Archive for the ‘Uncategorized’ Category

Spotted Hyenas (Crocuta crocuta) May Have Persisted in Europe until 7,000 BP

October 3, 2020

European climate might be more suitable for spotted hyenas than African climate, according to a 10 year old study published in Quaternary Science Review. Ironically, the spotted hyena is presently extinct in Europe and survives on the continent of Africa and nowhere else, except zoos. Hyenas thrived from Spain to the Ural Mountains for about 3 million years. Genetic evidence suggests hyenas from Africa invaded Europe in 3 waves: 3 million years ago, 1 million years ago, and again 300,000 years ago. The hyenas in Europe were a subspecies of the African hyena, given the scientific name Crocota crocota spelaea and are commonly known as the cave hyena, though most individuals never ventured into a cave. Their primary prey consisted of horse and bison, but their diet also included rhino, deer, ibex, bear, lion, wolf, and other hyenas. Some of these prey items were scavenged, but hyenas actively kill most of their food. European hyenas were on average 40% larger than African hyenas–evidence European climate and habitats were a more optimum environment for them. European female hyenas (for hyenas females are generally larger than males) weighed up to 225 pounds, while African hyenas weigh up to 140 pounds. Hyenas occurred in Europe during all climate phases of the Pleistocene, including interglacials, glacials, interstadials (warms ups during cold stages) and stadials (cool downs during warm stages). This suggests climate change alone can not explain their extinction in Europe. Competition with humans was likely the cause of their extinction there, though scientists believe hyenas succumbed to a combination of environmental change and competition with humans. I disagree with this notion because if humans are eliminated as a variable in the equation, hyenas would still occur in Europe. Thus, humans alone are the cause of their extinction. Hyenas persist in Africa because tropical diseases kept human populations low on large areas of that continent.

Cave hyena (Crocuta crocuta spelaea)

Image of Crocuta crocuta spelaea.

Fossil Presence of spotted hyenas in Europe from 126,000 years BP-21,000 years BP. Note how they still occurred in the middle of Europe during the Last Glacial Maximum (the white circles). Image from the below reference authored by Vareles et. al.

Scientists think hyenas went extinct in Europe about 11,000 years ago, but a new study touts evidence hyenas persisted in Spain until ~7,000 years ago. Some Spanish scientists studied hyena coprolites (fossil feces) found in 2 caves in Spain. The coprolites dated between 37,000 calendar years BP-7,000 calendar years BP. The authors of this study concede younger dated coprolites might have inaccurate dates due to contamination. However, the focus of their study was an analysis of pollen grains found in the hyena coprolites. Palynologists attempt to reconstruct past environments based on the composition of pollen grains, and they use them to estimate past climate. For example during cold dry climate phases pine and grass pollen predominates in samples, while moist warm climate phases show an increase in oak pollen. The pollen profile of the youngest dated coprolites are consistent with the floral composition of the early Holocene, so it seems likely the radio-carbon dates are accurate, and hyenas lived in Spain as recently as 7,000 years ago.

References:

Deidrich, L; and K. Zak

“Prey Deposits and Den Sites of the Upper Pleistocene Hyena Crocuta crocuta spelaea (Goldfuss 1923) in Hoorjostid and Ventral Caves of the Bohemian Karst (Czech Republic)”

Bulletin of Geoscience 84 (4) 2006

Ochard, J. et al

“Palynology and Chronology of Hyena Coprolites from the Pinur Karstic Caves Las Ventanas and Carihoula, Southern Spain”

Paleogeography, Paleoclimatalogy, and Paleoecology 552 August 2020

Vareles, S; J. Lobo, J. Rodriguez, and P. Baten

“Were the Late Pleistocene Climate Changes the Responsible for the Disappearance of the European Spotted Hyena Population? Hindcasting a Species Geographic Distribution over Time”

Quaternary Science Review 29 2010

Unusual Adoptions in the Animal World

September 28, 2020

11 cats live in my yard–2 adults, 3 subadults, and 11 kittens.  Stripey, the biological mother of 8 of my yard cats, is the tamest.  She runs inside our house like she owns it.  She is supposed to be an outdoor cat, so to coax her outside I open the door and throw food on the porch.  Naturally, this positive reinforcement encourages her to run inside the house whenever we open the door and are in an hurry to make it in time for a doctor’s appointment.  Stripey doesn’t let me exercise either.  When I jog up and down the street she follows me until I sit down in our special place and pet her.  2 of her subadult kittens are less tame, though they sit and watch me when I pet their mother.  The other adult cat in my yard is Midnight Runt who also sits and watches me pet Stripey but never quite has the nerve to get within arm’s length.  Midnight Runt is less tame than her subadult spawn, the Cardupnik, who purrs when she is near me and lets me pet her when she is eating. (Cardupnik is the Yiddish word for little person or shrimp.)

Stripey.  She lost her first 2 litters but has so far successfully raised her next 2.  She is less than 3 years old but has had 4 litters already.  Maybe I need to crush up some birth control pills in her cat food.

Midnight Runt watching me pet Stripey.

All the cats are good climbers.  A neighborhood dog chased some of them into this tree hollow.  They play on my roof every morning, hunting squirrels and birds there as well.

Stripey had a litter of 5 kittens a month ago.  The timing suggests she went into heat before her previous litter was weaned.  What a slut.  I really want 2 or 3 cats, not 10; but Stripey was not through increasing my cat population.  A kitten, a few weeks older than Stripey’s, wandered into my yard a week ago from the woods behind my house.  This kitten was stressed, mewling nonstop for 36 hours.  Its biological mother was probably a feral cat that was killed by a car, coyote, dog, or heartworm. Or perhaps the orphan wandered too far away and got lost.  Stripey adopted this orphan kitten, nursing it alongside her own.  The orphan has quickly learned when I put food out and no longer flees at the sight of me.  The orphan also watches me when I pet Stripey.  Nevertheless, there is a sad look in its eyes.

Stripey’s 5 biological kittens, plus the 1 she adopted.  The orphan is a few weeks older than the others.  The orphan is on the step.

It is not unusual for a mother cat to adopt kittens that are not her own.  The caring instinct is so strong they will sometimes adopt puppies, baby rabbits, and infant squirrels.  Their mortal enemies may be brought up to think they are a cat.

I did a little research and found some strange adoptions in the animal world.  Gorillas and crab-eating macaques have adopted kittens.  In the wild a lioness adopted a baby antelope.  Perhaps the most unusual adoptions occur in captivity where a baby hippo bonded to a giant tortoise, and a baby macaque became attached to a wild boar.  (See: https://www.thedodo.com/12-remarkable-interspecies-rel-523336558.html ) Most unusual of all would be an human raised by animals, but none of the accounts I researched are reliable.  Romulus and Remus, the legendary founders of Rome, were allegedly left for dead but were saved by a mother wolf that nursed them.  However, this legend originated 500 years after Rome was founded in 753 BC.  Reliable accounts of feral children do not clearly indicate they were raised by animals.  Instead, it seems more like they were living with wild or domestic animals and had little interaction with humans.  In some cases of neglect toddlers crawled around with cats and dogs and lived on pet food.  They never learned to act human during a crucial phase of development.  Another famous case involved a 5 year old slave of a goat shepherd in Spain.  He received some training in outdoor survival before his master abandoned him, and he lived in the wild for 12 years before police captured him.  He claims he blundered into a wolf’s den to escape a cold winter’s night and suckled from a mother wolf alongside her puppies, but he was not actually raised by a wolf.  He was probably used to suckling milk directly from goats, and it wasn’t that much of a stretch to nurse from another animal.

The 10th Anniversary of Georgia Before People

March 5, 2020

I started this blog during March of 2010 to promote my book.  I never imagined that I would enjoy my blog more than my book.  I looked at some of my early entries, and at first the blog seemed to be my private nature notebook opened to the public.  I was merely sharing what I studied and learned about pre-historic ecology along with my thoughts and opinions.  But gradually, I began writing more extensive essays.  Now, I have 113 followers who receive my weekly essay in their email box, though I wonder how many of them get marked as spam.  The number of people who read my blog has varied over the years.  2012 and 2017 were my biggest years.  I think I wrote some of my best essays during those years, but I don’t know if that is why the numbers were higher then.  I don’t really promote my blog on message boards like I used to, and my blog readership largely depends upon search engines.  Lately, readership has fallen off, and the effort I put into my blog has as well.  I’m spending more time looking at naked women on Twitter than researching the latest scientific papers.  If I was ambitious, I could go back and correct all the factual errors in my earlier blog entries and replace the photos that no longer show up, but life is too short.  I’m not getting paid to keep this blog up.  It is just an hobby for me.

Image

Site stats for my blog since 2011.

Image

Site stats for my blog since September of 2017.  Note the decline in readership.  I almost have 1 million views all time.

I reviewed my past blog entries and found a few of my favorite photos I’d like to share in celebration of my 10th anniversary.

This photo is from 2010 in an article entitled “Atlatl Adventures Part 1.”  There was never a part 2.

I can’t believe my luck.  I actually got a photo of a large bobcat.

Another lucky photo–a loggerhead shrike.  Unfortunately, my computer crashed in December of 2017and I lost my photo of a black bear I took at Great Smoky Mountains National Park.  I have that photo on my Facebook page, but a reader has to be friends with me to see it.  I didn’t realize that when I initially linked Facebook photos on my wordpress blog–hence the articles in 2016/2017 with a bunch of photos that don’t show up.

Bison at Land Between the Lakes.

Wakulla Springs 011

Wakulla Springs egret rookery.

 

Halloween Double Feature: The Lowenmensch and Brain-Eating Amoeba

October 26, 2019

I like to watch horror movie double features on Halloween.  My favorites are the movies made by Hammer Productions, a British company that produced horror movies from 1958-1976.  Turner Classic Movies often airs these every October.  For my annual Halloween blog article I am offering a scary double feature.

The Lowenmensch is a 1 foot tall figurine found in Hohlenstein-Stedelgre Cave, Germany during 1939.  Lowenmensch means Lion-Man in German, and the sculpture depicts a half-man, half lion.  The artifact is estimated to be between 35,000 years-40,000 years old.  Archeologists attempted to reproduce it, and they discovered that it took 370 hours to sculpt.  The artist could have spent 1 hour a day for about a year to make it.  Archeologists suggest this means other people were taking care of him, while he worked on this object because life during the Stone Age consisted of constant subsistence hunting and gathering.  I disagree with this notion.  People didn’t hunt and gather at night when they might be in danger from unseen predators.  Instead, I believe they likely hung around the campfire where there was more security within a crowd of other humans.  The artist probably made this sculpture at night by the light of the campfire.

The Lowenmensch.  Just imagine a beast that was half-man, half lion…a kind of werelion instead of a werewolf 

Who knows what this object symbolizes?  Lions (Panthera spelaea) were a common species that co-existed with humans in Europe 35,000 years ago,  and humans infrequently interacted with them.  The 2 species likely avoided each other most of the time.  Apparently, humans anthropomorphized animals tens of thousands of years before Disney and Warner-Robins.

The 2nd part of this double feature is scarier because it is real.  There is a species of amoeba that eats human brains.

Computer-generated representation of the amoeba Naegleria fowleri, which causes deadly brain infections.

The brain-eating amoeba (Naeglerea fowleri).

The brain-eating amoeba lives in the bottom sediment of warm freshwater lakes and ponds.  Normally, they eat bacteria.  But if a swimmer gets amoeba-filled water in their nose, the amoeba enter the olfactory nerves and penetrate the brain.  The amoeba can’t find bacteria in the brain, so they begin eating brain cells instead, and in response the human immune system fights the invasion, causing the brain to swell.  Symptoms of amoeba meningoencephalitis include headache, fever, nausea, stiff neck, disorientation, and hallucination.  The brain swelling stops the brain’s signals to the spinal cord.   The symptoms mimic bacterial and viral meningitis, often delaying the diagnosis.  The disease has a 97% mortality rate.  There is no sure known cure, but use of an experimental drug known as miltefosine saved 1 girl’s life.  Fortunately, this disease is extremely rare.  Just 146 cases have been recorded since 1962.

The crew of the U.S. Enterprise battled a giant space amoeba in 1 of my favorite episodes of the original Star Trek.

 

Paper Clowns

April 20, 2019

When I was in my mid-20s I was not an ambitious person.  I happened to be looking through the want ads 1 day and I thought I  found an ideal job.  A company would send me the material to construct paper clowns, and I would send them back, and they would pay me $5 for each clown I constructed.  I thought I could also save money by not having to drive to work everyday.  Better yet, it sounded like a job I could manage while high on pot.  I eagerly told my mother about this opportunity, but she was not enthused.  Instead, she gently insisted I get a real job with insurance benefits and paid vacations.  I did go out and get a real job and went on to meet my wife indirectly through work.  My mom was rewarded with a granddaughter, and I avoided the ignominy of being the kind of adult who lives in their parents’ basement and never really grows up.  There are many ways my mom influenced my life, but this incident always comes to mind when I think about them.

This is my mom with my father, my younger sisters, and me in 1967.

My mother, Audrey Gelbart, was born on  August 5th, 1939, in Cleveland, Ohio.  She was the product of a mixed marriage–her mother was a Yankee from New York and her father was a southerner from Georgia.  She grew up in Willoughby, Ohio with 2 brothers and a sister.  After graduating from high school she worked as a secretary in an hospital where she met my father who was a resident doctor there.  They married in 1961 and by 1966 they had 3 children.  She raised us while my father was busy working, and she always kept her house ultra clean.  She was a patient, sweet-tempered mother and grandmother, and a devoted wife.  She took good care of my father, especially during his many health crises, until his death in 2014.  My mom passed away on April 19th 2019.  We will miss her.

Georgia Before People has Run out of Gas

January 15, 2019

This is just an heads up.  The future content of my blog is about to change.  I started this blog during March 2010 to promote my self-published book of the same name.  I really enjoyed producing new blog entries, and in many ways I think the blog was better than the book itself.  Deciphering the latest scientific journal articles related to my subject into language a layman could understand became 1 of my favorite hobbies.  I’ve managed to keep the focus of my blog on the paleoecology of southeastern North America or at least on any natural history remotely related to it for 9 years, but I just can’t do that any more–there just isn’t enough new scientific literature available.  I’m too prolific and professional paleoecologists can’t keep up.  I’m still fascinated with this obscure topic.  However, I’m tired of relying on speculation, and it seems as if I’m becoming too repetitive.  I feel like I’ve beaten a dead horse until it has turned into an unrecognizable bloody pulp.  Back in November I wrote an 800 word blog entry, then realized I’d already written about the same study a few years earlier.  I just re-blogged the original essay instead of posting a different version of it.

Translating scientific studies also puts a crimp in my writing style.  Because the science isn’t always definite, I’m forced to write awkward phrases such as “the authors of the study suggest…”  too often.  I never want to write that phrase again.

I will still write essays for my blog, but they will no longer be focused on the obscure topic of paleoecology.  I’ll still write about natural history once in a while, especially if there is a new discovery of a Pleistocene-aged fossil site in Georgia or if I have a particularly interesting idea.  But no Pleistocene fossils have been discovered in Georgia since 2006.

I’ve been reading a lot of biographies lately.  I’ll probably write more about people, history, pop culture, food, and (I’m sorry) politics.  My output may or may not become more irregular.  Nothing lasts forever.

The Page-Ladson Site in Northwest Florida

November 19, 2018

I wrote a new blog article about this last night, but then realized I’d already written an article about this subject. I’m re-running this article this week because I don’t have time to write another one before the holidays. Happy Thanksgiving.

GeorgiaBeforePeople

During the late Pleistocene sea level contracted because much of earth’s atmosphere was locked in glacial ice.  The land area of what today is Florida doubled in size, and shorelines extended 50-100 miles west into the Gulf of Mexico.  The water table fell and many present day small rivers did not yet exist.  Instead, the land was pockmarked with many spring-fed ponds that attracted herds of megafauna and other wildlife.  The basal chemistry of these waters preserved bones and organic matter, and later when water tables rose, the Aucilla River began flowing and it covered these ponds with sediment.  The Aucilla River flows over 4 known Pleistocene pond sites–Page-Ladson, Latvis-Simpson, Sloth Hole, and Little River Quarry.  These sites contain deep layers of mastodon dung deposits.  Bones and artifacts are often mixed with the ancient piles of turds, and tracks are also visible where mastodons stepped on their own shit.  Scientists…

View original post 794 more words

The Ancient Rivalry Between Cats and Dogs

January 18, 2018

The PBS documentary series, Nature, recently featured a 2 part episode about cats.  During the first episode the narrator claimed cats caused the extinction of at least 40 species of dogs after the felines colonized North America.  I knew there had to be a journal article behind this claim, so I googled “cats caused extinction of 40 dog species.”  I found the paper (referenced below) and also discovered 90% of media outlets misreported the conclusions of the study.  Cats did contribute to the extinction of many dog species, but competition with other dog species and the extinct carnivores known as Barbourofelidae were also responsible for the extinctions.

Dogs originally evolved in North America, while cats originated in Asia.  About 40 million years ago a land bridge began to periodically emerge across the Bering Strait, allowing cats and dogs to colonize each other’s continent of origin.  When cats first colonized North America there were 3 subfamilies of dogs–the Hesperocyoninae, the Borophaginae (or bone-eating dogs), and the Caninae.  The Hesperocyoninae and the Borophaginae are extinct.  All living species of dogs, jackals, wolves, and foxes belong to the Caninae subfamily.

The scientists who authored the below referenced paper collected data about climate change, and the fossil occurrences of predators including Felidae (cats), Amphicyonidae (the extinct bear-dogs), Barbourofelidae, Nimravidae (false saber-tooths), and the Ursidae (true bears).  They used statistics to determine whether climate change or competition with other carnivores caused the extinction of some species of dogs.  They concluded the extinction of 1 subfamily of dogs, the Hesperocyoninae, was caused by competition with another subfamily of dogs, the Borophaginae.  Cooler climate may have contributed to the extinction of some Borophaginae species 15 million years ago.  Finally, competition with Barbourofelidae, cats, and the surviving subfamily of dogs (the caninae) drove the remaining species of Borophaginae into extinction.

Image result for Barbourofelidae

The Barbourofelidae are an extinct group of carnivores distantly related to cats but different enough to be classified as a separate family.

The species of dogs that did become extinct were often cat-like in build and probably occupied ecological niches preferred by cats.  So cats were just better than these cat-like canids at surviving in these niches.  But the Caninae were also better adapted to survive in the constantly evolving environment.  The cat and dog species that emerged from this age-old competition have achieved a kind of stalemate.  Representatives of both naturally occur on every continent but Antarctica and Australia.  (Dingos were brought to Australia by man.)  1 species of each–Canis familiaris and Felis catus —live in our homes and compete for our affections today.

Image result for cats and dogs playing together

References:

Silvestri, D.; A. Antonelli, N. Salamin, and T. Quentas

“The Role of Clade Competition in the Diversification of North American Canids”

PNAS 112 (28) 2015

R.D. Lawrence–Wildlife Writer

November 8, 2017

I enjoy deciphering articles published in scientific journals and translating them into language a layman can understand.  I learned how to do this because of my long fascination with Pleistocene ecology.  Information about Pleistocene ecology almost entirely comes from scientific journal articles, and I found the language in these publications can be unnecessarily complex and oftentimes the writing is just bad.  I had to learn how to interpret them.  Some scientists are good writers, but others are not.  R.D. Lawrence (1921-2003) was a writer who felt the same way I do about language in scientific journals.  At 1 point in his life he was studying to be a biologist.  He wrote a thesis about stickleback fish, and his professor told him it was good, but he wanted him to rewrite it in the language used by scientific journals instead of the easy to understand language Mr. Lawrence had used.  He rejected this “babblespeak” and dropped out of school.  He later wrote 36 books about Canadian wildlife and won 7 awards.

The late R.D. Lawrence relaxing at home with his pet raccoon.

R.D. Lawrence was born in Spain to a Spanish mother and an English journalist who worked for Reuters.  At the age of 14 he was separated from his family during the Spanish Civil War, and he joined the side fighting against the fascists.  (Ironically, his brother joined the fascists.)  Though just a teenager, he led 1 military attack in the sewers against the fascists.  Eventually, he escaped to southeastern France and was later reunited with his family in England.  He fought for Great Britain during World War II.  He was at Dunkirk, rode a tank in North Africa, and was severely wounded during the D-Day invasion.  His injuries ended his military career.  He moved to Canada and worked as a journalist, while studying nature in his spare time.  He gathered enough material so that he was able to start getting his books about Canadian wildlife published.  Recently, I’ve read 3 of his books.

Mr. Lawrence and his wife bought some land in the wilderness of Ontario during 1962.  Here, they built a cabin where they spent weekends.  (He still worked as a journalist during the week.)  He bought the land before most of Ontario was logged over and converted into suburbs, so much of the wildlife was naïve and not particularly afraid of people.  He wrote about his experiences at this cabin in his book, The Place in the Forest.  The semi-tame animals frequenting his cabin yard included red squirrels, fox squirrels, flying squirrels, white-footed mice, snowshoe hares, and birds.  Bird seed and table scraps encouraged the creatures of the forest to hang around the cabin, and if the door was left open, they would enter the cabin and help themselves.  Mr. Lawrence and his wife adopted 2 orphaned raccoon kits and after they were grown and freed, they often returned and joined the feast.  Mr. Lawrence also wrote about some of the less tame inhabitants in the local wilderness–beavers, deer, wolves, black bears, and birds of prey.  He didn’t let worms and insects go unnoticed either.  My favorite chapter relates his encounter with a bald-faced hornet’s nest when he was climbing a tree to photograph a hawk’s nest on another nearby tree.

Mr. Lawrence’s wife died of a brain aneurism at a quite young age, prompting him to move to British Columbia where he decided to buy a boat and travel up the Pacific coast from Vancouver to southern Alaska by himself.  He wrote about this experience in his book, Voyage of the Stella.  When he fished for salmon to eat, he often caught weird species of fish–wolf fish, Pacific lancet fish, barrel eyes, and dogfish. He fed these to the killer whales that occasionally swam near his boat, and he even dove in the water with them while wearing his scuba gear.  The killer whales never bothered him, but he once had to fend off a blue shark.  On his journey he also encountered pods of Dall’s porpoises and a pair of whale sharks.  He refueled his boat at the Indian villages that dotted the coast.  Most of the Indians were friendly, but 1 drunk tried to hit him over the head with a ketchup bottle while he was trying to eat supper at a restaurant. The brave war veteran floored the Indian with an open palm blow to the forehead.

Mr. Lawrence demonstrated even more courage in his next book, The Ghost Walker.  He spent 8 months in a wilderness cabin located in a remote area of British Columbia that was 60 miles from the nearest town, and the only feasible connection to civilization was an hazardous canoe ride down a river.  He used this makeshift cabin as an home base for tracking a large male cougar.  He gained the cougar’s trust, and the big cat let the man follow him around.  Mr. Lawrence experienced several dangerous situations, aside from trusting the cougar not to turn around and eat him.  During a blizzard, Mr. Lawrence sought shelter in a creekside cave but found himself staring eye-to-eye with an hibernating grizzly bear.  Mr. Lawrence popped out of the cave like a “champagne cork” and fled, dropping his backpack which the angry bear tore to shreds. On another occasion he slipped down an icy slope, hit a tree, and sustained a concussion.  He administered his own first aid.  He often tracked the cougar after sunset, walking in the dark woods by himself for hours.  He was 1 brave soul.

I have 1 criticism of Mr. Lawrence.  He imagined he had established ESP connections with a cougar and a killer whale.  There is no rational scientific basis for his belief.  I’m sure it was his imagination, not an ESP connection.  He was just lucky the animals he “communed” with didn’t decide to attack and eat him.

 

No Need for Males

September 23, 2017

I probably read the novels At the Earth’s Core and Pellucidar about 20 times when I was between the ages of 10 and 15.  They were written by Edgar Rice Burroughs, creator of Tarzan, who also wrote a crossover novel entitled Tarzan at the Earth’s Core. The world Burroughs created fascinated me.  An old scientist, accompanied by a classic American hero, builds a drilling machine that takes them to the center of the earth where they find a land of dinosaurs, pre-historic mammals, friendly natives, and barbaric ape-like cavemen known as the Sagoths.  The novels are full of chivalrous nonsense.  After the hero, David Innes, saves a beautiful native woman from being ravaged by a Sagoth he makes a faux pas–according to the custom among the natives of this world, a saved woman was to be embraced and kissed and made a mate or freed.  Innes didn’t know he was supposed to place his hand over her head to symbolize her freedom, otherwise she was considered his slave.  It takes him a while to realize his mistake and right his wrong.  Later, he has to save her again from a race of intelligent dinosaurs that rule this world.  This race of all female dinosaurs, known as the Mahars, raise humans like livestock.  Whenever they want something to eat, they hypnotize, then eat their human chattel.

Image may contain: 1 person

Illustration of human being hypnotized by intelligent parthenogenetic dinosaur in Edgar Rice Burroughs’ At the Earth’s Core.  In this fantasy novel the intelligent all female dinosaurs enslaved and fed upon humans until they were routed by the hero from the earth’s surface.

In Burroughs’s novel the Mahars used science and technology to eliminate the need for males, but in the real world evolution has eliminated males in 80 species of reptiles, amphibians, and fish.  Organisms that produce viable eggs without mating are known as parthenogenetic.  Species that are all female have a couple of advantages over species that need to mate.  They can reproduce when their population is low, and energy is not wasted on individuals that produce no eggs.  Most species are not parthenogenetic because in most cases the disadvantages outweigh the advantages.  Parthenogenetic species can suffer low genetic variability leading to an increase in harmful mutations.

The New Mexican whiptail lizard (Cnemidophorus neomexicanus) is an example of an all female parthenogenetic species.  The New Mexican whiptail lizard is an hybridized cross between the little striped whiptail lizard (C. ornatus) and the western whiptail lizard (C. tigris).  The New Mexican whiptail lizard produces viable eggs that all hatch to become female clones.  New lineages are created and genetic variability is established every time a western whiptail mates with a little striped whiptail.  New Mexican whiptails engage in lesbian sex.  This, of course, doesn’t fertilize the eggs, but lesbian whiptails do produce more viable eggs, probably because the sex stimulates hormone production.

Image result for Cnemidophorus neomexicanus

New Mexican whiptail lizards are all female clones.

Some species of vertebrates are facultive parthenogenetic species.  They normally mate with individuals of the opposite sex, but when populations are low can produce viable eggs without mating.  Komodo dragons, boa constrictors, and some species of sharks are able to switch from sexual breeding to asexual reproduction.  The offspring can then mate normally when they come into contact with males.  Other species are considered accidental parthenogenetic species.  They produce viable eggs without mating on very rare occasions.  Parthenogenetic cases have been reported for chickens, turkeys, and pigeons.

Many species of plants and invertebrates are parthenogenetic.  Unlike vertebrate parthenogenetic species which produce all females, invertebrates and plants can produce offspring that are all female, all male, or female and male.