Signs of Fall 7: Hurricanes

Hurricane Irma, NASA

This year’s Atlantic Basin hurricane season has already surpassed all predictions in both the number and intensity of storms, and we have, at this writing, six weeks left in the season for more storms to arise! There have been (as of October 19) fifteen named storms and ten hurricanes. Five of these hurricanes have been “major” (Category 3 or above) (Harvey (a 4), Irma (5), Jose (4), Lee (3) and Maria (5)). Three of these five major storms had extensive contact with land masses and have done considerable damage to both human habitations and natural ecosystems. An index that measures the number, the strength and also the duration of a season’s storms is called the “Accumulated Cyclone Energy” (ACE) Index. Based on this index, 2017 is already the eighth most intense hurricane season of all time!

Many animals were affected by Harvey, Irma and Maria. Cows, horses, chickens, goats, dogs and cats all suffered grievously from the effects of these storms and relied on their humans to help them survive. Zoo animals had to be sheltered in place or removed to safer, inland sites. Dolphins in Cuba were removed from their dolphinarium on Cayo Guillermo and helicoptered away from the path of Irma. The Humane Society has set up a special fund to help domesticated animals that have been displaced by these storms.

Wild animals also were affected by these hurricanes. Some large, strong flying birds were able to fly out ahead of the storms, but most species had to shelter in place and ride out the wind, rain, and flooding.

Hurricane Harvey was a slow moving, monster of a storm. After it hit the Texas Gulf coast, it inched its way along dumping a year’s worth of rain on some areas around Houston. The flooding was incredible and the effects will be felt for many years. On a beach near Texas City, Texas the storm pushed a seldom seen sea creature onto the sand. The three foot, toothed serpent was a fangtooth sea eel (Aplatophis chauliodus) a bottom dwelling predator that is normally found burrowed in the sediment at depths of 100 to 300 feet. The energy of the storm must have dislodged it and flung it up on to the shore. I could not find a free use photo of the sea eel and so include this LINK to an article (with pictures!) about it.

Harvey also forced many shore birds far inland. Sooty terns, magnificent frigate birds, royal terms, Caspian terns, least terns and Sabine’s gulls were pushed up to 200 miles into the Texas Hill Country. Many showed up around the lakes near Austin giving central Texas bird watchers a great chance to expand their life lists!

Photo by USFWS, Public Domain

West of Houston is the Atwater Prairie Chicken Refuge. The wild population of these endangered birds only numbered 42 individuals before the storm. After Harvey only 5 hens survived. The refuge also houses a population of bob-white quail that were decimated by the torrential rains and flooding. In nearby coastal refuges thousands of dead birds were reported (especially pelicans, terns and gulls). Song birds were also assumed to have been killed in large numbers, although their small carcasses were very difficult to observe or recover.      

The Aransas National Wildlife Refuge is just north of Rockport, Texas (the site of Harvey’s first landfall). It is a large, vital over-wintering reserve for a number of migratory bird species including the endangered whooping crane. Harvey pushed tons of saltwater into the refuge’s freshwater ponds and piled up massive quantities of man-made materials all over the refuge. Fortunately, the whooping cranes had not yet arrived when Harvey hit although their over-wintering habitat is severely damaged.

Raft of fire ants. Photo by The Coz, Wikipedia Commons

An animal that seems to have thrived in the post-hurricane floods in Texas was the exotic, invasive, and extremely destructive, fire ant. Reports described floating masses of fire ants held together by their intertwined legs, bobbing along in the flood waters around Houston. These masses dispersed when they reached dry land and inflicted their severe stings on anyone who came in contact with them.

Hurricane Irma was a fast moving, powerful wind and rain storm. It generated 185 mph winds and tore across several Caribbean islands, the Florida Keys, and up the entire state of Florida. Strong flying, tropical birds, as we saw in Harvey, were scattered out ahead of the storm and were seen as far north as Kentucky. Upland habitats of southeastern Florida and the Keys were defoliated by the wind. There will be, then, no food or shelter for the flocks of migrant species that will be following the Atlantic Flyway this fall and winter. The Everglade snail kite (an endangered raptor) had all 44 of its nests around Lake Okeechobee destroyed by Irma.  On the island of Barbuda, amazingly, many of the near-threatened Barbuda warblers survived the destruction of their dry shrubland habitat. Magnificent frigate birds, though, that nest in large numbers on Barbuda were decimated by the storm. The endangered Key deer were able to find shelter and high ground as Irma struck and were reported on Big Pine Key a few days after the storm.

Loggerhead sea turtle, Photo by Strobilomyces, Wikimedia Commons

Sea turtles were severely impacted by Irma. Hundreds of young, endangered loggerhead and green turtles were pushed onto shore by the storm where they were rescued by human volunteers. Nests, though, were washed away by the extensive beach and dune erosion of Irma. On beaches south of Cape Canaveral 90% of the loggerhead turtle nests were destroyed.  Green sea turtles were nesting in record numbers all along the Florida coast, and huge numbers of these nests were also lost.

One Florida Fish and Wildlife Commission spokesman talked about bears and racoons actually thriving in  post-impact ecosystems of Irma. Increased shelter (downed trees) and food (carcasses and scattered human food debris) will actually benefit these two hardy and omnivorous species.

Photo by USFWS, Public Domain

Hurricane Maria was also a fast moving wind and storm event. Winds in Maria reached 160 mph, and it hit the island of Puerto Rico head-on.  One site that is representative of the extensive destruction all across the island is the El Yunque Rain Forest. El Yunque is the only rain forest in the U. S. Forest System. It is the site of rare and unique trees, and numerous and endangered birds and amphibians. The entire rain forest was shredded by the winds of Maria destroying the forest’s ability to shelter and feed its numerous animal species. One inhabitant of El Yunque is the endangered Puerto Rican parrot. In 1989 after Hurricane Hugo there were only 22 of these parrots left. Careful conservation of these survivors and established breeding programs (both captive and wild) have brought the numbers of these parrots up to 500 individuals. Many wild parrots died due to Maria, but it is hoped that there are sufficient captive birds to re-establish a viable population.

Ecologists stress that forests like El Yunque in Puerto Rico and animals like the Puerto Rican parrot and the sea turtles we have discussed have evolved in environments where hurricanes regularly occur. The long-term impact of these hurricanes, as long as they do not ravage a site too frequently, may, in fact, be beneficial to the overall health and vigor of these ecosystems and species.   Climate change models, though, predict both increased intensity and increased frequency of these major hurricanes. The increased frequency, in particular, could be devastating to all of these sites and organisms.


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Signs of Fall 6: More on Yellowstone

Photo by L. Drake

On our drives and hikes through Yellowstone National Park we saw (as I mentioned last week) two wolves (pictured at a distance to the left), one bald eagle, a dozen sandhill cranes, a hundred elk, and a couple of hundred bison. The most abundant large organism we saw, though, numbered in the millions. We drove past and hiked through vast mountainsides covered with lodgepole pines. These pines were noteworthy not only for their incredible abundance but also for their remarkable uniformity. It was like someone had used CGI technology to replicate a tall, thin, astonishingly straight, incredibly uniform looking pine tree thousands and thousands of times over. These vast tree armies reminded me of the orc or elf or dwarf armies in the various Lord of the Rings movies. They were the most natural looking, unnaturally repetitive set of trees I think that I ever seen!

Photo by B. Olsen, Flickr

The lodgepole pine (Pinus contorta) is found broadly across western North America from the Pacific Ocean’s coast to the northern parts of the Rocky Mountains. There are four subspecies of P. contorta: the “beach pine” (P.c.bolanderi) of northern California, the “shore pine” (P.c.contorta) of northern California up into Alaska, the “tamarack pine” (or “Sierra lodgepole pine”) (P.c. murrayana) of the mountains of southern California and Nevada up the Sierra Nevada into the Cascades), and the “Rocky Mountain lodgepole pine” (P.c.latifolia) which we saw so abundantly in Yellowstone.

Many of the shore species grow in forms that fit the “contorta” species name: they are short, twisted, stunted, shrub-like trees. The Sierra lodgepole pine and the Rocky Mountain lodgepole pine, though, can reach substantial heights (130 to 160 feet) and girths (over six and a half feet dbh). The species designation “contorta,” though, is said to be based on the characteristically twisted needles seen on all of the sub-species. Lodgepole pines can live for up to 400 years if conditions are stable.

Photo by D. Sillman

Fire is an important environmental factor especially for the Rocky Mountain lodgepole pine. The mature tree is actually quite susceptible to fire-kill because of its thin bark, but its seed bearing cones are designed to only open after they have been heated to 113 to 140 degrees F. The lodgepole pines begin to make cones when they are six or ten years of age, and these cones (and their seeds) can accumulate for many decades on the forest floor. So when a lodgepole pine forest burns (which historically happens every  100 to 300 years) a new forest of pine seedlings quickly springs into existence. This is why lodgepole pine forests are typically so evenly aged (and so remarkably uniform in appearance!). The succession sequence in these fire driven forests, then, is short, rapid and focused on the tree species that is best adapted to the high altitude, short growing seasons, and relatively dry conditions of these sites: the lodgepole pine.

Native Americans of the Great Plains traveled great distances to the Rocky Mountains to gather lodgepole pine logs for their tipis. A typical tipi would use more than a dozen, 15 to 18 foot pine poles to support its buffalo skin encasement. The narrow diameter and straight growth aspect of these poles and the low density (and light weight) of the wood made them ideal structural supports for the frequently moved tipis.

Photo by D. Sillman

One of our hikes in Yellowstone was around Ice Lake in the northwestern section of the park. Ice Lake was the site of a severe forest fire in 1988 that destroyed its mature lodgepole pine forest. The logs from this burned forest still litter the surrounding landscape, and lay sun-bleached and slowly decomposing on the dry forest floor. A number of the logs have been actively split (by bears, perhaps, seeking grubs?) and their torn and shredded woody materials have been mixed in with the slowly accumulating needles from the new pines. After 28 years of growth the new pines are about 20 feet tall and 4 or 5 inches in chest high diameter. There were also a few standing,

Photo by D. Sillman

older trees that somehow survived the 1988 fire. Pine cones were seen on the older trees and also on many of the young, re-growth trees. They were also seen in the growing mass of dry material that was accumulating on top of the sandy soil. Although a few understory plants were observed (especially “fireweed” (pictured to the left)) in the incompletely shaded forest floor, most of the plant growth in this forest were lodgepole pine seedlings, saplings and pole trees. The scattered herbaceous plants provide food for grazers (like elk and deer), but they will soon be shaded out by the coalescing pine canopy.

Photo by D. Sillman

A similar burn area in between Yellowstone and the Grand Tetons was described in a recent New York Times article (September 13, 2017). This lodgepole pine forest burned seventeen years ago (in 2000). The pre-fire forest was 200 years old and, so, had a substantial cone and seed reserve. The post-fire response was robust with 32,000 lodgepole pine seedlings per hectare densely filling the burned area. This recovery forest, though, did not have its ecologically expected 100 to 300 years to grow and accumulate new cones and seeds. Instead, because of ongoing climate change and the associated elevated temperatures and reduced moisture (especially reduced snowfall) a part of this young forest re-burned in 2016. Because of the very short time interval between forest fires, this forest had a very small cone and seed reserve and re-generated a very sparsely treed pine forest (only 400 lodgepole pine seedlings per hectare (1.25% of the original post-fire forest)). These scattered pine trees will never completely shade their forest floor and, so, will be under intense competition from aspens and a wide variety of herbs and grasses. It is possible that this more sparsely treed forest will not be sustainable or stable. It is, in fact, possible that these more frequent burnings could lead to the extinction of the lodgepole pine!

Lodgepole pines make up 80% of the trees in Yellowstone National Park. The transition of this pine forest into one dominated by aspens or some other deciduous species would radically change the ecological dynamics of the entire Greater Yellowstone Ecosystem.  Every organism from marmots and elk to grizzly bears would be affected. We’ll just have to wait and see if the pine forests find some new way to survive.




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Signs of Fall 5: Yellowstone

Photo by L. Kalbers

I had the great pleasure of visiting Yellowstone National Park this past August as part of my daughter’s “wedding week.” My immediate, and wonderfully expanding family (Deborah and I, Marian and Lee, and Joe and Marlee) met up in Gardiner, Montana and did some day hikes in the park. We then took a long, touristy drive down through the park, past the Tetons and through Jackson Hole on our way to Victor, Idaho for the wedding. It was a wonderful week (and a wonderful wedding, too, by the way!).

I have been trying to write about Yellowstone ever since but have had trouble narrowing down my focus to some describable aspects of the place. I wanted enough detail so that I could be ecologically accurate on whatever subject I settled on, but I also wanted to connect the pieces of all of the geology and ecology that surrounded us. Yellowstone is not an easily narrowed space or topic!

When you drive into the park you feel that something has changed around you. There is something unusual about the shapes of the surrounding mountains and the dimensions of the valleys that they surround. Yellowstone is not Montana or Wyoming, it is a world unto itself. It looks different and it feels different, too. As my new son-in-law, Lee, pointed out, many of the mountains we were driving past and hiking through were actually rims of ancient, volcanic calderas, and many of the rock formations we were looking at were, in fact, relics of the eruptions that created these calderas. The size and scope of Yellowstone Lake in the center of the park is also startling: this is a region of mountains, dry grasslands and fast rushing rivers! Where did this huge mass of still water come from, and why is it bubbling around its edges?

Public Domain, Wikimedia Commons

So even without “book knowledge” of the fifty mile wide mantle plume of hot magma that rises up under the park, or a visualization of the melted ball of crust that the magma is generating and sustaining just three miles beneath the Earth’s surface, you can see that Yellowstone is topographically different from almost any other place on Earth. When you then add the geysers and mud pots and hot springs and the rainbow array of colors that all of the dissolved minerals and all of the ancient, thermophilic bacteria generate (2/3 of the world’s geysers and half of all of the world’s geothermal features are found in Yellowstone!) you know, to quote Dorothy from the Wizard of Oz, that this “isn’t Kansas anymore!”

National Park Service

The Yellowstone system has had three, “supervolcano” eruptions over the years: 2.1 million years ago, 1.3 million years ago, and 630,000 years ago. These eruptions deposited thick blankets of ash many hundreds of miles away, caused extensive species’ deaths and maybe even  extinctions and probably altered the climate of the entire Earth. Each eruption was thousands of times larger than the 1980 eruption of Mt. St. Helens, and they left behind the distinctive topography of present day park.  The North America tectonic plate, on which Yellowstone sits, is moving toward the southwest at a rate of about one half an inch a year. The plate, then, is slowly dragging itself across the stationary mantle plume and has generated a whole series of “ancient Yellowstones” off to the south and west of the park’s present day location.

USGS, Wikimedia Commons

The volcanic history of Yellowstone can also be tactilely experienced! On one of our hikes in the north-central part of the park, there were large boulders and scattered pieces of obsidian (volcanic glass). We picked up some of the smaller pieces and could feel their incredibly smooth textures and could rub our thumbs across their sharp edges.  Lee showed us on several medium-sized pieces etchings made by Native Americans hundreds of years before as they flaked off sharp arrow and spear points. These obsidian deposits were an important resource for weapons and tools of these hunter-gatherer peoples.

Obsidian can also be used to make surgical scalpels that have cutting edges that are sharper and more smoothly configured that even the finest metal blades. Cutting edges of only three nanometers are possible in these obsidian scalpels. Research has shown that surgical incisions with an obsidian blade generates less of an inflammatory response and initial scar tissue formation than the finest, metal scalpel. Possibly, someone will return to these obsidian cliffs to gather and flake these unique volcanic rocks to make the surgical tools of the future.

Photo by L. Drake

We saw so much in Yellowstone! Elk and bison, mule deer and bald eagles, moose (some of us saw moose, anyway, not everybody was that lucky), big-horned sheep, grizzly bears and wolves! Our wolves were out in a big, wet field about a quarter of a mile off of the roadway. They attracted a large, roadside crowd but seemed unconcerned by the growing audience or all of the attention and clamor. The two wolves played in ways familiar to anyone who has dogs: forelegs down, hind quarters up, circling, lunging and sparring with each other, tongues lolling out of their mouths, joy on their faces.

Photo by D. Sillman

The whole roadside traffic jam phenomena was amazing to experience. We frequently stopped to see people staring at an old log a hundred yards or so off the road (”we thought it was bear”), or at marmots emerging from their burrows (“we thought they were badgers”). One of our really great sightings, though, went unappreciated by the traffic: an isolated wetland full of sandhill cranes! As I wrote a couple of years ago, I had hoped to see the migrating sandhills down in New Mexico the March week that Deborah and I went down to see our daughter.  The cranes were reported pausing near Albuquerque along the Rio Grande up to a day before we got there! We went out right away, but they had flown on north toward their summer, breeding territories (maybe to Yellowstone!). We got a wonderfully long look at them in Yellowstone, though, and Deborah took a number of great pictures. While we were looking at them,  a couple of people drove by and stopped to check on what we were looking at. After we told them they said, “oh, just birds,” and drove on. How sad. What birds they were, indeed!




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Signs of Fall 4: Make Mine Plastic

Photo by jdxyw, Flickr

The family friend who leaned in to young Ben (Dustin Hoffman) at the party in the movie “The Graduate” and whispered the single word of advice that would lead to Ben’s future success and happiness (“plastics”) was well-meaning, I am sure. That the word carried a whole matrix of connotations (synthetic, cheap, superficial, fake, non-natural) was not the fault of the man giving the advice or even of the material he was advocating.  Plastic is something we all use, something upon which we all rely, and something that our society is making in absolutely unbelievable quantities.

Plastics are human manufactured materials. They were invented 110 years ago (the first plastic was “bakelite” invented by Leo Baekeland in New York in 1907). Plastics are large polymers of repeating organic subunits with very high molecular weights and, depending on the specific building block subunits, a wide range of properties and uses. Most of the organic building blocks of plastics come from petroleum or natural gas, but there is a great deal of research into and commercial interest in the use of renewable organic materials (cellulose etc.) to make these polymers.

Photo from Grendz,com

Roland Geyer (University of California, Santa Barbara) in a paper in Science Advances (July 19, 2017) estimates that since the invention of bakelite we have produced 8.3 billion tons of plastics. That is enough plastic, according to Geyer, to cover the entire country of Argentina ankle deep in plastic materials. Geyer also notes that almost all of this plastic is non-degradable and will, along with all of the rapidly accelerating yearly production of new plastics, be with us for hundreds of years. We are conducting an unintentional, global experiment in which we are wrapping the Earth in plastics.

National Geographic explored the Geyer article and noted that 91% of all plastics are not recycled. Most ends up in landfills but many millions of tons a year pollute our oceans, land masses, and food webs.

Photo by JJHarrison, Wikimedia Commons

Sea birds and many other marine vertebrates consume floating plastics in large, and often fatal, quantities. Matthew Savoca and his research group at University of California, Davis analyzed floating ocean plastics (Science Advances, November, 2016). They found that the floating plastics were covered with algae and that these algae were being consumed by zooplankta called krill. Further, when these tiny krill ate the algae, the algae released a distress chemical called dimethyl sulfide at levels detectable by seabirds and, probably, other marine vertebrates. These animals were attracted to the dimethyl sulfide because it indicated the presence of the krill and, maybe, the myriad of other organisms that feed upon the krill! So, the seabirds were attracted to and preferentially consumed the floating bits of ocean plastic!

In a related paper published by Jennifer Lowers of the University of Tasmania (Proceedings of the National Academy of Sciences (May, 2017)), another consequence of floating oceanic plastic debris was examined. Henderson Island is an uninhabited, “desert” island in the middle of the Pacific Ocean that is over 3000 miles from any industrial center or large town. Henderson Island’s shoreline, though, is covered with 17 tons of plastic debris. Turtles get caught in tangles of plastic lines and cords, crabs use plastic containers as homes and refuges, and debris is layered all the way up to the high tide line. It is the highest density of plastic pollution found anywhere in the world. All of this plastic debris has arrived at Henderson by the floatation delivery system of the converging currents of the central Pacific  The magnitude of this “pristine” island’s level of plastic pollution reflects the ever-building plastic content of our befouled oceans.

Photo by Mypix, Wikimedia Commons

A recent article in The Scientist (June 1, 2017) further illustrates the blessing and the curse of plastics. In the northcentral and northwest regions of China agricultural production has been historically inhibited by the very dry and relatively cool climate. Over the past thirty years, though, great increases in crop production has come about because of the use of plastic film soil mulching. China currently utilizes 80% of the world’s plastic sheet, field mulching (Photo is from a field on the Isle of Wight, U.K.). Long, white sheets of thin plastic spread across planted fields help to increase soil moisture and temperature and, thus, increase the growth of a wide variety of crop plants. Every year fields equal in size to half of the area of the state of California are covered in the “white revolution” wrapping of plastic. Remarkable increases in yield and moisture efficiency have been seen in maize, wheat, cotton and potatoes throughout this formerly unproductive region.

Unfortunately, though, there are costs of using so much plastic in these fields. The sheets are very difficult to recover after crop harvesting. The thin plastic tears and fragments and ends up becoming incorporated into the soil itself. This “white pollution” changes the physical and chemical properties of the soil and alters the soil microflora, micro and macro-fauna and the growth potentials of the crops subsequently planted in plastic laden soil.

The synthesis of many plastics involves the use of a diverse array of toxic chemicals, and a finished plastic frequently contains detectable levels of these toxins. Plastics, then, that accumulate as pollutants in soil and water systems slowly release these chemicals into their ecosystems and can represent micro-pollution sources that will persist for centuries.

Plastics also attract a wide array of fat-soluble, non-degradable toxic chemicals that enter ecosystems from a variety of other sources. Dioxins, PCB’s, DDT’s, and PAH’s have all been found adhering to the surfaces of floating, marine, plastic pollutants. These toxins, because of their hydrophobic natures accumulate in the tissues of any organism unlucky enough to consume them. These “bioaccumulated” chemicals are passed up food chains in ever increasingly large concentrations. “Higher order” consumers, then, (large fish, sea birds, etc.) will bear the brunt of negative impacts of these powerful, toxic pollutants.

So, whisper or shout the word “plastics!” To rework a phrase, they are “the answer to and the cause of so many of our problems!”




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Signs of Fall 3: Cavity Nesting Team 2017!

Photo by D. Sillman

Over the past three years I have written a number of blogs about the work of our Cavity Nesting Team in Harrison Hills Park in northern Allegheny County. The Team has twenty-eight nesting boxes scattered across the park that are monitored weekly from the first of April through the end of August. The Team’s goal is to encourage the reproduction of bluebirds and other cavity-nesting species and to better understand the dynamics of their biology and ecology. Data from our 2015 and 2016 studies helped us design two experiments for 2017

This year’s Cavity Nesting Team consisted of ten volunteers: Sharon Svitek, Deborah and I took turns monitoring the boxes in and around the “High Meadow.” Patrick and Mardelle Kopnicky and Dave and Kathy Brooke checked the boxes around the “Bat House Meadow.” Chris Urik and Odessa Garlitz took turns monitoring the boxes at the park entrance and up in the field near the Environmental Learning Center, and Paul Dudek checked the boxes around the pond and soccer fields in the southern end of the park. After each box was checked the observers uploaded their data to an on-line Google spreadsheet. Each week, Deborah compiled and distributed the growing data tables to each member of the team. Chris Urik also made GPS maps of the park showing the precise location of each nesting box.

Native cavity nesting bird species (eastern bluebirds, tree swallows, house wrens, Carolina wrens, titmice, chickadees, nuthatches, etc.) naturally use tree holes for their nesting sites. These holes are most often found in older, often dead or dying, trees, and they are typically abandoned cavities that have been chiseled out by woodpeckers. Any site management plan that favors woodpeckers (like allowing dead trees to remain in the forest and not managing the forest or manipulating it into an even aged stand) will favor cavity nesting bird species.

Nest boxes, of course, are artificial substitutes for these natural tree holes.

So what did we see in our 2017 study?

K. Thomas, Public Domain

Bluebird reproduction was very comparable to 2016. Half of our 28 boxes had bluebird nests (and 10 of these boxes also had bluebird nests in previous years). There were slightly fewer eggs this year (81 this year versus 83 in 2016). Overall fledgling numbers, though, and fledgling success was higher this year than last (70 fledglings in 2017 vs. 63 in 2016 (86% success vs. 76%).

There has been a steady decline in the number of nest boxes used by tree swallows in our three annual collections. This year only 3 boxes had confirmed tree swallow nests (compared to 9 boxes in 2015 and 6 boxes in 2016). Further, only two of these nests actually had eggs. There were no observed tree swallow nestlings/fledglings in 2017. This was due to difficult viewing conditions in these two nests (they were deep nests with many lining feathers, and the brooding adults refused to leave nest during observation) rather than to there not being any nestlings or fledglings to observe. But no data is available on the “egg outcomes” for these two nests. It is reasonable, though, that these 9 eggs fledged far fewer than the 22 tree swallow fledges of 2015!

K. Thomas, Public Domain

We hypothesized that last year’s decline in tree swallows may have been due to a hot, dry summer that reduced the mid-summer supply of insects (especially insects that have aquatic larvae) upon which the parental tree swallows rely to feed their young. The weather of 2017, though, was normally wet and moderate in temperature. Aquatic insects should have been quite abundant for the June nesting tree swallows.

We also discussed the possible impact of purple martins on the tree swallows (purple martins returned to Harrison Hills in 2015 after a long absence). There are no reports in the scientific literature that describe any negative interactions between  purple martins and tree swallows. The director of the Harrison Hills purple martin project (Ken Kostka) indicates that martins take larger insect prey at higher altitudes than tree swallows, so competition for food resources does not seem a reasonable explanation for the apparently declining numbers of tree swallows.Some nesting pairs of tree swallows, though, have been observed in the purple martin communal nest complex near the Environmental Learning Center. Exactly how many tree swallows have nested with the martins has yet to be determined. Could the tree swallows of Harrison Hills Park be using these communal, martin nests instead of the isolated nesting boxes and thus be avoiding our weekly egg/fledgling counts?

Photo by dfraulder, Wikimedia Commons

The increased presence of house wrens may also explain some of the decline in tree swallow numbers. Eight nesting boxes this year had house wren nests (compared to 9 in 2016). The only year we observed robust tree swallow nesting and reproduction (2015) we had no house wrens nesting in our boxes. The house wrens concentrate their nesting just prior to the onset of the tree swallows’ reproduction. Possibly their presence kept the tree swallows out of our nesting box system.

House wrens are extremely aggressive and destructive birds. They are one of the most common causes of nest failure in bluebirds, tree swallows and chickadees. They destroy eggs, kill nestlings, and even kill adult birds (typically then throwing the broken eggs or dead birds from the invaded nest so that they can then start their own nesting cycle). Also, male house wrens attempt to attract females by building numerous “dummy nests” (piles of sticks sometimes stacked up on the active nests of other birds!).Our experiments this year involved devising ways to reduce the impact of house wrens on our other cavity nesting bird species.

Experiment #1:  we tried to orient the nest box openings away from surrounding vegetation and edge ecotones (habitats in which we hypothesized house wrens were likely to lurk). Reducing the visual stimulation of nesting birds entering and leaving their nest box, we hypothesized, might reduce the frequency of nest parasitism.  This re-orientation of the box openings, though did not have any effect on house wren activity.

Experiment #2: we planned to remove the house wren “dummy nests” to discourage house wren reproduction. This also was not successful. Timely dummy nest removal would have required more frequent interventions with our nest boxes than our sampling scheme allowed. Our boxes were significantly and comparably (compared to 2016) utilized by house wrens for reproduction possibly (as I indicated above) to the detriment of the tree swallows.

So, our nest boxes are serving our bluebird population very well. We are trying to figure out why tree swallow numbers are so low, and would like to come up with an effective plan to reduce the use of our boxes by house wrens. All that will part of 2018!

Happy Fall, everyone!

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Sings of Fall 2: Kiski the Eagle

Photo by Frommer, Wikimedia Commons

Last April, I had the honor to give a “Last Lecture” to my colleagues and students at Penn State New Kensington on the occasion of my pending retirement from Penn State. The title of my talk was “The Bald Eagles of Pennsylvania.” I chose this topic not because it was part of my research agenda or because I was an expert on eagles (neither was anywhere close to the truth!), but, rather, because I get a visceral thrill when I see a bald eagle flying overhead and the bald eagle population of Pennsylvania has undergone dramatic (and wonderfully positive) changes over the 34 year time period that I had had the privilege of teaching at Penn State. I felt that I could use the topic of bald eagles to convey to my audience both my love of the natural world and as an example of how a few simple, logical conservation measures could lead to the repair and resurgence of some part of our historically and carelessly damaged environment.

When Deborah and I moved to Western Pennsylvania in 1983, it was possible to see bald eagles (mostly up around Lake Erie) but they were very uncommon and to see them required a lot of hiking or canoe paddling (and luck!). In the past four or five  years, though, mating pairs, year round residents, and overwintering groups have all been seen with great regularity all around our area. I live in Kiski Township in southern Armstrong County and over the past three or four years I have seen bald eagles flying over my house! I have also seen them flying overhead when Deborah and I drove back and forth to work . Once Deborah and I even saw a bald eagle perched along the Kiski River just across the street from the Sunoco Station in North Apollo!  The sight of these birds, even though it is getting more and more common, is still very exciting (you can talk about cell phones being a driving distraction, an eagle flying over your car is a REAL distraction!!).

Photo by C. Chapman, Wikimedia Commons

A couple of weeks ago, a bald eagle was spotted behaving oddly down along the Roaring Run Watershed Association Trail in Kiski Township. The eagle, a mature male, was perched on a low branch close to the trail and was apparently unconcerned and unaffected by passing trail hikers and bikers. Many people took pictures of this eagle, but a few recognized that this bird was quite probably in great distress. After twenty-four hours, one of the officers of the Roaring Run Watershed Association called the game commission, and with luck and agility (and a blanket) they were able to capture the obviously ill eagle.

The eagle (which would be named “Kiski” in the media) was taken to the Verona wildlife rehabilitation center where it was x-rayed. A foreign object was noted in Kiski’s stomach, and he was transferred to the Tamarack Wildlife Rehabilitation Center in Saegertown, PA. The object in Kiski’s stomach was made out of lead (a fish sinker from a scavenged fish? Shotgun pellets or lead bullets from a scavenged kill of un-buried gut pile?), and Kiski had extremely toxic levels of lead in his body.

Kiski was thirty years old! This is extremely old for a wild bald eagle (fifteen or twenty years is the expected life span in the wild). News reports indicated the he was brought to Pennsylvania when he was quite young (possibly from  Saskatchewan). He was banded when he was released in 1987 near Harrisburg, PA, and is thought to have mated several times over the years producing offspring that have added to our re-surging population of bald eagles.

Kiski was struck by a car in 2012 up in Butler County (a common bald eagle accident because of their propensity to feed on road kills) and was treated for head injuries and bruises at the wildlife rehabilitation center in Harrisville. He was subsequently released back into the wild and then was re-identified after he was captured on the Roaring Run Trail.

Photo by A. Morffew, Flickr

Lead is an extremely serious threat to bald eagles. The University of Minnesota Raptor Center reports that over the past twenty-five years 21 to 25% of the sick or injured eagles they have treated have had toxic levels of lead in their bodies. In 2011, the Upper Mississippi River Wildlife Refuge reported that 38% of the dead eagles they recovered had been killed by lead poisoning. The Pennsylvania Game Commission reported that in 2015 and 2016 40% of the dead bald eagles that they recovered had toxic levels of lead in their bodies. The feeding habits of this magnificent bird and their opportunistic consumption of carrion exposes them to high levels of lead in unrecovered ammunition and fishing tackle.

It is very sad that the story of Kiski the eagle does not have a happy ending. Kiski died of lead poisoning about a week after he was taken to the Tamarack Rehab Center. The veterinarians and technicians at Tamarack did all that they could, but the lead levels were just too high, and Kiski, the “grand old man” that he was, to quote one of his Harrisville care givers, was possibly too old and debilitated to continue his struggle for life.

Kiski the eagle represents both a great success story and also a pointless tragedy. Our eagles are back, but we need to help them stay healthy and active. Lead in the environment hurts everyone whether it is in water, air, or in a solid form that can be ingested by animals. There are many reasonable alternatives to lead! We as reasonable people need to agree on this and do what we can to make our environment safe for all of Kiski’s offspring and for all of us!



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Signs of Fall 1: Finding Baby Birds

Photo by D. Sillman

This is a photograph that popped up in my email a couple of weeks ago. It was accompanied by a phone call asking what kind of a bird it was and what “we” should do with it. I recognized the type of bird right way, but after hearing its story of being found and then transported many miles away from its home, I despaired a bit for its future.

Every one of us has either found a baby bird hopping around on the ground making loud, “I-don’t-know-how-to-fly” noises, or we have received such a bird from some well-meaning relative, friend, or acquaintance. This is a situation that pits our emotional selves (“the poor little bird!”) against our scientific selves (“he’s fine, or if he isn’t, that’s fine, too!”).

What do the experts say about this? The United States Fish and Wildlife Service (US-FWS) has an excellent web page about what to do when you find a baby bird. They categorically state that the best thing you can do for the bird is to leave it alone. Its chances for survival are much higher if you don’t interfere with whatever is going on (and this is very important: you don’t know what’s going on when you see this little bird trundling around on the ground! Maybe there are reasons (and benefits) for his being there, maybe it’s just some random mishap. Knowing that you don’t know what is going on may be the first step toward some type of ecological, Socratic wisdom!).

Sialis is a web site named after the genus (and also the species) name of the eastern bluebird (Sialis sialis). It is a wonderful set of pages loaded with a great deal of practical information about bluebirds and many other types of small birds. The web site is the expression of a single person’s emotional and intellectual connection to all of these fantastic, little creatures. I recommend you go there and browse around its pages. Anyway, Sialis has the same basic philosophy as the US-FWS: if you find a bird, leave it alone! Although, the site does then goes into a detailed set of possible contingencies, exceptions and scenarios.

Baby robins, Free Image, Pixabay

First and foremost you should know that it is illegal to possess a wild bird or any other wild animal. The laws that govern this are extremely logical and are designed to let wild animals live as freely as possible away from human interference. Also, an untrained person trying to raise, say, a wild baby bird almost certainly guarantees that that baby bird is going to die.

So, what if there are dogs and cats around in the yard where the baby bird is chirping about? Best thing to do is to put the dogs and cats somewhere else and let the bird follow its destiny. If that’s not possible, gently remove the bird from the ground level (picking it up in a pillow case or t-shirt is best so that you don’t snag its toenails or feathers) and place it up somewhere out of reach of muzzles and claws (in a bush or up on a tree branch, or back in its nest if the nest is visible and accessible). Your scent will not affect the treatment of the baby bird by its parents (that’s an old Mother’s Tale designed to keep children from handling baby birds). You might even make an artificial nest or protective enclosure for the bird to help to keep it safe (check out the Sialis description of these kinds of nests and enclosures!). If none of these options are possible, then you might have a reason to take the bird out of its yard. This removal should only be done with great caution and reluctance, though. The baby bird’s parents are probably lurking nearby with beaks full of mushed crickets and caterpillars. The web sites say you watch the bird for at least two hours before presuming that it is abandoned.

Why would the baby bird be on the ground in the first place? Maybe the nest got too crowded, and the bird and possibly several or all of its clutch-mates had to abandon their cozy egg-home. Getting out of the nest, in fact, may help to reduce predation on the nestlings! Nest predators (like possums, raccoons, hawks, jays, crows, and maybe even snakes) eventually will cue in on the constant in’s and out’s of the parental birds carrying their phenomenal load of nestling food into the nest. Getting out of the nest as early as possible might just be a very solid survival strategy! Also, many bird species have several days of almost-flying fledging in which the nestlings exercise their growing wings to get to the point of being able to fly. These grounded fledges make up a significant proportion of the “saved” baby birds, but they really don’t need to be saved: their moms and dads are close by and are both watching and feeding them continuously.

Now, that baby bird might be on the ground by accident and for no good reason or for any benefit to themselves is also a possibility. Maybe their nest fell apart, maybe there was a wind storm, maybe the branch the nest was placed was rotten. Equally possible, though, is that the parental birds screwed up. They didn’t display the optimal behaviors in nest site selection or building or in their nestling rearing practices. If so, Natural Selection might be best served if those parental genes were not continued in the population.

Like Richard Dawkins has said: Nature is not cruel or kind, it is just indifferent to suffering.

Photo by K, Munsel, Wikimedia Commons

The little bird that started this whole story is a cedar waxwing nestling that must have gotten blown out its nest in the storm of the night before. He was scooped up into a box and then put into a bag to keep him away from a cat and a dog, and then he was driven to Penn State New Kensington. I retired from Penn State a couple of months ago, but was very happy to get this email and the subsequent phone calls.

I reminded the caller not to give the baby bird any fluids (they would choke) and to see if it would eat some crickets (we keep a supply on hand for our departmental frogs). Young cedar waxwings are fed a rich supply of insects and only slowly transition into almost exclusively fruit eating adults.  I also said that they needed to take it to a rehab center. Only a trained person (or a parental bird!) would know how to feed and care for such a young bird.

The very good news is that Lil Waxy (my name for the baby bird) ate a couple of crickets and was taken to and accepted by the wildlife rehab center in Verona. They said that were expecting quite a few cedar waxwing nestlings (the waxwings have a second nesting cycle in August and tend to build their nests quite high up in trees). They would keep the young waxwings together (they are an obligatory group oriented species) until the spring when the migrating waxwing flocks returned to Western Pennsylvania. Then they would release the kept individuals and let them re-join the large flocks. It was a happy ending.

It costs a great deal of money to hand raise and keep young songbirds! I have sent the Verona facility a donation already. If you would like to help out, just click on this link. Maybe Nature isn’t kind, but we all can be!




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Signs of Summer 15: Ecology of Our Bodies (Fasting)

Photo by lyzadanger, Wikimedia Commons

Last week I talked about fad diets and Metabolic Syndrome (the syndrome of obesity, high blood pressure, low serum HDL’s, high serum triglycerides, and elevated fasting glucose). Metabolic Syndrome is caused by an imbalance between energy consumption and energy utilization by the body. Quite simply, too many calories are being consumed and too few calories are being used in metabolism. This simple equation, though, is just the start of the discussion of the syndrome because, quite possibly, it is not just the amounts of calories being consumed but the types of calories (and this is the foundation of many of the fad diets I talked about last week). It is also possible that modern foods because of the nature of their cultivation, growth, processing or preparation tip the metabolic balance of a person’s physiology to obesity and to the array of Metabolic Syndrome signs. It is also possible that our modern lifestyle has so modified (or destroyed) our natural, bacterial microbiome that these important mutualistic organisms no longer help us to control the flow of energy through our bodies.

There is, though, another way to look at our interactions with food and eating. Possibly, the constancy of food availability due to the efficiency of our agricultural systems has disrupted our natural metabolic cycles, or, possibly, our natural, day/night activity patterns have been so compromised by artificial lights and societal activity patterns, that the circadian rhythms of our body’s homeostasis have spun out of control.

Public Domain

Let’s think about how we have consumed food through most of our evolutionary existence. One very influential evolutionary model stresses periods of feast and famine. Hunter-gatherer humans eked out a meager, barely sustainable existence by gathering edible roots, plants and seeds from their surrounding environments. These times of low calorie acquisition were then punctuated by hunters from the human group bringing in large game items upon which the tribe would then feast. This model has led some to propose that human physiology, since it evolved under stresses of feast and famine, would work most optimally if extended period of fasting (one to several days) were intruded into a person’s weekly or monthly feeding cycles.

This hunter model has a distinctly male orientation (and, not surprisingly, it was written primarily by male ethnologists who were predominantly in contact with the males of the tribes they were studying). This model emphasizes the bravery, skill and potential sacrifice (limb and life!) of the male hunters to sustain the vigor and continued existence of their tribe. It is also, upon closer examination particularly of low latitude hunter/gatherer peoples, not at all accurate.

iKung bushmen. Photo by I. Sewell, Wikimedia Commons

Present day hunter/gatherer societies (with the exception of those in high latitude (resource limited) environments) derive two-thirds of their caloric intake from plant food sources (K. Milton, The American Journal of Clinical Nutrition, December 2000). Often these tribes rely heavily upon a specific plant’s seed, nut, stalk or root that is abundantly and consistently available in their environments (like the iKung in the Kalahari and the mongongo nut, or the tribes in New Guinea and the wild sago palm, or the native American tribes in California and acorns from wild oak trees). These sustaining plants are easy to find in the tribe’s environment and not difficult or dangerous to gather and harvest. Even in habitats like the game-rich Serengeti of Tanzania, the hunter/gatherer people (the Hazda) primarily rely on wild plants for their food.

The idea, then, they humans evolved under this extended stress period of caloric deprivation is probably not accurate. There is, though, a more subtle way to think about fasting. Within a twenty-four hour period, humans were, under natural conditions, active during the daylight hours and inactive at night. Were the genes and proteins that regulate digestive metabolism influenced by this very distinct day/night pattern? If so, do they still exhibit this day/night tendency? Is it possible to use intermittent fasting (fasting for the length of the “night” interval of a twenty-four hour period) to optimize the activity of these genes and proteins? These types of fasts are referred to as “time-restricted feedings,” and they are the focus of some very interesting research (as summarized in an article by B. Grant in The Scientist, June 1, 2017).

Photo by

The liver is the organ that controls almost all of intermediate metabolism for the body. The products of digestion (the sugars, amino acids, and, eventually, the lipids) all pass through the liver for processing, storage, or subsequent transport to the other cells of the body. The genes that regulate the activity of these vital liver cells turn on and off during each twenty-four time period. Experiments in mice showed that 90% of the liver cell genes stop their activity oscillations during periods of intermittent, twenty-four hour fasts or time restricted feedings of 8, 9, and 12 hours (during the twenty-four period). Stopping these oscillations increased insulin sensitivity (i.e. decreased insulin resistance), decreased blood glucose and protected the mice against diabetes, cardiovascular disease, high cholesterol, and fatty liver disease.

In the brain, neurons in times of caloric restriction make proteins that help to protect themselves from DNA damage or protein degradation. One of these proteins, “brain derived neurotropic factor” (BDNF), increases under these types of stresses and leads to greater number of mitochondria in the neurons of the hippocampus (the part of the brain involved in the consolidation of short-term memory into long-term memory).  In fasting rats, the increased energy robustness of these vital memory neurons may explain their improved performance on learning and memory tests. Further, fasting, along with exercise reduces inflammation in the brain tissue by decreasing levels of inflammatory cytokines and stimulates the hippocampal neurons to grow nerve fibers and make new synapses! These impacts on the hippocampus may be the basis of memory improvement after fasting that is seen in Alzheimer’s disease animal models and animal post-ischemic stroke experiments.

The immune system is also affected by periodic fasting. In mice, the autoimmune T-lymphocytes of Multiple Sclerosis decrease both in number and activity after fasting. This reduces the destruction of myelin sheath around nerve fibers. Further, oligodendrocytes (the glial cell in the Central Nervous System that synthesizes myelin) are stimulated after fasting and re-myelination of many damaged nerve fibers occurs. In the mouse-model of Multiple Sclerosis, 20% of the mice went into non-symptomatic states and 50% went into less severe symptomatic states after fasting.

Lung cancer cell. dividing NIH. Public Domain

Cancer treatments (using mouse models of breast cancer and melanoma) that couple chemotherapy with fasting showed a synergistic effect leading to accelerated control and destruction of the cancerous cells. Researchers feel that the fasting preferentially stresses the rapidly replicating cancer cells while simultaneously stimulating stem cells to replace the cancerous cells with normal cells. There are suggestions, then, that not only the epidemic of Metabolic Syndrome but also the incidence of diabetes, Alzheimer’s disease, Multiple Sclerosis and cancer may be treatable with some sort of fasting co-therapy. Consideration of our evolutionary history takes us in such surprising directions!

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Signs of Summer 14: The Ecology of Our Bodies (Fad Diets)

Photo by Evan-Amos, Wikimedia Commons

Over the years I have read about, been lectured to about, and even tried a number of the fad diets that have been popularized in the media. Most of these feeding regimes have their foundations in the very casual (and often very selective) reading and interpretation of nutritional science literature. Fragments of ideas and stretches of inference from very slim data sources regularly get translated into diet books or TV celebrity-endorsed diet programs that have little or no long-lasting benefit and even less basis in physiological reality.

In Wikipedia (my quick source for background information on almost everything) thirty-four fad diets are listed. Many of these diets focus on abundant consumption of a single type of food (the grapefruit diet, the morning banana diet, fruitinarianism, etc.). While others stress avoidance of entire food groups (like carbohydrates (Atkins diet, the Zone diet, the Sugar Busters diet)) or the massive consumption of those same groups (like carbohydrates (Good Carbohydrate Revolution, the Pritkin Principle)). Further, many of these fads diets define themselves by connection to very visible, highly fit groups or individuals (the Israeli Army diet, the Scarsdale Medical diet, the South Beach diet) without full consideration of the pre-selection and non-dietary forces that might be operational in generating each of these remarkably fit groups of people. The connecting principle of these diets, though, is that they are not scientific and also that are not, in the long run, effective.

Photo by N. McCord, Wikimedia Commons

One very recent fad diet that has tried to wrap itself in a cloak of science is the Paleolithic Diet (also called the Paleo Diet or the Caveman Diet). The foundation of this diet is evolutionary: Humans evolved in extremely stressful environments for several million years. It is logical, in this evolutionary framework, to assume that Natural Selection not only molded our limbs and jaws and brains but also selected for optimal digestive and metabolic systems based on the available foods in our ancestral ecosystems. Therefore, the Paleo Diet maintains, if we only eat those foods for which our bodies are adapted, we will be healthy and fit and happy!

Let’s poke at these ideas a bit and see if they hold up to any scrutiny:

  1. We must remember that Paleolithic humans lived short, and probably quite brutish lives (although this idea is disputed by some of the paleo-promoters). The logic of a very high rate of infant mortality, a high risk of serious injury particularly in the active-hunter age groups (ten to thirty years old), and little or no potential for effective medical intervention for the other disease or injury events that plague everyone through life makes the conventional estimate of life spans between twenty-five and thirty years quite reasonable. Was there time in these short life spans for the more subtle impacts of diet to be selected for? Can’t twenty-year-old’s eat anything and thrive? (I think that I lived on tortilla chips and salsa when I was twenty!).
  2. We can only guess what foods our paleolithic ancestors ate and in what proportions they actually ate them. Further, early human populations living in different ecosystems, quite logically, ate very different foods. Even if we assume that there was a sufficient selective force asserted by diet, the direction of that force would be different in different human cohorts.
  3. One should not ignore the idea that the diet selection force for humans was for an omnivory of almost unprecedented flexibility! Humans had no control over their food sources and had to eat and be able to digest and metabolize almost every type of food stuff in their environments.
  4. And, finally, there is a prevailing myth that humans moving into the ages of agricultural and technological existence stopped evolving: Culture took over from Nature. This simply is not true. Humans evolved under the selective influence of agriculture (to better digest the foods being produced in our agroecosystems) and have continued to evolve to living in densely populated urban areas, to living in extreme environments, and to living with our ever changing, surrounding microbial world. Even if the true diet of our paleolithic ancestors could be described, we are not that person anymore!

Photo by

One of the reasons that these fad diets have been so popular (and abundant!) is that we in our industrialized society are getting fatter and sicker with each passing year. “Metabolic Syndrome” is the name given to the collective package of this set of modern maladies. Metabolic Syndrome involves some combination of three or more of the following conditions: central obesity (fat accumulation around the trunk of the body and waist in a person who is overweight), high blood pressure, low levels of the “good” cholesterol (HDL’s), elevated levels of triglycerides, and elevated fasting glucose levels. Also, often included in this list of metabolic syndrome signs is insulin resistance (or “pre-diabetes”).

In the United States 34% of adults have Metabolic Syndrome. Worldwide, 25% of adults have either a partial or complete set of Metabolic Syndrome signs.

What causes Metabolic Syndrome? It is at its core a consequence of an imbalance between energy consumption and energy use by the body. Quite simply, too many calories are being consumed and too few calories are being used in metabolism. This simple equation, though, has had many very subtle, but very important tweaks. Possibly, it is not just the amounts of calories being consumed but the types of calories (this is the foundation of many of the fad diets I listed above!). Possibly, modern foods because of their specific plant sources or because of the nature of their cultivation, growth, processing or preparation tip the metabolic balance of a person’s physiology to obesity and the array of Metabolic Syndrome signs. Possibly, our modern life style has so modified (or destroyed) our bacterial microbiome that these important mutualistic organisms no longer help us to control the flow of energy through our metabolisms. Any of these things are possible, but the exact cause of Metabolic Syndrome is not yet known.

The factors that are correlated with Metabolic Syndrome are very straightforward: diet (especially the consumption of sugar-sweetened beverages), sedentary behavior (low levels of physical activity and exercise), disrupted sleep patterns, stress, excessive alcohol consumption, and aging. There may also be some genetic predispositions to developing Metabolic Syndrome.

Next week, I will talk about another way to look at Metabolic Syndrome, a way that focuses on our day/night patterns, our circadian rhythms of mental, behavioral and physiological activity rather than on the actual food we consume. Fasting is a logical way to modify the health effects of this model and recent studies on the impact of food deprivation have revealed some very interesting insights into our physiology.

Until next week!

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Signs of Summer 13: Our W.E.I.R.D. World

Klebsiella pneumoniae. Photomicrograph by NIAD, Wikimedia Commons

Two of the greatest accomplishments in human history were the formulation of germ theory (the recognition that many diseases were caused by microscopic entities (primarily bacteria and viruses)) and the development of sanitation technologies (which controlled our exposure to the potentially pathogenic bacteria and viruses around us). Stephen J. Gould, discussing the history of medicine, asserted that sanitation has saved more human lives and prevented more disease and human suffering than any other single medical invention or advance. No antibiotic or other drug, no medical therapy or surgical procedure comes close to the profound impact on human survival as sanitation.

Germ theory was first outlined in the Sixteenth Century, but it did not achieve widespread acceptance in science or medicine until Louis Pasteur and Robert Koch described and defined the science of microbiology in the mid Nineteenth Century. Even after Pasteur and Koch’s incredibly compelling experiments and papers many doctors and scientists clung to the old ideas of “bad air” (“miasma”) as the cause of disease and rejected the ideas of microscopic pathogens as delusional fantasies. The ongoing revolution in thought in the Nineteenth Century in which germ theory supplants these old ideas of disease is a fascinating story that highlights the inherent conservatism of human thought and the destructive influence of blind, collective belief in the control of our concepts of truth and reality. Two books about this time period that I highly recommend are Steven Johnson’s “The Ghost Map” and J. G. Farrell’s “The Siege of Krishnapur.”  Both focus on the causes and treatments of one of the great killers of humanity (cholera), and in both the “old guard” of medicine belittle and dismiss the forces of science and innovation until the reality of the new ideas is too overwhelming to ignore.

So, germ theory (and its technological outgrowth, sanitation) are concepts that have been solidly with us for less than two hundred years. The successes of these ideas and technologies in saving lives are undeniable, but we are starting to see some points of conflict between our new “sanitary” way of living with the bacteria and viruses (and also potential protist and invertebrate parasites) around and within us and the way we have co-evolved with these organisms over the past hundreds of thousands or even millions of years.

Public Domain

For example, modern industrialized societies have taken the idea of sanitation to its logical extreme especially when it comes to infants and children. If exposure to potential pathogens may cause disease, then, logically, you should do anything you can to eliminate the chance of any exposure or contact with any microbe at all. Extremely clean nurseries and homes (and all of the cleaning and sanitizing products that have made this possible) were the goals of the modern, industrialized household. Isolating children from portions of the human population that might carry pathogens and restricting the exposure of children to dirt and contaminants of the surrounding world were considered to be obligations of the modern parent.

These acts, though, had profound impacts on the immune systems of the “sanitized” children. The human immune system has evolved to “expect” a series of pathogen exposures especially in early life. These pathogens allow the immune system to learn to synthesize the correct types of proteins and immune cells to form an efficient, disease fighting system for life. Research indicates that when these early life microbial exposures do not occur, the immune system develops some odd, and potentially destructive pathways that include the generation of allergies, eczema, asthma and, possibly a number of “autoimmune” disease syndromes. This is the essence of the “hygiene hypothesis.” The stunting of the immune system’s evolutionarily derived education/maturation period may at least partially explain the epidemic of allergy and asthma cases that are seen in our industrialized societies.

Hookworm larvae, CDC, Wikimedia Commons

An intellectual continuation of the hygiene hypothesis involves the influence of parasites on the human homeostasis. A number of scientifically credible papers have been published over the past decade in which the influence of hookworm infections on the potential of an individual to resist immune disruptions were examined. For example, in the AAAS (“American Association for the Advancement of Science”) Newsletter of Feb. 20, 2011 a gene was described in a population of Brazilian school children that conveyed resistance to hookworm infections. The children that carried this gene, though, had a higher incidence of asthma than children who did not have a genetic protection against hookworm. Papers in the journal Inflammatory Bowel Diseases indicate that the presence (or introduction) of hookworms into patients with ulcerative colitis or Crohn’s disease lessens the severity of these autoimmune conditions. Further, other studies (some anecdotal and some scientific) point toward the efficacy of hookworm infections as protections against or treatments for a range of immune system disruptions including multiple sclerosis and many allergy syndromes.

Photo by RNW, Flickr

An article in a recent (July 14, 2017) New York Times describes Dr. Ben Trumble’s research on the Tsimané people of Bolivia. Dr. Trumble (of Arizona State University) studies evolutionary medicine and became interested in the incidence of late-onset Alzheimer’s disease in the Tsimané. Many of the Tsimané, once they survive a very high infant mortality period, live well into their ninth decade, so Dr. Trumble was able to test a substantially large cohort for mental acuity. He also did DNA analysis to look for the ApoE4 gene (the gene referred to as the “Alzheimer’s gene” in many industrialized nation studies). He was very interested to see if there were any differences in the incidence of dementia and correlations of ApoE4 in these pre-industrial people compared to the “Western Educated Industrial Rich and Democratic” people (which he refers to as the “WEIRD’s”).

The results were very interesting. In a WEIRD population, an individual with two ApoE4 genes (about 2% of the population) develops late onset Alzheimer’s ten times more frequently than someone who lacks this gene (about 75% of the WEIRD population, by the way, lacks ApoE4). In the Tsimané, though, individuals with two or even with just one ApoE4 genes actually had higher mental acuity test scores than those individuals who lacked the gene. The “Alzheimer’s gene” of western medicine seemed to be working in different ways in the pre-industrial Tsimané. The difference, Trumble hypothesized, was parasites. The Tsimané have very high levels of parasites in their bodies (70% of Tsimané are infected with parasites at any one time!). Trumble suggests that the presence of the parasites allowed the ApoE4 gene to take on a protective role in brain homeostasis, while the absence of the parasites led to the unregulated, and potentially destructive activity of ApoE4 which possibly caused or at least accelerated the mental declines of Alzheimer’s.

Last week, I had the pleasure of talking to Dan Cummings (a PhD student from the University of New Mexico) who is a member of the Tsimane Health and Life History Project.  Dan talked about not only the Alzheimer’s research mentioned above but also about some findings concerning the remarkable cardiovascular health of older Tsimané individuals. The working hypothesis in these studies is that the robust, late life health of these people is related to their life-long exposure to parasites!

Our immune systems are designed to identify and destroy foreign cells inside our body. When it works, our bodies stay free of disease and are able to maintain homeostasis. When our immune system does not work properly, though, cancers can grow out of control, powerful cells and chemicals can destroy our own tissues, and greatly exaggerated (and potentially destructive) reactions to non-dangerous substances can occur. We are just beginning to see how our immune system gets and stays “educated” and focused! Our microbiome, our surrounding microflora, and even our parasites may be important evolutionary and physiological players that enable us to keep the system functioning!


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