// Variety for variety's sake // 05.05.09
"The Agricultural Revolution began at the wane of the last Ice Age, about 10.000 years ago, in the so called Fertile Crescent between the Tigris and the Euphrates." - Richard Dawkins
The Isthmus of Panama is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It was formed some 3 million years ago during the Pliocene epoch. It contains the nation of Panama and the Panama Canal. Like many isthmuses, it is a location of great strategic value.
Orang Utan means "Man of the Woods" in Malay. A tree-dwelling animal, it shares a common ancestor with humans dating from around 14 million years ago.
Gibbons, unlike the great apes which are our closer relatives, are monogamous.
Neanderthal
Fossils were found in 1856 near Düsseldorf, Germany in the Neander Valley. Workers were mining for limestone when they found a skull and other bones. Thal (or in modern German, Tal) means 'valley'.
Cat's eyes
Nocturnal animals have a tapetum - a layer of tissue that lies immediately behind or sometimes within the retina - that reflects light back to their eyes so they get a chance to see the light twice and absorb as much as possible. Shine a torch into their eyes and they will reflect the light.
Marsupial means 'pouch' in Latin. Marsupials are born as tiny embryos equipped only to crawl, crawl for their tiny lives through the forest of their mother's fur, into pouch where they clamp their mouths to a teat. The other group of mammals are called placental because they nourish their embryos with various versions of a placenta; a large organ though which miles of capillary blood vessels belonging to the baby are brought into close contact with miles of blood vessels belonging to the mother. This excellent exchange system (for it serves to remove waste from the foetus as well as feed it) enables the baby to be born very late into its career. It enjoys the protection of its mother's body until it is capable of keeping up with its own herd. Marsupials do it differently. The pouch is like an external womb, and the large teat to which the baby becomes attached works a bit like an umbilical cord. It emerges from the pouch as if in second birth. It happens that Australia, for much of its history since it split from Gondwana (a southern precursor-super continent), had no placental mammals.
Merchant's Tale
If nuclear war destroy humanity and most of the rest of life, a good bet for survival in the short term is rats. I have a post Armageddon vision - we and all other large animals are gone. Rodents emerge as the ultimate post-human scavengers. The gnaw their way through London, New York and Tokyo, digesting spilled larders, ghost supermarkets and human corpses, turning them into a new generation of rats and mice, whose racing populations explode out of the city and into the countryside. When all the relics of human proflicy are eaten, populations crash again and the rodents turn on each other. In a period of intense competition, short generations with perhaps radioactively-enhanced mutation rates, boost rapid evolution. With human ships and planes gone, islands become islands again, with populations isolated save for occasional lucky rafting; ideal conditions for evolutionary divergence. Within 5 million years a whole new range of species replace the ones we know. Herds of giant grazing rates are stalked by sabre toothed predatory rats. Given enough time, will a species of intelligent, cultivated rats emerge? Will rodent historians and scientists eventually organise careful archaeological digs (gnaws) through the strata of our long-compacted cities, and reconstruct the peculiar and temporally tragic circumstances that gave the rat it's big break?
Toolbox routines
As of 2009, the mouse is one of the few mammals apart from ourselves whose genome has been completly sequenced. Two things about this have sparked unwarranted surprise. The first is that mammal genomes seem rather small; of the order of 30,000 genes or less. The second is that they are so similar to each other. Human dignity seemed to demand that our genome should be much larger than that of a tiny mouse. But by what standard do we decide how many genes are needed to specify a body? The assumption is that the genome is a kind of blueprint, with each gene specifying its own little piece of body. But it is not like a blueprint, it is more like a recipe, a computer program or a manual of instructions for assembly. If you think of a genome as a blueprint you may expect a big, complicated animal like yourself to have more genes than a little mouse, but that isn't the way genes work.
Curl Your Tongue into a Tube
"Suppose there are two blood types called A and B, which confer immunity to different diseases. Each blood type is susceptible to the disease against which the other has immunity. Diseases flourish when the blood type that they can attack is abundant, because an epidemic can get going. So if B people, say, happen to be common in the population, the disease that hurts them will enjoy an epidemic. Consequently, B people will die until they cease to be common and the A people will increase and vice versa. Whenever we have two types, the rarer of which is favoured because it is rare, it is a recipe for polymorphism; the positive maintenance of variety for variety's sake. The ABO blood group system is a famous polymorphism which has probably been maintained for this kind of reason.
Astonishingly, our ABO blood type polymorphism is present in chimpanzees. It could be that we and chimps have independently 'invented' the polymorphism, and for the same reason. But it is more plausible that we have both inherited it from our shared ancestor and independently kept it going during our six million years of separate descent." - Richard Dawkins
"The Agricultural Revolution began at the wane of the last Ice Age, about 10.000 years ago, in the so called Fertile Crescent between the Tigris and the Euphrates." - Richard Dawkins
The Isthmus of Panama is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It was formed some 3 million years ago during the Pliocene epoch. It contains the nation of Panama and the Panama Canal. Like many isthmuses, it is a location of great strategic value.
Orang Utan means "Man of the Woods" in Malay. A tree-dwelling animal, it shares a common ancestor with humans dating from around 14 million years ago.
Gibbons, unlike the great apes which are our closer relatives, are monogamous.
Neanderthal
Fossils were found in 1856 near Düsseldorf, Germany in the Neander Valley. Workers were mining for limestone when they found a skull and other bones. Thal (or in modern German, Tal) means 'valley'.
Cat's eyes
Nocturnal animals have a tapetum - a layer of tissue that lies immediately behind or sometimes within the retina - that reflects light back to their eyes so they get a chance to see the light twice and absorb as much as possible. Shine a torch into their eyes and they will reflect the light.
Marsupial means 'pouch' in Latin. Marsupials are born as tiny embryos equipped only to crawl, crawl for their tiny lives through the forest of their mother's fur, into pouch where they clamp their mouths to a teat. The other group of mammals are called placental because they nourish their embryos with various versions of a placenta; a large organ though which miles of capillary blood vessels belonging to the baby are brought into close contact with miles of blood vessels belonging to the mother. This excellent exchange system (for it serves to remove waste from the foetus as well as feed it) enables the baby to be born very late into its career. It enjoys the protection of its mother's body until it is capable of keeping up with its own herd. Marsupials do it differently. The pouch is like an external womb, and the large teat to which the baby becomes attached works a bit like an umbilical cord. It emerges from the pouch as if in second birth. It happens that Australia, for much of its history since it split from Gondwana (a southern precursor-super continent), had no placental mammals.
Merchant's Tale
If nuclear war destroy humanity and most of the rest of life, a good bet for survival in the short term is rats. I have a post Armageddon vision - we and all other large animals are gone. Rodents emerge as the ultimate post-human scavengers. The gnaw their way through London, New York and Tokyo, digesting spilled larders, ghost supermarkets and human corpses, turning them into a new generation of rats and mice, whose racing populations explode out of the city and into the countryside. When all the relics of human proflicy are eaten, populations crash again and the rodents turn on each other. In a period of intense competition, short generations with perhaps radioactively-enhanced mutation rates, boost rapid evolution. With human ships and planes gone, islands become islands again, with populations isolated save for occasional lucky rafting; ideal conditions for evolutionary divergence. Within 5 million years a whole new range of species replace the ones we know. Herds of giant grazing rates are stalked by sabre toothed predatory rats. Given enough time, will a species of intelligent, cultivated rats emerge? Will rodent historians and scientists eventually organise careful archaeological digs (gnaws) through the strata of our long-compacted cities, and reconstruct the peculiar and temporally tragic circumstances that gave the rat it's big break?
Toolbox routines
As of 2009, the mouse is one of the few mammals apart from ourselves whose genome has been completly sequenced. Two things about this have sparked unwarranted surprise. The first is that mammal genomes seem rather small; of the order of 30,000 genes or less. The second is that they are so similar to each other. Human dignity seemed to demand that our genome should be much larger than that of a tiny mouse. But by what standard do we decide how many genes are needed to specify a body? The assumption is that the genome is a kind of blueprint, with each gene specifying its own little piece of body. But it is not like a blueprint, it is more like a recipe, a computer program or a manual of instructions for assembly. If you think of a genome as a blueprint you may expect a big, complicated animal like yourself to have more genes than a little mouse, but that isn't the way genes work.
Curl Your Tongue into a Tube
"Suppose there are two blood types called A and B, which confer immunity to different diseases. Each blood type is susceptible to the disease against which the other has immunity. Diseases flourish when the blood type that they can attack is abundant, because an epidemic can get going. So if B people, say, happen to be common in the population, the disease that hurts them will enjoy an epidemic. Consequently, B people will die until they cease to be common and the A people will increase and vice versa. Whenever we have two types, the rarer of which is favoured because it is rare, it is a recipe for polymorphism; the positive maintenance of variety for variety's sake. The ABO blood group system is a famous polymorphism which has probably been maintained for this kind of reason.
Astonishingly, our ABO blood type polymorphism is present in chimpanzees. It could be that we and chimps have independently 'invented' the polymorphism, and for the same reason. But it is more plausible that we have both inherited it from our shared ancestor and independently kept it going during our six million years of separate descent." - Richard Dawkins
