Does a Clam Know it’s Alive?

August 15, 2018

The late Carl Sagan guessed there might be 1 million civilizations in our galaxy, the Milky Way.  He based this guess on the Drake Equation–a formula that takes the number of stars in the galaxy and multiplies it by fractions of: sun-like stars, sun-like stars with planets, planets in inhabitable zones, planets where life evolved, planets with intelligent beings, and the percentage in the lifetime of a planet with a civilization.  However, the Rare Earth Hypothesis proposed by Peter Ward and Don Lee in 2000 posits microbial life may be widespread in the universe, but complex life must be extremely rare.  Since the Rare Earth Hypothesis was proposed, astronomers have discovered 3600 exoplanets in solar systems outside our own.  The evidence so far indicates the Rare Earth Hypothesis might be the more accurate guess.  Of the 3600 exoplanets discovered just 1 is a rocky earth-like planet that orbits in an inhabitable zone.  It is known as Proxima b. All other planets found in habitable zones are gas giants with no surface, similar to Jupiter and Saturn.  Though Proxima b is located in an habitable zone, it probably does not support life because it is tidally locked, meaning 1 side of the planet always faces its sun.  Half of the planet is too hot, and the other half is too cold.

Complex life evolved on earth thanks to numerous unique characteristics that apparently are extremely rare elsewhere in the galaxy and probably the universe.  Earth is just the right distance from the sun, and the sun is just the right kind of star.  Our sun is bigger than 95% of other stars.  The habitable zones of planets orbiting smaller stars would have to be much closer, but this would make the planets tidally locked like Proxima b or Mercury.  Moreover, most other solar systems are binary.  Solar systems with 2 or more suns force planets to have wild perturbations in their orbits, causing a great frequency of cosmic impacts that extinguish complex life.  Earth is the only known planet with abundant tectonic activity which helps control CO2 buildup.  Without tectonic activity CO2 concentrations in the atmosphere amplify heat and scorch complex life into extinction.  Venus is an example of this kind of uninhabitable world.  And earth is lucky to have a large moon that stabilizes earth’s tilt.  The earth’s tilt varies between 23.5-25 degrees, but planets without a large moon may vary in their tilt by up to 90 degrees.  The resulting climate instability would cause the complete extinction of complex life.

Microbial life first evolved on earth about 4 billion years ago, but complex plants and animals don’t appear in the fossil record until about 700 million years ago–a colossal gap in time.  Most earth-like planets in the universe probably resemble the early earth of 2.5 billion years ago.  The earth of that time was mostly ocean with a few volcanic islands.  The ocean was brown from cosmic-impacted debris, and the sky was red in an atmosphere of little free oxygen.  Eventually, plate tectonics formed continents, and shallow water environments supported greater populations of photo-synthesizing bacteria that produced enough oxygen to support complex life.

Image result for Illustration of earth's oceans 4 billion years ago

Illustration of early earth’s atmosphere.  Land was restricted to a few volcanic islands and the sky was red in an atmosphere with little free oxygen.

Image result for Thermophilic archaea

Early microbial life on earth resembled these primitive thermophilic Archaea.  They can survive in temperatures exceeding the boiling point.  This suggests microbial life may be widespread in the galaxy, though complex life is much more rare.  It took over 3 billion years for microbial life to evolve into complex life on earth.

Though complex life must be rare, there are between 1-2 billion galaxies in the universe, each with up to 1 billion stars that in turn have close to 10 planets in their systems.  The universe is so vast complex life likely evolved elsewhere besides earth.  But why?

I think the universe would not exist without complex life aware of its existence.  Suppose complex life never evolved anywhere.  Sure, there could be billions of galaxies, but if there was nothing aware of all that matter, it might as well not exist.  No sentient being would know it was there, so it would not be there.  This is why I think the universe produces worlds where complex life evolved.  It is an attempt by the universe to exist.  It becomes self aware through the minds of many individual sentient beings.  This complex life can’t be just a tree or a clam or a thermophilic micro-organism.  I doubt those living things are aware of their own existence let alone the existence of the universe.  Dogs and cats are aware of their existence, but I doubt they contemplate the existence of the universe.  Give them a smelly piece of meat and a caress and that’s as far as their in depth thought of the universe goes.  I believe the universe strives to produce life that recognizes it exists.  Otherwise, it will cease to exist or it may as well not exist because no sentient being would know of its existence.  Without complex life equivalent or above the intelligence of humans, the universe would have no knowledge of its existence, so it would not exist.

Image result for clam

I doubt a clam knows it is alive.  I believe the universe depends on life more complex than this for its existence.  The existence of complex life and the universe is an interdependent relationship.

Reference:

Ward, Peter; and Donald Brownlee

Rare Earth: Why Complex Life is Uncommon in the Universe

Copernicus 2000

 

Advertisements

Pleistocene Bread

August 9, 2018

It is the 20th anniversary of my sourdough starter.  With my sourdough culture I make great bread, pancakes, and dumplings; and it can also serve as an excellent coating for fried fish and shrimp.  Wild yeast living in the atmosphere of Augusta, Georgia helps my bread rise without the need for store-bought yeast during summer months.  (The wild yeast needs some help when the house is cold.)  The discovery of bread must have been an happy and tasty accident.  Hunter-gatherers collected the seeds of wheat and other grains, but to make them more palatable, they removed the chaff, pounded the grains with rocks, and cooked them in water.  Crushed grains left over night or for a few days fermented.  This gruel could be consumed as a primitive beer or baked into bread.  Archaeologists debate over whether beer was a byproduct of bread-making or vice-versa.  Most think the effort to gather individual grass seeds was so tedious when many other plant and animal foods were available that only the desire for alcohol would’ve inspired primitive people to labor so intensely.  It should be noted this primitive beer did not taste like modern beer.  It was sour.  Bitter hops weren’t added to beer until the year 736 AD in Germany.

I started my sour dough culture in 1998 by exposing flour and water to air.

My sourdough bread fresh from the oven.

Archaeologists believe humans didn’t deliberately plant wheat until 10,000 years ago.  Yet, burnt bread crumbs, resembling toaster detritus, were recently discovered at a site dated to 14,400 years ago in Jordan.  The Natufians, hunter-gatherers roaming through the Middle East then, lived in sunken houses with stone floors and fireplaces, and apparently, they made bread.  Today, this region is a desert, but during the late Pleistocene it was an open woodland with many species of edible grasses growing between widely spaced trees.  The people often feasted on gazelle, wild sheep, and hare; and they ate bread too.  The bread was made with a mixture of primitive wheat, rye, millet, barley, possibly oat, and papyrus root.  The latter ingredient likely added necessary sugar to help fuel the yeast.  Modern bakers always add a little sugar or honey to their bread dough.  Archaeologists sifting though the site found 65,000 plant specimens including 95 species, but papyrus was by far the most common making up 50,000 of the specimens.  They also found mustard seed, peas, and of course the wheat, barley, rye, millet, and oats.  Mustard greens are edible, and the seeds were probably used as a condiment.  So some people were already eating bread during the Pleistocene.

Image result for Natufian house foundation

Artist’s representation of Natufian houses in Jordan 14,000 years ago.  The foundations are still visible.  They made bread in these houses.  The landscape was not as barren then as depicted in the illustration.

Reference:

Otaegui, P.; et. al.

“Archaeobotanical Evidence Reveals the Origin of Bread 14,400 Years Ago in North-Eastern Jordan”

PNAS July 2018

See also: https://markgelbart.wordpress.com/2012/08/05/humans-cultivated-figs-during-the-pleistocene/

Were Southeastern Wolves Feral Indian Dogs?

August 2, 2018

Archaeologists uncovered 10,000 year old dog (Canis familiaris) skeletons at 2 sites in Illinois.  The sites are known as Koster and Stillwell.  This is the earliest known evidence of domesticated dogs in North America, though scientists believe dogs traveled over the Bering Land Bridge with humans as long as 15,000 years ago about the same time they were first tamed.  Late Pleistocene evidence of dogs in America has either faded away or has yet to be found, but they were probably here.  The specimens from Illinois date to the Pleistocene/Holocene boundary.  The Stillwell dog was about the size of an English setter, and these early Indian dogs anatomically resemble coyote/dog hybrids (known as coydogs).  I hypothesize the wolves that lived in southeastern North America until about 1917 may have been Indian dogs that simply reverted to a wild state.

Image result for Audubon painting of Indian dog

Audubon’s painting of an Indian dog.  Indian dogs were so wolfish that European colonists often mistook them for wolves.

Image result for Florida black wolf

Illustration of black wolf pack by Kelly Quinn.

Scientists classified the wolves that lived in southeastern North America until Europeans wiped them out as the red wolf (Canis rufus), but nobody really knows what they were.  A DNA test of a few specimens from Arkansas found they were hybrids of coyote (Canis latrans) x timber wolf (C. lupus), and wolves currently living in eastern Canada also appear to be coyote/timber wolf hybrids.  However, this still doesn’t explain what the now extinct wolves that lived in Georgia, South Carolina, and Florida were.  The so-called red wolf is not well represented in the fossil record, and the few specimens identified as red wolves may actually be coyotes.  They don’t appear in the fossil record until after dire wolves became extinct, and I think dogs brought by humans went wild and occupied the vacant niche created when dire wolves became extinct.  Although southeastern wolves varied in coat color, many were melanistic.  The gene for a black coat color in wolves originated in domesticated dogs and that was passed to the wolf population in the rare instances when wolves mated with dogs.  So I believe the wolves that lived in southeastern North America were feral Indian dogs with perhaps some admixture of timber wolf and/or coyote.  They were a primitive dog that like the dingo and Carolina dog readily reverted to the wild, especially those left behind when Indian tribes moved away from an area or died out.  Audubon almost mistakenly shot some Indian dogs because he reported that they looked just like wolves.  This resemblance may have contributed to their extinction, though diseases brought by the European colonists’ dogs were probably a bigger factor.  Europeans often mistook Indian dogs for wolves and killed them or deliberately exterminated them to prevent them from breeding with their well bred dogs..  A DNA study of the Koster specimen determined modern dogs have none of the earlier Indian dog ancestry, suggesting the ancient Indian dogs are extinct.

The Carolina dog descends from a later lineage of dogs brought by Eskimos about 1000 years ago.  Strange as it may seem, these dogs quickly evolved from long-furred Eskimo dogs well adapted to cold climates to the short-haired “Old Yeller” type dogs at home in the hot humid south.  Like the earlier Indian dogs, Carolina dogs also easily revert to a wild state.

The original Indian dogs may be extinct, but they did leave a modern day legacy. The only genetic imprint they left in modern dogs is a sexually transmitted cancer.  Geneticists found this cancer originated in the ancient Indian dogs and was passed on to modern dog breeds.

Reference:

https://www.sciencenews.org/article/dogs-lived-and-died-humans-10000-years-ago-americas

Did Large Carnivores Influence Dune Formation in Ice Age Georgia?

July 26, 2018

Over 100 years ago Australians built a 3480 mile long fence to keep dingoes away from livestock. For ecologists this provides a grand experiment of how the exclusion of a large predator influences ecosystems. However, there exists a considerable amount of conflicting scientific literature about this. Many studies report overgrazed regions on the dingo-less side of the fence that have poor soils as a result. The fence bisects a national park. One study confined to part of this park counted 85 dingoes and 8 kangaroos on the side of the fence with the dingoes, and 1 dingo and 3200 kangaroos in a comparably sized lot on the side that is supposed to be without dingoes. Tame livestock, feral goats and hogs, and rabbits along with the kangaroos contribute to these overgrazed landscapes. Parma wallabies, the greater bilby, and small rodents thrive on the side of the fence with the dingoes because the large canines suppress populations of smaller predators. Another study that claims to be more comprehensive than any other found no differences between either side of the fence. The authors of this study suggest there are no differences because dingoes have never been completely eliminated on the supposedly dingo-less side of the fence. They say other studies concluding there is a difference are local and anecdotal.

Image result for dingoes and sand dunes

Dingo on a sand dune.

I think the most interesting study is a recent paper that found the presence of dingoes influenced sand dune formation in arid regions. On the dingo-less side of the fence sand dunes were larger and stabilized with shrubby plants growing on top. On the side of the fence with dingoes sand dunes were more shallow, bald, and dispersed by wind because plant growth was sparse. This seems counterintuitive. But this difference in dune formation is caused by the suppression of small carnivore populations. Dingoes reduce populations of foxes and feral cats (neither of which are native to Australia). In turn dusky hopping mice and rabbit populations increase, and they eat the seeds of plants and shrub saplings that keep dunes stabilized.

This last study is most interesting to me because sand dunes rolled across parts of Georgia during the coldest driest stages of Ice Ages, and I wonder if large predators influenced their shape and pattern. The arid climate caused some small rivers in Georgia to run dry. Wind blew the riverine sand into big dunes that are still evident today, though scrubby vegetation has since stabilized them. (See: https://markgelbart.wordpress.com/2012/04/09/the-ohoopee-sand-dunes/ ) I’ve hypothesized overgrazing by megafauna alongside shrinking water holes located in the river bed may have contributed to the erosion leading to sand dune formation. But maybe the presence of large carnivores played a role as well. Dire wolves, jaguars, and cougars suppressed populations of bobcats and foxes; causing an increase in rodent and rabbit numbers. The small herbivores stripped the vegetation bare, allowing sand dunes to roll. On the other hand hawks, owls, and snakes probably always remained abundant, and they likely provided a check on rodent and rabbit populations. Nevertheless, the notion large carnivores may have influenced dune formation in Georgia is an intriguing idea.

References:

Glen, A.; and C. Dietman, M. Soule, and B. Mackey
“Evaluating the Role of the Dingo as a Trophic Regulator in Australian Ecosystems”
Australian Ecology August 2007

Harris, Emma
“Dingoes have Changed the Actual Shape of the Australian Desert”
The Atlantic July 6, 2018

Piedmont Plant Species Bartram First Encountered at the Augusta Shoals

July 22, 2018

I’ve read all or parts of Bartram’s Travels hundreds of times, but whenever I re-read it I always find something new that fascinates me.  William Bartram journeyed from Savannah, Georgia to Augusta during 1773, and in his book he describes the flora of the maritime forests, lower coastal plain, and upper coastal plain.  The descriptions are so packed with information I didn’t notice until recently a small paragraph about some piedmont plant species he first encountered alongside the shoals of Augusta.  He refers to this spot as a cataracts.  Several important Indian trails converged here because the shoals afforded a shallow crossing.  Augusta developed as an Indian trading village because of these shoals.  Bartram describes Augusta as a small village that reaches all the way to the “cataracts,” and it was surrounded by “gay lawns and green meadows.”  Augusta is on the edge of the hill country, and species that prefer higher elevations begin to occur here.  Bartram arrived in May when all of these species were in full bloom.  He listed Rhododendron ferruginumPhiladelphus inodorus, Malva, and Pancratium fluitans.   I haven’t visited the shoals in a while, but I don’t recall seeing any of these species next to the shoals.  They’ve been eliminated from the immediate vicinity, though the first 3 are commonly planted as ornamentals in people’s yards.  Bartram wrote Pancratium fluitans inhabited every rocky islet on the shoals.  (The common name of this species is rocky shoals spider lily.  It’s modern scientific name has been changed to Hymenocallis coronaria.)  Unfortunately, today there are just 50 populations of this species left because reservoirs inundate their favored habitat.  The natural beauty of rocky shoals has diminished since Bartam saw them.

Scenes around Augusta, Georgia - Savannah River shoals - Stock Image

Augusta shoals.  The lock was built 100 years after Bartram saw it.

Image result for rhododendron ferrugineum

Rhododendron ferrugineum is a common ornamental plant in Augusta.  It grew wild near the Augusta shoals.

Image result for Philadelphus inodorus

Scentless mockorange is also commonly planted as an ornamental but wild populations grew near the shoals.

Image result for malva sylvestris

Common mallow is a non native species that was already widespread in Augusta by 1773.  This is probably the Malva species Bartram mentions.  There is a native species of mallow–Carolina mallow (Modiola caroliniana), however Bartram described the mallow he saw as blue, and this is the wrong color for Carolina mallow.

Image result for Pancratium fluitans

Rocky Shoals spider lily.  Only 50 populations of this species still exist.  Most have been wiped out by reservoir creation.  In Bartram’s day they inhabited every rocky islet on the Augusta shoals.

Pleistocene Peaches (Prunus kunningensis =P. persica)

July 17, 2018

The ancestor of the modern cultivated peach (P. persica) depended upon megafauna for dispersal and is now extinct in the wild.  Asian elephants and primates such as macaques and early humans ate the fruit and distributed the seeds throughout the environment, but without these species P. persica disappeared from the wild, and now only exists in cultivated fruit orchards tended by modern humans.  Peaches originated in China, and peach seeds dating to 2.5 million years BP have been found there.  Scientists designated these ancient peaches as a unique species they refer to as P. kunningensis, but they admit there is no real difference between this species and P. persica.  Peaches have been cultivated in China for at least 7500 years where evidence of early peach cultivation has been found in the Yangtze River Valley.  Farmers began grafting varieties with larger fruit to pit ratios on to root stocks of other peach trees then.

Peach cultivation spread from China to Persia (today known as Iran) and from there to Europe.  Early Spanish explorers brought the fruit to southeastern North America during the 1500’s, and John Lawson found peach trees thriving in Indian villages when he explored and settled in North Carolina between 1700-1711. (See: https://markgelbart.wordpress.com/2012/07/27/john-lawsons-voyage-to-carolina-1700-1711/ )  The quality of some of the fruit was so much better than European peaches Lawson mistakenly thought some varieties originated in North America.  The real reason American peaches were better than the European fruit was because the climate in southeastern North America was similar to their land of origin–China.  Lawson planted peaches in his orchard, and he had 1 freestone yellow nectarine tree that produced 15-20 bushels every year, unless there was a late spring frost. (A nectarine is simply a smooth-skinned variety of peach.)  He claimed peach trees planted from seed bore fruit in 2-3 years, and the fruit from the offspring was the same as from the parent.  Peaches were so abundant he fed the excess fruit and corn to the hogs, resulting in sweet pork. He also made vinegar from peaches.

Lawson’s account of raising a peach orchard from seeds fascinated me.  Most fruit varieties are mutants grafted on to rootstocks because most wild trees produce fruit of inferior quality.  I researched online and found a discrepancy.  Some agreed with Lawson and claimed fruit from peach seeds produced fruit similar to their parent, but a study written by an horticulturalist from LSU found that fruit grown from seed was usually inferior.  So I conducted my own experiment.  I noticed peach trees often germinated in my compost pile.  I took these seedlings and transplanted them in my yard.  Now, 5 years later I have 4 trees that are bearing heavily.  1 tree produces freestone peaches during the last 2 weeks of June.  All the peaches on this tree were infested with plum curculio larva.  Plum curculio is a beetle that damages all kinds of fruit.  However, I cut away the worm-infested, bird-pecked parts and tasted the fruit.  (Birds get a double treat from my peaches–fruit and protein.)  For an early ripening variety it is a good peach.  The other 3 trees have fruit that ripens throughout July.  1 of them was partially infested with plum curculio, but the fruit is excellent.  Another tree produces very large peaches that are as good as the best farmer’s market peaches.  The 4th tree produces small, bitter, heart-shaped peaches that in appearance resemble the most common variety grown in Georgia and South Carolina–the red globe peach.  I’ve concluded Lawson was mostly right, and the LSU study was wrong.  75% of my peach seeds produced good quality fruit.

Late June peaches from a tree I planted from seed in my yard.  The fruit from this tree had an 100% plum curculio infestation rate.  They were still edible, if I cut away the damaged part.  The quality was good for an early season peach.

This tree produces large luscious peaches. None were insect-damaged but some cracked open because of rain, even though the soil in my yard is sandy and well-drained.  This was the best-tasting peach I ate all season.

This tree is a bit of a natural dwarf.  The fruit is small and bitter.  I’ve read thinning out the fruit may have improved the quality.  I might try that next year.

My experience with this peach tree growing experiment has taught me a few things.  Spraying insecticide doesn’t work.  Rain washes the insecticide off, and the insects just return.  The peaches with no insect damage were growing in open sunlight with no undergrowth.  I hypothesize shade and undergrowth shelters insects from predators and harsh sunlight.  I can’t do anything about reducing the shade over my other 2 peach trees, but I will try harder to control the Virginia creeper.  This vine is tenacious, but I think a thicker layer of mulch might suppress it.  Peaches need more nitrogen than other fruits–more evidence they evolved in plots rich in megafauna manure.  My fastest growing peaches just happen to be growing over the drain field to my septic tank.

The Georgia extension office recommends 58 varieties of peaches, but they don’t even list 3 of my favorite varieties–Indian blood cling, Oregold, and Halehaven.  Peaches stay in storage for just 2 weeks, so many varieties that have different ripening schedules have been developed to extend the season.  They recommend 1 late April variety, 12 May varieties, 16 June varieties, 23 July varieties, and 6 August varieties.  The mid-season free-stone peaches are the best-tasting.  There are also white peaches.  These are sweeter and more aromatic, and in my opinion taste like a completely different fruit.  After my difficult experience however, I recommend other fruit for the casual home gardener in Augusta, Georgia.  Blueberries, figs, muscadine grapes, and even apples are much easier to grow than peaches here, even though Georgia is known as the peach state.

References:

Su Tao; et. al.

“Peaches Precede Humans: Fossil Evidence from Southwest China”

Scientific Reports 2015

A 9 Mile Long Dogwood and Magnolia Grove in Alabama (circa 1775)

July 12, 2018

When William Bartram traveled through the south from 1773-1776 he observed many environments that today are either extinct or very rare.  In southern Alabama just east of Mobile he journeyed through a grove of dogwoods and magnolias that was 9 miles long.  This is how he described it.

We now enter a very remarkable grove of Dog wood trees (Cornus florida) which continuing nine or ten miles unalterable, except here and there a towering Magnolia grandifloria; the land on which they stand is an exact level; the surface a shallow, loose, black mould, on a stratum of stiff, yellowish clay; these trees were about twelve feet high, spreading horizontally; their limbs meeting and interlocking with each other, formed one vast, shady, cool grove, so dense and humid as to exclude the sun beams at noon-day.  This admirable grove by the way of eminence has acquired the name of the Dog woods.

The existence of an almost pure stand of dogwoods this large has long puzzled me.  Dogwood is a common understory tree throughout the south but I’m unaware of any natural location where it largely dominates as a canopy species.  Recently, I reread the passage, and the next morning I had a eureka moment–I believe passenger pigeon flocks created this unusually large stand of dominant dogwood trees.  The dogwood grove Bartram observed was likely the site of a massive passenger pigeon roost 50-100 years before he traveled through it.  Flocks of migrating passenger pigeons (Ectopistes migratorius) formerly caused eclipses of the sun lasting for 6 hours, and when they roosted their colonies would so damage the forest it would appear as if a tornado had struck.  The weight of the roosting birds would bust limbs and even crack enormous tree trunks in half.  The dung overfertilized the trees, often killing all of them.  These enormous colonies covered many square miles.  This explains the extent of Bartram’s dogwood grove.

Dogwood trees were already common in the understory of the forest, and the fruit ripens in the fall…exactly when passenger pigeons migrated to the south after nesting in the midwestern states.  It seems likely passenger pigeons fed on the dogwood and magnolia berries in the surrounding forest, and deposited the still viable seeds under their roosts in their dung.  Dogwood trees sprouted in the nutrient rich soil and thrived in the open sunlight created when the overstory trees were destroyed by the passenger pigeons.

Map of Alabama highlighting Conecuh County

Bartram’s dogwood grove was probably located in Conecuh County, Alabama.

Image result for passenger pigeon migration

Passenger pigeon migrations eclipsed the sun.

Bartram describes adjacent open plains that also resemble a landscape recovering from a passenger pigeon invasion.  Most of the 70 mile forest surrounding the dogwood grove consisted of oak, hickory, black walnut, elm, sourwood, sweetgum, beech, scarlet maple, buckeye, and black locust with an understory of dogwood, crabapple, and plum.  (Chestnut and pine grew on rocky hills.)  But some pockets of treeless plains within the forest and alongside the dogwood grove were composed of shrubs covered in grape vines.  The shrubs included silver bud, buckeye, bignonia, azalea, and honeysuckle.

Image result for Cornus florida fruit and berries

Dogwood berries.  Passenger pigeons ate them.  They taste bittersweet to me.

Image result for Flowering dogwood

Flowering dogwood.  Bartram’s dogwood grove must have been beautiful during early March when the tree blooms.

I’ve always wondered how forests recovered following an invasion of passenger pigeons.  It didn’t occur to me until just recently that Bartram had described just such a site, though he was unaware of how the landscape he described originated.  In summary I shall list the lines of evidence for my hypothesis that Bartram’s dogwood grove was the result of a massive passenger pigeon roost 50-100 years earlier.

  1. The size of the site (9 miles in extent) is the same size as many passenger pigeon roosts described by colonists.
  2. Heavily fertilized soils support monocultures.  The site, fertilized by pigeon dung, supports just 1 dominant species with 1 minor component.
  3. From Bartram’s description all of the dogwood trees appear to be the same age, suggesting they all germinated during the same year.
  4. Passenger pigeons arrived in the region when dogwood trees bear fruit.  This makes my hypothesis plausible because passenger pigeons are the only species that could have planted dogwood seeds on such a large scale.
  5. Adjacent areas also appear to be recovering from a passenger pigeon invasion.  Bartram describes pockets of plains where there are no overstory trees, just shade intolerant shrubs covered in grape vines.
  6. The complete absence of overstory trees indicates a sudden traumatic tree-killing event in the recent past

The Pliocene Marine Extinction Event

July 5, 2018

A major marine extinction event rubbed out at least 36% of the ocean’s vertebrate genera about 2.5 million years ago.  Scientists believe the extinctions were caused by a sea level fluctuation, resulting from glacial expansion.  Ice Ages increased in intensity during the late Pliocene and as more atmospheric moisture became locked in glaciers, sea level fell.  Habitat for many coastal species simply disappeared because their near shore environments rose above sea level.  A new study determined 55% of marine mammals, 43% of sea turtles, 35% of sea birds, and 9% of sharks and rays went extinct. I believe this estimate may undercount the actual loss because there are likely some extinct species yet to be discovered by paleontologists.  Many species of invertebrates became extinct as well.

Most of the genera lost were impressive and interesting.  Metaxytherium were a widespread genera of dugongs that grazed sea grass off coasts all across the world.  Thalassocrus were a group of aquatic sloths that evolved from giant ground sloths.  Giant predatory sperm whales (Livyatan) preyed on whales.  Psephopherus, giant sea turtles, laid their eggs on beaches.  The islands off the coast of South Africa, where several species of extinct penguins nested, became connected to land when sea level fell, and predators were able to invade and destroy their colonies. And of course the famous giant white shark, Megalodon, hunted the many species of now extinct whales that lived during the Pliocene.  Most species of baleen whales were smaller and more agile then because they had to avoid these large predators.

Image result for Metaxytherium'

Metaxytherium floridanum swam near and over what today is Florida.

Image result for Thalassocnus

Thalassocrus, an aquatic genera of sloths.

Image result for Livyatan melvillei and megalodon

2 of the largest predators that lived during the Pliocene–Livyatan melvillei and Carcharocles megalodon.  Both grew to 60 feet long.  Baleen whales were smaller and more agile then, enabling them to escape predation.  The extinction of these predators allowed baleen whales to evolve to a greater size, so they can gorge on food, then fast when they migrate to warmer calving grounds where killer whales, their only modern marine predator, are uncommon.

During the Pleistocene new marine species evolved that were better adapted to the fluctuating sea levels of alternating glacials and interglacials.  New genera increased by 21%.  However, this means there is still a deficit of -15% fewer marine vertebrates than there were during the Pliocene.  Sea life may reclaim the land though, if sea levels keep rising.

An octopus recently found its way into a Miami parking garage.  If sea levels keep rising, marine life may reclaim territory it lost during Ice Ages.

Reference:

Pimiento, C. et. al.

“The Pliocene Marine Megafauna Extinction and its Impact on Functional Diversity”

Nature Ecology and Evolution 1 June 2017

The Adaptability of Pleistocene Peccaries

June 30, 2018

Two lineages of peccaries lived all across North America for over 5 million years but both became extinct about the time man appears in the archaeological record.  The long-nosed peccaries in the Mylohyus genus were forest edge species, and the flat-headed peccaries in the Protherohyus-Platygonnus genuses inhabited scrubby thickets.  A new study looked at dental microwear and bone chemistry in these lineages and compared them with the teeth and bone chemistry of the extant white-lipped peccary to determine the dietary similarities and differences of the extinct and extant species of peccary.  Peccaries in the Mylohyus genus co-existed with Protherohyus peccaries during the Miocene over 5 million years ago.  The former ate more woody browse and forest vegetation, while the latter mostly ate grass.  During the Pliocene between 5 million years BP-2million years BP both Mylohyus and Platygonnus ate mostly woody browse in Florida.  Their diets shifted during the early-mid Pleistocene with an increased consumption of grass.  During the late Pleistocene Mylohyus ate more forest vegetation such as twigs, acorns, and nuts, while Platygonnus ate more tough leaves and grass.  This study shows how adaptable these lineages were to environmental change–their diets shifted with changes in climate.  It seems obvious to me that overhunting and/or disruption of the overall ecosystem by humans, not whole scale environmental change, caused the extinctions of both Mylohyus and Platygonnus.  Surviving extant species of peccaries live in deserts and remote jungles where human populations remain sparse.

Image result for mylohyus nasutus

Image result for Platygonus compressus

Illustration of Platygonnus peccary.

Image result for white-lipped peccary

White-lipped peccaries eat forest vegetation.  They can be dangerous.

The proliferation of feral pigs (Sus scrofa) in North America today demonstrates how favorable the environment still would be for Pleistocene peccaries, if they still existed.  Pigs co-evolved with humans in Eurasia to produce large litters, making them capable of surviving human hunting pressure.  Pigs produce litters of 8-12, but peccaries only birth 2-4 young.

Some archaeologists reject the likelihood that humans hunted peccaries to extinction because there are no known kill sites, other than a peccary shoulder blade with a spear hole in it next to a spear.  See: https://markgelbart.wordpress.com/2014/03/10/the-sheridan-cave-pit-fossil-site-in-wyandot-county-ohio/

This is a ridiculous assumption. There are also no known white-tailed deer kill sites in the archaeological record, but we know Indians hunted deer.  Evidence humans killed Pleistocene peccaries simply faded away over time.

Reference:

Bradham, J. et. al.

“Dietary Variability of Extinct Tayassuids and Modern White-Lipped Peccaries (Tayassu pecari) as Informed from Dental Microwear and Stable Isotope Analysis”

Palaeogeography, Palaeoclimatology, Palaeoecology April 2018

 

New Study Supposedly Debunks Proposed Pre-Clovis Evidence from the Coats-Hines and Topper Sites

June 23, 2018

Archaeologists claimed they had “unequivocal” evidence humans butchered a mastodon at the Coats-Hines site located in Tennessee.  Now, some of these same archaeologists recently published a paper admitting their evidence was equivocal.  I wrote a beautiful article on my blog about the Coats-Hines site a number of years ago, and it always gets a lot of hits early during the school year because a teacher uses it as a reference for a school assignment.  Unfortunately, the assumption the site includes evidence of human-butchered mastodon remains may be bogus.  (See: https://markgelbart.wordpress.com/2013/04/15/the-coats-hines-pre-clovis-site-in-williamson-county-tennessee/ )

The Coats-Hines site is located adjacent to a golf course.  During construction of the golf course 40 years ago workers found the remains of a mastodon.  Further digging by trained experts over the years yielded the remains of 3 more mastodons, white-tailed deer, muskrat, turkey, and painted turtle.  This most recent paper noted the additional identification of ground sloth bones (probably Harlan’s) from the site.  A mastodon vertebrae apparently had cut marks on it, suggesting evidence of anthropogenic butchery, and it was associated with supposedly human-made artifacts.  In a paper published just 7 years ago the archaeologists wrote it was “unequivocal” evidence of human butchery.  However, in his more recent study Jesse Tune admits the cutmarks could’ve been caused by the bone being tumbled against rocks in an high energy stream environment.  He thinks the artifacts associated with that specimen are geofacts.  A geofact is a natural stone formation that resembles an human-modified object.  The stones come from local outcrops that naturally eroded into the stream.  There are definitive human-made tools at Coats-Hines, but they were found some distance away from the mastodon bones.  Coats-Hines was a former stream, and deposits of different ages can get mixed together when currents erode through different aged strata.

Jesse Tune used what he learned from studying the Coats-Hines site to debunk claims made for the antiquity of the Topper site in South Carolina, and the Burnham site in Oklahoma.  Archaeologists excavating these sites claim the evidence they found was older than the Last Glacial Maximum.  (The LGM dates to roughly between 18,000 years BP-22,000 years BP.)  Jesse Tune thinks the evidence at these sites consists of geofacts eroded from adjacent local outcrops that perhaps mixed with real artifacts of more recent origin in an high energy stream.

The new paper (referenced below) includes the Coats-Hines site as a proposed pre-LGM site.  This puzzles me because I can’t find anyone who ever claimed the artifacts and evidence from Coats-Hines dated to before 22,000 years ago.  The sediment around the mastodon bone thought by some to be butchered by humans produced a radio-carbon date of 13,100 years BP (~=15,000 calendar years BP).  This is well after the LGM.  I always considered Coats-Hines to be pre-Clovis but not pre-LGM.  It seems as if the authors of this paper are making a straw man argument because as far as I can determine, nobody claimed Coats-Hines was pre-LGM.

Image result for straw man

Who claimed Coats-Hines was pre-LGM?  I asked 2 authors of the below study but I didn’t get a response.  Are they making a strawman argument about Coats-Hines?

References:

Tune, Jesse; et. al.

“Assessing the Proposed Pre-Last Glacial Maximum Human Occupation of North America at Coats-Hines-Litchy, Tennessee and Other Sites”

Quaternary Science Reviews April 2018

Wolf, Aaron; Jesse Tune, and John Broster

“Excavations and Dating of Late Pleistocene and Paleoindian Deposits at the Coats-Hines Site, Williamson County, Tennessee”

Tennessee Archaeology 5 (2) Fall 2011