Pleistocene Hackberries (Celtis sp.)

I’ve come across anecdotal evidence, suggesting hackberry trees were locally abundant during Ice Ages. Today, hackberry is a minor component of deciduous forests. I know of 3 sites dating to the Pleistocene where the remains of hackberry have been found. Plant remains dating to the Pleistocene are relatively rare, so the occurrence of this species might be significant and not just a coincidence. Hackberry seeds were found associated with the skeletons of a flat-headed peccary herd that was buried by a sandstorm in western Kentucky thousands of years ago. (See: https://markgelbart.wordpress.com/2013/03/10/when-sand-dunes-buried-herds-of-flat-headed-peccaries/ ) Hackberry along with oak were the most abundant plant remains and DNA dating to the Pleistocene found in Hall’s Cave located on the Edward’s Plateau in Texas. (See: https://markgelbart.wordpress.com/2020/06/29/new-study-of-the-seda-dna-in-halls-cave-texas/ ) Hackberry trees are still common near the cave entrance. And hackberry leaves were found in Kingston Saltpeter Cave in North Georgia, though it’s unclear if the leaves were actually in the layer with the Pleistocene animal remains.

I hypothesize there were 3 factors why hackberry thrived when other deciduous species declined in abundance during Ice Ages. Foresters note Georgia hackberry grows well on dry rocky sites. The Ice Ages were arid because much of earth’s water became locked in glacial ice, and dry environments prevailed in many locations. Perhaps hackberry was better able than other hardwood trees to endure the lower atmospheric CO2 levels that occurred during Ice Ages. Hackberry also may not have been a preferred food of the megafauna. So, when megafauna consumed other plants, they were eliminating competition for sunlight and growing space. Though this is just speculation and probably impossible to determine because evidence has eroded away, I envision groves of widely spaced oak and hackberry trees growing with bunch grass and bare soil between the trees in dry environments across the piedmont region of southeastern North America during Ice Ages. Pollen records suggest pine was more abundant than hardwoods during Ice Ages, but pine produces much more pollen than hackberry and may be overrepresented by comparison. Hackberry pollen rarely shows up in pollen records. However, there are very few (if any) local pollen records from this region dating to the Last Glacial Maximum, and pollen records are not always all inclusive.

Hackberry trees belong to the Celtis genus and were formerly thought to be in the same family as elm, but modern botanists recently decided the Celtis genus belongs in the Cannabis family. This means they are related to hemp and marijuana. There are 66 species in the Celtis genus worldwide, and they are found in the Northern Hemisphere, South America, and central Africa. 3 species live in eastern North America–common hackberry (Celtis occidentalis), Georgia hackberry also known as dwarf hackberry (C. tenuifolia), and sugarberry (C. laevigata). Common hackberry’s continuous range is just north of Georgia, but disjunct populations do occur in the state. Georgia hackberry is found in the piedmont region of southeastern North America, plus southern Missouri and parts of Appalachia, Louisiana, and Texas. Sugarberry is found throughout the southeast.

Range map for Georgia hackberry, also known as dwarf hackberry. It prefers dry rocky piedmont soils.

Range map for sugarberry.

Georgia hackberry. It is usually a medium sized tree.

Georgia hackberry leaves.

Hackberry fruit is edible. I’ve tasted the fruit of Georgia hackberry, and it’s bittersweet and mostly skin and seed. Sugarberry looks bigger and may have more flesh. American Indians pounded the fruit, seed and all, into pemmican–a mixture of berries, jerky, and meat fat. Many species of brush-footed butterflies feed upon hackberry leaves during their caterpillar stage. The fruit stays on the tree all winter and provides food for birds.

Hackberry emperor butterfly larva like to feed upon hackberry leaves. Other caterpillars in the brush-footed butterfly family also feed upon hackberry leaves.

Sugarberry fruit. I have never eaten sugarberries, but I have tasted Georgia hackberries. They are more skin and seed than fruit, and they taste bittersweet. These look fleshier. Native Americans pounded the fruit into pemmican.

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The Population of China is Projected to Dramatically Fall before the End of the Century

The population of humans on earth is over 8 billion and growing rapidly. This population explosion of a single species of large vertebrate is probably unsustainable. It is a matter of time before a threshold is reached when an increasing number of humans outstrips the ability of advanced agriculture to feed all of humanity. Most natural resources are also finite. Competition for dwindling resources could cause devastating wars, resulting in the deaths of millions. Pollution and human produced garbage from expanding populations risk turning the whole planet into a toxic waste dump. Humans can either voluntarily choose to reduce their population or the limits of the natural world will do it for them in the form of war, famine, and/or a poisoned atmosphere. China understood this over 40 years ago and instituted the 1 child per family policy. China is a totalitarian society and was able to implement this draconian policy that would be impossible to implement in a free country. From 1980-2016 the Chinese government enforced this policy using heavy fines, forced abortions, and forced sterilizations. It worked. The Chinese government ended this policy when they realized they were facing a dramatic population decline in the future that put at risk their goal of global economic dominance.

China’s 1 child policy enforced from 1980-2016 worked. China’s population is projected to fall dramatically by the end of the century. Graph from the Pew Research Center.

Sexist Chinese parents selected for woman more often than men, and today there are 30 million more men than women in China. Still, women in China are having a hard time finding suitable husbands. Graph also from the Pew Research Center.

Though the population of people on earth needs to decline because of finite resources, China’s policy was draconian. China is an inhumane totalitarian state.

China’s population is projected to begin declining by 2050, if it hasn’t already, and by 2100 they expect their population will be less than 800 million. India is projected to surpass China in number of people next year. During the time the 1 child policy was in effect sexist Chinese parents often chose to abort female fetuses because male heirs were greatly preferred. At first the birth ratio was 112 males born to 100 females born, but between 2002-2008 it was 118 males born to 100 females born. Today, there are 30 million more males in China than females. Yet, women are having a hard time finding suitable mates. The females who were born were given more family resources to put toward education, and they are more career-oriented and don’t need husbands. Women got used to having few or no children, and many like it. They don’t want to have babies. Successful career women can afford to be picky, and in China they really are. The culture has totally changed. I suppose there are many men in China who aren’t getting laid, and porn is heavily restricted there. I’m really glad I don’t live there.

Japan is a free society, but they are also facing a population decline. The Japanese are in general also a sexist people. Career women who become pregnant are expected to quit their jobs and become full-time mothers. Liberated women are choosing careers over motherhood, and the birthrate is declining. The population in Japan is expected to fall below 50 million people by 2100. By 2050 1/3rd of the population there will be over 60, and this will put a strain on the economy. It will be expensive to support that many old people. Elder care will depend heavily upon robots.

Economists hate population declines because they cause economies to shrink. However, people who care about ecology should rejoice. I don’t agree with the methods used by totalitarian China to reduce their population, nor do I condone Japanese sexism, but reducing the human population on earth should be a goal of society. Humanity should work on improving the quality of life for everybody, and that is much easier with fewer people to help. Culture and attitudes need to change. People should know it is ok to have as many kids as they want, but large families should be discouraged. People should also know it is ok, if one decides not to have children at all. There are already enough of us.

What did Entelodonts and Anthracotheres Eat?

Most species of mammals living during the Oligocene (33 million years BP-25 million years BP) left no living descendants, but some were related to ancestors of extant species. Anthracotheres and entelodonts are examples of this evolutionary tree that includes more dead ends than living branches. Anthracotheres and entelodonts were related to each other, but they were also likely related to early whales and the ancestors of hippos. Genetic studies support the vertebrate paleontologists who believe these animals were related to each other. The genetic evidence indicates hippos are the closest living relatives of whales, and the cladistic analysis by scientists is probably correct. Entelodonts and anthracotheres may have been dead ends, but they were successful for a very long time. Their known fossil record stretches from the mid-Eocene about 40 million years ago to the early Miocene about 15 million years ago. Anthracotheres were semi-aquatic and about the size of a juvenile elephant. Entelodonts were not quite as large and lived on land. Entelodonts are also known as “hell pigs,” but scientists no longer think they were closely related to pigs. Some have speculated they were highly carnivorous and rammed their prey, knocking their prey down before tearing them apart with their fearsome teeth. Entelodont teeth have been found in Eocene-aged fossil sites in Georgia. Anthracotheres and entelodonts ranged throughout Eurasia, Africa, and North America.

Anthracotheres were semi-aquatic relatives of enteledonts, hippos, and early whales. A study of tooth wear suggests they ate leaves and fruit.

Enteledonts were related to anthracotheres, hippos, and early whales. A study of tooth wear suggest they were omnivorous like wild boars.

An image of the teeth used in the study. This image is from the below referenced study.

Studies of anthracothere and entelodont diet are contradictory. The latest study of their diet looked at anthracothere and entelodont teeth under a microscope. They compared the microwear on their teeth with the microwear on the teeth of 29 extant species of mammals whose diets are known. Scientists couldn’t determine which species of anthracothere the teeth used in the study came from, but they did identify the entelodont teeth to be from Entelodont magnus. The entelodont and anthracothere teeth came from a fossil site in southwest France. The results of this study suggest anthracotheres were herbivores and ate leaves, grass, and fruit. Probably, much of their forage was aquatic plants. Microwear on entelodont teeth resembled that from extant wild boar, suggesting they ate roots, tubers, plants, and meat. They may have actively hunted or scavenged meat.

Reference:

Rivals, F. ; R. Balyaev, V. Basova, N. Prilepskaya

“Hogs, Hipps, or Bears? Paleodiet of European Oligocene Anthracotheres, and Entelodonts”

Paleogeography, Paleoclimatalogy, Paleoecology 611 Feb 2023

https://www.sciencedirect.com/science/article/pii/S003101822200534X

A Camera Trap Study in the Chernobyl Exclusion Zone

I’ve stated it before and I’ll state it again: the presence of humans is worse for wildlife than radiation contamination. Ever since the Chernobyl nuclear plant suffered a meltdown in 1986, forcing the evacuation of humans from the area, wildlife populations have exploded there. Species of mammals and birds, rare or extirpated elsewhere in Europe, thrive in the Chernobyl Exclusion Zone where people are almost completely absent. Studies show wildlife populations in the Chernobyl Exclusion Zone are even higher than those in protected national parks in the region, and the diversity and abundance of wildlife here exceeds that of most American national parks.

During the 1986 meltdown a dense cloud of radiation struck a 2-3 square mile area, turning the green coniferous trees red, and today it is known as the red forest. 80% of it burned in a wildfire during 2015, and a year later scientists set up 21 camera traps here to study wildlife populations. Over a year the cameras took 45,859 images, and the scientists were able to identify animals in 19,391 of them including 14 species of mammals, 23 species of birds, and even some large insects. The height of the cameras selected for large species, but they did get images of smaller species too.

A 2-3 square mile area of forest near the Chernobyl nuclear plant turned red from radiation contamination. Scientists set up 21 camera traps to record the species of mammals that live here.

This chart is the result of the camera trap study conducted in the Chernobyl red forest. They also recorded some large insects, but that part of the chart wouldn’t fit on this image. From the below referenced study.

Endangered Przewalski’s horses live in the Chernobyl Exclusion Zone. They were recorded from 6 of the 21 camera traps.

Moose were 1 of the more common large mammals found in the camera traps. The red forest is converting to a young deciduous successional forest with the types of plants moose like to eat.

Moose, red deer, roe deer, brown hare, and wolf were photographed by most of the traps. A deciduous undergrowth is replacing the burned and dead coniferous trees. Moose and roe deer prefer to eat this type of plant growth, and this may explain why they are common here. Brown bear, bison, and beaver were not photographed in the study, but this is not surprising because they are uncommon is this part of the Chernobyl Exclusion Zone. For me the most surprising discovery were feral dogs photographed by 6 of the cameras. I thought wolves would have wiped out feral dogs, but apparently, they have found a niche.

A previous study of the red forest area in 2009 found low mammal abundance. This new study contradicts the earlier study. Perhaps animals are finally returning to one of the more contaminated areas. Possibly, the fire improved habitat for them.

Reference:

Beresford, N.; S. Gashek, M. Wood, and C. Barnett

“Mammals in the Chernobyl Exclusion Zone’s Red Forest: A Motion-activated Camera Study”

Earth Syst. Sci. Data 15 911-920 November 2022

https://essd.copernicus.org/articles/15/911/2023/

Some Surprising Hybrids

“Nature is a mad scientist,” said the Kramer character from an old episode of Seinfeld when he discovered his average-sized girlfriend’s parents were little people or midgets as we used to know them. (Midget is too honest a word for modern sensibilities.) The many hybrids that have occurred in captivity is an example of how crazy nature can be. Most of the big cats in the Panthera genus (lions, leopards, tigers, snow leopards, and jaguars) have crossbred in captivity, though most of these hybrids are infertile. A recent genetic study suggests some of these species interbred in the wild during the last 2 million years, and it aided their evolutionary survival. (See: https://markgelbart.wordpress.com/2020/08/13/post-speciation-admixture-in-big-cats/) But surprisingly, there are a few cases on record of cougars mating with leopards and producing viable hybrids. Cougars and leopards are not in the same genus, and they are not closely related, but in a German zoo around 1900 these species did breed. Cougars and leopards are separated by at least 7 million years of evolution, and these cases are hard to believe. In 1 case a male leopard crossed with a female cougar, and in another case a male cougar crossed with a female leopard. A cross between a leopard and a cougar is known as a pumapard. The cubs survived though they were bad-tempered and poorly behaved. They stayed small. There is also a case of a much smaller male ocelot breeding with a female cougar. 4 litters were produced, but all the cubs died due to maternal neglect. The mother even ate 1 of the litters. Some cat breeders don’t want this known, but there is no evidence domestic cats have ever successfully bred with another species other than the European wild cat which is basically the same species.

A cougar and a leopard living in a zoo together produced viable offspring. This is astonishing considering they’ve been separated by at least 7 million years of evolution.

Cubs from a cross between an ocelot and cougar. A female cougar and a male ocelot made at least 4 litters in a zoo. None of the cubs survived because the mother would not take care of them, and on 1 occasion ate them.

Other surprising hybrids have occurred in zoos. A black bear successfully produced offspring with a brown bear. These 2 species are in the same genus, and genetic studies suggest there was some interbreeding between the 2 species during the early Pleistocene. Recently, a black rhino interbred with a white rhino in a South African zoo, and in 1968 a Baird’s tapir interbred with a lowland tapir. An Asian elephant once bred with an African elephant. These 2 species are not in the same genus, and Asian elephants are more closely related to extinct mammoths, than African elephants. Many species of primates will interbreed in captivity. Lemurs will breed with other species of lemurs, macaques with other species of macaques, and baboons with other species of baboons. Male chimpanzees will mate with their more docile relatives–the bonobos. During the early 20th century a Russian scientist experimented with creating a cross between a chimpanzee and a human. Perhaps fortunately, he was killed in a political purge in 1920. The evolutionary ancestors of humans frequently interbred with the evolutionary ancestors of chimpanzees, but this was over 6 million years ago. It would be difficult to cross a human with a chimpanzee today because the human chromosome number 2 is structured like 2 ape chromosomes put together. However, horses and zebras have similar differences, and they have been bred in captivity. It seems like something from the H.G Wells novel The Island of Dr. Moreau, but it is likely a human x chimpanzee hybrid could theoretically be produced.

An Asian elephant mated with an African elephant in a zoo. The hybrid lived for 10 days. Nobody knows why it died.

A few years ago, Hungarian scientists were experimenting with ways to increase egg production for endangered Russian sturgeon. They used American paddlefish (also endangered) eggs as a control in their study. They were shocked when the paddlefish eggs were fertilized with Russian sturgeon sperm. The 2 species diverged 164 million years ago, long before dinosaurs became extinct. They called the hybrid a sturddlefish. They have no plans to sustain the hybrid.

A sturddlefish resulted from the accidental crossing of an American paddlefish and a Russian sturgeon during a scientific experiment in Hungary. This is the most astonishing hybrid of all. These 2 species last shared a common ancestor 164 million years ago.

Reference:

http://messybeast.com/genetics/hybrid-cats.htm