Green Sahara Periods

I subscribed to The Economist magazine for awhile.  It’s an excellent magazine for news about world affairs.  I’m interested in world affairs, but not to the depth it gets covered in this periodical, and I recently decided not to renew my subscription.  Some of their articles are redundant because they’ll often have 2 articles in  1 issue about the same subject that say the same thing.  Their articles are also far too wordy.  The editors of this magazine need to learn how to be more succinct.  They could probably cut the word count of their articles by 75% and not lose anything in the translation.  In 1 of the last issues I read there was an article (actually 2) about the expansion of the Sahara desert.  The unnamed author of this article assumed the expansion of the Sahara desert was caused by man-made climate change.  His assumption was just plain ignorant.  Astronomically forced insolation can entirely explain the expansion and retraction of the Sahara desert.

Map comparing vegetation of North Africa during dry and humid climate cycles.  The Sahara desert becomes a lush environment at regular intervals that last for about 6,000 years.  The current natural cycle causes the present day arid conditions.

Scientists have determined  the Sahara desert becomes a lush environment with lightly wooded grasslands, lakes, and rivers at cyclical intervals.  They refer to these times as Green Sahara Periods.  Animal life colonizes the region during Green Sahara Periods, and the environment resembles the Serengeti Plain rather than the desert it is today.  The increase in moisture that transforms the desert into a rich natural community is caused by the 23,000 year variation in the earth’s wobble.  The earth normally spins like a top, and like the child’s toy this spin can wobble.  The wobble leads to a seasonal variation when the earth is closest to the sun (perihelion).  At the point in the cycle when earth is closest to the sun during summer, the amount of solar heat increases in this region.  This differential heating of the atmosphere causes low pressure systems to form over the Sahara, drawing in monsoonal precipitation from the Atlantic Ocean.  10 times more rain falls on the Sahara during humid periods than during present day conditions.  This transforms the region into a much more inhabitable environment.

Evidence of Green Sahara Periods dates to the late Miocene ~9 million years BP.  The last 4 Green Sahara Periods occurred from 6,000-10,000 years BP; 77,000-81,000 years BP; 102,000-108,000 years BP; and 122,000-128,000 years BP.  Notice 1 cycle was skipped.  This was during the Last Glacial Maximum when the earth was particularly arid.  Perhaps, other factors outweighed the 23,000 year cycle.  Scientists have noticed Green Sahara Periods have become less frequent since the mid-Pleistocene.

Evidence for Green Sahara Periods can be found on the land and in the ocean.  Explorers crossing the Sahara desert find dry lake beds and river drainages; and there are many rock paintings depicting scenes rich in wildlife that no longer occur in the region.  Samples of cores drilled from the ocean bottom find fluctuations in dust levels at regular intervals.  Sediment dated to dry periods contains high amounts of dust blown from land in sand storms.  Of course, the amount of sand greatly decreases during humid periods.  The shells of microscopic sea creatures, known as foraminifera, excavated from ocean cores also show isotopic variations that relate to changes in precipitation.

Rock painting in the Sahara desert depicting giraffes, goats, dogs, and people.  Giraffes no longer occur in this region.

The Green Sahara Periods influenced human history.  The rich environment allowed humans to expand from Africa into Asia across the Levantine gateway.  During desert cycles hunter-gatherers could not cross from 1 continent to the other.  1 study suggests humans may be hastening the expansion of the desert by grazing their livestock on the edges of the desert.  I don’t buy this.  Humans likely play a minor role compared to the natural cycle.  If precipitation increased, the desert would begin retracting, regardless of human activity.

Reference:

Larrasoara, J; A. Roberts, E. Rohlirn

“Dynamics of Green Sahara Periods and their role in Hominim Expansion”

Plos One 2013

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The Alcovy Conservation Center (part I)

We took my daughter to Atlanta for her birthday, so she could see a Braves game with her aunt and a friend.  I stayed in an air-conditioned hotel room with my wife and mother-in-law and watched the game on television.  The best way to attend a Braves game is to rent an hotel room in Battery Park and walk to the stadium because the traffic  and parking are a nightmare.  My wife is disabled and a sports stadium is just no place for a person in a wheelchair (think bathroom logistics).  That’s why we didn’t go ourselves.  We were hoping to have dinner with my daughter next to the stadium before the game, but the traffic was so bad we got separated (we were in 2 different cars) before I had a chance to give my daughter my camera.  Otherwise, this blog entry would have photos from inside Sun Trust Park. She did take photos with her phone but hasn’t figured out how to upload them to the computer yet.  I got stuck in Atlanta traffic.  Getting stuck in Atlanta traffic makes me feel like committing suicide.  This was vacation 2019 for us.  Actually, my idea of an ideal vacation is to get drunk and listen to music, then watch internet porn the following day to forget how shitty my hangover makes me feel.  Oh wait…that sounds like every Thursday night.

The original plan for the following day was to visit Fernbank Forest, but I learned online those bastards charge $18 to walk in their woods.  When I visited Fernbank Museum a few years ago their forest was closed for repairs and I couldn’t see it even after I paid their damn fee.  (Why does a natural forest need to be repaired?)  I guess I will never see it.  As an alternative, I chose to visit the Alcovy Conservation Center in Covington, Georgia.  It is maintained by the Georgia Wildlife Federation and it is free.  It’s mostly used for school field trips.  Visitors are supposed to check in but there was no one there, not even other visitors.  (The Fernbank Forest is notoriously crowded.)

Kiosk at Alcovy Conservation Center.  The land includes 115 acres of woodland, meadow, and wetland.

Big black oak.  There were a number of really big black oaks in this park.

Open woodland.

This is an old fencerow in an old pasture.  Birds and squirrels planted these trees.

I enjoyed my visit to the Alcovy Conservation Center.  I had time to see just half of it.  I didn’t even see what it is most famous for–a tupelo swamp.  This type of natural community is common in the coastal plain but uncommon in the piedmont where the conservation center is located.  There are just 4 other sites in the piedmont region with tupelo swamps.  I also didn’t see the canebrake and marsh.

I did see some enormous black oaks.  Other common plants I encountered were water oak, willow oak, river birch, sweetgum, shortleaf pine, loblolly pine, hickory, pawpaw, dogwood, muscadine grape vine, and trumpet creeper.  This is the only site in Georgia where I have seen pawpaw growing in the wild.

Pawpaw tree.  I wonder if the pawpaws will be ripe when I visit again in late August.

I didn’t come at a good time to see wildlife–it was late morning and sultry.  There were many small drab birds, probably sparrows, but they wouldn’t stay still for identification.  I saw dark phase tiger swallowtail butterflies.  I didn’t know tiger swallowtails came in a dark phase until I searched my field guide for identification.  It too wouldn’t cooperate for my camera.  Charles Wharton, the late author of The Natural Communities of Georgia, wrote white tail deer grew larger along the Alcovy river bottoms than anywhere else in Georgia.  They were sensibly resting in the shade, while we slogged through the heat, and we didn’t see them.  The squirrels were also resting in the shade.  I walked on a path known as fox squirrel trail but saw no squirrels of any kind.  This site hosts a disjunct population of the bird-voiced tree frog, but it is probably past mating season for them.  However, on the plus side, I didn’t see a single fly or mosquito.

The Georgia Wildlife Federation encourages wildlife here.  There is a chimney swift tower, many bluebird boxes, and they even have at least 1 bat box.  I’ll be back to see the parts I missed.

Chimney swift tower.  Chimney swifts with their nestlings live in my home chimney.  I notice some people put caps on their chimneys to prevent birds from nesting there.  If you put a cap on your chimney to block chimney swifts, you can’t be my friend.

The Human History of Sicily in 1345 Words

Humans first began colonizing Sicily about 14,000 years ago.  Historians aren’t sure where these people originated, but they probably came from what today is mainland Italy, Spain, and/or North Africa.  Different tribes roamed various parts of the island where they fished, hunted large mammals, and foraged in the forest for plant foods.  The oldest known culture is the Mycenaean, a people who established trade routes and flourished on the island from 1600 BC-1200 BC.  This culture died out, possibly following some natural disaster, such as an earthquake that weakened the stability of that society.  Greeks started colonizing the island in 734 BC, forcing the native tribes away from the coast and into the interior.  The Greeks were 1 of the dominant civilizations in the Western World during this time, but they weren’t a single country.  Instead they were made up of many different city states–some were democratic while others were ruled by autocratic kings.  The Greeks fought with the Carthaginians for control of Sicily, and the Greeks eventually forced them off the island.  The Carthaginians descend from the Phoenicians of the bible and were a sea-faring, trading civilization.  The Greek city states of Sparta and Athens then fought for control over the island, and the former were victorious.

Almost a century later Carthaginians invaded the island again. The first great king of Sicily, Gelon, led an army that defeated the Carthaginians in battle.  (The Carthaginains still controlled a small part of the island, but Gelon had most of it.)  Gelon also founded the Greek city of Syracuse on Sicily where he established the capital of his state.  He forcibly moved the richest, best educated people he conquered to Syracuse, and the city became renowned for its high culture.

Gelon, the first great king of Sicily.

Sicily was ruled by a series of tyrant kings after Gelon’s death.  They all varied in their competence and cruelty.  Timoleon was the next great ruler of Sicily.  He drove the Carthaginians off the island after they had tried to regain control once again.  His sensible administration of the island led to it becoming the first great granary of the rising Roman empire.  Rome became the big world power during the 3rd century BC and after they defeated Carthage in 2 major wars, Sicily became part of the Roman empire, though most of the inhabitants spoke Greek instead of Latin.  Rome ruled Sicily for centuries and aside from several slave revolts Sicilian history was uneventful during this time period.

The Roman empire collapsed circa 500 AD and split into 2 kingdoms.  Western Rome, influenced by the pope, was Roman Catholic, while eastern Rome, ruled from Constantinople and known as the Byzantine Empre, was Greek Orthodox.  For a brief time the German Ostrogoth tribe conquered the western empire and ruled Sicily, but this didn’t last long.  The Byzantines took control of Sicily for about 200 years until Arabs invaded the island when they were spreading the Muslim religion across the Mediterranean at the point of a sword.  The Byzantines frequently tried to regain control of Sicily, but they could never beat the Arabs.  However, Arab kings, though they were brothers, were constantly fighting each other in a kind of Civil War that made them weak.  Meanwhile, the Normans, used as mercenaries to protect the western Roman empire, were becoming numerous and troublesome to the pope in southern Italy.  (Normans were Vikings that had conquered northern France and shortly after assimilated the French culture.) To get rid of them, the pope gave Sicily to King Robert of the Normans.  Sicily, of course, was ruled by Arab brothers and wasn’t the pope’s territory to give.  Nevertheless, Robert and his Viking army invaded Sicily and eventually defeated the Arabs.

Illustration of Norman invasion of Sicily.

The Normans ruled Sicily for over an hundred years, until 1 of their kings married into German royalty and passed the torch onto them.  There was 1 great German King during this era by the name of Hohestaffer.  The Pope asked him to lead a Crusade to retake Jerusalem.  But instead of all out warfare, he managed to regain the city with a peace agreement.  This pissed the pope off because he hated Muslims and wanted bloodshed.  Worse yet, Hohestaffer was reportedly decent to the Muslim citizens who still lived on Sicily.  So the pope sent an army after Hohestaffer, but the German king defeated it, took his army to Rome, and made the pope surrender.

The Catholic church always hated this German line of kings, and several generations later they replaced this lineage with French Royalty.  The French kings never lived on the island and seldom even visited it.  Instead, they doled the land out to their buddies who served as absentee landlords that got rich from the poor laboring peasants.  Sicily was always kind of a backwater region controlled by distant royalty who gave their powerful friends vast estates.  This created enormous income inequality that persists today.  The Sicilians often rebelled, and during 1 rebellion King Ferdinand of Spain came to their rescue and established Spanish rule.  Spain owned Sicily for centuries, but again, the system of vast estates that enriched super rich land barons remained.  Most of the population consisted of poor peasants who never even had the chance to own land, despite the existence of large amounts of fallow acres on these huge estates.  Spain introduced the Inquisition to Sicily, explaining why it remained backwards for so long.  Many Muslims and Jews were expelled from Sicily during Spanish rule.  At this point in history Muslims were more civilized and scientifically advanced than Christians, and Jews were worldly merchants.  The Mafia probably originated during Spanish rule.  The land barons paid bandits protection money–in other words they paid them not to be robbed.  In return the bandits helped the land barons suppress peasant rebellions.

Spain ruled Sicily for about 400 years, but in a war against the Holy Roman Empire they lost it.  Austrians defeated the Spanish in a major battle on Sicily, and the Holy Roman Empire briefly owned it.  Another peace treaty granted the island to a king of the Piedmont province located in what today is Italy.  The next peace treaty granted the island to Austrian royalty who ruled Sicily from Naples.  The French under Napoleon’s brother ran the Austrian royalty out of Naples, but the British (at war with Napoleon) occupied Sicily and protected the royalty, until Napoleon’s eventual defeat.  Austrian royalty regained Naples after Napoleon lost.

Naples and Italy were controlled by Austrian royalty until Italian independence in 1861.

Unhappy peasants often rebelled in Sicily and Naples.  Royalty often were forced to flee, and they would agree to democratic reforms.  But as soon as the kings repressed the insurrections, they would tear up the newly written constitutions and re-establish autocratic rule.  Emmanuel II of the Piedmont kingdom in central Italy was different.  He supported democracy and wanted Italy to be united.  He invited the French to help him kick the Austrians out of a couple Italian provinces which were then united under his rule.  However, it was a mercenary, Giuseppe Garibaldi, who liberated Sicily and Naples from Austrian rule.  Italy was born in 1861.  A decade later the French were forced to leave Rome after their defeat during the Franco-Prussian War, and the pope retreated inside the Vatican.  (The pope and the Catholic church always opposed democracy).  This established the modern day boundaries of Italy. Nevertheless, the peasants in Sicily were still oppressed, squeezed between land barons and the mafia.  Many left for a better life in the U.S. and South America.

Italy was democratic until 1922 when Benito Mussolini took over.  He suppressed the mafia on Sicily for 14 years, so they were glad to help U.S. troops, when along with the British, they kicked the Germans and the Italian army off the island in 1943. The loss of Sicily caused Mussolini to lose power.  Since World War II, Sicily and Italy been under a democratic socialist government, and the people are probably better off than at any other time in their history.

Reference:

Norwich, John

Sicily: An Island at the Crossroads of History

Random House 2015

Pleistocene Cuckoos (Coccyzus sp.)

I frequently hear yellow-billed cuckoos (C. americanus) during summer, but I almost never see them.  They spend most of their time perched in tree tops and they blend in well, so they are difficult to spot.  I’ve never even seen this species perched, but I have occasionally spotted them flying in front of me, while I’m jogging or driving.  They are long birds with reddish brown wings and a checkered tail.  I discovered this species lives in my neighborhood a few years ago when I was learning bird calls from the Cornell University ornithology website.  I searched for yellow-billed cuckoos on this site and was pleasantly surprised to recognize their distinctive call.  Here’s a link.

https://www.allaboutbirds.org/guide/Yellow-billed_Cuckoo/sounds

Video of a perched cuckoo.  I’ve never seen one perched. Old timers called these birds rain crows because they will sometimes call in response to thunder.

Yellow-billed cuckoos spend summers in North America and winter in South America.  Caterpillars are the most important item in their diet, and they specialize in eating large spiny caterpillars that taste bad to most other species of birds.  They are so well-adapted to eating caterpillars that when their stomachs become clogged with spines, they vomit up their stomach lining and grow a new one.  They also feed on other large insects such as cicadas, locusts, and dragonflies.  Fruit balances out the rest of their diet.  They lay their eggs at intervals, and their nests often contain different aged nestlings.  The young are covered in porcupine like quills, and they are capable of climbing trees to avoid predators.  They leave the nest just 17 days after hatching.

Yellow-billed cuckoo range map.

2 other species of cuckoos in the coccyzus genus live in North America–the black-billed cuckoo (C. erythropthalmus) and the mangrove cuckoo (C. minor).  Surprisingly, genetic evidence suggests the black-billed cuckoo is not a sister species of the yellow-billed cuckoo.  The black-billed cuckoo also summers in North America and winters in South America, but it breeds in more northerly locations.  These species independently evolved the habit of migrating north to find summer breeding ranges.  The pearly-breasted cuckoo (C. euleri), restricted to South America, is a sister species to the yellow-billed.  I looked at a photo of this species and I can’t tell the difference between the 2.  The mangrove cuckoo ranges from South Florida and the Bahamas to the coasts of Mexico and Central America.

Fossil evidence of cuckoos in the coccyzus genus has been excavated from sites in Florida, Virginia, the Bahamas, Dominican Republic, and Bolivia.  They are a bird of deep forest and therefore the process of preservation is rare in their habitat, explaining why they are absent in much of the fossil record.  Coccyzus cuckoos likely increased in abundance during warmer wetter stages of climate.

Cuckoos belong to the Cucilidae family which includes 135-147 species, depending upon the taxonomist’s opinion.  All Eurasian species are parasitic–they lay their eggs in other birds nests.  (These are the species depicted in cuckoo clocks.)  Yellow-billed cuckoos are occasionally parasitic.  During times of plenty when there are outbreaks of fall webworms or tent caterpillars, they will lay an egg in the nests of other cuckoos, robins, catbirds, or woodthrushes.  The cuculidae family also includes anis of South America and Mexico, coucals of Melanesia and Australia, and New World ground cuckoos.  Roadrunners belong to the New World ground cuckoos.  Most other species of New World ground cuckoos are parasitic, and 1 species specializes in preying upon army ants.

References:

Forbush, Ed

A Natural History of American Birds of Eastern and Central North America

Bramhall House 1955

Hughes, Janice

“Phylogeny of the Cuckoo Genus Coccyzus (Aves: Cuculidae): a test of monophyly”

Systematics and Biochemistry 2006

Cooking an Old Rooster

Not many people know this, but every single packaged chicken in chain grocery stores is a female.  Most male chickens are aborted upon hatching because they don’t lay eggs and fight each other all the time and accordingly are not economical to keep.  Before modern agriculture when most rural folks kept chickens, they ate their roosters.  The classic French dish, chicken coq au vin, is made by slow cooking an old tough rooster in wine.  On a recent visit to a new Vietnamese grocery store I found a rooster.  It costs 3 times more than most grocery store chickens, but I wanted to try making the classic French dish authentically, so I sprung for it.

Asian supermarkets sell birds with the head and feet attached.  The cock’s comb is edible according to some vintage cookbooks, but it looks like cartilage to me.  I gave it to the cats.

First I butchered the rooster into 10 pieces.  (I wrapped up the feet and put them in the freezer for future stock-making.)  Next, I dredged the chicken in seasoned flour and browned the pieces in bacon grease.  I placed the pieces in a casserole dish and sautéed mushrooms and onions in the pan I browned the chicken in.  I smothered the chicken with the onions and mushrooms and deglazed the other pan with red wine.  I used an inexpensive Merlot.  I poured the wine on the chicken and vegetables.  I happened to have parsley so I sprinkled chopped parsley over this.  I covered the casserole dish and put it inside the oven at 350 degrees for 1 hour.  If I had to do it over again, I would go with 300 degrees for 2 hours.  The first temperature and time would be perfect for a grocery store broiling hen, but it didn’t tenderize the rooster as much as I would’ve liked.  Nevertheless, I enjoyed eating the rooster.  The flesh had a better texture than most grocery store chickens.  Almost all grocery store chickens are embalmed with a salt water solution, and in my opinion this gives the flesh a weird texture.  I’ve given up even looking for non-embalmed chickens.  Producers inject salt water in chickens because modern breeds have such large breasts, the white meat will dry out without the solution.  This dish is traditionally served with pearl onions, but I just used a regular chopped onion.  The wine gravy is delicious and really pairs well with the meat.

The finished product. Tastes like chicken.