Archive for September, 2015

The Lost Pleistocene World of the Seychelles Islands

September 29, 2015

The Seychelles Island group was part of the southern supercontinent Gondwanaland before the latter broke apart.  It then split away from India 60 million years ago and has been isolated from all continents ever since.  Presently, the Seychelles Islands include separate mountaintops totaling about 282 square miles, but during the last Ice Age it was 1 giant island of about 80,000 square miles…roughly the size of Georgia and half of Florida combined.  Sea level rise has inundated most of the island.

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The Seychelles Islands are located northeast of Madagascar.  They are mountain tops of  a large desert island that existed during Ice Ages.

Map of Seychelles and other islands during the Last Glacial Maximum ~29,000 BP-~15,000 BP.

A human seafarer wrecking his boat on the Pleistocene Seychelles would have discovered both a deserted and a desert island that could have inspired the setting of Robinson Crusoe.  The Seychelles Island was drier with a more sparse tree canopy than is found on the island group today.  A giant species of tortoise (Aldabrachelys gigantea) shaped the landscape into a short grass plain known as “tortoise turf.”  This long lived species (a captive specimen reached the age of 255) still occurs on 1 of the Seychelles atolls.  The Aldabra tortoise creates pathways and selects for shorter species of grasses that grow below its preferred level of foraging.

Primitive amphibians closely related to species found in India occur on the Seychelles.  Caecilians and soogloossid frogs live here.  The presence of these primitive amphibians on India and the Seychelles provides biological evidence that they were once part of the same land mass.

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There are 5 species of caecilians living on the Seychelles.  They are primitive amphibians.

The only dangerous animal for a Pleistocene Robinson Crusoe stranded on the Seychelles would have been the Australian saltwater crocodile (Crocodylus porosus).  Early European explorers reported them as “abundant” on the Seychelles, but they were extirpated here by 1819.  Naturalists wrongly assumed they were African species–either Nile crocodiles or mugger crocodiles.  But a genetic study suggests they were the Australian species.  These saltwater crocodiles occasionally do swim miles into the ocean and surface currents helped carry them to the far away Seychelles.

Saltwater Crocodile | Crocodylus porosus photo

Australian saltwater crocodiles lived on Seychelles until 1819.

At least 238 species of birds live on the Seychelles.  More species than that probably lived on the island before the Indian Ocean submerged most of it.  Sea birds like nesting on islands where few predators roam.  Many species of migratory songbirds get blown off course and learn to survive on islands.  Some evolve into new species.  Pigeons are notorious for getting blown out to sea.  The Seychelles has 5 different species of pigeons.  Settlers wiped out 1 species of parrot (Psitticula wardi) native to the Seychelles.  A fruit-eating bat known as a flying fox is the only native species of mammal on the island group.

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The Seychelles Parakeet is now extinct.

The coc-de-mer coconut palm (Ladoica maldivica) would have provided plenty of food for a stranded Pleistocene Robinson Crusoe.  It produces the largest seed in the world, weighing 50 pounds.  Unlike other coconuts, this species doesn’t float, explaining why it occurs nowhere else.  They produce a toxin that prevents other plants, including competing members of their own species, from growing near its root system.  These slow-growing plants take 800 years to reach full size.

Surviving almost impossible odds – how the Seychelles Coco-de-Mer palm parents its seeds

The coco-de-mer coconut palm is the largest seed in the world, growing to over 50 pounds.

The jellyfish tree (Medusagayune oppostifolia) is a rare species living on the granite mountaintops.  This relic was likely widespread over the Seychelles before the Indian Ocean inundated most of it.

The jellyfish tree is a rare relic that was probably more widespread on Seychelles during Ice Ages.

 

See also: https://markgelbart.wordpress.com/2011/11/11/banana-hole-fossil-sites/

Ostriches (Struthios sp.) Occurred in India during the Late Pleistocene

September 24, 2015

The ratites are ground dwelling birds that originated on the supercontinent of Gondwanaland before it split apart.  The ratites include the kiwi bird of New Zealand, the cassowary of New Guinea and northern Australia, the emu of Australia, the rhea of South America, penguins of Antarctica, and the ostrich of Africa.  About 10 million years ago, Africa collided with Eurasia, allowing ostriches to expand their range north.  The fossil record suggests ostriches occurred on the Himalayan Highlands from the Miocene until the mid-Pleistocene.  During the late Pleistocene ostriches shifted their range south and lived in western and central India.  Ostriches disappeared from India about 10,000 years ago and are now confined to Africa.

Ostrich

Ostriches belong to the ratite family along with emus and cassowaries.  They evolved on Gondwanaland before Australia, Africa, Antarctica, and South America broke apart.  Ostriches colonized Asia and occurred in India during the late Pleistocene but became extinct there about 10,000 years ago.

Pike Place Market Creamery - Seattle, WA, United States. Ostrich egg compared to chicken egg

Ostrich egg compared to chicken egg.  Ostrich egg shell fragments dating to the Pleistocene are more common in India than the actual ostrich bones.

Ostriches prefer a type of habitat known as the Sahel.  Sahel vegetation grows on semi-arid tropical steppe and consists of grassland and savannah with some woodland and shrub land.  A latitudinal band of Sahel vegetation currently exists between the Sahara desert and the Sudanese savannah.  The presence of ostriches in the Asian fossil record suggests Sahel-like vegetation existed in the Himalayan Highlands for millions of years.  Sahel-like landscapes predominated in central and western India from over 60,000 years ago to ~10,000 BP. Habitat on the Himalayan Highlands may have deteriorated into pure desert during severe glacial episodes, and ostriches used the Indus River corridor as a route to central India.  Ostriches and humans (Homo sapiens) were the only new large vertebrates to colonize this region during the late Pleistocene.  Most anthropologists believe humans first colonized India by following a coastal route, but people may have used the Indus River corridor to colonize India from the Himalayan Highlands instead.

Sahel Beautiful Landscapes of Sahel

Photo of Sahel-vegetation, the favored habitat of the ostrich.  The Sahel belt is a zone between the Sahara desert and the Sudanian savannah.  Habitat like this was common in India during the late Pleistocene.

Other species of large vertebrates that prefer Sahel-like vegetation still occur in India.  Lions, wild asses, and rhinos still find suitable habitat in India but it occurs in patches.  The shift from glacial to interglacial vegetation patterns may not explain the disappearance of ostriches from India because grasslands and savannah still exist there.  Humans may have overexploited ostriches.  Archaeologists have found beads made with ostrich eggshells and ancient rock paintings of the big birds in India.

India did not suffer a major extinction event at the end of the Pleistocene.  A study of 21 Pleistocene mammals determined just 1 species, a baboon, became extinct then.  Baboons are highly adaptable apes that directly compete with humans for the same resources.  I believe humans are behind the extirpation of baboons and ostriches from India.  Tropical diseases kept human populations low, however, and other species of megafauna were able to survive human impacts.  Later, the Hindu prohibition against killing became popular, helping to protect animal populations.  The Hindu religion may be as old as 7000 years, beginning at a time when India was still a vast wilderness.

Scientists can’t determine what species of ostrich lived in Pleistocene India.  It may have been a unique species or the same still extant in Africa.   Ostrich egg shell fragments are far more common at fossil sites than the actual ostrich bones.

Reference:

Blinhorn, James; Hema Achyuthan, and Michael Petragla

“Ostrich Expansion into India during the Late Pleistocene: Implications for Continental Dispersal Corridors”

Palaeogeography, Palaeoclimatology, Palaoecology 2015

https://www.academia.edu/8976173/Ostrich_expansion_into_India_during_the_Late_Pleistocene_Implications_for_continental_dispersal_corridors

Pleistocene Gray Whale (Eschichtius robustus) Calving Grounds off the Georgia Coast

September 21, 2015

During warm climatic phases of the Pleistocene, the north polar ice cap mostly or even completely melted.  The Arctic Ocean became an ice free corridor when interglacial summers were warmer and longer than those of the 21st century.  Many species of marine mammals used this ice free corridor as a migratory route between the Atlantic and Pacific Oceans.  A study of gray whale genetics suggests the gray whale enjoyed a gene flow between Atlantic and Pacific populations until the Last Glacial Maximum when the polar ice cap expanded and blocked the Arctic Ocean corridor.  It remained blocked from about ~30,000 BP-~10,000 BP.  Then, the corridor began opening intermittently and there was some mixing of populations early during the Holocene.

Human hunters extirpated the Atlantic population of gray whales by 1620.  It’s amazing how fast this was accomplished.  Whalers eliminated this population about a century after bringing their hunting technology to the American side of the ocean.  Humans almost overhunted the Pacific population into oblivion, but laws outlawing the practice saved the species, and populations are on the rebound.  Present day global warming is causing the Arctic Ocean corridor to open intermittently again.  Gray whales are using this corridor again and have recently been spotted in the Atlantic Ocean.  Gray whales may recolonize the Atlantic Ocean because of global warming.

Human divers discovered fossil evidence of gray whales off the coast of Georgia.  A gray whale jaw and jaw fragments from another individual were found on JY Reef located to the east of St. Catherine’s Island.  Today, this site is in deep water, but at the time these whales died, it was a shallow shell bed located near the shore.  One of the specimens dates to 41,000 BP, and the other was found embedded in oyster shells dated to 48,000 BP.  The vertebrae of an unidentified species of whale was also found here.

Some scientists hypothesize gray whales used the warm waters off the Georgia coast for breeding and calving, much like the small surviving population of right whales (Eubalaena glacialis) does today.  Killer whales probably hunted the whale calves as seen in the below video.  Gray whales migrate to cooler waters to feed.  During cooler phases of the Pleistocene this migratory route may have been shorter.

Video of a mother gray whale protecting her calf from a >2 hour killer whale attack.  Scenes like this likely occurred off the coast of Georgia until ~1620 AD.

Scientists are searching the continental shelf off the coast of Georgia for subfossil evidence of the gray whale barnacle, Cryptolepes rhachianecti.  This would be additional evidence for the former presence of gray whales here.

CETACEAN - WHALE - GRAY WHALE WITH CRYPTOLEPAS RHACHIANECTI - SAN IGNACIO LAGOON BAJA MEXICO (5).JPG

Gray whale barnacles.  Gray whales help spread the species and provide protection from predators such as starfish, sea worms, and fish.

Gray whales survived the climatic fluctuations of the Pleistocene, but in the Atlantic they couldn’t withstand 100 years of human hunting.

See also https://markgelbart.wordpress.com/2013/03/25/pleistocene-fossils-found-on-the-georgia-bight/ and https://markgelbart.wordpress.com/2014/09/12/the-paleoenvironment-of-the-georgia-bight-when-it-was-above-sea-level-80000-bp-7000-bp/

References:

Alter, S. Elizabeth; et. al.

“Climate Impacts on Transocean Dispersal and Evolution of Gray Whales from the Pleistocene to 2100”

Molecular Ecology April 2015

Noakes, Scott; Nicholas Pyenson, and Greg McFall

“Late Pleistocene Gray Whales (Eschrichtius robustus) offshore Georgia, USA, and the Antiquity of Gray Whale Migration in the North Atlantic Ocean”

Palaeogeography, Palaeoclimatology, Palaeoecology 2013

Llama and Deer Abundance during the Pleistocene in Southeastern North America

September 16, 2015

Studies of bone chemistry suggest the species of North American llamas that lived in North America during the Pleistocene enjoyed a diet similar to that of the white-tailed deer (Odocoileus virginianus).  The species of llamas that co-existed with deer then were the large-headed (Hemiauchenia macrocephala) and the stout-legged (Paleolama mirifica).  Evidence determined from the below referenced studies suggests the large-headed llama preferred open woodland habitat because it was a mixed feeder capable of grazing grasses and browsing on trees and shrubs.   One scientist thinks they may have grazed on green grass during the summer and browsed on woody vegetation during the winter.  In any case it was a very adaptable species with a wide geographic and temporal range, having existed for over 2 million years.  The stout-legged llama was a denizen of deep forests, dependent upon browsing the plant foods found in shady environments.  White-tailed deer are also browsers that prefer deep forest and forest edge.  I’ve considered the ecological interrelationship between Pleistocene llamas and deer and have reached some hypothetical conclusions about the former abundance and distribution of each species.

Llama, deer | by mezzoblue

Llama and deer on a farmed ranch.  Llama and deer co-existed in southeastern North America during the Pleistocene and consumed many of the same plant foods.  Llamas are closely related to camels.

The large-headed llama was probably far more abundant in Florida during the Pleistocene than white-tailed deer based on the abundance of each in the fossil record.  The former species has been found at over 60 fossil sites in Florida.  Remains of this species have been found off the coast of Georgia (which was above sea level during glacial episodes) as well as the coastal plains of South Carolina and Texas.  The large-headed llama also ranged from southern California north to Washington, Idaho, South Dakota, and southern Canada.  Their range included Oklahoma, Kansas, and Nebraska as well.  Curiously, no certain remains of this species have been found from central Georgia north to Wisconsin and Maine.  Clayton Ray, former curator for the National Museum of Natural History, commented that a partial tooth found at Ladds in Bartow County, Georgia resembled a “camelid” but was not enough evidence to definitely state the presence of llamas there.  Based on the geographical occurrence of this species’ remains and isotopic evidence suggesting it preferred open woodlands, I’ve concluded its Pleistocene range extended from western North America to the southeastern coastal plain and Florida.  Many species of western plants are found on the southeastern coastal plain where they occur as relics, and this is evidence an ecologically similar corridor once connected western prairies to southeastern savannahs.  The large-headed llama likely was a common animal of long-leaf pine savannahs that formerly prevailed on southeastern coastal plains.  Their fossil remains are so common at the Harleyville fossil site in South Carolina that it is known as “camelot.”  This site dates to 400,000 years ago before bison colonized the region.  Llamas had even less competition for food during the middle Pleistocene.

White-tailed deer and long-nosed peccaries (Mylohyus nasatus) were likely the most common hooved animals in north Georgia during the late Pleistocene based on their abundance in the fossil record here.  This is evidence that forests grew more dense to the north of the coastal plain.  There is not enough fossil or pollen evidence to determine where exactly in the piedmont forests began to become more dense.  The latitude where the density of the canopy increased from open woodland to closed forest fluctuated depending upon climatic cycles and other factors.  Despite the lack of fossil evidence, I believe large-headed llamas occasionally ranged into the piedmont and mountain regions of the south whenever habitat became favorable.  They advanced wherever forests became more open.  But deer were probably more common than llamas in the upper south for most of the Pleistocene.

Fossil remains of the stout-legged llama seem to be restricted to Florida and the coastal plain of Texas south to South America.  This suggests the stout-legged llama was not as cold tolerant as its cousin.  Instead, they preferred warm sub-tropical forest.

Both species of North American llamas were 2 to 3 times larger than white-tailed deer.  Large-headed llamas grew to 660 pounds, while stout-legged llamas reached 600 pounds.  Their larger size meant they reproduced more slowly than white-tailed deer and were less able to withstand human hunting pressure.  Changing climatic conditions could not have caused their extinctions because the foods they ate always remained abundant.  White-tailed deer populations, especially in Florida but wherever their ranges overlapped, increased following the extinctions of llamas because they no longer had to share the edible plant material the environment provided.

References:

Kohn, Matthes; and M. McKay

“Dining in the Pleistocene: who’s on the menu”

Geology 33 (8) 2005

Yann, L.; and L. Desantis

“Effects of Pleistocene Climates on Local Environments and Dietary Behavior of Mammals in Florida”

Palaeogeography, Palaeoclimatology,  Palaeoecology 2014

A Viable Scientific Explanation for why Africans Dominate Sports

September 10, 2015

Thomas Jefferson declared that “…all men were created equal…” Everybody knows this statement isn’t literally true.  When I was a little guy in grade school I wanted to become an NFL star.  Then I ran track in the 7th grade and much to my disappointment discovered there were many faster runners than me.  I knew I was too small and slow to ever make it as a professional football player.  Later in life, I wished I was 3 inches taller because I learned the chicks dig taller men.  Alas, I realized in some respects I was even less than average.

Thomas Jefferson didn’t actually mean all men were created equal, but he did believe all men should be treated equally under the law.  The subject of this blog entry is a touchy topic, so I want to make it clear that I agree with  the true meaning of Jefferson’s declaration, and I don’t believe in discriminating against people of varying races or religions.  I do not believe any race is superior to any other, though there are clear physical differences between races.  My essay is based on scientific facts published in peer-reviewed literature.  A scientific fact can not be considered racist or bigoted.

Athletes of African descent dominate running and jumping events in track, basketball, and certain positions in football such as running back, wide receiver, and defensive back.  There is not a single white cornerback in the NFL and only a handful of white running backs. This disparity can’t be explained by socio-economic factors alone.  While it is true that the average African-American family is economically poorer than the average white family, the total population of poor white people in America far outnumbers the total population of poor black people.  The pool of potential white participants who would like to escape poverty by playing basketball in the NBA or cornerback in the NFL is large but there are very few able to compete at that level due to a lack of natural ability.  There is an interesting and viable scientific explanation for this disparity.

Africa is the original birthplace of the human race.  Genetic studies show the original home of all species includes a more genetically diverse population.  After a new species evolves, they colonize new regions.  The populations that colonize new regions descend from the smaller gene pool that invaded the new territory. The history of Homo sapiens is an especially excellent illustration of this concept.  The ancestors of all Homo sapiens currently living on earth originally evolved in south Africa about 200,000 years ago.  About 60,000 years ago, a small population of humans left Africa and eventually the ancestors of this group spread throughout the world.  The entire population of Europeans, Asians, and Australian aborigines descend from just 1 or a few tribes that left Africa long ago.  This means Africans are more genetically diverse than the people who colonized the rest of world.  There is more genetic diversity in an African village of 70 people than there is in all of China.

The Khomani bush people of south Africa are the oldest race known.  Scientific studies show they are genetically the most diverse people in the world.  All of humanity descends from their ancestors.  Photos of Khomanis are remarkable.  Of course, they all have dark skin, but their facial features show a wide variation.  Some look Caucasian, some look Asian, and some have Negro features.

Khomani African Bushmen are genetically the oldest human race.  Their ancestors are the ancestors of tribes that gave birth to other Africans, Caucasians, and Asians.  Facial features within this tribe vary–some look Asian, others Negroid, and some resemble Caucasian.  Note the woman on the left.  She looks Asian, while the baby has Negroid features.

These Khomani children could almost pass for white.

As the descendants of the Khomani colonized the rest of Africa, the various tribes became geographically isolated.  Humans evolved in Africa for 140,000 years before any left the continent, so the overall population on this continent remained genetically more diverse than the human populations in the rest of the world.  This genetic diversity meant extremes in various body types were more pronounced in Africa than in Europe and Asia.  For example 7 foot tall Watusi tribesmen lived within miles of 4 foot tall pygmies.  Studies show that people who lived in west Africa evolved (on average) an higher ratio of fast twitch muscle fibers than any other population of people.  This made them extraordinary sprinters and jumpers.  This explains why all cornerbacks in the NFL  and most Olympic sprinters are of west African descent.   Studies show that people living in east Africa evolved the ability to produce more energy producing enzymes.  This helps with long distance running and explains why Kenyans are dominating marathon running.

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Pygmy tribes live just a few miles from the very tall Watusis, demonstrating the amount of genetic diversity in Africa.  You won’t find any pygmies in the NFL or NBA.  Almost all African-Americans in those sports leagues are of west African descent located to the northwest of pygmy tribal areas.

finish line in men's 100 meters at olympics

The average human of West African descent has an higher ratio of fast twitch muscle fibers than other humans.  This explains why people of West African descent dominate sprinting, basketball, and certain positions in football such as running back, receiver, and defensive back.

Studies have also found that the average African has a greater bone density than the average white person.  This durability aids in contact sports.  Africans have a much lower rate of developing osteoporosis and hip fractures.  African women are less than half as likely to suffer hip fractures when they get older than white women.  They are even less likely to get hip fractures than white men.  However, this greater bone density is a disadvantage in competitive swimming.

Note: None of these minor physiological differences are related to intelligence in anyway.

References:

Entine, Jon

Taboo: Why Black Athletes Dominate Sports and why We’re Afraid to Talk About it

Public Affairs 2000

Henn, Brenna; et. al.

“Hunter-gatherer Genome Diversity Suggests a Southern African Origin for Modern Man”

PNAS 2011

Hockberry, Marc

“Racial Differences in Bone Structure”

Transactions of American Clinical Climatological Annual 2007

Survival of the Fittest and Dwarfism–A Paradox

September 4, 2015

The concept of natural selection forms the basis for the Theory of Evolution.  Environmental forces select the fittest members of each population to pass on their genes.  Most people think survival of the fittest means selecting the biggest, fastest, and strongest; and that is often true.  However, insular evolution (the evolution of species on islands) shows that survival of the fittest can mean the opposite as well.  During the Pleistocene many species of megafauna became stranded on islands.  Islands are often devoid of large predators.  Megafauna evolved to a greater size in response to predation, so without the presence of predators, there was no longer selective pressure toward a larger size.  Smaller individuals were just as likely to survive.  Moreover, these smaller individuals had an advantage on islands where less food was available.  On continents megafauna could migrate to different regions when forage became scarce, but they didn’t have this luxury on islands.  Smaller individuals were more likely to survive during times of scarcity because they required less food.  This explains the tendency toward dwarfism among Pleistocene megafauna that lived on islands.

During the Pleistocene there were 8 species of dwarf ground sloths living on Cuba, 7 on the island of Hispaniola, and 1 on Puerto Rico.  Megaloncus rodens was 1 of the species that lived on Cuba, and it grew to 200 pounds.  By contrast the smallest species of continental ground sloth grew to 500 pounds.  Dwarf ground sloths survived in the Caribbean until as recently as 4700 BP, about 1200 years after humans colonized the region.  Humans must be responsible for their extinction because there was no major climatic change during this time period.

Skeletal mount of Caribbean dwarf ground sloth (Megalocnus rodens) next to a paleontologist in 1920.  All continental species of ground sloths were larger than men.

Full-sized Columbian mammoths (Mammuthus colombi) swam to the Channel Islands off the coast of California and eventually evolved into a dwarf species known as Mammuthus exilis.  Evidence suggests they arrived as early as 250,000 years BP and survived 2 complete glacial/interglacial cycles but became extinct when men found the island.  The late surviving population of mammoths living on Wrangel Island off the Alaskan coast were not a dwarf species, but those living on St. Paul’s Island off Alaska were.

Each island in the Mediterranean Sea had its own species of dwarf elephant or mammoth.  Dwarf elephants lived on Cyprus, Malta, Sicily, Sardinia, and Stylus (now underwater).  Dwarf mammoths lived on Crete.  Every time sea level fell in response to glacial expansion, new waves of elephants colonized these islands, and all evolved into dwarf species.  Distances were shorter between the mainland and the islands during glacial expansions, and it was easier for these large animals to swim there.  Some of these dwarf species were still large animals, weighing as much as 500 pounds, but others reached heights of just 3 feet tall.

Size comparison between human, full sized elephant, and 2 different species of dwarf elephants.

Some Mediterranean islands also hosted populations of dwarf hippos.  Sicily, Malta, Crete, and Cyprus were home to 4 different species of dwarf hippos respectively.  There were 3 different species of dwarf hippo living on Madagascar until 1000 years ago when humans wiped them out.

Hippo in Middle~Late Pleistocene Mammalian by sinammonite

Artist’s depiction of extinct Mediterranean dwarf hippos.  P. minor lived on Cyprus, H. melitensis lived on Malta, H. creutzburgi lived on Crete, and H. pentlandi lived on Sicily.

Stegodon floresiensis insularis was a dwarf species of elephant that lived on the Indonesian island of Flores.  It shared the island with a dwarf hominid, Homo floresiensis, known famously as the hobbit.  This hominid likely evolved from Homo erectus, but in isolation from the parent population became a dwarf species.  The hobbit grew to 3.5 feet tall and had the brain capacity of a chimpanzee.  Nevertheless, the area of their brain associated with language was well developed, and they may have been as intelligent as modern humans because their ratio of brain capacity to body size was similar.  They hunted dwarf stegodons.  Komodo dragons and even marabou storks were a threat, especially to juvenile hobbits.  Homo floresiensis lived as recently as 14,000 BP.

Artist’s depiction of real life hobbits (Homo floresiensis) battling marabou storks on the Indonesian island of Flores.

Ground sloths, elephants, and hippos were/are excellent long distance swimmers.  That explains how they colonized islands.  The ancestors of the hobbit either built rafts or accidentally rafted to the island on flood debris.  If they built rafts, they may have forgotten the technology after several generations.

There are over 200 medical causes of dwarfism, and some traits that cause it can be inherited.  A human dwarf is defined as an adult less than 4’10” in height.  Some kinds of dwarfism in children can be treated with growth hormones and drugs that stimulate appetite.  Parents fear their children will face societal prejudice, if they don’t reach a “normal” height.  Few realize the trait for dwarfism could potentially be favorable for natural selection, if environmental conditions on earth deteriorate.  The traits that favor future survival of the fittest on this island earth can’t be predicted.

What happened when James Lusted, who stands just 3ft 7in tall, took his fiancee for a romantic meal at a Harvester in Cardiff?

If the world suffered a severe shortage of food for millennia, human evolution would tend toward dwarfism.  Humans with smaller body size have an  advantage in environments with less food.

References:

Muhs, Daniel; et. al.

“Late Quaternary Sea-Level History and the Antiquity of Mammoths (M. exilis and M. colombi) on the Channel Islands National Park, California, USA”

Quaternary Science Review May 2015

Poulakatis, Nikos; et. al.

“Ancient DNA Forces Reconsideration of Evolutionary History of Mediterranean Pygmy Elephants”

Biology Letters 2006