Friday, October 24, 2014

The Nature of Mutation

When cells (or sub-cellular agents such as viruses) replicate, there is a chance that the genetic material (DNA or RNA) that codes for the cell's structure and function may be changed due to the deletion, alteration or displacement of certain genes; the more cells in the population, the more likely such mutations will occur.  Genetic mutation, which may also develop due to radiation, toxins or other external factors, plays a key role in the emergence of disease and has been vital to the process of evolution over the past 3.6 billion years.

Mutations of the genetic code may be favorable, benign or pathologic.  Those that make the cell or organism less viable or more susceptible to environmental threats, will be deleted from the population;  on the other hand, those mutations that favor survival will persist in the cell line and will be passed on to future generations.

In the case of infections, such as ebola, mutations may increase or decrease factors such as virulence.  Ebola is characterized by an extremely high viral load in the tissues and fluids of the victim, increasing the number of replications and, thus, the chance for mutations to occur.  While the media has reported that the ebola virus may "learn" to spread in new ways, changes in the pattern of disease merely reflect the emergence of traits (through mutation) that favor survival of the virus and are thus retained and disseminated in the viral population.

Thursday, October 23, 2014

Nature's Sweet Spot

Many if not most naturalists and "outdoors people" who live in the American Heartland would identify mid-late autumn as the best of nature's seasons.  Sunny skies, mild daytime temperatures, dry air and crisp, clear nights are the norm and colorful foliage adorns the landscapes.  After a few overnight frosts, annoying insects are down for the count while native birds and mammals become more active and conspicuous in the autumn chill.

Overhead, flocks of migrant cranes and waterfowl fill the skies, settling on our fields and lakes to rest and feed and attracting hordes of birders and hunters in the process.  Dry trails, painted woodlands and pleasant weather entice hikers and naturalists into the forests and mountains before ice and snow coat the landscape.

Commonly referred to as "Indian Summer," these glorious weeks are nature's sweet spot, warm enough to invite exploration but cool enough to invigorate humans and wildlife alike.  There is no other time of year when we so clearly sense that we are part of nature, a reality that we too often ignore.

Tuesday, October 21, 2014

Conceding Victory to Nature

Since moving to Columbia, Missouri in the late 1990s, we have watched as the Parks Department attempted to establish a prairie at Forum Nature Area, on the Hinkson Creek floodplain.  Annual mowing was utilized to retard tree invasion and periodic burns were used to eliminate alien plant species.

Despite these well-intentioned efforts, groves of sycamore, cedar and burr oak continued to invade the grassland; after all, intermittent floods inundate the valley, fueling the growth of water-loving trees and shrubs.  Since grass and wildflowers are more tolerant of drought and wind than are trees, natural prairies tend to develop on sunny, dry, windswept uplands, not on moist floodplains.  Coming to this realization and, no doubt, discouraged by the cost and manpower required to maintain the prairie, the Parks Department recently planted native floodplain trees across the valley floor; within a few years, Forum Nature Area will look more like a bottomland forest preserve than a floodplain grassland.

In our effort to diversify habitats for native wildlife, we humans often ignore the relationship between natural ecosystems and the environmental factors that fostered their development.  It is best that we let nature be the architect of her wild lands, whether they appeal to human visitors or not.  While the construction of well-engineered trails that provide access without disturbing the ecosystem is an acceptable intervention, nature knows best when it comes to the landscape.  Try as we might to mold her realm, Mother Nature will eventually exert her will and proclaim victory.

Monday, October 20, 2014

River of Floods

Near the end of the Pleistocene Epoch, as the last of the Continental Ice Sheets was retreating into Canada, a massive lake of meltwater formed along the southern margin of a glacial lobe, covering much of southern Manitoba and a swath of America's Northern Plains.  Known as Glacial Lake Agassiz, its surface area fluctuated over thousands of years; during its maximum extent (some 11-12,000 years ago), the lake's southern arm extended down the border of present-day North Dakota and Minnesota and Lake Agassiz drained southeastward through the valley of the Minnesota River.

As the ice continued to recede, the meltwater shifted northward as well, finding outlets to the east and gradually abandoning its southern arm.  About 9,000 years ago, the Red River began to form in that broad lake bed, meandering northward to the ever-changing contour of Lake Agassiz.  Eventually, when the glacial ice had retreated into northern Canada and the Northern Plains began to rebound from its weight, the Red River emptied into Lake Winnipeg, the largest remnant of Lake Agassiz; Lake Winnipeg now drains into Hudson Bay via the Nelson River.

Today, the Red River snakes northward across the flat bed of Lake Agassiz, covering 545 miles on its journey from Wahpeton, North Dakota, and Breckenridge, Minnesota, to Lake Winnipeg.  Bordered by rich agricultural land and flowing past several large cities (Fargo, Grand Forks and Winnipeg), the river is highly prone to flooding, especially in late winter or early spring when the frozen ground and dormant vegetation cannot absorb excess moisture.  Snowmelt and heavy spring rains overwhelm the capacity of the shallow river and floodwaters spread across the ancient lake bed, inundating farms, towns and urban areas.

Sunday, October 19, 2014

First White-throats in Missouri

As our autumn colors begin to peak, I encountered the first white-throated sparrows of the season at the Fourm Nature Area, in Columbia.  As usual, it was their distinctive song that caught my attention, a tune that will diminish in winter and then build to a frenzy in early spring.

Summer residents of open forest across Canada, the Great Lakes region and New England, these stocky sparrows are among the most common winter residents in the American Heartland and Southeastern States.  Though they migrate across the Great Plains and Intermountain West, white-throats have begun to winter along the Front Range urban corridor over the past decade; they have long been winter residents in coastal regions of California.  Best found along wood borders near thickets and brushy fields, these hardy birds are easily drawn to feeding stations where they scour the ground for fallen seed.

Songbirds and shorebirds migrate in response to the solar cycle and their dates of arrival and departure are fairly predictable each year; white-throated sparrows generally begin to appear in Missouri in mid October and most will depart for Canada by mid-late April.  Waterfowl, on their other hand, migrate in response to food availability and their schedule is far more variable; indeed, as our climate warms, their autumn migrations may be delayed and their journeys will likely be shortened.  On the other hand, sudden, intense storms with heavy snow and severe cold may send them south in huge flocks, sometimes well ahead of their usual schedule.

Saturday, October 18, 2014

The Connecticut River

The Connecticut River, the largest and longest river in New England, rises in northernmost New Hampshire, just south of the Quebec border.  After coursing southward through a series of lakes, the river angles southwestward, becoming the border between New Hampshire and Vermont and receiving numerous tributaries from the northwest flank of the White Mountains.  At St. Johnsbury, Vermont, the Connecticut begins a more southerly course, entering the basin of Glacial Lake Hitchcock, which extends southward to central Connecticut, just below Hartford; Lake Hitchcock formed late in the Pleistocene (some 15,000 years ago) as glacial meltwater accumulated behind a moraine; layers of sediment accumulated for over 3000 years before lake waters broke through the moraine, draining southeastward to Long Island Sound.

Receiving numerous tributaries from the east slope of Vermont's Green Mountains, the west flank of New Hampshire's mountain corridor and the east wall of the Berkshires of western Massachusetts and northwestern Connecticut, the Connecticut River carries an abundant supply of sand and silt to Long Island Sound, producing vast, shifting sandbars and negating the establishment of a seaport at its mouth.  Numerous dams disrupt its course and Quabbin Reservoir, constructed in the 1930s siphons off much of the flow from one of the Connecticut's major tributaries, the Chicopee River;  this massive reservoir, the largest body of water in New England, supplies water to Greater Boston and much of eastern Massachusetts.

Tidal waters reach almost 60 miles into south-central Connecticut and rich wetlands flank lower portions of the river, home to a tremendous diversity of aquatic wildlife and a magnet for migrant flocks of waterfowl and shorebirds. Some 410 miles south and 2700 feet below its source, New England's Great River meets the sea.

Friday, October 17, 2014

Gonzalo rakes Bermuda

Forty million years ago, Bermuda, 640 miles ESE of Cape Hatteras, North Carolina, was part of a volcanic island chain that towered above the Atlantic Ocean.  Over time, that chain eroded into a series of seamounts that have since been capped by limestone and sand as sea levels rose and fell; today, Bermuda consists of 138 islands and islets that represent high ground atop one of the broad seamounts (see Bermuda's Natural History).

As I write this post, Hurricane Gonzalo is approaching Bermuda from the SSW; its outer bands are now raking the archipelago while its eyewall, some 60 miles away, is packing winds of 125 miles per hour.  Now classified as a Category III Hurricane, Gonzalo may weaken a bit as is pushes ashore but significant wind and wave damage is anticipated.

Fortunately, thanks to accurate weather forecasting, residents of Bermuda have had at least four days to prepare for the storm.  Nevertheless, the benefits of living on that island paradise are soon to be weighed against the primary risk (not to mention sea level rise from global warming); though the archipelago lies in the Temperate Zone, Bermuda enjoys a mild year-round climate due to the path of the Gulf Stream, which also fuels tropical storms.

Thursday, October 16, 2014

October Splendor at Eagle Bluffs

It was a beautiful autumn morning at Eagle Bluffs Conservation Area on the Missouri River floodplain.  Under bright blue skies, fall colors painted the fields and dappled the wooded hills while steam rose from the refuge ponds, entering the crisp morning air.

As is typical for October, American coot were abundant in the lake shallows and flooded fields and massive flocks of red-winged blackbirds moved through the marshes and grasslands.  Other common birds included pied-billed grebes, great blue herons, great egrets, belted kingfishers and song sparrows.  Raptors were limited to a few red-tailed hawks, American kestrels and a lone Cooper's hawk; ducks were also relatively scarce, represented by small groups of mallards and northern shovelers and skittish flocks of blue-winged teal.

Autumn colors should peak within another ten days and the waterfowl count will build significantly in the coming weeks as both migrant and wintering species arrive from the north.  Joining the geese and ducks will be a variable number of trumpeter swans, sandhill cranes, horned grebes, loons and those rare, unexpected visitors that draw local birders to this fabulous refuge.

Wednesday, October 15, 2014

Trust & Healthcare

During my years as an academic Hospitalist and now as a volunteer educator, I have taught medical students and residents that trust is the most important aspect of the doctor-patient relationship.  While patients understand that medicine is an inexact science, that mistakes may occur and that successful results are not guaranteed, they need to know that their provider will do whatever he/she can to diagnose and treat their condition and will keep them informed regarding what they discover and what they don't yet know.  Their trust is earned by such an approach and the willingness of their provider to consult specialists, when appropriate, augments their level of comfort.

Unfortunately, the member nations of the World Health Organization have not engendered the trust of the international community in their approach to the ebola epidemic in West Africa; resources were initially inadequate and the disease will now be much more difficult to contain.  In a similar vein, the CDC, while attempting to calm the American public, offered reassurances that they were in no position to meet; containment of ebola in Texas has been hampered by a number of missteps, including inadequate resources and a lack of strict attention to the enforcement of protocol and quarantine measures.

As a result, the CDC must now re-earn the trust of the American public.  Of more concern, they have lost control of the message which is now in the hands of cable news programs and the social media; as one might expect, hyperbole, inappropriate comparisons and inflammatory statements have entered the public discourse and, as a result, anxiety has become systemic.  The management of a public health emergency requires careful planning, public education, honest discussion and aggressive intervention; until those factors come together, public trust and cooperation will be lacking and the control of ebola in America will be hampered.

Tuesday, October 14, 2014

Life & Deaths

Threats such as ebola and terrorism are especially anxiety-provoking since we humans are well aware of our own mortality.  Indeed, as children, the death of a friend or family member is often the event that puts an end to our innocent, fantasized image of the world.

Throughout the remainder of our lives, the deaths of loved ones, acquaintances and celebrities mark the course of our journey; though we know that our own life will end, how and when remains a mystery.  Many humans soothe their anxiety by leaning on religious faith and its promise of eternal life.  Others, less inclined toward mysticism, embrace fatalism or commit themselves to a lifestyle that, based on their knowledge or experience, will offer the best chance of a long, productive life.

Regardless of how we approach this natural fear, the deaths of others have a significant impact on our life and keep us attuned to our own mortality.  Those of us with friends or family members who died at a young age are perhaps more sanguine about the future, thankful for the many years that we have enjoyed and less stressed by the prospect of a sudden, random demise.  As a natural species, our bodies evolved to survive long enough to reproduce and raise our young; as intelligent creatures, we hope and plan for a long, rewarding life while knowing it could end tomorrow.

Monday, October 13, 2014

Spring in October

Here in the American Heartland, October is beloved for its sunny, mild days, crisp nights, colorful foliage and dry air.  We do not associate this autumn month with balmy conditions, torrential rain and tornadic thunderstorms; of course, there are exceptions.

Thanks to a deep atmospheric trough and its potent low pressure center, a line of severe thunderstorms developed across the Southern Plains last evening, pushed across Missouri and Arkansas this morning and, as of this evening, stretch from the Great Lakes to the Gulf Coast.  Heavy rains, flooding, damaging winds, hail and tornadoes have created havoc across the region and will push into the Southeastern States overnight.  On a positive note, this potent storm system will eventually deflect Hurricane Gonzalo away from the Eastern Seaboard.

In central Missouri, we received thunderstorms with heavy rain this morning, followed by a balmy, southerly flow ahead of the approaching cold front; the afternoon temperature approached 70 degrees F and, despite the pumpkins and colorful leaves, it felt more like April than October.  As the low moves east of us tonight, "wrap-around" showers are expected overnight before cooler and dried air filters in from the west.  Though we may relish the weather of a "typical" Midwestern autumn, a restless jet stream can remind us that fall, like spring, is a season when the clash of air masses may have stormy consequences.

Sunday, October 12, 2014

Orange is the new Green

Crossing the Great Plains in mid October, one finds that the verdant grasslands and cropfields have given way to a scenic landscape of orange.  Reflecting the bright sunshine of autumn, the rolling terrain is a kaleidoscope of color, from brilliant gold to creamsicle orange to a rusty bronze.

Cattle, pronghorn and, on some ranches, bison graze the colorful grasslands which are patrolled by red-tailed hawks, northern harriers, turkey vultures, American kestrels and restless flocks of crows.  Ring-necked pheasants forage near the highways, Franklin's gulls cavort above the fields and, within the dense vegetation, a variety of small mammals escape the eyes of Interstate travelers, feasting on seeds and grain.

Within six weeks, these fields of orange will fade to brown, perhaps crusted with ice and snow.  Before then, spectacular flocks of cranes and geese will pass overhead and many will stop to rest and feed on the colorful quilt of America's Great Plains.

Saturday, October 11, 2014

Black Bears in Colorado

Black bears are common throughout the western 2/3 of Colorado, from the Front Range foothills to the western canyonlands.  Favoring elevations below the Subalpine Zone, they are most abundant in shrublands and montane forest and their population is highest across southern and western portions of the State.  According to the Colorado Division of Wildlife, about 17-18,000 black bears inhabit Colorado and their population has remained relatively stable in recent decades; of course, the human population has expanded significantly and bear-human encounters have increased in concert.

More than 80% of Colorado black bears are brown in color, often light cinnamon or even blonde; indeed, some grizzly sightings in the State have been attributed to sightings of large, brown-colored black bears.  Omniverous, plant material (including vegetation and berries) accounts for up to 90% of their diet though they also consume insects, small animals, fish, carrion and, as we know, human garbage.  Adult black bears have a home range of 10 to 200 square miles and are active from March to late November in Colorado; during hibernation, they utilize natural caves and hollow logs or dig out dens beneath fallen trees, rock outcrops or stumps.

Despite their widespread range in Colorado, black bears are seldom encountered unless the natural food crop is reduced and they visit camps or towns in search of nourishment.  Since they are most active in the hours surrounding dawn and dusk, hikers are advised to be especially cautious during those periods.  Black bears avoid human contact whenever possible and are rarely aggressive unless cubs are present; on the other hand, given the fact that adult males weigh up to 500 pounds and that these bears can easily outrun humans, it is best to avoid surprise encounters and to observe them from a safe and nonthreatening distance.

Friday, October 10, 2014

Migrating Solitaires

Late this morning, my wife and I hiked around Hines Lake at Robert Eastman Park; this park is in southwest Metro Denver, near the foot of the Dakota Hogback.  On our lakeside hike, birds were rather sparse; sightings included a lone cormorant, several common mergansers, mallards, pied-billed grebes, red-winged blackbirds and a few ring-billed gulls.

Climbing back to the parking lot, however, I watched as waves of Townsend's solitaires moved from the foothills onto the Colorado Piedmont, funneling eastward through a break in the Hogback. Their annual vertical migration was likely accelerated by cold rain and snow in the upper foothills and mountains that began yesterday afternoon and ended this morning.  Indeed, after breeding in open coniferous forest, Townsend's solitaires move to the lower foothills and Piedmont each autumn, switching from a mixed diet of insects and berries to a strict diet of juniper berries.

Once settled in for the winter, the solitaires are highly territorial, defending their berry cache from one another (though they still must contend with robins, waxwings and other berry consumers).  Our resident solitaire arrived on the farm several days ago, delivering his high-pitched call from the top of a large honeylocust.  Just yesterday, I watched as he chased another solitaire from the property, ensuring an ample supply of berries to survive the winter.

Thursday, October 9, 2014

October Birding at Chatfield

As I headed to Chatfield State Park this morning, rain clouds billowed above the Front Range foothills. Beneath the waning sunshine, the golden leaves of cottonwoods glowed along the South Platte and Plum Creek corridors and clumps of yellow rabbitbrush adorned the grasslands.  As usual, black-billed magpies foraged along the Park's roadways and small flocks of Canada geese, awaiting cohorts from the north, grazed on lawns near the outbuildings, beach and campgrounds.

Out on the reservoir, double-crested cormorants and ring-billed gulls dominated the scene, joined by smaller flocks of American white pelicans, western and pied-billed grebes and, near the inlets, mixed flocks of gadwall, coot, shovelers, common mergansers and mallards.  A group of Townsend's solitaires, down from the mountains for the colder months, fed in junipers near the campground while northern flickers, black-capped chickadees and blue jays were the most conspicuous woodland species.  Western meadowlarks, magpies and a few vesper sparrows were observed on the grasslands, which were patrolled by a pair of red-tailed hawks; the only other raptor sighting was of a sharp-shinned hawk that strafed the lakeside woods, hoping to snare a songbird.

Today's visit to Chatfield was far from my most productive birding experience at the Park, a refuge that many (including myself) consider to be one of the best birding locations in Metro Denver.  Nevertheless, the fresh, cool air, relative solitude and beautiful autumn colors more than compensated for the "lackluster" birding.

Wednesday, October 8, 2014

Gay Rights, Marriage & Divorce

The Supreme Court's decision not to address District Court rulings regarding gay marriage has reignited the rhetoric of conservative, homophobic politicians and organizations.  Claiming to defend the sanctity of heterosexual marriage and the welfare of the family, these zealots harbor no respect for homosexual relationships.  Opposing the right of gays to marry and to receive the social benefits that come with marriage, they claim that such policies will erode our social structure and destroy the American family.

One wonders why their focus is on gay marriage and not on divorce, which puts an end to more than 50% of heterosexual marriages and has a far greater impact on the emotional and financial welfare of children.  While most of us support the right to divorce, especially when one spouse is subjected to abuse, we also know that many who oppose gay marriage have been divorced themselves, perhaps multiple times.

These social watchdogs, politically astute, cannot afford to focus on heterosexual divorce and its consequences.  After all, their crusade against gay marriage is motivated by homophobia and religious zealotry, not by their professed concern for the welfare of children and families.

Tuesday, October 7, 2014

Staunton State Park

Stretching across the south flank of Black Mountain, Staunton is one of the newest and most beautiful of Colorado's State Parks.  Backed by spectacular granite cliffs and knobs, the Park's rich, open forest of pine, fir and aspen is accessed by an excellent network of multi-use trails.  To reach the parking lots for this 3800 acre preserve, follow U.S. 285 southwest from Denver; about 6 miles west of Conifer, turn right (north) on Elk Creek Road and follow signs to the Park entrance; a day use fee is charged.

Today, beneath deep blue skies and amidst the brilliant glow of aspen, my wife and I hiked to the base of Staunton Rocks, enjoying views of the massive cliffs and rock formations within the Park, including Lions Head (9450 feet).  Views also extend far to the south, including the high ridge of the Platte River Mountains, Windy Peak, Devil's Head and Pike's Peak, some 60 miles distant.  Along the way, we were serenaded by mountain chickadees and pygmy nuthatches and scolded by Steller's jays and red squirrels.  Though we hoped to encounter elk or hear their bugling, our hike was a bit late in the morning for that stirring experience; the Park's other mammalian residents include mule deer, yellow-bellied marmots, Colorado chipmunks, coyotes, Abert's squirrels, black bear and the elusive mountain lion.

A popular destination for hiking, rock climbing, horseback riding, cross-country skiing and snow shoeing, Staunton State Park is named for Frances H. Staunton who donated most of the land; her family established a ranch on the property in the early 1900s and an old saw mill site is protected within the Park.  Another highlight at this fabulous preserve is Elk Falls, which drops almost 100 feet into the North Fork of Elk Creek.

Sunday, October 5, 2014

Red-breasted Nuthatch

Attractive, energetic and aggressive, red-breasted nuthatches are permanent residents across southern Canada, the Pacific Northwest, New England and southward through the mountain ranges of North America; throughout the remainder of the Continental U.S., they are winter residents and visitors though they often arrive by September.  Like the call of their larger cousin, the white-breasted nuthatch, their shorter, high-pitched "yank-yank" is always a welcome sound for those who relish crisp, autumn weather.  Favoring coniferous woodlands, red-breasted nuthatches have become year-round residents on our Littleton, Colorado farm, attracted by the pinon pines, Austrian pines, junipers and spruce trees on the property.

In spring, males pick a few potential nest sites, beginning to drill cavities in the soft wood of conifers or aspen trees; females take note of the activity and choose a mate based on his efforts.  She then completes the excavation and the male resorts to bringing food and protecting the site from other suitors; both end up placing nodules of pine resin along the rim of the cavity to deter predators.

During the warmer months, these small birds scour tree trunks and larger limbs for insects and continue to hunt for hibernating invertebrates in winter; however, they are more likely to feast on conifer seeds during the colder months and are easily drawn to feeders with sunflower seed and suet.  Darting back and forth, they typically grab a morsel of food, store it in tree bark and return to the feeder several times each minute; they otherwise roam the winter woods, often in the company of chickadees, titmice, kinglets, downy woodpeckers and other nuthatches.

Saturday, October 4, 2014

Autumn at Deer Creek Canyon

Reflecting the bright October sun and stretching beneath a clear blue sky, Deer Creek Canyon Park was a riot of color yesterday morning.  Incising the Front Range foothills southwest of Denver (just west of Chatfield State Park), the canyon is a popular area for biking, hiking and wildlife watching.

Early autumn colors painted the vegetation though the brilliant orange of Gambel oak had yet to materialize; east of the park, the redrocks of the Fountain Formation (Pennsylvanian sandstone) adorn the landscape throughout the year.  Contributing to nature's palate were a variety of colorful foothill birds, including Steller's and scrub jays, rufous-sided towhees, pine siskins and both American and lesser goldfinches.  The highlight of my visit was provided by a large flock of mountain bluebirds, forced down from the higher peaks by recent snows and fueling up before their journey to the Southern Plains and Desert Southwest, where they will spend the winter months.

Mule deer are always common at the Park and, though seldom encountered, mountain lions and black bear inhabit the canyon.  Other mammalian residents include rock squirrels, Colorado chipmunks, striped skunks, red and gray fox, bobcats and coyotes; Deer Creek Canyon Park is also one of the better locations in Metro Denver to observe golden eagles.  Needless to say, the crisp sunny weather and colorful landscape of October make the canyon especially inviting.

Friday, October 3, 2014

The Expendable Species

Throughout the first 120,000 years of human existence, we were just another species in natural ecosystems, moving about and subsisting via a combination of hunting and gathering.  Then, about 10,000 years ago, humans began to establish permanent settlements, relying heavily on the domestication of animals and the cultivation of crops.  This break from the natural world accelerated during the industrial revolution and our negative impact on ecosystems began to increase exponentially as pollution, habitat destruction, human overpopulation and the overconsumption of natural resources took a toll on other species.

While human activity has favored some species by creating new habitats (reservoirs in desert regions, forest clearings and nutritious crop fields are a few examples) our overall impact has been decidedly negative.  Indeed, the pollution of air and water by human industry is altering the global climate and threatening the welfare of all species, including our own.  Nevertheless, we have a history of assessing the value of other species that share this planet, granting them protection or minimizing their importance as we continue to plunder Earth's natural resources.

In the end, humans are the most expendable natural species on this planet.  Our value now derives primarily from efforts to diminish or reverse the negative effects that our species has already unleashed.  While other natural species fit into ecosystems as producers, predators, prey, scavengers and nutrient recyclers, we have created our own overpopulated, unnatural ecosystems that degrade the health and function of the natural environment.  Our superior intelligence, which enabled this dominance, has led us to imagine that we are the designated stewards of Planet Earth, a mystical assumption that, in the collective human mind, inflates our own importance.  While healthy natural ecosystems are vital to the welfare of humans, they would thrive in our absence.