the record of human evolution.

In March 2002, White and the Middle Awash team announced that they had recovered a well-preserved, nearly complete, million-year- old fossilized skull and thighbones of Homo erectus, along with various early Acheulean stone tools to provide the most recent clue in the mystery of the evolutionary role of this ancient human ancestor. While other paleoanthropologists have insisted that these early African and European specimens belong to different species, White's important discovery supports the theory that Homo erectus was a single species that emerged nearly 2 million years ago in Africa and migrated across the Asian and European continents.

Tim White is a professor of integrative biology and co-director of the Laboratory of Human Evolutionary Studies at the University of California, Berkeley. Since 1991 he has co-directed a research project in Ethiopia that has acquired new data on early hominid skeletal biology, environmental context, and behavior, pushing back the record of human evolution more than 2 million years. White has worked on hominids spanning the Pliocene and Pleistocene, from both phylogenetic and functional perspectives. In the early 1990s, he and his colleagues found what was then the oldest known human ancestor, dated at 4.4 million years old. He currently is involved in fieldwork in both Ethiopia and Turkey.

Just last June, White hit the headlines for his discovery of three 160,000-year-old skulls, again in the Afar region. They are the oldest skulls of modern humans found to date and feature a higher cranial vault and don't have the prominent brow ridges characteristic of older species. Though clearly Homo sapiens, these skulls bore slight differences that identified them as more primitive; therefore, the team christened them with the subspecies name Homo sapiens idaltu, These fossils further provide strong evidence that modern humans evolved in Africa, and that the contemporary Neanderthals of Europe were in effect an evolutionary "dead end" and did not contribute to our genetic heritage as has long been supposed.

Although genetic studies have for years now suggested an "Out of Africa" theory of human evolution, the fossil evidence to support that had been fragmentary and incomplete. Now, however, a sequential series of fossils from Ethiopia, dated to nearly 2 million years ago to the present, offer solid evidence for the evolution of humans in Africa.

As scientists like White, Currie, and Eldredge have been uncovering and examining the fossil record to piece together the emergence of past life on Earth, other scientists like Peter Grant and his wife, Rosemary Grant, and Sean Carroll have been studying evolution as it's happening, in real time.

V. DARWIN'S FINCHES

Documenting evolution in action

For the last 30 years, Peter and Rosemary Grant, both of whom are members of the department of ecology and evolutionary biology at Princeton University, have observed up close the evolution, ecology, and behavior of Darwin's finches* on the Galapagos Islands in what is considered one of the classic studies in evolutionary biology. Through their groundbreaking research into adaptive radiation - the evolutionary process through which a single lineage gives rise to species occupying diverse environmental niches - we have had the opportunity to vicariously witness evolution in action.

Some of the Galapagos Islands are pristine preserves, islands where strict regulations and limited tourism insure the habitats remain much as they always have. For the Grants, the subjects of Jonathan Weiner's 1994 Pulitzer Prize-winning book, The Beak of the Finch: A Story of Evolution in Our Time, the islands provide an almost perfect "laboratory" in which they can quantify the effects of natural selection on the finches with no outside human influences to complicate the interpretation of their data.

Over the years, the Grants have studied more than 10 generations of finches and more than 13,000 individual birds. They spend up to three months in the Galapagos each year. There, on the barren 100- acre volcanic island of Daphne Major, they live in a clearing not much larger than their tent, tagging and tracking every finch. By tracing the fates of individual birds of some of the 13 species of finches on Daphne Major and other islands, they have documented changes - notably in beak shape and body size - in response to the everchanging ecological factors. They have found that changes in food availability, as a result of droughts or heavy and prolonged rains, for example, have resulted in natural selection; birds with beaks of certain sizes and shapes survived better than others.

The Grants and their students have watched species go back and forth from being alike to being different, something that would have amazed Darwin who never imagined that such evolutionary modifications could occur so quickly. Overall, they have found that the finches display striking patterns of morphological and behavioral variation, with some populations proving to be exceptionally variable, and that the primary driving force in the adaptive radiation of these species is ecological, with climate change playing an influential role in guiding the evolution of the birds and directing the traits into different directions.

Peter and Rosemary Grant have collaborated extensively in field studies, most notably long-term studies of the unusually large range of morphological variation in three species of Darwin's finches in the Galapagos Islands, which were chronicled in Jonathan Weiner's 1994 book, The Beak of the Finch. The studies reveal a range of genetic, ecological, and behavioral factors causing morphological variation, and demonstrate that selection was capable of acting on this variation to cause evolutionary changes within observable periods of time. The Grants are both professors in the Department of Ecology and Evolutionary Biology at Princeton University, New Jersey; they will make a joint presentation at the conference.

They also have found evidence for rare hybridization between cactus finches (Geospiza scandens) and medium ground finches (G. fortis). Surprisingly, the hybrids survived well and bred after the abundant rain in 1983 altered the food supply. With ground finches' genes flowing into the cactus finch gene pool, a process known as introgression, the cactus finches' beaks started becoming more blunt like the ground finches, resulting in heterosis, superior fitness of the hybrids to the parental stock. That two distantly related species can produce hybrids, which in turn play an evolutionary role, had not been expected and came as a surprise to many biologists.

In Darwin's Finches, Peter Grant chronicles this remarkable ongoing study, revealing in detail how interspecific competition and natural selection act strongly enough on contemporary populations to produce observable and measurable evolutionary changes, illuminating how complex communities develop from simple ones, and how microevolutionary processes can account for macroevolutionary patterns.

Peter and Rosemary Grant have collaborated extensively in field studies, most notably long-term studies of the unusually large range of morphological variation in three species of Darwin's finches in the Galapagos Islands, which were chronicled in Jonathan Weiner's 1994 book, The Beak of the Finch. The studies reveal a range of genetic, ecological, and behavioral factors causing morphological variation, and demonstrate that selection was capable of acting on this variation to cause evolutionary changes within observable periods of time. The Grants are both professors in the Department of Ecology and Evolutionary Biology at Princeton University, New Jersey; they will make a joint presentation at the conference.

The morphological changes that Darwin's finches undergo are the result of genetic changes that occur not because new genes are produced but because selection pressure alters their relative fitness.

While the Grants continue their project observing the finches' morphological changes, molecular biologist Sean Carroll has been using the techniques of developmental genetics to voyage inside animal genomes to find the specific genetic changes that underlie the evolution of species.

VI. EVO-DEVO

The evolution of animal design

One of the great biological enigmas is the process by which overall animal design and body parts evolve. Morphological differences are obviously the developmental products of genetic variation between animals; yet the precise mechanisms surrounding these changes still elude science. Carroll, professor of molecular biology and genetics at the University of Wisconsin-Madison, has been working to decipher the genetic evolutionary controls responsible for the formation, number, and ultimate morphology of animal body parts. In much the same manner as the fossil detectives, this evo-devo scientis\t is uncovering clues by focusing on genes that create a "molecular blueprint" for body patterns and genes that play major roles in the origin of new features.

Carroll's research has demonstrated that genes controlling the formation of many structural body parts are shared by very different kinds of animals. He and colleagues have found, for example, genes that regulate the most fundamental aspects of development of limbs, are the same for the Drosophila melanogaster legs, the fruit fly (Carroll's primary model to date), as for mouse limbs, fish fins, and the tube feet of sea urchins, even though evolution has rendered different end results. Though separated by as much as 600 million years of evolution, these and related observations demonstrate that there is an ancient "genetic tool kit" around which much of animal diversity has evolved.

Since D. melanogaster has proven to be a key model system for elucidating the genetics and molecular biology of animal development, Carroll has been able to more easily initiate studies of additional insects, arthropods, and even distantly related animal taxa to uncover the genetic and evolutionary basis of animal diversity, as well as provide realistic and fresh insights into animal origins and their genesis. The investigations ongoing in Carroll's lab have produced some of the first empirical examples of the mechanisms governing the diversification of fruit flies, butterflies, and other animals. In illustrating the central role that changes in the regulation of developmental genes play in the diversification of body design, he and his colleagues have thus begun to draw a more comprehensive picture of the genetic control of body pattern formation and evolution.

Until the arrival of molecular genetics and molecular embryology, zoologists historically defined evolutionary classifications by using morphology, or comparisons of form and structure, to study the master blueprint of life. Now, however, comparison of genes from different species and how they are deployed has become a powerful new approach to studying evolutionary development. In addition to studying the formation of animal body design in real time, Carroll's laboratory has also utilized these genetic techniques to glimpse into the distant past.

For the past decade, he and his colleagues have illuminated how the Hox genes - the family of genes that ensures appropriate placement and proper formation of organs and systems in the developing animal shape evolutionary diversity. Ubiquitous and highly conserved, Hox genes mutate very slowly throughout animal evolution and thus provide powerful clues to the evolutionary history of an organism. Despite different appearances, most animals share a similar assortment of Hox genes. By decoding the Hox gene sequences of ancient groups of animals, they have inferred which groups of animals were related, as well as which developmental genes were present in shared ancestors that prowled the Cambrian seas over 500 million years ago. Such studies have both redrawn our picture of the animal evolutionary tree as well as given glimpses into the complexity of long-extinct primitive animals.

The interrelatedness of all living things on Earth is humbling and astounding. All the talent and technology brought to bear on elucidating evolution in the last century and a half have continued, again and again, to validate Darwin's core hypothesis - that all organisms on Earth descended from a single, common ancestor. And, yes, human beings - Homo sapiens sapiens - "descended from a hairy quadruped, furnished with a tail and pointed ears, probably arboreal in its habits," as Darwin wrote in his original exposition on common descent. But, at this stage, in the 21st century, what meaning can we glean from that? How does modern knowledge of evolution bear on the relationships among humans and on human responsibilities to other living species, to the biosphere? And how has our newfound understanding of evolution impacted the way society views God?

"Evo-devo" biologist Scan Carroll has focused his research on the genetics and molecular biology of animal development and how that relates to the evolution of morphological diversity. In the Laboratory of Molecular Biology at the University of Wisconsin- Madison, where he is a professor of molecular biology, genetics, and medical genetics and an investigator for the university's Howard Hughes Medical Institute, Carroll and his colleagues have redrawn the evolutionary tree using DNA evidence to conclude that the vast majority of animals belong to one of three primary evolutionary lines, rather than the multiple branches suggested by previous morphological studies.

VII. GOD and DARWIN

Finding a unifying principle

From the trenches where science and religion meet, theologian John Haught, Thomas Healey Distinguished Professor of Theology at Georgetown University and founder of the Georgetown Center for the Study of Science and Religion, has studied Darwinian evolution and contributed much to the often-provocative discussion about the relationship between science and religion.

John Haught, the Thomas Healy Distinguished Professor of Theology at Georgetown University, Washington, D.C., has focused his teaching and research on systematic theology, with particular interest in issues pertaining to science, cosmology, ecology, and religion. He is the author or editor of more than a dozen books discussing the interface of science and religion, including God After Darwin: A Theology of Evolution (2000), Science and Religion: From Conflict to Conversation (1995), and The Promise of Nature: Ecology and Cosmic Purpose (1993). In 1996, he established the Georgetown Center for the Study of Science and Religion.

Haught argues in Deeper Than Darwin (Westview Press, 2003) that, although evolutionary biology is fundamentally correct, it does not - and cannot - offer an adequate explanation of living phenomena, nor does it tell us everything we need to know about life. "While evolutionary biology gives an enlightening account of some aspects of life," he writes, "like all sciences it leaves out a lot. And although Darwinian concepts can even shed light on human existence, their explanatory power is easily exaggerated. To find the deepest, though certainly not the clearest, understandings of life and the universe, we may still profitably consult the religions of the world."

Though many religions have accepted evolution and acknowledged that Darwinian theory is a well-founded theory, creationists and fundamentalists still attempt to fan the flicker of the past flame and often claim banner headlines in the process. Meanwhile, many scientists have claimed that Darwinism is a victory for the materialist worldview. Haught views the lingering debate between religious anti-Darwinians and Darwinian materialists as misdirected.

Instead, he proposes, evolution actually provides a fertile setting for mature reflection on the idea of God, because it is exactly the process we would expect a loving and caring God to institute in order to create life. He believes that evolutionary biology can actually enrich theological conviction and vice versa. He suggests that Darwinian theory, often understood to exclude a belief in God, can actually aid Christians in developing a more biblical faith by replacing the God of static design and controlling power with the God of vulnerable, self-giving love.

In God After Darwin (Westview Press, 2000), Haught puts forth the notion that evolution is a "gift to theology," proffering the premise that it points the way to a new understanding of God and the natural world. Further, he proposes an alternative vision of the universe - as a work in progress, still unfinished. He writes: "A world in evolution does not follow a strict plan but is nonetheless given its being, value, and meaning by God's vision for it. The God of evolution does not fix things in advance nor selfishly hoard the joy of creating. Instead, God shares with all creatures their own openness to an indeterminate future." In a postmodern world, Haught's concept of an evolving natural world seems to make God more comprehensible to humankind as a whole. The challenge now is to dig deeper in our understanding of all that is happening in the story of life.

EPILOGUE

Evolving into the future

It has often been said only by discovering our past will we be able to understand our true destiny. The knowledge that has come from the research and work of Sean Carroll, Tim White, Rosemary Grant and Peter Grant, from Philip Currie, Niles Eldredge, and Christian de Duve has deeply enriched the script of life, casting light on the pathways to the future.

In exploring the relationships among ecology, cosmology, and theology, Haught, too, has powerfully described the importance of viewing Earth and the cosmos as our home, to begin again to connect with nature. How else will we ever care about stewarding it? Science now seems to point to the inseparability of mind and nature. What this means is that "we can no longer separate concern for our own destiny" from that of the whole universe, he says. The cosmos is linked with our humanity, and "we can no longer plausibly think of the physical universe as though it were not our home."

Tim White, who has strived to engage local scholars in the field and make the research in eastern Africa an international effort, views the discoveries and knowledge that have come from research into who we are and where we came from as having broader applications for uniting people. As humanity proceeds in this century, it needs to adopt and incorporate a critically important ethic he calls "evolutionary mindedness." If we don't understand what extinction is, he offers, we will never realize or be able to come to terms with the ramifications of a great loss of biodiversity. This approach embodies the power to change perspective.

But, as Eldredge has warned, \we must change our perspective now. We are rapidly approaching the limits of Earth, and soon we will be at grave risk from our own activities. Redefining our position in and responsibilities to the natural world is an immediate priority, he asserts. Our knowledge of evolution has clearly shown that our fate is inextricably linked to that of other species. We are not only responsible for the biodiversity crisis; we are responsible for taking action to try and lessen the impact of the "sixth extinction" now in progress.

Looking to the future, it is disheartening to think that Homo sapiens sapiens may not represent evolution's ultimate achievement on Earth. In fact, de Duve lays it on the line - we are not the final outcome of evolution. But who - or what - might our distant descendants be? In a strange way, evolution always seems to offer hope.

"Studying dinosaurs gives one a very different perspective on life," offers Currie. "No matter how successful the dinosaurs became, the most visible and characteristic species perished 65 million years ago. Yet, they didn't die out either. In their descendants, the birds, more than 10,000 species of dinosaurs are still alive today."

One thing is certain, de Duve adds. "In any event and no matter what course is chosen, human beings will not remain indefinitely unchanged," he contends. The question then is not whether the human species will change, but how fast and in what direction. We do have a choice, and now "we must prepare the future."

Even when, and if, all the imaginable physical evidence that details the story of life is gathered, we will never know the whole story. There is, in the end, a mystery to life. Who hasn't at one point or another had feelings of, as de Duve has defined it, "the "ineffable"?

"The Story of Life" is still unfolding. . . .

To be continued.

*Darwin's finches are so named because they helped inspire the British naturalist's theory of evolution by natural selection. While visiting the islands during his voyage on the Beagle, Darwin was confused by the different shaped beaks of each species. He thought they all fed on the same foods, more or less. He even thought they belonged to different taxonomic families of birds. Later, back in England, he began to pay attention to the gradation of beaks. "The most curious fact is the perfect gradation in the size of the beaks of the different species of [finches]," the naturalist wrote in his Journal of 'Researches in 1845. "Seeing this gradation and diversity of structure in one small intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends." The Grants' research has borne this out.

A.J.S. Rayl is an author and freelance journalist, based in Malibu, California. Her work has appeared in such publications as Air & Space Smithsonian, Astronomy, Discover, and The Scientist, among others.

Copyright Minnesota Monthly Publications Aug 2003

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