Tag Archives: insects

Consider her ways

104-98.6 million years ago

There are some pieces of paleontology that really stand out in the popular imagination. Dinosaurs are so cool that even if they hadn’t existed we would have invented them. (Maybe we did, in the form of dragons. And tune in early April for the dinosaur-griffin connection.) Also, as I suggested in the preceding post, transitions from one form of locomotion to another – flightless dinosaurs to birds, fish to tetrapods, land mammals to whales – really grab the imagination (and annoy creationists) because the largest and most distinctive named folk categories of animals (snakes, fish, birds) are built around modes of locomotion.

Evolutionary biologists tend to see things differently. Turning fins into legs, legs into wings, and legs back into flippers is pretty impressive. But the really major evolutionary transitions involve the evolution of whole new levels of organization: the origin of the eukaryotic cell, for example, and the origin of multicellular life. From this perspective, the really huge change in the Mesozoic – sometimes called the Age of Dinosaurs – is the origin of eusociality among insects like ants and bees. An ant nest or a bee hive is something like a single superorganism. with most of its members sterile workers striving – even committing suicide — for the colony’s reproduction, not their own. (100 million years ago – corresponding to March 29 in Logarithmic History — is when we find the first bee and ant fossils, but the transition must have been underway before that time.)

Certainly the statistics on social insects today are impressive.

The twenty thousand known species of eusocial insects, mostly ants, bees, wasps and termites, account for only 2 percent of the approximately one million known species of insects. Yet this tiny minority of species dominate the rest of the insects in their numbers, their weight, and their impact on the environment. As humans are to vertebrate animals, the eusocial insects are to the far vaster world of invertebrate animals. … In one Amazon site, two German researchers … found that ants and termites together compose almost two-thirds of the weight of all the insects. Eusocial bees and wasps added another tenth. Ants alone weighed four times more than all the terrestrial vertebrates – that is, mammals, birds, reptiles, and amphibians combined. E. O. Wilson pp 110-113

E. O. Wilson, world’s foremost authority on ants, and one of the founders of sociobiology, thinks that the origin of insect eusociality might have lessons for another major evolutionary transition, the origin of humans (and of human language, technology, culture, and complex social organization). In his book The Social Conquest of Earth he argues that a key step in both sets of transitions was the development of a valuable and defensible home – in the case of humans, a hearth site.

One trait found in both ants and humans is large-scale warfare. Wilson gives an idea of the nature of ant warfare in fictional form in his novel Anthill. It’s an interesting experiment, but also disorienting. Because individual recognition is not important for ants, his story of the destruction of an ant colony reads like the Iliad with all the personal names taken out. But Homer’s heroes fought for “aphthiton kleos,” undying fame (and got some measure of it in Homer’s poem). The moral economy of reputation puts human cooperation in war and peace on a very different footing from insect eusociality.

Consider her ways” is the title of a short story by John Wyndham, about a woman from the present trapped in a future ant-like all-female dystopia. It was made into an episode of Alfred Hitchcock Presents. The title is from Proverbs 6:6, “Go to the ant, thou sluggard, consider her ways and be wise.”

Coals to Newcastle

340-320 Mya

It seems like Gaia really went on a bender in the late Carboniferous, getting drunk on oxygen. By some estimates, the atmosphere was over 30% oxygen back then, compared to 21% today. Living things took advantage of the opportunity. Insects apparently face an upper limit in size because they rely on diffusion through tracheas instead of forced respiration through lungs to get oxygen into their bodies. With more oxygen in the air, this limit was raised. The Carboniferous saw dragonflies with a wingspan up to 70 centimeters, and body lengths up to 30 centimeters, comparable to a seagull.

dragonfly

This happened because plants were turning carbon dioxide into organic matter and free oxygen, and the organic matter was accumulating. With carbon dioxide being removed from the atmosphere, the late Carboniferous and subsequent early Permian saw a reduced greenhouse effect, and global cooling. This was another Ice Age, with ice caps around the southern pole.

A lot of organic carbon ended up being buried. Much of the world’s coal, especially high quality anthracite, has its origin in Carboniferous tropical forests. Western Europe and eastern North America lay in the tropics at the time, and got a particularly generous allotment of coal. Three hundred million years later this bounty would fuel the early Industrial Revolution. (Thanks partly to some of my Welsh ancestors, who helped dig it up back in the day.)

coal age

We are upside-down bugs

502-475 Mya

“We are upside-down bugs” is not as catchy a song lyric as “We are stardust.” But the story may be just as interesting.

The proto-evolutionist anatomist Etienne Geoffroy Saint-Hilaire (1772-1844) proposed long ago that all animals – insects to vertebrates — share a “unity of composition.” He was opposed by his sometime friend and sometime rival, anti-evolutionist anatomist Georges Cuvier (1769-1832), who argued that the animal world is organized in four great “embranchements,” with nothing in common in their body plans. Geoffroy Saint-Hilaire noted that insects have their nervous systems running ventrally (through their bellies) and their digestive systems dorsally (through their backs), the opposite of vertebrates. So he proposed the daring hypothesis that, from head to tail, vertebrates and insects have the same body plan, but belly to back they are flipped around.

Remarkably enough, a modernized version of this hypothesis has been vindicated by developmental genetics. Vertebrates have a series of genes, the Hox genes, that control development. They are laid out in order, with the genes switching on the development of the head followed by genes for the upper body, etc. It turns out that much the same genes in the same order control development in insects (not exactly the same, but clearly related), even though the actual structure of insect bodies is very different. On the other hand, the gene that turns on ventral development in the fruit fly Drosophila is related to the gene that turns on dorsal development in the toad Xenopus, while the gene that turns on dorsal development in Drosophila is related to the gene that controls ventral development in Xenopus.

The hypothesis that seems to account for this is that back in the day –- before the Cambrian explosion – there was a small wormy bilaterally symmetrical organism, ancestor to almost all animals (except sponges and jellyfish). Some of the descendants of that primordial animal gave rise to protostomes (where the first opening in the embryo becomes a mouth) including arthropods (spiders, insects, etc.), molluscs (including clams, crustaceans, octopuses), and annelids (earthworms).

But somewhere along the pathway leading to the deuterostomes (where the first opening in the embryo becomes the anus, the second becomes the mouth), including the chordates, the vertebrates, and us, another set of descendants started swimming upside down. And the rest is (pre)history: this initial minor quirk of evolutionary history was well-entrenched by the Ordovician 488 Million years ago.

Consider her ways

There are some pieces of paleontology that really stand out in the popular imagination. Dinosaurs are so cool that even if they hadn’t existed we would have invented them. (Maybe we did, in the form of dragons. And tune in April 2 for the dinosaur-griffin connection.) Also, as I suggested in the preceding post, transitions from one form of locomotion to another – flightless dinosaurs to birds, fish to tetrapods, land mammals to whales – really grab the imagination (and annoy creationists) because the largest and most distinctive named folk categories of animals (snakes, fish, birds) are built around modes of locomotion.

Evolutionary biologists tend to see things differently. Turning fins into legs, legs into wings, and legs back into flippers is pretty impressive. But the really major evolutionary transitions involve the evolution of whole new levels of organization: the origin of the eukaryotic cell, for example, and the origin of multicellular life. From this perspective, the really huge change in the Mesozoic – sometimes called the Age of Dinosaurs – is the origin of eusociality among insects like ants and bees. An ant nest or a bee hive is something like a single superorganism. with most of its members sterile workers striving – even committing suicide — for the colony’s reproduction, not their own. (100 million years – corresponding to March 29 in Logarithmic History — is when we find the first bee and ant fossils, but the transition must have been underway before that time.)

Certainly the statistics on social insects today are impressive.

The twenty thousand known species of eusocial insects, mostly ants, bees, wasps and termites, account for only 2 percent of the approximately one million known species of insects. Yet this tiny minority of species dominate the rest of the insects in their numbers, their weight, and their impact on the environment. As humans are to vertebrate animals, the eusocial insects are to the far vaster world of invertebrate animals. … In one Amazon site, two German researchers … found that ants and termites together compose almost two-thirds of the weight of all the insects. Eusocial bees and wasps added another tenth. Ants alone weighed four times more than all the terrestrial vertebrates – that is, mammals, birds, reptiles, and amphibians combined. E. O. Wilson pp 110-113

E. O. Wilson, world’s foremost authority on ants, and one of the founders of sociobiology, thinks that the origin of insect eusociality might have lessons for another major evolutionary transition, the origin of humans (and of human language, technology, culture, and complex social organization). In his book The Social Conquest of Earth he argues that a key step in both sets of transitions was the development of a valuable and defensible home – in the case of humans, a hearth site.

One trait found in both ants and humans is large-scale warfare. Wilson gives an idea of the nature of ant warfare in fictional form in his novel Anthill. It’s an interesting experiment, but also disorienting. Because individual recognition is not important for ants, his story of the destruction of an ant colony reads like the Iliad with all the personal names taken out. But Homer’s heroes fought for “aphthiton kleos,” undying fame (and got some measure of it in Homer’s poem). The moral economy of reputation puts human cooperation in war and peace on a very different footing from insect eusociality.

Consider her ways” is the title of a short story by John Wyndham, about a woman from the present trapped in a future ant-like all-female dystopia. It was made into an episode of Alfred Hitchcock Presents. The title is from Proverbs 6:6, “Go to the ant, thou sluggard, consider her ways and be wise.”

We are upside-down bugs

488 Million years ago

“We are upside-down bugs” is not as catchy a song lyric as “We are stardust.” But the story may be just as interesting.

The proto-evolutionist anatomist Etienne Geoffroy Saint-Hilaire (1772-1844) proposed long ago that all animals – insects to vertebrates — share a “unity of composition.” He was opposed by his sometime friend and sometime rival, anti-evolutionist anatomist Georges Cuvier (1769-1832), who argued that the animal world is organized in four great “embranchements,” with nothing in common in their body plans. Geoffroy Saint-Hilaire noted that insects have their nervous systems running ventrally (through their bellies) and their digestive systems dorsally (through their backs), the opposite of vertebrates. So he proposed the daring hypothesis that, from head to tail, vertebrates and insects have the same body plan, but belly to back they are flipped around.

Remarkably enough, a modernized version of this hypothesis has been vindicated by developmental genetics. Vertebrates have a series of genes, the Hox genes, that control development. They are laid out in order, with the genes switching on the development of the head followed by genes for the upper body, etc. It turns out that much the same genes in the same order control development in insects (not exactly the same, but clearly related), even though the actual structure of insect bodies is very different. On the other hand, the gene that turns on ventral development in the fruit fly Drosophila is related to the gene that turns on dorsal development in the toad Xenopus, while the gene that turns on dorsal development in Drosophila is related to the gene that controls ventral development in Xenopus.

The hypothesis that seems to account for this is that back in the day –- before the Cambrian explosion – there was a small wormy bilaterally symmetrical organism, ancestor to almost all animals (except sponges and jellyfish). Some of the descendants of that primordial animal gave rise to protostomes (where the first opening in the embryo becomes a mouth) including arthropods (spiders, insects, etc.), molluscs (including clams, crustaceans, octopuses), and annelids (earthworms).

But somewhere along the pathway leading to the deuterostomes (where the first opening in the embryo becomes the anus, the second becomes the mouth), including the chordates, the vertebrates, and us, another set of descendants started swimming upside down. And the rest is (pre)history: this initial minor quirk of evolutionary history was well-entrenched by the Ordovician 488 Million years ago.

Consider her ways

There are some pieces of paleontology that really stand out in the popular imagination. Dinosaurs are so cool that even if they hadn’t existed we would have invented them. (Maybe we did, in the form of dragons. And tune in April 2 for the dinosaur-griffin connection.) Also, as I suggested in the preceding post, transitions from one form of locomotion to another – flightless dinosaurs to birds, fish to tetrapods, land mammals to whales – really grab the imagination (and annoy creationists) because the largest and most distinctive named folk categories of animals (snakes, fish, birds) are built around modes of locomotion.

Evolutionary biologists tend to see things differently. Turning fins into legs, legs into wings, and legs back into flippers is pretty impressive. But the really major evolutionary transitions involve the evolution of whole new levels of organization: the origin of the eukaryotic cell, for example, and the origin of multicellular life. From this perspective, the really huge change in the Mesozoic – sometimes called the Age of Dinosaurs – is the origin of eusociality among insects like ants and bees. An ant nest or a bee hive is something like a single superorganism. with most of its members sterile workers striving – even committing suicide — for the colony’s reproduction, not their own. (100 million years – corresponding to March 29 in Logarithmic History — is when we find the first bee and ant fossils, but the transition must have been underway before that time.)

Certainly the statistics on social insects today are impressive.

“The twenty thousand known species of eusocial insects, mostly ants, bees, wasps and termites, account for only 2 percent of the approximately one million known species of insects. Yet this tiny minority of species dominate the rest of the insects in their numbers, their weight, and their impact on the environment. As humans are to vertebrate animals, the eusocial insects are to the far vaster world of invertebrate animals. … In one Amazon site, two German researchers … found that ants and termites together compose almost two-thirds of the weight of all the insects. Eusocial bees and wasps added another tenth. Ants alone weighed four times more than all the terrestrial vertebrates – that is, mammals, birds, reptiles, and amphibians combined.” E. O. Wilson pp 110-113

E. O. Wilson, world’s foremost authority on ants, and one of the founders of sociobiology, thinks that the origin of insect eusociality might have lessons for another major evolutionary transition, the origin of humans (and of human language, technology, culture, and complex social organization). In his book The Social Conquest of Earth he argues that a key step in both sets of transitions was the development of a valuable and defensible home – in the case of humans, a hearth site.

One trait found in both ants and humans is large-scale warfare. Wilson gives an idea of the nature of ant warfare in fictional form in his novel Anthill. It’s an interesting experiment, but also disorienting. Because individual recognition is not important for ants, his story of the destruction of an ant colony reads like the Iliad with all the personal names taken out. But Homer’s heroes fought for “aphthiton kleos,” undying fame (and got some measure of it in Homer’s poem). The moral economy of reputation puts human cooperation in war and peace on a very different footing from insect eusociality.

Consider her ways” is the title of a short story by John Wyndham, about a woman from the present trapped in a future ant-like all-female dystopia. It was made into an episode of Alfred Hitchcock Presents. The title is from Proverbs 6:6, “Go to the ant, thou sluggard, consider her ways and be wise.”

We are upside-down bugs

“We are upside-down bugs” is not as catchy a song lyric as “We are stardust.” But the story may be just as interesting.

The proto-evolutionist anatomist Etienne Geoffroy Saint-Hilaire (1772-1844) proposed long ago that all animals – insects to vertebrates — share a “unity of composition.” He was opposed by his sometime friend and sometime rival, anti-evolutionist anatomist Georges Cuvier (1769-1832), who argued that the animal world is organized in four great “embranchements,” with nothing in common in their body plans. Geoffroy Saint-Hilaire noted that insects have their nervous systems running ventrally (through their bellies) and their digestive systems dorsally (through their backs), the opposite of vertebrates. So he proposed the daring hypothesis that, from head to tail, vertebrates and insects have the same body plan, but belly to back they are flipped around.

Remarkably enough, a modernized version of this hypothesis has been vindicated by developmental genetics. Vertebrates have a series of genes, the Hox genes, that control development. They are laid out in order, with the genes switching on the development of the head followed by genes for the upper body, etc. It turns out that much the same genes in the same order control development in insects (not exactly the same, but clearly related), even though the actual structure of insect bodies is very different. On the other hand, the gene that turns on ventral development in the fruit fly Drosophila is related to the gene that turns on dorsal development in the toad Xenopus, while the gene that turns on dorsal development in Drosophila is related to the gene that controls ventral development in Xenopus.

The hypothesis that seems to account for this is that back in the day –- before the Cambrian explosion – there was a small wormy bilaterally symmetrical organism, ancestor to almost all animals (except sponges and jellyfish). Some of the descendants of that primordial animal gave rise to protostomes (where the first opening in the embryo becomes a mouth) including arthropods (spiders, insects, etc.), molluscs (including clams, crustaceans, octopuses), and annelids (earthworms).

But somewhere along the pathway leading to the deuterostomes (where the first opening in the embryo becomes the anus, the second becomes the mouth), including the chordates, the vertebrates, and us, another set of descendants started swimming upside down. And the rest is (pre)history: this initial minor quirk of evolutionary history was well-entrenched by the Ordovician 480 Million years ago.