Tag Archives: horses

Land of the throats

17.3-16.3 million years ago

There’s a great expansion in the diversity of horses in the mid-Miocene, especially horses that are adapted to grazing rather than browsing. The shift to grazing is going on world wide among many different groups. In South America the big grazers are the liptoterns, ungulates not closely related to horses that evolve to look a lot like them, with high-crowned grazing teeth, single-toed hoofed feet and legs built for speed. (Edgar Rice Burroughs took the name thoat – what his characters rode around on on Barsoom/Mars — from one genus of liptotern, Thoatherium.)

thoat

We often think of evolution as a matter of organisms adapting to their environments, but when the environment is other organisms, each side may be chasing a moving target. Or sometimes the sides may reach an equilibrium. In the case of grazing animals, there’s a process of coevolution that goes on between grazers and grasses. Where grazers are active, the plants that survive are grasses, which keep leaves above the ground but grow from underground. And this works in the other direction: in moderately dry climates, grasses are more productive than taller brushy plants, so it’s when grasses take over that there’s enough food around for grazers – a mutually reinforcing cycle. With drier climates from the mid-Miocene on, grasslands and grazers get to be more and more important.

So a lot of the story of life on Earth is not just the appearance of this or that cool animal, but also the evolution of ecosystems. At the same time grasslands were spreading on land, for example, kelp forests were spreading in coastal oceans. We’ll see how important grasslands are in human evolution and history. And kelp forests, with their rich fish populations, might have been important too, as the highway that the earliest Americans followed along the Pacific coast to the New World.

Planet of the horses

18.3-17.3 million years ago.

We’re now running through Big History 100,000 years a day.

Horses have probably been the single most important domesticated animal in human history. Also, more than with other livestock, people get attached to horses as individuals. I’m guessing that in history and literature there are more horses with individual names than any other animal. (Alexander the Great’s horse was Bucephalus, “Ox-head”; Charlemagne’s was Tencendur; Don Quixote’s was Rocinante; Gandalf’s was Shadowfax.) We’ll be hearing a lot more about horses and horse folk on Logarithmic History once we get to human history.

Being so charismatic, horses have featured in a big way in arguments over evolution. Thomas Henry Huxley (1825-1895), “Darwin’s bulldog,” knew he needed to find good evidence for evolution. When he visited the United States in 1876, he was ready to give a lecture based on horse fossils from Europe. But visiting Yale, he was so impressed with O. C. Marsh’s collection of horse fossils from the western United States, that he rewrote his lecture around it.

Henry Fairfield Osborn (1857-1935) was director of the American Museum of Natural History and a huge presence in American paleontology. He was active at a time when most scientists accepted evolution, but many weren’t so keen on Darwin’s theory of natural selection. He thought horses were a fine example of “orthogenesis,” the tendency of species to follow a fixed line of evolution, reflecting internal forces, maybe related to willpower. He thought that humans shared a migratory spirit with horses, so that anywhere horse fossils were found would be a good place to look for human fossils. This theory didn’t pan out too well. A massive AMNH expedition to Central Asia led by Ray Chapman Andrews found all sorts of wonders – dinosaur eggs, baluchitheres – but no fossil “pro-men.” Orthogenesis leant itself naturally to diagrams showing evolution from early to modern horses going in a straight line.

horseladder

George Gaylord Simpson (1902-1984), paleontologist, was one of the great figures in the evolutionary Modern Synthesis that brought together Darwin’s theory of natural selection and Mendel’s genetics. There was no room for orthogenesis in the Modern Synthesis, and Simpson emphasized that the evolution of horses was a matter of adaptation to a changing environment – especially the spread of grasslands. Also that horse evolution looked more like a bush than a ladder.

horsebush

Stephen Jay Gould (1941-2002) was the most widely recognized American evolutionary biologist of recent times. (For example had a spot on The Simpson’s — “Lisa The Skeptic,” Season 9.) Gould had his own take on the modern synthesis, taking the “bushes not ladders” theme for horses and other animals (including human ancestors), and pushing it a step further. According to the theory of “punctuated equilibrium” (formulated in collaboration with Niles Eldredge), species mostly change relatively little during the time they exist (evolutionary stasis). Most evolutionary change happens when a small population buds off to form a new species and reproductive isolation allows it to conserve any evolutionary novelties it has developed. This opens up the possibility of “species selection.” Applied to horses, for example, this could mean that horses were evolutionarily successful for some time not so much because individual horses were well-adapted, but because something about horses collectively (their harem mating system, maybe) made one horse species especially likely to produce new species. Both horses and primates seem to be especially prone to bud off new species:

Speciation and chromosomal evolution seem fastest in those genera with species organized into clans or harems (e.g., some primates and horses) or with limited adult vagility and juvenile dispersal, patchy distribution, and strong individual territoriality (e.g., some rodents). This is consistent with the … hypothesis … that population subdivision into small demes promotes both rapid speciation and evolutionary changes in gene arrangement by inbreeding and drift.

The world at 1000 BCE

Logarithmic History today covers 1137-964 BCE. Here’s a quick look at the world around 1000 BCE

The world population is about 50 million.

The Bantu expansion is just beginning, from a homeland on the present Nigeria/Cameroon border. It will eventually cover most of Africa south of the equator. The expansion is sometimes told as a story of first farmers replacing hunter-gatherers. But, as with the Indo-European expansion, this now looks to be too simple. Other farmers and herders reached east Africa before the Bantu; traces of their languages survive as eastern Bantu substrates. So the Bantu had something extra – social organization? malaria resistance? – going for them.

Seafarers with roots in the Lapita culture have already reached Western Polynesian – Samoa and Tonga, previously uninhabited.

The Olmec are flourishing in Meso-America. A controversial find (the Cascajal block) suggests they are just taking up writing.

In China, the Mandate of Heaven has passed from the Shang Dynasty to the Zhou.

In the Near East and Eastern Mediterranean, the Late Bronze Age collapse has opened up space for smaller states. Tyre and other Phoenician city-states are sailing the Mediterranean. Phoenicians using an alphabet that Greeks will eventually adapt. Further south, Philistines and Israelites have been duking it out, with Israelites gaining the upper hand under David* (king from 1010 to 970 BCE). The Iron Age conventionally begins now, with the widespread use of iron – more abundant and cheaper than bronze.

On the steppe, horses have long been domesticated, but people are now learning to make effective use of cavalry – fighting in formation and firing volleys from horseback. This is the beginning of 2500 years in which the division between Steppe and Sown will be central to Eurasian history.

* Everybody knows that David killed Goliath (1 Samuel 17). However, according to 2 Samuel 21:19, Goliath was killed by Elhanan of Bethlehem. Probably the Elhanan story is the original one, and the whole David-and-Goliath story amounts to later resume-padding at the expense of a subordinate. See The Historical David: The Real Life of an Invented Hero for this and other demonstrations of how we can recover likely truths from historical texts.

Horse clans

The Botai culture (3700 – 3100 BCE), in present-day Kazakhstan, represents an uncommon mode of subsistence: equestrian hunting. The fact that the Botai folk have domesticated horses makes them different from most hunters and gatherers, while the fact that they depend heavily on hunting makes them different from later herders in the region.

The most famous equestrian hunters are the American Plains Indians of the seventeenth to nineteenth centuries. These were a varied assortment of tribes, with origins among more settled Indian groups, who took up riding after Spaniards reintroduced the horse (which had gone extinct in North America, along with other megafauna, twelve thousand years earlier). Plains Indians depended on hunting bison for most of their diet. The Botai folk were not hunting bison of course, but wild horses. Horses supplied the overwhelming part of their diet; 90% of animal bones in their settlements come from horses. There was an argument for a while about whether the Botai folk really had domesticated horses. However, this has been settled by the discovery of pottery containing residues of mare’s milk; obviously no one is arguing that they were milking wild horses. So unlike American Indians, Botai folk milked their horses.  It is also likely that they were riding horses and using them for traction. There is evidence for bit wear on the teeth of some of their horses, and it’s hard to see how they could have gotten whole wild horse carcasses back home (as they did) without having tame horses to pull the carcasses, probably on sledges.

The fact that the Botai folk had horse milk in their diet, along with lots of horse meat, is interesting. Horse milk is sweet (6.3% lactose vs. 1.3% fat, close to human milk), sweeter than cow’s milk (4.6% lactose vs. 3.4% fat). Any Botai individual who carried the lactase persistence allele, which allows carriers to digest lactose (milk sugar) past infancy and into adulthood, would presumably have had a strong fitness advantage. The ability to digest lactose might have been particularly important for kids making the transition from mother’s milk to horse meat.

Horses and horse riding and horse traction play an enormous role in Eurasian history. They are probably a major factor in the expansion of speakers of Indo-European languages. The Botai folk were almost certainly not the original Proto-Indo-European (PIE) speakers – the PIE vocabulary doesn’t fit – but they or people like them might have played some role in Indo-European origins, even if their language didn’t prevail.

Land of the thoats

There’s a great expansion in the diversity of horses in the mid-Miocene, especially horses adapted to grazing rather than browsing. The shift to grazing is goes on world wide among many different groups. In South America the big grazers are the liptoterns, ungulates not closely related to horses that evolve to look a lot like them, with high-crowned grazing teeth, single-toed hoofed feet and legs built for speed. (Edgar Rice Burroughs took the name thoat – what his characters rode around on on Barsoom/Mars — from one genus of liptotern, Thoatherium.)

thoat

Not from the horse family

We often think of evolution as a matter of organisms adapting to their environments, but when the environment is other organisms, each side may be chasing a moving target. Or sometimes the sides may reach an equilibrium. In the case of grazing animals, there’s a process of coevolution that goes on between grazers and grasses. Where grazers are active, the plants that survive are grasses, which keep leaves above the ground but grow from underground. And this works in the other direction: in moderately dry climates, grasses are more productive than taller brushy plants, so it’s when grasses take over that there’s enough food around for grazers – a mutually reinforcing cycle. With drier climates from the mid-Miocene on, grasslands and grazers get to be more and more important.

So a lot of the story of life on Earth is not just the appearance of this or that cool animal, but also the evolution of ecosystems. At the same time grasslands were spreading on land, for example, kelp forests were spreading in coastal oceans. We’ll see how important grasslands are in human evolution and history. And kelp forests, with their rich fish populations, might have been important too, as the highway that the earliest Americans followed along the Pacific coast to the New World.

Planet of the horses

Horses have probably been the single most important domesticated animal in human history. Also, more than with other livestock, people get attached to horses as individuals. I’m guessing that in history and literature there are more horses with individual names than any other animal. (Alexander the Great’s horse was Bucephalus, “Ox-head”; Charlemagne’s was Tencendur; Don Quixote’s was Rocinante; Gandalf’s was Shadowfax.) We’ll be hearing a lot more about horses and horse folk on Logarithmic History once we get to human history.

Being so charismatic, horses have featured in a big way in arguments over evolution. Thomas Henry Huxley (1825-1895), “Darwin’s bulldog,” knew he needed to find good evidence for evolution. When he visited the United States in 1876, he was ready to give a lecture based on horse fossils from Europe. But visiting Yale, he was so impressed with O. C. Marsh’s collection of horse fossils from the western United States, that he rewrote his lecture around it.

Henry Fairfield Osborn (1857-1935) was director of the American Museum of Natural History and a huge presence in American paleontology. He was active at a time when most scientists accepted evolution, but many weren’t so keen on Darwin’s theory of natural selection. He thought horses were a fine example of “orthogenesis,” the tendency of species to follow a fixed line of evolution, reflecting internal forces, maybe related to willpower. He thought that humans shared a migratory spirit with horses, so that anywhere horse fossils were found would be a good place to look for human fossils. This theory didn’t pan out too well. A massive AMNH expedition to Central Asia led by Ray Chapman Andrews found all sorts of wonders – dinosaur eggs, baluchitheres – but no fossil “pro-men.” Orthogenesis leant itself naturally to diagrams showing evolution from early to modern horses going in a straight line.

horseladder

George Gaylord Simpson (1902-1984), paleontologist, was one of the great figures in the evolutionary Modern Synthesis that brought together Darwin’s theory of natural selection and Mendel’s genetics. There was no room for orthogenesis in the Modern Synthesis, and Simpson emphasized that the evolution of horses was a matter of adaptation to a changing environment – especially the spread of grasslands. Also that horse evolution looked more like a bush than a ladder.

horsebush

Stephen Jay Gould (1941-2002) was the most widely recognized American evolutionary biologist of recent times. (For example had a spot on The Simpson’s — “Lisa The Skeptic,” Season 9.) Gould had his own take on the modern synthesis, taking the “bushes not ladders” theme for horses and other animals (including human ancestors), and pushing it a step further. According to the theory of “punctuated equilibrium” (formulated in collaboration with Niles Eldredge), species mostly change relatively little during the time they exist (evolutionary stasis). Most evolutionary change happens when a small population buds off to form a new species and reproductive isolation allows it to conserve any evolutionary novelties it has developed. This opens up the possibility of “species selection.” Applied to horses, for example, this could mean that horses were evolutionarily successful for some time not so much because individual horses were well-adapted, but because something about horses collectively (their harem mating system, maybe) made one horse species especially likely to produce new species.

Opinions about Gould – as a theorist and a human being — are pretty divided. For a negative take, here’s a piece by Robert Trivers, one of the great figures in evolutionary biology.

The world at 1000 BCE

Logarithmic History today covers 1001-837 BCE. Here’s a quick look at the world around 1000 BCE

The world population is about 50 million.

The Bantu expansion is just beginning, from a homeland on the present Nigeria/Cameroon border. It will eventually cover most of Africa south of the equator. The expansion is sometimes told as a story of first farmers replacing hunter-gatherers. But, as with the Indo-European expansion, this now looks to be too simple. Other farmers and herders reached east Africa before the Bantu; traces of their languages survive as eastern Bantu substrates. So the Bantu had something extra – social organization? malaria resistance? – going for them.

Seafarers with roots in the Lapita culture have already reached Western Polynesian – Samoa and Tonga, previously uninhabited.

The Olmec are flourishing in Meso-America. A controversial find (the Cascajal block) suggests they are just taking up writing.

In China, the Mandate of Heaven has passed from the Shang Dynasty to the Zhou.

In the Near East and Eastern Mediterranean, the Late Bronze Age collapse has opened up space for smaller states. Tyre and other Phoenician city-states are sailing the Mediterranean. Phoenicians using an alphabet that Greeks will eventually adapt. Further south, Philistines and Israelites have been duking it out, with Israelites gaining the upper hand under David* (king from 1010 to 970 BCE). The Iron Age conventionally begins now, with the widespread use of iron – more abundant and cheaper than bronze.

On the steppe, horses have long been domesticated, but people are now learning to make effective use of cavalry – fighting in formation and firing volleys from horseback. This is the beginning of 2500 years in which the division between Steppe and Sown will be central to Eurasian history.

* Everybody knows that David killed Goliath (1 Samuel 17). However, according to 2 Samuel 21:19, Goliath was killed by Elhanan of Bethlehem. Probably the Elhanan story is the original one, and the whole David-and-Goliath story amounts to later resume-padding at the expense of a subordinate. See The Historical David: The Real Life of an Invented Hero for this and other demonstrations of how we can recover likely truths from historical texts.