Marine High Stands During the Sangamonian Interglacial at Myrtle Beach, South Carolina

I’ve always been fascinated with the Sangamonian Interglacial, known as the Eemian Interglacial in Europe. It’s the most recent climate phase when average annual global temperatures were the same or even higher than those of today. No major extinction of megafauna occurred during this phase–the best evidence against climate models of Pleistocene megafauna extinction. The Sangamonian Interglacial lasted from 132,000 years BP-118,000 years BP, although the below referenced study frames it between 128,000 years BP-117,000 years BP. Climate was likely not noticeably different during the discrepancy between these 2 parameters. The north polar ice cap completely melted during the Sangamonian Interglacial, resulting in higher sea levels than today. The north polar ice cap also completely melted during the early Holocene about 10,000 years ago. (Note: and polar bears did not become extinct as alarmists claim will happen.) Scientists are also interested in the Sangamonian because it provides an analogue for today’s climate but without the influence of manmade greenhouse gases. Recently, scientists studied ancient shorelines that existed during the Sangamonian Interglacial at Myrtle Beach, South Carolina. They appear today as ridges or terraces, referred to as outcrops as well, and they consist of crushed consolidated seashells including coral, clams, and oysters. 1 of these outcrops has a layer of peat inside the shelly sediment, suggesting the existence of a marsh, and another 1 has an eolian or windswept sand dune embedded in the layer from dunes that formed during an arid climate cycle.

Location of the area studied in the below referenced paper. Yellow lines represent high stands. Peninsular Florida was mostly submerged with the exception of a few islands. During the Pliocene shoreline was even higher and extended into the middle of South Carolina where the shoreline consisted of sea cliffs. Today, it is the eroded Orangeburg Escarpment.

Another map from the below referenced study showing terraces from former shorelines when sea level was higher than today.

Cold water coral (Desmophyllum pertusum) occurs on the Blake Plateau off the coast of South Carolina. It forms an important ecosystem. Scientists date ancient shorelines using radiometric dating, specifically Uranium series dating of coral found in the terraces.

Ribbon corals, also known as sea whips occur in shallow water off the coast of South Carolina. They are not a true coral.

The scientists dated these old shoreline ridges using uranium series dating from coral fossils and by using optically stimulated luminescence. (See: https://en.wikipedia.org/wiki/Optically_stimulated_luminescence ) They determined sea level rose no more than 15 feet during the early Sangamonian. Throughout the Sangamonian sea level fluctuated between 9-21 feet higher than that of today. Sea level rose rapidly during the early Sangamonian, stabilized, then rose again. Fluctuations were rapid and corresponded with unstable ice sheets. This new study agrees with earlier studies of these marine high stand terraces at other locations. During Ice Ages sea levels retreated as more of earth’s moisture became locked in glaciers, and dry land habitat occurred as much as 50 miles off the modern-day coast.

Reference:

Dean, S.; et al

“Last Interglacial Relative Sea Level Changes at Myrtle Beach, S.C.”

Quaternary Science Review 375 2026 (in progress)

Click to access 125489.pdf

New Study of Avifauna at Panola Mountain State Park

There is an ongoing study of birds at the Panola Mountain State Park in Rockdale County, Georgia located on the outskirts of Atlanta. Panola Mountain State Park is 1600 acres and features an erosion resistant granite monadnock, wetlands, lakes, and a restored grassland. Farmland and a golf course were converted to a grassland starting in 2001 by removing non-native plants and planting native bluestem grasses that originally occurred throughout much of the state. Periodic controlled fires help maintain the native landscape. The grassland is surrounded by forests.

191 species of birds are known to occur in the park and 90 species have been banded here. Scientists capture birds with mist nets that they set up at least once a month from morning until noon, and they’ve been doing this since 2007. The most recent study analyzed evolutionary changes in the birds that live in the park either seasonally or year-round.

Map showing location and banding areas in Panola Mountain State Park. It’s located on the outskirts of Atlanta. From the below referenced study.

Graph showing average annual temperature increase over the past 17 years from a nearby weather station. Also from the below referenced study.

There is an erosion resistant granite monadnock in the park. I will probably visit this park some day.

Restored grassland in the park where birds are captured and studied.

Western palm warblers migrate through the park.

Indigo buntings live year-round in the park. They are vicious little birds. I saw one chasing another bunting into a window. It pecked the stunned bird in the head until it was dead.

Field sparrows and other species of sparrows thrive in the restored grassland.

Average annual temperatures at this locality have increased by 4 degrees F over the past 17 years, according to data from the nearby Jonesboro weather station. Scientists expected changes in local birds that followed Bergman’s Rule and Allen’s Rule. Bergman’s Rule states that species of animals in warmer climates will grow on average to a smaller size than those same species that occur in colder climates. Allen’s Rule states that species of animals in warmer climates will grow longer appendages than their northern cousins. Scientists captured 2,938 birds including 668 recaptures for the body size part of the study. They analyzed 9 species. Gold finches, field sparrows, and savannah sparrows grew smaller wings in contradiction to Allen’s Rule. The other 6 species had unchanged wing lengths. Bergman’s Rule was contradicted by data from 4 species. Scientists hypothesize local variations contributed to these contradictions. Birds often live for part of the year in other locations that may have had different temperatures.

1,128 birds including 45 recaptures were used to study the migratory phenology (the time of year when birds begin their migration). They found 1 species did have an earlier spring migration and 2 species started migrating later in the fall. The study also looked at demographics. 1 species had a higher male sex ratio than previously, and another species had a higher population of juveniles than formerly.

The authors of this paper believe restoring grasslands can help mitigate the detrimental effects of climate change because they see so little change here. In my opinion that is a stretch. It’s a relatively small sample size from just 1 location, and climate has always changed, and those changes are not always detrimental.

Reference:

McMahaon, A.; K. Stumpf and C. Muise

“Changes in Morphology, Phenology, and Demography of Several Avian Species over 18 Years at a Restored Grassland”

Georgia Journal of Science 83 (2) 2025

https://digitalcommons.gaacademy.org/cgi/viewcontent.cgi?article=2774&context=gjs

How did Steller’s Sea Cows (Hydromalis gigas) Avoid Killer Whales (Orcinus orca)

The rich kelp forests surrounding the Commander Islands off the Alaskan Coast hosted the last of the Ice Age giants until 1768. Steller’s sea cows were manatees that diverged from tropical ancestors by evolving the ability to survive in frigid waters. This species was likely already in decline when discovered by Europeans in the middle of the 18th century. Sea cows formerly had a much larger range, occurring as far south as the Catalina Islands off the coast of California, but it seems likely indigenous fisherman were wiping them out before Europeans delivered the coup de grace to the final relict population just 37 years after discovering them. Some scientists think climate change caused the range reduction, but this seems unlikely because their favored habitat–kelp forests–remained widespread.

Killer whales hunt other whales. They must have hunted sea cows as well.

There are 20 ecotypes of killer whales. Scientists will eventually distinguish several species, but for now they are considered 1 species.

Sea cow range map. By the time Europeans discovered them, they were restricted to a final relict population located around islands off the Alaskan coast.

Artist’s rendition of a sea cow. They were big vegetarians that ate kelp all day. They did ram boats when hunted.

Steller’s sea cow was first described by George Steller, a German naturalist who sailed with a Russian exploration ship. (Their mission was to determine if Asia was connected to North America which it was during Ice Ages.) He had the chance to study sea cows when he was shipwrecked on Bering Island for 9 months. He published his description of sea cows along with the first scientific descriptions of northern fur seals, sea lions, and sea otters. He also found mammoth skeletons from a late population of them. He observed live sea cows and dissected dead ones. His work was difficult–arctic foxes, too naive to fear humans, swarmed his study area and stole his maps, books, and ink. He paid sailors with tobacco to help him dissect the beasts, and they complained. Nevertheless, his descriptions of sea cows are the only science-based observations we have. Sea cows were massive mammals 10 feet long and 20,000 pounds. They had tough skin and thick layers of blubber, and they traveled in small family groups. Gulls perched on them and fed on their parasites. The flesh was red and tasted like beef. Sea cow meat kept for a long time perhaps because the kelp they spent all day eating was high in nitrites, the same chemical used to preserve lunch meat. The blubber was reportedly as sweet as butter. Steller found 30 square feet of chewed up kelp in just 1 sea cow stomach, and dislodged, bitten off, kelp from sea cow feeding washed up on shore in great piles. Their stomachs were full of parasitic worms. When hunted by humans, sea cows would defend each other and ram boats.

I wonder how sea cows defended themselves from killer whales. Steller never saw any species preying on sea cows, but killer whales are known to attack blue whales–the largest animal to ever live. I’m sure the tough skin and thick blubber helped sea cows survive unsuccessful killer whale attacks. They likely placed themselves between killer whales and their more vulnerable calves, like whales, and they likely displayed communal defense and fought off killer whale attacks by ramming them. Their habitat may have been their best defense. They stayed hidden within kelp forests and were difficult to find for passing killer whale pods that didn’t know they were there.

There are 20 different ecotypes of killer whales, and they each vary in diet preference, genetics, appearance, and vocalization. Although there is only 1 official species of killer whale, that is likely to change soon. Scientists are on the verge of naming several new species after further study.

Reference:

Steller, G.; translated by W. Miller, J. Miller, and P. Royster

The Beasts of the Sea

Novi Commentaris Academiae Scientatum Imperiali Petropoitanae Tomii ad annum 1751

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1019&context=libraryscience

Pleistocene Dust Storms

Dry climates prevailed worldwide during Ice Ages because so much of earth’s atmospheric moisture was locked into massive Ice Sheets. Less precipitation meant less vegetative cover, and with fewer plant roots holding soil into place, the strong winds, also caused by Ice Sheet expansion, blew dirt and sand great distances. Some settled into huge sand dunes; other particles were blown all over the planet into the oceans and as far north as Greenland. Scientists take ice cores from the 125,000-year-old glacier in Greenland, and they have a year-by-year diary of past climatic conditions. Rings from summer melting mark the years exactly. Oxygen isotope ratios from air bubbles trapped inside the annual rings help scientists determine past average annual temperatures, but they also can determine how dry the climate was based on the quantity of dust and sand from inside each annual ring. The quantity of dust particles deposited was highest during the dryest years of the Ice Age.

Pleistocene sandstorms were fatal to the animals and plants buried under the dust. Animals that escaped these massive storms still suffered, perhaps fatally from getting the dust in their lungs. These sandstorms benefitted Pacific Ocean ecosystems because iron from sediment blown into the ocean fed phytoplankton, the base of the food chain. Scientists think most of the minerals came from the Gobi Desert which expanded during Ice Ages. Some recent studies suggest dust storms in Europe were even larger when they occurred during late winter and early spring. In North America, especially along the Mississippi River, waterways shrank, and exposed riverine sands blew into large dunes, still visible today.

Sand blown from the Gobi Desert during Ice Ages fertilized the Pacific Ocean.

Windblown sediment from the edge of Ice Age glaciers and exposed riverine sand blew into huge dunes still visible today.

Map showing where windblown sediment deposited from melting glaciers settled. This sediment is known as loess.

This diagram shows how dust particles were deposited into the Greenland Ice Sheet. The ice core rings are an annual diary of climate going back 125,000 years.

These are the types of minerals found in ice cores. Iron-rich minerals fertilized oceans.

The best facsimile of these ancient dust storms from the historical record occurred during the Dust Bowl era of the 1930’s. The ravages of World War I reduced Russian and European production of wheat. American farmers took advantage of the high wheat prices and ploughed over all the prairie grasses in order to plant as much wheat as possible, and at first they thrived because they planted during an unusually wet weather cycle. Starting in 1930 several years of severe drought shriveled all the plants, leaving thousands of square miles bare of any vegetation. High winds blew this dried out soil as far east as the Atlantic Coast. In the dust bowl area including Oklahoma, Texas, New Mexico, Kansas, Nebraska, and Colorado; the dust was so thick it covered houses, cars, and livestock. Many of the farmers left, leading to the famous Okie migration to California. In response to this disaster the government used the Civilian Conservation Corps to plant 200 million trees and created the Great Plains Shelter Belt. The government also advised famers to use better farming techniques such as contour ploughing (perpendicular to hills) and crop rotation to reduce soil erosion. Some programs even pay farmers not to plant–a socialist policy modern conservative farmers still use, demonstrating their political hypocrisy.

Main area of the 1930’s dust bowl disaster.

Poor farming practices led to this scary disaster.

The dust covered everything and caused health problems. The dried-out soil carried diseases and pesticides that made people suffer from long term health problems.

Cougars Kill California Condors

The California condor (Gymnogyps californiana) was the first species listed as endangered after the Endangered Species Preservation Act passed, and 40 years ago, there were so few, biologists captured the entire population, so they could be bred in captivity. Since then, wildlife officials have been releasing some back into the wild, and their numbers are slowly increasing. They still face a number of serious threats. When they scavenge animals killed by hunters using lead shot, they get lead poisoning. They also are poisoned when they consume rodents that died after eating poisoned baits. Windmills slaughter birds of all kinds. One year (2010), scientists found 3 condors killed by cougars (Puma concolor). Apparently, the condors were roosting in trees near a carcass they’d been feeding upon, and the cougars climbed into the trees and killed them in their sleep.

Scientists found 3 California condors killed by cougars in New Bitter Creek National Wildlife Refuge. Map from the below referenced journal article.

Evidence a cougar killed a condor. From the below reference.

The entire population of California condors was captured 40 years ago. Captive breeding brought them back from the edge of extinction but they still face some serious threats.

California condors released back into the wild may be naive to the threat of natural predators. Andean condors (Vultur gryphis) co-exist with cougars in South America, but there are few or no known cases of cougars preying upon them. Cougars benefit Andean condors because the birds scavenge upon llamas and deer killed by cougars. Flocks of condors may even drive cougars from their kills. (They are very large birds.)

During the Pleistocene California condors occurred all across North America, and fossil specimens have been found in New York and Florida. Following the extinction of Pleistocene megafauna, the range of the California condor shrunk to the Pacific coast where they survived by feeding upon whale carcasses. At first they benefitted from the arrival of Europeans because they scavenged all the dead livestock on the range. But lead poisoning from hunters’ shotgun shells soon began to take their toll.

Reference:

Branney, A.; J. Brandt, J. Felch, J. Lombardi

“Observations of a Puma Predation on Endangered California Condors: Implications for Species Recovery”

Ecosphere 16 (6) June 2025

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.70255

Climate Models are not Wild Guesses

Whenever I’ve discussed anthropogenic global warming on this blog, I’ve often written climate models were wild guessing. I’ve come across a study that suggests I was wrong. The study looked at 11 scientific papers with 14 projection models that estimated changes in average global temperatures over time. The papers were published between 1970-1993. The authors of this study then compared those projections from the models to average temperatures as of 2017. Though some models slightly overestimated temperatures and others slightly underestimated temperatures, most were remarkably consistent. The models were based on estimates calculating natural climate change plus manmade emissions of CO2 influence.

Climate models were remarkably consistent with real observations. Chart from the below study.

Energy use is projected to increase exponentially in the future, and this means an increase in burning fossil fuel and even greater CO2 emissions. The creation of bitcoins alone equals the energy use of New York state or the country of Poland. I don’t understand how cryptocurrency is even legal. Bitcoin creators are wasting earth’s resources creating artificial wealth out of nothing. Data centers that support internet infrastructure already use almost 5% of the power generated in the world. This computational infrastructure is going to increase as humans rely more and more on robots.

Bitcoin mining uses an enormous amount of energy, creating nothing that is useful for society. A few people will get rich at the expense of a lot of chumps.

Data centers will expand, as humans rely more and more on robots, hence increasing energy use even more.

As more fossil fuel is used, earth’s climate is headed for an uncomfortable atmosphere that resembles what it must have been like for dinosaurs during the Cretaceous Age. There is no reversing this nightmare scenario. People aren’t going to give up driving cars and central heating and air conditioning. (Especially air conditioning, since the world is going to become so much warmer.) Selfish totalitarian rulers don’t care about the environment. Wind and solar won’t be able to provide enough power for the world to end use of fossil fuels. We are doomed to live in a world of misery caused by climate change.

Robots will contribute to an apocalyptic future, but probably not in the way depicted in the Terminator movies. Instead, the energy demand to drive robots will cause global warming that will devastate the atmosphere.

Reference:

Hausfather, Z.; H. Drake, T. Abbott, G. Shmidt

“Evaluating the Performance of Past Climate Model Projections”

Geophysical Research Letters 2021

https://www.semanticscholar.org/paper/Evaluating-the-Performance-of-Past-Climate-Model-Hausfather-Drake/93cf8a01b3674e63a74d983573f05f5136c6ca1d

Pleistocene Insects from the Yukon

Scientists can learn about past climates and environments by studying the insect species composition found in dated layers of sediment. This isn’t possible in most parts of the world because of poor preservation processes, but it is in the Yukon were rapid sedimentation combined with permafrost conditions have preserved insect remains for the past 250,000 years in some localities. This includes 2 full glacial and interglacial climate phases. Today, the Old Crow River valley consists of coniferous forest, wetlands, and wet tundra; but in the past the environment has fluctuated between dry desert grassland during Ice Ages, and open spruce parkland during Interglacial periods. (This region was north of the massive glaciers that covered most of Canada when Ice Ages occurred.) The present day Interglacial is different from previous Interglacial periods because forests are thicker. The extinction of megafauna likely explains why denser forests predominate today. During past Interglacial times herds of horses, camels, mastodons, mammoths, and ground sloths kept woodlands more open.

Location of study area from the below referenced paper.

Insect remains found in sedimentary cores from the Yukon.

A specimen of Dyschirius laevifasciatus was found in a Yukon sediment core. It no longer lives this far north.

A species of rove beetle (not the one in the above photo) that today is only known from the Pacific Coast formerly lived in the Yukon interior. It probably lived on a glacial lake shoreline, similar to the beach zones it occurs in today.

Some fossil insect remains suggests previous Interglacial periods were warmer than the present day Interglacial. Scientists found remains of Dyschirius laevifasciatus, a species of ground beetle that lives much farther south today in sediment layers dating to the Sangamonian Interglacial. Beetles in this genus prefer wet sand habitats, and these remains indicate a glacial lake beach occurred here. They also found remains of a species of rove beetle (Kallisus nitodus) that not only doesn’t live this far north but is today only known from the Pacific Coast. This species formerly was able to range into drier inland habitats. Why its range has contracted is a mystery. Perhaps, it never recolonized the region after a glacial lake dried up.

The insect species composition during previous Interglacial periods differs from present day species composition. There were some species that live in wooded areas–bark beetles, a species of weevil, and a few ant species–but much fewer than today. Even though the climate was warmer and probably wetter than today, forests weren’t as dense, and trees grew farther apart, like a parkland. Steppe grassland species still occurred.

The scientists who authored the below referenced study took sample cores from 4 sites in the Old Crow River Valley. They often encountered ice wedges marking areas when the permafrost melted during previous Interglacial periods. Then the water refroze. The insects were buried in sediment when rivers flooded and when glacial lake levels rose as temperatures increased. The scientists used wet screening to find the subfossil insect parts. Insect exoskeletons float to the surface when sediment is immersed in water. From dozens of sample cores they collected thousands of specimens from over 100 species. Radiocarbon dating can only be used for organic material that is younger than 50,000 years, but insect species composition can be used in conjunction with other methods to date sedimentary layers older than this. Layers with mostly steppe grassland species indicate Ice Ages, and layers with some woodland species indicate Interglacial periods.

Though climate changed in the Yukon, evidence from this study suggests it has changed less here than in other regions of the world. The Yukon is near the Arctic Circle and has remained cold for millions of years.

Kazima, S. et. al.

“Middle Pleistocene (MIS 5) to Holocene Fossil Insect Assemblages from the Old Crow Basin, Northern Yukon, Canada”

Quaternary International 341 August 2014

https://www.researchgate.net/publication/329626444_Middle_Pleistocene_MIS_7_to_Holocene_fossil_insect_assemblages_from_the_Old_Crow_basin_northern_Yukon_Canada

African Monkey Speciation

About 75 species of monkey occur in Africa, but scientists don’t agree on the exact number. Changing climates over time have contributed to the large number of species. Most species of monkeys depend on trees for safety and foraging resources. During dry climate phases, wooded habitats in Africa often became restricted to riverside gallery forests because trees need to grow near water when conditions are arid. As a consequence, monkey populations restricted to riverine forests became isolated from each other and evolved into different species. This is known as speciation. Africa is home to 16 species of colobus monkeys, 13 species of mangabey monkeys, 1 species of macaque, 1 species of gelada baboon, 5 species of baboons in the Papio genus, 2 species of mandrills, and 33 species of guenon monkeys. The diversity of guenon species gives scientists an interesting opportunity to study how these monkeys speciated.

Black and white colobus monkeys are the most common species of colobus monkey.

There are 13 species of mangabey monkeys. Monkeys get isolated from each other during dry climate phases when they become restricted to smaller forest islands separated by unsuitable desert grassland habitat. That explains why there are so many different but closely related species.

There are about 33 species of guenon monkeys.

1 study looked at the entire genome of mona monkeys. Another study looked at the entire genome of 22 species of guenon monkeys.

1 study looked at the entire genome of 22 species of guenon monkeys. Scientists believe monkeys began to diverge from each other about 10-15 million years ago. The study found genetic evidence of ancient hybridization which contributed to speciation. Species of monkeys isolated for a long enough time to become distinct species hybridize when populations come back into contact with each other following climate change. This hybridization contributes to further speciation. Populations isolated during dry climate phases then reconnect during wet climate phases when forest habitats again expand. Scientists found that some modern species of guenon can hybridize with each other and produce fertile offspring despite having been isolated from each other for 5 million years. Hybrids can eventually evolve into yet another species. Scientists determined clades with the most species are more admixed.

Another study looked at the genome of just 1 species of guenon–the mona monkey (Cercopithecus mona). There are eastern and western populations of this species separated by the Niger River. Scientists who wrote this study determined the 2 populations diverged 84,000 years ago. The eastern population shows evidence of hybridization with their closest relatives, but the western population does not. Scientists think these populations are beginning to evolve into different species. Guenon monkeys have rapidly evolved resistance to the malaria virus–another interesting discovery of this study.

Some speciation can also occur when populations of the same species stay in contact with each other. Some populations of monkeys become better adapted to different tree canopy levels. Monkeys preferring to forage on the ground or lower in the tree canopy may stop mating with monkeys that forage higher in the tree canopy and speciation may occur as a result of this difference in preferences. Monkeys in these situations may evolve different color patterns and physical appearances and stop recognizing monkeys with different preferences as potential mates.

References:

Ayoola, A. et al

“Population Genomics Reveals Incipient Speciation, Introgression, and Adaptation in the African mona monkey (Cercopithecus mona)”

Molecular Biology and Evolution 38 (3) 2021

https://academic.oup.com/mbe/article/38/3/876/5912538

Jensen, A. et al

“Complex Evolutionary History with Extensive Ancestral Gene Flow in an African Primate Radiation”

Molecular Biology and Evolution 40 (12) December 2023

https://academic.oup.com/mbe/article/40/12/msad247/7439455

New Study Reviews Evidence of Human-Megafauna Interactions in Mexico During the Late Pleistocene

A new study reviewed all the documented evidence of humans hunting or butchering megafauna in Mexico during the late Pleistocene. The authors of this study believe there is not enough research yet on this subject. Species from 14 different families of mammals became extinct during the late Pleistocene in Mexico including ground sloths, glyptodonts, elephant relatives, toxodons, horses; and some species of bears, wolves, and big cats. There is evidence of humans hunting or butchering some of these species, but the authors of this study make the wishy-washy conclusion that there is not enough evidence to determine whether human hunting caused their extinctions.

The authors of this study found 30 Mexican sites in the literature with evidence of humans exploiting megafauna. 15 sites were in the Trans Mexican Volcanic Belt, 5 sites were in the Sierra Madre Oriental, 4 sites were in the Yucatan, 2 sites were in the northern Gulf Coastal Plain, and 2 sites were in the Sierra Madre Del Sur. 4 regions of Mexico have no evidence of human-megafauna interaction. Species of megafauna exploited by humans at these sites include 15 mammoths, 3 gompotheres, 3 camels or llamas, 2 horses, 1 bison, 1 ground sloth, 1 glyptodont, 1 pronghorn, 1 black bear, 1 big horned sheep, 1 tapir, 1 peccary, 1 saber-tooth, and 1 undetermined species of large canid. The evidence at some sites is obvious. At the Tocuila site there was evidence of 7 butchered mammoths. At other sites such as the 1 with the peccary, saber-tooth, and canid the bones are merely found in association with archaeological evidence.

Regions of Mexico. Map from the below study. The Trans-Mexican Volcanic Belt had the most evidence of human-megafauna interaction. It may have hosted the most favorable habitat for large mammals.

Artist’s depiction of paleoindians hunting mastodon. I don’t know who drew this. I doubt it took this many men to bring down a large mammal. 1 accurately thrown spear could kill it.

The authors of the study report that not many of these sites had good isotopic data or radiocarbon dates on the bones. Instead, the sites were dated using a combination of biochronology and radiocarbon dates of the organic matter where the bones were found. The authors mention the ridiculous conclusion from a study I wrote about a few months ago (See: https://markgelbart.wordpress.com/2024/11/20/flawed-study-suggests-anthropogenic-fires-caused-the-extirpations-of-megafauna-near-the-la-brea-tar-pits/ ) that determined megafauna near the La Brea Tar Pits became extinct because the environment became more arid. I suggested this was an absurd assumption because horses, camels, and lions are all well-adapted to living in arid environments.

Reference:

Solis-Torres, O.; J. Arroyo-Cabrales, P. Roberts, and N. Amano

“A Critical Review of Late Pleistocene Human and Megafaunal Interactions in Mexico”

Quaternary Science Reviews April 2025

https://www.sciencedirect.com/science/article/pii/S0277379125000204

3 New Studies Support Human Overhunting as the Cause of Late Pleistocene Megafauna Extinctions

3 new studies support human overhunting as the cause of Late Pleistocene extinctions in South America, and perhaps the most interesting study is an isotopic analysis of the Anzick child’s remains. The Anzick child was an 18-month-old toddler deliberately buried after his death. The body was discovered in Wilsall, Montana during 1968 and was associated with over 100 Clovis artifacts. Radiocarbon dates suggest the toddler lived sometime between 12,900 years BP-12,695 years BP. In 2014 local Indian fanatics insisted scientists let them rebury the body because of their stupid religious beliefs, but genetic evidence suggests this tribe was not even directly descended from the baby’s parents. Instead, the baby was more closely related to Indians living in Central and South America today. Nevertheless, scientists still had isotopic data from the child’s bone chemical composition, and they were able to determine the baby’s mother’s diet. (The child likely still got most of his nutrition from nursing.)

Scientists used a statistical model of the isotopic composition to determine mammoth made up 35%-40% of the mother’s diet, showing that megafauna was the most important resource for the Clovis people in this region. Elk made up 15%-17% of their diet, camel and/or bison made up 21% of their diet, horse made up 6% of their diet, and small mammals only 4% of their diet. (Bison and camel had a similar diet, so scientists can’t distinguish their isotopic signatures.) The ancestors of the Clovis may have been generalist foragers who had already reduced populations of horses and camels, but they became big game hunting specialists during the Clovis era. This study also compared the Anzick child’s isotopic composition with those from other large carnivores that lived in the region then. The Clovis diet was most similar to that of the scimitar-toothed cat. This big, fanged cat is thought to have specialized in hunting juvenile mammoths. Archaeologists and anthropologists who proclaimed humans hardly ever hunted mammoth were certainly wrong. Large mammals were the central item in the diet of the Clovis culture, and humans surely overexploited them into oblivion.

Pie charts from the below referenced study (Chatters et. al.) showing the percentage of mammals that made up each species diet. Humans enjoyed a diet most similar to Homotherium–the scimitar-toothed cat. FYI, Arcotodus = short-faced bear, Aenocyon = dire wolf, Miracinonyx = psuedo cheetah, Canis = timber wolf, Panthera = giant lion, Bootherium = helmeted musk-ox, Cervus = elk, Equini = horse, Mammuthus = mammoth, Camelops = camel, Bison = bison, Ovis = big horn sheep, Rangifer = caribou, Antilocapra = pronghorn.

Another study examined the database of 1600 reliable radio-carbon dates of human-occupied sites in South America during the Late Pleistocene. The scientists used 6 different statistical models to estimate the earliest human arrival in South America, and the how rapidly humans colonized the continent. They estimated humans arrived in South America between 16,600 years BP-15,100 years ago, but they lean toward the more recent date. The initial colonizers lived in low population densities and are less visible in the archaeological record. The scientists didn’t use dates earlier than this because the evidence is inconclusive. Both human and megafauna populations increased following the Last Glacial Maximum, but eventually the latter became extinct as humans became more common in the environment. The extinctions seem to correspond to human population densities and not climate change. Grassland environments favorable to megafauna retracted during a Late Pleistocene climate fluctuation, but megafauna began declining 500-1400 years before this, and there was still plenty of grassland habitat available.

A third study, authored by several of the scientists who wrote the study discussed above, compared megafauna populations both spatially and temporarily with the prevalence of fishtail projectile points. Fishtail projectile points were the most common arrowhead used by South American Indians to hunt large mammals. Megafauna populations began to increase about 17,500 years ago when climate following the Last Glacial Maximum improved. (Megafauna population densities were estimated using radio-carbon dates of subfossil remains in the paleobiology database. In my opinion this is a little dubious because the fossil record might not represent actual population densities.) About 13,500 years ago when Indians started using Fishtail projectile points, megafauna populations began to decline. Patagonian grassland and the Pampas hosted the highest populations of megafauna, while the Andes hosted the lowest. Species of megafauna covered in this study included Hippidion (a genus of horses restricted to South America during the Late Pleistocene), horses belonging to the Equus genus, llama, 3 species of ground sloth, glyptodont, notiomastodon, and gompothere. The last 2 were elephant-like species. South America suffered an even larger percentage of large mammal extinctions than North America during the end of the Pleistocene. 82% of South America’s large mammals became extinct compared to 70% of North America’s large mammal extinctions. The authors of this study feel confident humans were primarily responsible because megafauna began declining centuries before any major climate fluctuation, but they did decline when Fishtail point projectiles became more prevalent in the archaeological record.

Fishtail projectile points were used by Paleoindians to kill large mammals. An increase of their appearance in the archaeological record is associated with a decline in megafauna populations.

Chart showing the correlation between the prevalence of Fishtail projectile points and a decline in megafauna populations. From the below referenced study by Prates (2021).

References:

Chatters, J.; B. Pottter, S. Fiedel, J. Morrow

“Mammoth Featured Heavily in Western Clovis Diet”

Science Advances 10 (49) December 2024

www.science.org/doi/10.1126/sciadv.adr3814dr3814

Prates, L.; G. Politis, S. Perez

“Rapid Radiation of Humans in South America after the Last Glacial Maximum: A Radiocarbon-based Study”

PLOS ONE July 2020

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236023

Prates, L.; S. Perez

“Late Pleistocene South American Megafauna Extinctions Associated with Rise of Fishtail Points and Human Populations”

Nature Communications 12 (2175) 2021

https://www.nature.com/articles/s41467-021-22506-4