CREATURES GREAT & SMALL
‘When the head is empty,
then you become aware suddenly
that a bird is singing over there.’
Masanobu Fukuoka
By around 150 million years ago, at the beginning of the Cretaceous Period, Gondwana and Laurasia were splitting even further, continuing the process that would lead to today’s continents.
Bird-hipped dinosaurs had long since joined lizard-hipped dinosaurs in the expanding, diversifying forests. They included several armoured plant-eating species like the most recognizable dinosaur for most of us, Stegosaurus. They defended themselves from carnivores with spikes and horns on their heads, backs and tails.
And the lizard-hipped dinosaurs now included plant-eaters that were the largest land animals ever. These were the Sauropods – up to 30 metres long (much of this in their flexible neck) and 100 tonnes in weight. From the trees’ point of view they were a very challenging predator, but they were generally slow-moving and gentle, except when they had to use their powerful tails to defend themselves or their young.
There were also large dinosaur carnivores that preyed on the browsers’ young. (In a part of Australia now within the Antarctic Circle, Giganotosaurus species were preying on the gentle Muttaburrasaurus.) Child-care was a must, and some browsers apparently had communal nests, where they shared responsibility for hatchlings.
Now many species of quite small dinosaurs were emerging, such as the rabbit-sized Microceratops - on the ground, in the trees, in the water or in the air. There were also lots of new amphibians such as frogs, and new reptiles such as crocodiles – as well as the Quetzalcoatlus (named after an Aztec god), which had a 15 metre wingspan, making it the biggest flying life-form of all time.
And a few true birds were emerging and starting to diversify. (Fossilized feathers from this period have been found in Victoria, and a small bone in Queensland.)
They would go on to create many ways of caring for their young, including lifetime pair-bonding with nurture from both parents; communal nesting; and forced fostering.
(In Australia today several birds have unusual nurturing behaviours. The emu father hatches and protects the eggs. Mud-nesters like white-winged choughs share the caregiving across their whole community. And parasitic cuckoos lay their appropriately pigmented eggs in the nest of a selected local bird species.)
Some bird species actively demonstrate the behaviour their young will need in adult life This among other things has led to much rethinking about birds’ ability to learn. They need light bones and small brains to fly successfully but this does not mean that they are ‘birdbrains’.
As we shall see, intelligence is evident in some behaviours that are linked to sexual selection and have to be learned and improved on throughout a male adult’s life. It is also seen in the ability of a few bird species to adapt to, and thrive in, our built-in environment.
However most birds cannot adapt quickly enough when humans invade and destroy their breeding habitat. When the tipping point is reached, most die out and we are left with bigger and bigger populations of fewer and fewer species.
(Australian researchers are noting the different functioning in birds’ right and left brains – one eye searching for food, while the other keeps watch for predators. They are also able to take in and store new information in an urban environment, and incorporate it into their daily behaviour. Indian mynahs have been seen using a discarded plastic bag as a nest-liner. Song-birds can learn human songs, using the left side of their brain. Cockatoos have been taught to use human language in a meaningful way.)
Back in our story a new kind of mammal appeared in what would become South America.
Like monotremes these tiny shrew-like marsupials were nocturnal omnivores. But the one or two fertilized eggs of the females developed into tiny foetuses inside a simple womb and were released through a very small birth canal (or vagina). Each foetus felt its way up towards her nipples deep in an external pouch, with maybe only one of a litter actually reaching it. Once there it latched onto a nipple, and drank from it until old enough to emerge and learn to forage for itself. Even then it still slept in the pouch and sought refuge there when necessary.
In this period India had split away from Gondwana, but Africa and South America were still connected, and Antarctica was joined to Australia and South America by continental shelves. Since Antarctica was warm enough at this point to support plant-life a few marsupial species from South America migrated across it into Australia.
(They were the ancestors of the wide range of marsupials that live here today, retaining the nocturnal lifestyle adopted for living with dinosaurs, because it is equally fitted for Australia’s predominantly hot and dry climate.
(During this period high sea levels covered much of southern Australia and divided the rest into four islands, around them the shallow Eromanga Sea. It was home to many large marine reptiles, like crocodiles, which looked after their hatchlings, and were essentially the same as today. And on the muddy sediment on the floor of this sea were many animals, whose fossils would later be opalised by the action of water. Today they are mined at Coober Pedy, White Cliffs and Lightning Ridge.
(Volcanic activity was raising the Great Dividing Range along today’s eastern coast, and what would be the north of Australia was a paradise for dinosaurs. Among them were a small plant-eater, Wintonopus, and one of its predators, Tyrannosauropus, about 12 metres long.)
There were also modern ranging spiders in the forests now - on the forest floor under the leaf-litter. They lived for only one or two years, but their mating behaviour, usually conducted on a tree-trunk, was similar to that of primitive spiders.
(In today’s Sydney, one descendant of these spiders often comes into our homes to shelter from the rain, usually taking up position on the cornice between wall and ceiling. It is a Huntsman, of the Isopoda or Delena species, quite large, and moving quickly when disturbed. But it is no danger to humans. On the contrary, it helps control flies and mosquitoes, and puts on speed only to scuttle away from us as fast as possible.
(It is unusual among spiders in that its courting is gentle and even affectionate – the male is smaller but in no danger. The female also has a well-developed maternal instinct. She spins a pure white egg-sac in a rock crevice or under the bark of a tree. And then she fasts for several weeks, staying with her spiderlings until they are strong enough to disperse.)
Now early placental mammals evolved, with more complex brains than marsupials and interactions between their nerves and hormones that are the basis of ours. This suggests a similar range of sensations and a similar responsiveness to internal stimuli.
Their foetuses finished developing in the womb, absorbing nutrients through a placenta, and the mother’s womb and birth canal evolved accordingly. Their young could move independently soon after birth but returned to suckle for some time.
As among monotremes and marsupials, the females still lived with their young, and the males appeared only at mating time. Like earlier mammals they relied on a strong sense of smell, and although they had a wider variety of emotions these were all linked to eating, escaping danger and specific gender roles. The world of giant dinosaurs was hazardous, but some were paving the way for primates by living in the trees, and a few others even seem to have stalked and eaten dinosaur young.
Meanwhile adult male dome-headed dinosaurs were fighting over sexually disposed females by bashing their tough foreheads together until one prevailed.
However in a few animal species less ‘boneheaded’ males were now wooing females with a specific sound, and perhaps even colour. Early serenaders included crested dinosaurs, a few bird species and insects like cicadas. In each case this required the females to distinguish the appropriate sound or colour and respond accordingly.
So the brains of both genders were undergoing significant change, in the form of pre-programming in the central nervous system. This can be seen today in species where the females select the males that are best able to perform a rigidly repetitive call or dance, or are most striking in their adult appearance.
But this possibility of using creative persuasion rather than combat would also lead over time to the emergence of several bird species whose sexual display of intricate songs, bower building or mimicry requires a great deal of learning by practice.
(In Australia today whipbirds, tiny bright blue fairy-wrens, bower-birds and lyre-birds are examples of this diversity and creativity.)
Sometimes the artistry is also part of a camouflage strategy, which birds share with many insects.
(In the Blue Mountains of NSW Crimson Rosellas freeze when alerted, hiding very successfully among the branches of a eucalypt. Their beautiful colours merge with the tree’s older green leaves, its young crimson tips and the patches of blue sky behind.)
But sexual display is usually what evolutionists call costly signalling. A verbal translation of their artistry could be: ‘Wouldn’t you like offspring as wonderful as I am?’
Since it has to be balanced by security considerations it is more likely to develop (and go to extremes) in species without significant coevolving predators. And males with elaborate visual or auditory displays can’t be expected to be faithful partners or nurturing parents. On the contrary they are usually very promiscuous – you could say ‘all show and no help with the kids’.
The best-known examples are peacocks with their superb but cumbersome tails, or the various spectacular birds of paradise in New Guinea’s rainforests.
The females in these species are obviously choosing the fittest male on different criteria from those used by females in species where the males are non-showy, and more obliging. Diversity is clearly an integral part of evolution here as it is elsewhere.
(Meanwhile among the long-living primitive spiders, the Trapdoor Spider had emerged in Australia, named for the camouflage lid that most of the family make on their burrows today. They shelter from their predators there, and also wait for passing prey, rapidly snatching them and then disappearing again. They are rather timid with humans, and so of little danger to us.)
Bird-hipped dinosaurs had long since joined lizard-hipped dinosaurs in the expanding, diversifying forests. They included several armoured plant-eating species like the most recognizable dinosaur for most of us, Stegosaurus. They defended themselves from carnivores with spikes and horns on their heads, backs and tails.
And the lizard-hipped dinosaurs now included plant-eaters that were the largest land animals ever. These were the Sauropods – up to 30 metres long (much of this in their flexible neck) and 100 tonnes in weight. From the trees’ point of view they were a very challenging predator, but they were generally slow-moving and gentle, except when they had to use their powerful tails to defend themselves or their young.
There were also large dinosaur carnivores that preyed on the browsers’ young. (In a part of Australia now within the Antarctic Circle, Giganotosaurus species were preying on the gentle Muttaburrasaurus.) Child-care was a must, and some browsers apparently had communal nests, where they shared responsibility for hatchlings.
Now many species of quite small dinosaurs were emerging, such as the rabbit-sized Microceratops - on the ground, in the trees, in the water or in the air. There were also lots of new amphibians such as frogs, and new reptiles such as crocodiles – as well as the Quetzalcoatlus (named after an Aztec god), which had a 15 metre wingspan, making it the biggest flying life-form of all time.
And a few true birds were emerging and starting to diversify. (Fossilized feathers from this period have been found in Victoria, and a small bone in Queensland.)
They would go on to create many ways of caring for their young, including lifetime pair-bonding with nurture from both parents; communal nesting; and forced fostering.
(In Australia today several birds have unusual nurturing behaviours. The emu father hatches and protects the eggs. Mud-nesters like white-winged choughs share the caregiving across their whole community. And parasitic cuckoos lay their appropriately pigmented eggs in the nest of a selected local bird species.)
Some bird species actively demonstrate the behaviour their young will need in adult life This among other things has led to much rethinking about birds’ ability to learn. They need light bones and small brains to fly successfully but this does not mean that they are ‘birdbrains’.
As we shall see, intelligence is evident in some behaviours that are linked to sexual selection and have to be learned and improved on throughout a male adult’s life. It is also seen in the ability of a few bird species to adapt to, and thrive in, our built-in environment.
However most birds cannot adapt quickly enough when humans invade and destroy their breeding habitat. When the tipping point is reached, most die out and we are left with bigger and bigger populations of fewer and fewer species.
(Australian researchers are noting the different functioning in birds’ right and left brains – one eye searching for food, while the other keeps watch for predators. They are also able to take in and store new information in an urban environment, and incorporate it into their daily behaviour. Indian mynahs have been seen using a discarded plastic bag as a nest-liner. Song-birds can learn human songs, using the left side of their brain. Cockatoos have been taught to use human language in a meaningful way.)
Back in our story a new kind of mammal appeared in what would become South America.
Like monotremes these tiny shrew-like marsupials were nocturnal omnivores. But the one or two fertilized eggs of the females developed into tiny foetuses inside a simple womb and were released through a very small birth canal (or vagina). Each foetus felt its way up towards her nipples deep in an external pouch, with maybe only one of a litter actually reaching it. Once there it latched onto a nipple, and drank from it until old enough to emerge and learn to forage for itself. Even then it still slept in the pouch and sought refuge there when necessary.
In this period India had split away from Gondwana, but Africa and South America were still connected, and Antarctica was joined to Australia and South America by continental shelves. Since Antarctica was warm enough at this point to support plant-life a few marsupial species from South America migrated across it into Australia.
(They were the ancestors of the wide range of marsupials that live here today, retaining the nocturnal lifestyle adopted for living with dinosaurs, because it is equally fitted for Australia’s predominantly hot and dry climate.
(During this period high sea levels covered much of southern Australia and divided the rest into four islands, around them the shallow Eromanga Sea. It was home to many large marine reptiles, like crocodiles, which looked after their hatchlings, and were essentially the same as today. And on the muddy sediment on the floor of this sea were many animals, whose fossils would later be opalised by the action of water. Today they are mined at Coober Pedy, White Cliffs and Lightning Ridge.
(Volcanic activity was raising the Great Dividing Range along today’s eastern coast, and what would be the north of Australia was a paradise for dinosaurs. Among them were a small plant-eater, Wintonopus, and one of its predators, Tyrannosauropus, about 12 metres long.)
There were also modern ranging spiders in the forests now - on the forest floor under the leaf-litter. They lived for only one or two years, but their mating behaviour, usually conducted on a tree-trunk, was similar to that of primitive spiders.
(In today’s Sydney, one descendant of these spiders often comes into our homes to shelter from the rain, usually taking up position on the cornice between wall and ceiling. It is a Huntsman, of the Isopoda or Delena species, quite large, and moving quickly when disturbed. But it is no danger to humans. On the contrary, it helps control flies and mosquitoes, and puts on speed only to scuttle away from us as fast as possible.
(It is unusual among spiders in that its courting is gentle and even affectionate – the male is smaller but in no danger. The female also has a well-developed maternal instinct. She spins a pure white egg-sac in a rock crevice or under the bark of a tree. And then she fasts for several weeks, staying with her spiderlings until they are strong enough to disperse.)
Now early placental mammals evolved, with more complex brains than marsupials and interactions between their nerves and hormones that are the basis of ours. This suggests a similar range of sensations and a similar responsiveness to internal stimuli.
Their foetuses finished developing in the womb, absorbing nutrients through a placenta, and the mother’s womb and birth canal evolved accordingly. Their young could move independently soon after birth but returned to suckle for some time.
As among monotremes and marsupials, the females still lived with their young, and the males appeared only at mating time. Like earlier mammals they relied on a strong sense of smell, and although they had a wider variety of emotions these were all linked to eating, escaping danger and specific gender roles. The world of giant dinosaurs was hazardous, but some were paving the way for primates by living in the trees, and a few others even seem to have stalked and eaten dinosaur young.
Meanwhile adult male dome-headed dinosaurs were fighting over sexually disposed females by bashing their tough foreheads together until one prevailed.
However in a few animal species less ‘boneheaded’ males were now wooing females with a specific sound, and perhaps even colour. Early serenaders included crested dinosaurs, a few bird species and insects like cicadas. In each case this required the females to distinguish the appropriate sound or colour and respond accordingly.
So the brains of both genders were undergoing significant change, in the form of pre-programming in the central nervous system. This can be seen today in species where the females select the males that are best able to perform a rigidly repetitive call or dance, or are most striking in their adult appearance.
But this possibility of using creative persuasion rather than combat would also lead over time to the emergence of several bird species whose sexual display of intricate songs, bower building or mimicry requires a great deal of learning by practice.
(In Australia today whipbirds, tiny bright blue fairy-wrens, bower-birds and lyre-birds are examples of this diversity and creativity.)
Sometimes the artistry is also part of a camouflage strategy, which birds share with many insects.
(In the Blue Mountains of NSW Crimson Rosellas freeze when alerted, hiding very successfully among the branches of a eucalypt. Their beautiful colours merge with the tree’s older green leaves, its young crimson tips and the patches of blue sky behind.)
But sexual display is usually what evolutionists call costly signalling. A verbal translation of their artistry could be: ‘Wouldn’t you like offspring as wonderful as I am?’
Since it has to be balanced by security considerations it is more likely to develop (and go to extremes) in species without significant coevolving predators. And males with elaborate visual or auditory displays can’t be expected to be faithful partners or nurturing parents. On the contrary they are usually very promiscuous – you could say ‘all show and no help with the kids’.
The best-known examples are peacocks with their superb but cumbersome tails, or the various spectacular birds of paradise in New Guinea’s rainforests.
The females in these species are obviously choosing the fittest male on different criteria from those used by females in species where the males are non-showy, and more obliging. Diversity is clearly an integral part of evolution here as it is elsewhere.
(Meanwhile among the long-living primitive spiders, the Trapdoor Spider had emerged in Australia, named for the camouflage lid that most of the family make on their burrows today. They shelter from their predators there, and also wait for passing prey, rapidly snatching them and then disappearing again. They are rather timid with humans, and so of little danger to us.)
* * * * * * *
Diagram of the concept of
three layers in the human brain
formed as our ancestors evolved
Dramatic illustration
of how the three interconnecting layers function
(Two more Google images - click to enlarge)
Diagram of the concept ofthree layers in the human brain
formed as our ancestors evolved
Dramatic illustrationof how the three interconnecting layers function
(Two more Google images - click to enlarge)
2 comments:
I picked that Fukuoka quote on the first line. What a legend that guy is. Do nothing
Quetzalcoatlus, wow, what a beast
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