As coperation is the best startegy for smaller animals to survive on this planet, many species evolved to utilized their numbers to defend themselves from large predators, to hunt for food and work more efficiently. Example of this, starts from algae to humans.
If an animal is large and strong, coperation takes a back stage and aggression takes its place. Most of the large predators stay alone. For herbivores, even size may not be restriction but for carnivores, its as if a rule that larger you are loner you be. Survival of carnivores depends on their skill to hunt their prey which makes aggression as a necessary trait for them. Aggression is needed to overpower their prey. Thus, more aggressive an animal (carnivores), more will it be able to hunt. This aggression will be a guarantee for a good hunter and thus continuous supply for food. Here, nature plays its part in making aggressive trait as a necessary condition to survive and as time passes, this trait become more and more prominent. Aggression, as negative effect reduces the coperation among the same species.
Now, consider the scenario, when nature was full of life and preys were abundant. Aggressive carnivores flourished and coperation died among them. This scenario may also seems to result in more coperation as competition was non-existent. Herbivores or other animal for whom aggression is not the key may opt for coperation whether competition exists or not. Coperation in herbivores as well in carnivores increases the efficiency of food collection but if this efficiency doesn't offer much advantage then nature doesn't give special preference to this trait. When aggression is selected preferentially than coperation in carnivores with no competition, animal (carnivores) stay alone, as aggression among them result in grouping very difficult.
As the preys go down and competition increases, even a small advantage in collecting food becomes preferential. Competition also results in infighting among species. Advantages of coperation in this case may be counted as defence against the same species, dividing the society in small small groups to defend and fight among each other. Also, hunting in groups, give them advantage than the loners. Nature selects for coperation also and what we get a balance of aggression and coperation among carnivores.
Group psychology differ from a lone hunter. Nature will give preference for stronger groups who can hunt better. Numbers here appears to be an advantage. More the number, more be the hunt. But again, number offers a two way sword, as number rises, need for food also increases. This gives rise to a critical size above which a group looses its advantage of numbers. This critical size depends on the surrounding environment and availability of food. Rough terrains with scarce food available, have smaller critical size than the fertile plains. Here, other factors such as presence of other hostile species may also effect this size.
Now, with this we can prepare a mathematical model for calculating the critical size of a group of particular species which may survive in a particular region. I will not go in maths too much as generating this model will require so much of data which I don't have. I will just compare the different regions and critical size of a human group which may exist their.
I will start from southern african regions which lie near to equator, have warm climate with frequent rains and all weather forests. This climate and rich flora makes this region an ideal place for all herbivores. This also make it a good hunting ground for carnivore animals like humans. Ancestors of humans, apes have this as an ideal place for living. Though food-wise this region seems good, this also attract predators. Rich flora makes this land unaccessible for two leg animals like humans. Apes and monkeys have acrobatic abilities which makes them more suited for this kind of region than humans. Constraints to movement make hunting very difficult for human as well making them a easy prey for four legged predators. Also, there are many small insects and bugs which make life difficult for slow humans in this region. Critical size for a human group which can survive here, comes out very low. This size should be large enough to help humans in hunting for their food, as well defend themselves against different predators. In the same place it should not be too large that it may act as a constraint to movement for a group or make them more visible to attract different predators from large to small. This critical size may lie in between 10 to 50. The density of population also becomes limited as different groups keep on moving and control a large territory.
Now, desert regions of north africa presents a completely different picture of landscape. Scarcity of water and extreme temperatures make life impossible in this region. Flora is scarce and limited to some wet areas which lie in patches throughout the desert with long distance in between them. Large amount of body hairs which act as protection as well keeping a constant body temperature in equator region become a negative trait in dry and hot desert. First, sand particles entangled in hairs result in rashes, second hairs don't allow body to cool down in extremely hot climate. So, humans adapt this will very thin hairs though in larger numbers. Hairs still act as a protection in cold winters and nights of desert. Survival in this region also needs more numbers, so, group can gather food from a larger area. Threat of predator is less here, also, land movement doesn't have any constraint due to two legs. Size and stamina become crucial as these enable humans to cover more area thus collect more food. Group size is only limited by the speed of humans. Even a large group can't cover more area if humans can't walk to that distance. In equator region, movement was necessary for defending against predators but in desert movement becomes necessary for collecting food. Movement in equator regions was limited to a particular territories but in desert, scarcity of food make defined territories impossible. Human group needs to keep on moving in search of food and group shoul be able to gather food from one area in few days. Gathering and saving becomes necessary. Very small group may not guarantee constant supply of food and large groups will not be able to sustain itself with limited food. Here, critical size of a human group may lie in between 25-100. The density of population here is highly restricted as different groups keep on moving for food in a very large territory. Even the different territories often are so far each other that groups don't have any contact with each other.
West of north african region lies arabian desert. This area though have similar climate as of north africa, differs in one aspect. In arabian desert, the density of wet patches is little bit higher than in north africa. There are some river plains, also marshy areas are present in north west and south part of arab. These small patches of fertile lands make it possible to increase the critical group size even further. With the added advantage of farming, critical group size in this region hovers in between 50-500. No wonder, first human cities were evolved here. Due to higher density of fertile patches compared to sahara, population density is little bit higher than sahara region but more or less restricted to some fertile patches only. Though, distance between these patches were less than the saharan thus motivating some group of people here to indulge in continuous trade with different groups.
Moving to indian region presents another variation here. This land is surrounded by rough, cold peaks himalayas from north and sea from south. More of its a bowl of life, with land varing climates existing in short distance. Northern parts are cold and covered with icy peaks of mountains. A short distance in south, lies the sindhu-ganges plains and in east lies full year blooming forests. Below this region, there are Thar desert, arid Kutch, tropical forests. Next level in south have a mix of tropical forests, arid lands, deccan plateau and coastal areas. Deep sputh contains forests and climate similar to equator regions as of africa with added marshy patches near coastal regions. The huge variation in climate makes large movement of human group difficult. Middle plains have large fertile lands which can provide food for large human groups. Deep south also have a fair share of fertile land. But the area in between and extreme north are not supportive for large groups. So, it provides a right mix for large cities and trade by smaller groups. Human groups adapted to desert life are more suited for continuous movement thus making them more adapt for carring out trading. Himalayas and ocean provide a good defense from any incursion from other parts of the world, before the development of other means of transportation. Size of group is only limited here by the human movement. Critical size of human groups lies around 25-500. Here, population density, depending on the area were comparitively higher, specifically large river plains had many groups scattered in that area. Trade also proliferated as different groups were in continuous contact.
Moving in to north china again presents with varing climate from cold and dry north west to fertile south east. This land is also isolated from other parts of world by the hard terrains in north and north west and by ocean in south and east. South-eastern part contains a very fertile land. Southern part extends upto the indonesian archipelago which is covered with tropical forests. In west Himalaya divides the region and in north-west pamir plateau isolate china from rest. North west region have a very rough weather and presents really harsh living conditions. Fertile lands were having critical size of groups around 50-500 and northern parts were having critical group size as 10-100. Southern part, having higher popular density, helped in proliferation of trade.
If an animal is large and strong, coperation takes a back stage and aggression takes its place. Most of the large predators stay alone. For herbivores, even size may not be restriction but for carnivores, its as if a rule that larger you are loner you be. Survival of carnivores depends on their skill to hunt their prey which makes aggression as a necessary trait for them. Aggression is needed to overpower their prey. Thus, more aggressive an animal (carnivores), more will it be able to hunt. This aggression will be a guarantee for a good hunter and thus continuous supply for food. Here, nature plays its part in making aggressive trait as a necessary condition to survive and as time passes, this trait become more and more prominent. Aggression, as negative effect reduces the coperation among the same species.
Now, consider the scenario, when nature was full of life and preys were abundant. Aggressive carnivores flourished and coperation died among them. This scenario may also seems to result in more coperation as competition was non-existent. Herbivores or other animal for whom aggression is not the key may opt for coperation whether competition exists or not. Coperation in herbivores as well in carnivores increases the efficiency of food collection but if this efficiency doesn't offer much advantage then nature doesn't give special preference to this trait. When aggression is selected preferentially than coperation in carnivores with no competition, animal (carnivores) stay alone, as aggression among them result in grouping very difficult.
As the preys go down and competition increases, even a small advantage in collecting food becomes preferential. Competition also results in infighting among species. Advantages of coperation in this case may be counted as defence against the same species, dividing the society in small small groups to defend and fight among each other. Also, hunting in groups, give them advantage than the loners. Nature selects for coperation also and what we get a balance of aggression and coperation among carnivores.
Group psychology differ from a lone hunter. Nature will give preference for stronger groups who can hunt better. Numbers here appears to be an advantage. More the number, more be the hunt. But again, number offers a two way sword, as number rises, need for food also increases. This gives rise to a critical size above which a group looses its advantage of numbers. This critical size depends on the surrounding environment and availability of food. Rough terrains with scarce food available, have smaller critical size than the fertile plains. Here, other factors such as presence of other hostile species may also effect this size.
Now, with this we can prepare a mathematical model for calculating the critical size of a group of particular species which may survive in a particular region. I will not go in maths too much as generating this model will require so much of data which I don't have. I will just compare the different regions and critical size of a human group which may exist their.
I will start from southern african regions which lie near to equator, have warm climate with frequent rains and all weather forests. This climate and rich flora makes this region an ideal place for all herbivores. This also make it a good hunting ground for carnivore animals like humans. Ancestors of humans, apes have this as an ideal place for living. Though food-wise this region seems good, this also attract predators. Rich flora makes this land unaccessible for two leg animals like humans. Apes and monkeys have acrobatic abilities which makes them more suited for this kind of region than humans. Constraints to movement make hunting very difficult for human as well making them a easy prey for four legged predators. Also, there are many small insects and bugs which make life difficult for slow humans in this region. Critical size for a human group which can survive here, comes out very low. This size should be large enough to help humans in hunting for their food, as well defend themselves against different predators. In the same place it should not be too large that it may act as a constraint to movement for a group or make them more visible to attract different predators from large to small. This critical size may lie in between 10 to 50. The density of population also becomes limited as different groups keep on moving and control a large territory.
Now, desert regions of north africa presents a completely different picture of landscape. Scarcity of water and extreme temperatures make life impossible in this region. Flora is scarce and limited to some wet areas which lie in patches throughout the desert with long distance in between them. Large amount of body hairs which act as protection as well keeping a constant body temperature in equator region become a negative trait in dry and hot desert. First, sand particles entangled in hairs result in rashes, second hairs don't allow body to cool down in extremely hot climate. So, humans adapt this will very thin hairs though in larger numbers. Hairs still act as a protection in cold winters and nights of desert. Survival in this region also needs more numbers, so, group can gather food from a larger area. Threat of predator is less here, also, land movement doesn't have any constraint due to two legs. Size and stamina become crucial as these enable humans to cover more area thus collect more food. Group size is only limited by the speed of humans. Even a large group can't cover more area if humans can't walk to that distance. In equator region, movement was necessary for defending against predators but in desert movement becomes necessary for collecting food. Movement in equator regions was limited to a particular territories but in desert, scarcity of food make defined territories impossible. Human group needs to keep on moving in search of food and group shoul be able to gather food from one area in few days. Gathering and saving becomes necessary. Very small group may not guarantee constant supply of food and large groups will not be able to sustain itself with limited food. Here, critical size of a human group may lie in between 25-100. The density of population here is highly restricted as different groups keep on moving for food in a very large territory. Even the different territories often are so far each other that groups don't have any contact with each other.
West of north african region lies arabian desert. This area though have similar climate as of north africa, differs in one aspect. In arabian desert, the density of wet patches is little bit higher than in north africa. There are some river plains, also marshy areas are present in north west and south part of arab. These small patches of fertile lands make it possible to increase the critical group size even further. With the added advantage of farming, critical group size in this region hovers in between 50-500. No wonder, first human cities were evolved here. Due to higher density of fertile patches compared to sahara, population density is little bit higher than sahara region but more or less restricted to some fertile patches only. Though, distance between these patches were less than the saharan thus motivating some group of people here to indulge in continuous trade with different groups.
Moving to indian region presents another variation here. This land is surrounded by rough, cold peaks himalayas from north and sea from south. More of its a bowl of life, with land varing climates existing in short distance. Northern parts are cold and covered with icy peaks of mountains. A short distance in south, lies the sindhu-ganges plains and in east lies full year blooming forests. Below this region, there are Thar desert, arid Kutch, tropical forests. Next level in south have a mix of tropical forests, arid lands, deccan plateau and coastal areas. Deep sputh contains forests and climate similar to equator regions as of africa with added marshy patches near coastal regions. The huge variation in climate makes large movement of human group difficult. Middle plains have large fertile lands which can provide food for large human groups. Deep south also have a fair share of fertile land. But the area in between and extreme north are not supportive for large groups. So, it provides a right mix for large cities and trade by smaller groups. Human groups adapted to desert life are more suited for continuous movement thus making them more adapt for carring out trading. Himalayas and ocean provide a good defense from any incursion from other parts of the world, before the development of other means of transportation. Size of group is only limited here by the human movement. Critical size of human groups lies around 25-500. Here, population density, depending on the area were comparitively higher, specifically large river plains had many groups scattered in that area. Trade also proliferated as different groups were in continuous contact.
Moving in to north china again presents with varing climate from cold and dry north west to fertile south east. This land is also isolated from other parts of world by the hard terrains in north and north west and by ocean in south and east. South-eastern part contains a very fertile land. Southern part extends upto the indonesian archipelago which is covered with tropical forests. In west Himalaya divides the region and in north-west pamir plateau isolate china from rest. North west region have a very rough weather and presents really harsh living conditions. Fertile lands were having critical size of groups around 50-500 and northern parts were having critical group size as 10-100. Southern part, having higher popular density, helped in proliferation of trade.
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