In an effort to explore how humans respond to bargaining situations, economists have administered... more In an effort to explore how humans respond to bargaining situations, economists have administered a number of different experiments. Among the simplest and most widely used of these experiments, the ultimatum game, seems to provide a number of robust and important insights into human economic reasoning that strongly contradict the predictions of standard game theory. Because the ultimatum game yields results in many different places (including Taiwan, Israel, Tokyo, Pittsburgh, Slovenia and even in Java), many economists have come to think of this bargaining behavior as a product of innate human-universal economic reasoning processes. For example, Roth (1995) proposed that humans possess an evolved cognitive process that balances an immediate self-interest with a drive to directly punish associates for inequitable transactions. However, recent data from a remote region in the Peruvian Amazon substantially deviates from the typical ultimatum game responses, suggesting that game perfo...
Recent research into human origins has largely focused on deducing past events and processes from... more Recent research into human origins has largely focused on deducing past events and processes from current patterns of genetic variation. Some human genes possess unexpectedly low diversity, seemingly resulting from events of the late Pleistocene. Such anomalies have previously been ascribed to population bottlenecks or selection on genes. For four species of matrilineal whale, evidence suggests that cultural evolution may have reduced the diversity of genes which have similar transmission characteristics to selective cultural traits, through a process called cultural hitchhiking. Cultural evolution is characteristic of human societies and so should be considered as a potential determinant of human genetic diversity. A stochastic simulation of gene and cultural dynamics in an array of hunter-gatherer tribes shows that cultural selection has the potential to severely reduce genetic diversity if: inter-tribe gene flows are reasonably low (<~0.6-15 genes/tribe/generation); cultural evolution changes fitness by >~0.3-3%/generation; and fitness is changed more by cultural innovation within a tribe than cultural assimilation from neighboring tribes. Thus cultural hitchhiking may explain low diversity and short coalescence times in mitochondrial and, especially, Y-linked human genes.
Differences in social norms are a key source of behavioral variation among human populations. It ... more Differences in social norms are a key source of behavioral variation among human populations. It is widely assumed that a vast range of behaviors, even deleterious ones, can persist as long as they are locally common because deviants suffer coordination failures and social sanctions. Previous models have confirmed this intuition, showing that different populations may exhibit different norms even if they face similar environmental pressures or are linked by migration. Crucially, these studies have modeled norms as having a few discrete variants. Many norms, however, have a continuous range of variants. Here we present a mathematical model of the evolutionary dynamics of continuously varying norms and show that when the social payoffs of the behavioral options vary continuously the pressure to do what others do does not result in multiple stable equilibria. Instead, factors such as environmental pressure, individual preferences, moral beliefs, and cognitive attractors determine the o...
Demography plays a large role in cultural evolution through its effects on the effective rate of ... more Demography plays a large role in cultural evolution through its effects on the effective rate of innovation. If we assume that useful inventions are rare, then small isolated societies will have low rates of invention. In small populations, complex technology will tend to be lost as a result of random loss or incomplete transmission (the Tasmanian effect). Large populations have more inventors and are more resistant to loss by chance. If human populations can grow freely, then a population-technology-population positive feedback should occur such that human societies reach a stable growth path on which the rate of growth of technology is limited by the rate of invention. This scenario fits the Holocene to a first approximation, but the late Pleistocene is a great puzzle. Large-brained hominins existed in Africa and west Eurasia for perhaps 50,000 years with, at best, slow rates of technical innovation. The most sophisticated societies of the last glacial period appear after 50,000 years ago and were apparently restricted to west and north-central Eurasia and North Africa. These patterns have no simple, commonly accepted explanation. We argue that increased high-frequency climate change around 70,000-50,000 years ago may have tipped the balance between humans and their competitor-predators, such as lions and wolves, in favor of humans. At the same time, technically sophisticated hunters would tend to overharvest their prey. Perhaps the ephemeral appearance of complex tools and symbolic artifacts in Africa after 00,000 years ago resulted from hunting inventions that allowed human populations to expand temporarily before prey overexploitation led to human population and technology collapse. Sustained human populations of moderate size using distinctively advanced Upper Paleolithic artifacts may have existed in west Eurasia because cold, continental northeastern Eurasia-Beringia acted as a protected reserve for prey populations.
Darwin realized that his theory could have no principled exception for humans. He put the famous ... more Darwin realized that his theory could have no principled exception for humans. He put the famous teaser, “Light will be thrown on the origin of man and his history,” near the end of The Origin of Species. If his evolutionary account made an exception for the human species, the whole edifice might be questioned. As the Quarterly Review’s reviewer of The Descent of Man and Selection in Relation to Sex probably the long-hostile and devoutly Catholic St. George Mivart) gloated, the Descent “offers a good opportunity for reviewing his whole position” – and rejecting it (Anonymous, or St. George Mivart, 1871). Darwin apparently hoped someone else would apply Darwinism to the origin of humans. Lyell (1863), Huxley (1863), and Wallace (1864, 1869) all wrote on the subject, but their work was unsatisfactory because all three had reservations about a selectionist account of human mental evolution. Darwin’s views on the origin of humans did not rely entirely on selection but had a supplementar...
… : Values in Action Conference Series, 2005 …, 2008
... Why didn't free enterprise evolve long ago and far away? Conference paper for Gruter Ins... more ... Why didn't free enterprise evolve long ago and far away? Conference paper for Gruter Institute project Free Enterprise Values in Action, Paul Zack and Oliver Goodenough, directors. March 15, 2005. Please do not cite for publication without permission ...
In an effort to explore how humans respond to bargaining situations, economists have administered... more In an effort to explore how humans respond to bargaining situations, economists have administered a number of different experiments. Among the simplest and most widely used of these experiments, the ultimatum game, seems to provide a number of robust and important insights into human economic reasoning that strongly contradict the predictions of standard game theory. Because the ultimatum game yields results in many different places (including Taiwan, Israel, Tokyo, Pittsburgh, Slovenia and even in Java), many economists have come to think of this bargaining behavior as a product of innate human-universal economic reasoning processes. For example, Roth (1995) proposed that humans possess an evolved cognitive process that balances an immediate self-interest with a drive to directly punish associates for inequitable transactions. However, recent data from a remote region in the Peruvian Amazon substantially deviates from the typical ultimatum game responses, suggesting that game perfo...
Recent research into human origins has largely focused on deducing past events and processes from... more Recent research into human origins has largely focused on deducing past events and processes from current patterns of genetic variation. Some human genes possess unexpectedly low diversity, seemingly resulting from events of the late Pleistocene. Such anomalies have previously been ascribed to population bottlenecks or selection on genes. For four species of matrilineal whale, evidence suggests that cultural evolution may have reduced the diversity of genes which have similar transmission characteristics to selective cultural traits, through a process called cultural hitchhiking. Cultural evolution is characteristic of human societies and so should be considered as a potential determinant of human genetic diversity. A stochastic simulation of gene and cultural dynamics in an array of hunter-gatherer tribes shows that cultural selection has the potential to severely reduce genetic diversity if: inter-tribe gene flows are reasonably low (<~0.6-15 genes/tribe/generation); cultural evolution changes fitness by >~0.3-3%/generation; and fitness is changed more by cultural innovation within a tribe than cultural assimilation from neighboring tribes. Thus cultural hitchhiking may explain low diversity and short coalescence times in mitochondrial and, especially, Y-linked human genes.
Differences in social norms are a key source of behavioral variation among human populations. It ... more Differences in social norms are a key source of behavioral variation among human populations. It is widely assumed that a vast range of behaviors, even deleterious ones, can persist as long as they are locally common because deviants suffer coordination failures and social sanctions. Previous models have confirmed this intuition, showing that different populations may exhibit different norms even if they face similar environmental pressures or are linked by migration. Crucially, these studies have modeled norms as having a few discrete variants. Many norms, however, have a continuous range of variants. Here we present a mathematical model of the evolutionary dynamics of continuously varying norms and show that when the social payoffs of the behavioral options vary continuously the pressure to do what others do does not result in multiple stable equilibria. Instead, factors such as environmental pressure, individual preferences, moral beliefs, and cognitive attractors determine the o...
Demography plays a large role in cultural evolution through its effects on the effective rate of ... more Demography plays a large role in cultural evolution through its effects on the effective rate of innovation. If we assume that useful inventions are rare, then small isolated societies will have low rates of invention. In small populations, complex technology will tend to be lost as a result of random loss or incomplete transmission (the Tasmanian effect). Large populations have more inventors and are more resistant to loss by chance. If human populations can grow freely, then a population-technology-population positive feedback should occur such that human societies reach a stable growth path on which the rate of growth of technology is limited by the rate of invention. This scenario fits the Holocene to a first approximation, but the late Pleistocene is a great puzzle. Large-brained hominins existed in Africa and west Eurasia for perhaps 50,000 years with, at best, slow rates of technical innovation. The most sophisticated societies of the last glacial period appear after 50,000 years ago and were apparently restricted to west and north-central Eurasia and North Africa. These patterns have no simple, commonly accepted explanation. We argue that increased high-frequency climate change around 70,000-50,000 years ago may have tipped the balance between humans and their competitor-predators, such as lions and wolves, in favor of humans. At the same time, technically sophisticated hunters would tend to overharvest their prey. Perhaps the ephemeral appearance of complex tools and symbolic artifacts in Africa after 00,000 years ago resulted from hunting inventions that allowed human populations to expand temporarily before prey overexploitation led to human population and technology collapse. Sustained human populations of moderate size using distinctively advanced Upper Paleolithic artifacts may have existed in west Eurasia because cold, continental northeastern Eurasia-Beringia acted as a protected reserve for prey populations.
Darwin realized that his theory could have no principled exception for humans. He put the famous ... more Darwin realized that his theory could have no principled exception for humans. He put the famous teaser, “Light will be thrown on the origin of man and his history,” near the end of The Origin of Species. If his evolutionary account made an exception for the human species, the whole edifice might be questioned. As the Quarterly Review’s reviewer of The Descent of Man and Selection in Relation to Sex probably the long-hostile and devoutly Catholic St. George Mivart) gloated, the Descent “offers a good opportunity for reviewing his whole position” – and rejecting it (Anonymous, or St. George Mivart, 1871). Darwin apparently hoped someone else would apply Darwinism to the origin of humans. Lyell (1863), Huxley (1863), and Wallace (1864, 1869) all wrote on the subject, but their work was unsatisfactory because all three had reservations about a selectionist account of human mental evolution. Darwin’s views on the origin of humans did not rely entirely on selection but had a supplementar...
… : Values in Action Conference Series, 2005 …, 2008
... Why didn't free enterprise evolve long ago and far away? Conference paper for Gruter Ins... more ... Why didn't free enterprise evolve long ago and far away? Conference paper for Gruter Institute project Free Enterprise Values in Action, Paul Zack and Oliver Goodenough, directors. March 15, 2005. Please do not cite for publication without permission ...
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