Tag Archives: South America

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.

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Luzia

11.5 kya. Luzia is an adult female Homo sapiens fossil from central Brazil. She’s named after Lucy, the famous Australopithecus afarensis from Laetoli, but she’s no relation, or at least no more relation than the rest of us. When Luzia was discovered (1975) she presented quite a puzzle. She’s one of the earliest known South American human fossils. Her skull, well-preserved, looks nothing in particular like the skulls of later Indians. It’s more similar to the skulls of modern Australian aborigines and Africans. She’s also short, under five feet.

luzia

There hasn’t been any analysis of Luzia’s DNA but we now (as of last year) may have a better idea who her relations are. Southeast Asia was occupied for tens of millennia by hunter-gatherers of the Hoabinhian culture, which persisted through melting ice caps and rising sea levels, up to the arrival of farmers originally from South China. Scattered groups of foragers in the region are remnants of this population. It is likely that the Hoabinhians, or nearby Melanesians, or related folk, traveled up the Pacific coast and were the first human arrivals in the New World. (A direct trip across the Pacific is another possibility, but seems less likely.) These early Americans were largely replaced (they may never have been very numerous) by the ancestors of modern Indians, making a modest contribution to the DNA of the latter.

We noted earlier that there seem to be linguistic traces of this early migration in some of the languages of South America. It’s also worth mentioning that early twentieth century anthropologists thought Melanesia and native Amazonia show some striking cultural similarities, especially relating to men’s houses, all-male cults, myths of matriarchy, and sacred flutes. Some anthropologists have coined the term “Melazonia” to capture the similarities in social systems in the two places. Here’s from a recent book.

One of the great riddles of cultural history is the remarkable parallel that exists between the peoples of Amazonia and those of Melanesia. Although the two regions are separated by half a world in distance and at least 40,000 years of history, their cultures nonetheless reveal striking similarities in the areas of sex and gender. In both Amazonia and Melanesia, male-female differences infuse social organization and self-conception. They are the core of religion, symbolism, and cosmology, and they permeate ideas about body imagery, procreation, growth, men’s cults, and rituals of initiation.

Note that “40,000 years” may be too big by a factor of 3. The usual assumption has been that these similarities result from parallel cultural evolution  – easier to imagine for cultural evolution than for language history – but maybe there is an ancient historical connection too.

The Great American Interchange

For most of the last 100 million years, South America was an island continent, like Australia, with its own peculiar mix of species, largely isolated from other continents (although monkeys, and guinea pig relations, rafted across.) By contrast, North America was intermittently connected with Eurasia and exchanged species off and on. South America supported a rich array of marsupials, including a marsupial version of a saber-toothed tiger. It also had predatory flightless “terror birds” that seemed bent on reoccupying the two-legged predatory dinosaur niche.

terror bird

There was also a profusion of notoungulates (probably distantly related to hoofed animals in North America and Eurasia), and liptoterns. (Below is a late surviving liptotern, Macrauchenia, looking like a Dr. Seuss invention.)
macrauchenia

South America was close enough to North America for the two continents to start exchanging species by 14 million years ago, but the really massive exchange began with the establishment of the Isthmus of Panama, and climate changes, about 3 million years ago. 38 genera of land mammals walked north from South America. 47 genera walked south from North America. So the initial exchange was unbalanced; the subsequent evolution was even more so. Only a handful of South American invaders – notably armadillos and (for a while) ground sloths – succeeded in establishing themselves in North America, while North American invaders generated a profusion of new species. Many of the really distinctive South American forms would go extinct over the next millions of years.

Paleontologists dispute the causes of the turnover, but it looks an awful lot like North American species had a competitive edge. This is one instance of a phenomenon we’ve seen already in animal evolution, and will see again in human history, of large land areas generating more competitive forms.

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.

Land of Samba

1934-1938

South America avoided the all-out international total wars that consumed Eurasia in the twentieth century. (Civil wars are another matter.) But international events made themselves felt even here. Brazil had its own fascist party, the Integralists, with its paramilitary wing, the Green Shirts. However in Brazil, even the fascists couldn’t quite get into the whole National Socialist racial purity thing; the Integralist slogan called for a “Union of all races and peoples.” The Integralists fought the Communists in the early 1930s, but eventually both sides were suppressed by the dictatorial Estado Novo (New State) in 1937, led by Getúlio Vargas.

vargas

In much of the world at the time, liberalism and free trade were out, and nationalism and protectionism were in. In Latin America, this move went under the name of “populism,” favoring urban businessmen and workers at the expense of the old export-oriented land- and mine-owners. This often meant cultural as well as economic nationalism. Brazil today is famous for its Carnival celebrations, including samba parades. Ironically these took much of their current shape during the 1930s as a means of bringing rowdy public celebrations under official control: samba parades from this point on were officially sponsored, and were expected to march in orderly lines and to celebrate edifying nationalist themes. Early twentieth century samba musicians incorporated a variety of musical styles in their performances; in the 1930s, in the name of “authenticity,” they were encouraged to purge their music of foreign influences, including jazz.

The Great American Interchange

For most of the last 100 million years, South America was an island continent, like Australia, with its own peculiar mix of species, largely isolated from other continents (although monkeys, and guinea pig relations, rafted across.) By contrast, North America was intermittently connected with Eurasia and exchanged species off and on. South America supported a rich array of marsupials, including a marsupial version of a saber-toothed tiger. It also had predatory flightless “terror birds” that seemed bent on reoccupying the two-legged predatory dinosaur niche.

terror bird

There was also a profusion of notoungulates (probably distantly related to hoofed animals in North America and Eurasia), and liptoterns. (Below is a late surviving liptotern, Macrauchenia, looking like a Dr. Seuss invention.)
macrauchenia

(The picture is from the American Museum of Natural History’s travelling exhibit on “Extreme mammals,” which I had a chance to see this week at the Natural History Museum of Utah – strongly recommended if you get a chance.)

South America was close enough to North America for the two continents to start exchanging species by 14 million years ago, but the really massive exchange began with the establishment of the Isthmus of Panama, and climate changes, about 3 million years ago. 38 genera of land mammals walked north from South America. 47 genera walked south from North America. So the initial exchange was unbalanced; the subsequent evolution was even more so. Only a handful of South American invaders – notably armadillos and (for a while) ground sloths – succeeded in establishing themselves in North America, while North American invaders generated a profusion of new species. Many of the really distinctive South American forms would go extinct over the next millions of years.

Paleontologists dispute the causes of the turnover, but it looks an awful lot like North American species had a competitive edge. This is one instance of a phenomenon we’ve seen already in animal evolution, and will see again in human history, of large land areas generating more competitive forms.

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.)

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.