How did humans sleep before the modern era?
Because the tools to measure sleep under natural
cond... more How did humans sleep before the modern era? Because the tools to measure sleep under natural conditions were developed long after the invention of the electric devices suspected of delaying and reducing sleep, we investigated sleep in three preindustrial societies [1–3]. We find that all three show similar sleep organization, suggesting that they express core human sleep patterns, most likely characteristic of pre-modern era Homo sapiens. Sleep periods, the times from onset to offset, averaged 6.9–8.5 hr, with sleep durations of 5.7–7.1 hr, amounts near the low end of those industrial societies [4–7]. There was a difference of nearly 1 hr between summer and winter sleep. Daily variation in sleep duration was strongly linked to time of onset, rather than offset. None of these groups began sleep near sunset, onset occurring, on average, 3.3 hr after sunset. Awakening was usually before sunrise. The sleep period consistently occurred during the nighttime period of falling environmental temperature, was not interrupted by extended periods of waking, and terminated, with vasoconstriction, near the nadir of daily ambient temperature. The daily cycle of temperature change, largely eliminated from modern sleep environments, may be a potent natural regulator of sleep. Light exposure was maximal in the morning and greatly decreased at noon, indicating that all three groups seek shade at midday and that light activation of the suprachiasmatic nucleus is maximal in the morning. Napping occurred on <7% of days in winter and <22% of days in summer. Mimicking aspects of the natural environment might be effective in treating certain modern sleep disorders.
American journal of human biology : the official journal of the Human Biology Council
The large human brain, the long period of juvenile dependence, long life span, and male support o... more The large human brain, the long period of juvenile dependence, long life span, and male support of reproduction are the co-evolutionary result of the human niche based on skill-intensive techniques of resource accrual. The regulation of fertility under traditional conditions is based upon a co-evolved psychology and physiology where adjustments of investment in offspring depend upon the returns to skill and mortality hazards. When all wealth is somatic, the hormonal system controlling ovulation and implantation translates income into genetic descendants. In modern society the existence of extra-somatic wealth is a critical condition to which our evolved proximate physiological mechanisms do not respond. However, psychological mechanisms regulating parental investment in offspring quality may lead to greater and greater investment in own and offspring education, a smaller desired family size, a delay in the onset of reproduction, and a reduction in the total numbers of offspring produced. This delay in reproduction can cause many individuals to produce fewer children than desired because fecundity falls during the reproductive part of the life course. As more individuals in a society follow this pattern, more will fail to reach their desired family size. At the same time the effective use of birth control decreases the numbers of families producing more children than desired. Below replacement fertility can result. Predictions from this model were tested using data from the National Survey of Families and Households and the Albuquerque Men study. Am.
Reciprocity is a vital feature of social networks, but relatively little is known about its tempo... more Reciprocity is a vital feature of social networks, but relatively little is known about its temporal structure or the mechanisms underlying its persistence in real world behavior. In pursuit of these two questions, we study the stationary and dynamical signals of reciprocity in a network of manioc beer (Spanish: chicha; Tsimane': shocdye') drinking events in a Tsimane' village in lowland Bolivia. At the stationary level, our analysis reveals that social exchange within the community is heterogeneously patterned according to kinship and spatial proximity. A positive relationship between the frequencies at which two families host each other, controlling for kinship and proximity, provides evidence for stationary reciprocity. Our analysis of the dynamical structure of this network presents a novel method for the study of conditional, or non-stationary, reciprocity effects. We find evidence that short-timescale reciprocity (within three days) is present among non-and distant-kin pairs; conversely, we find that levels of cooperation among close kin can be accounted for on the stationary hypothesis alone. Entropy 2013, 15 4933
Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studie... more Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studies have examined their interactions. We measured changes in salivary oxytocin, testosterone and cortisol among Tsimane' men returning home after hunting, an ancient context of male status competition, parental investment and cooperation. Contra normal diurnal rhythm, oxytocin increased relative to baseline and this increase was positively associated with duration of the hunt and change in testosterone, but not cortisol, social context, hunting outcome or physical activity. The concurrent increase in endogenous peripheral oxytocin and testosterone is unexpected given their opposing independent effects on social cognition and behaviour, and has not been observed before. We discuss the potential significance of these effects for the biology of pair-bonding, parenting and social foraging in humans and other species.
This study reports the results of research into infant development among the Ache of eastern Para... more This study reports the results of research into infant development among the Ache of eastern Paraguay. The Ache were full time hunter-gatherers until the mid-1970s and now practice a mixed economy of settled agriculture and mobile foraging in the forest. Data on infant development and infant care in foraging societies are critical to an understanding of the factors that have shaped the evolution of human infancy and parental care strategies. The Denver Developmental Screening Test (DDST) was administered to 32 children between the ages of 2 months and 4 years. We found that, although Ache children did not differ from American children on the personal-social sector of the test, they showed significant delays in the acquisition of linguistic, fine-motor and gross-motor skills. This difference was most dramatic with respect to gross-motor development; Ache children are more than a year behind their American counterparts 3 years of age. We interpret these results in terms of traditional practices of infant care among the Ache and attempt to relate those practices to their subsistence ecology and to adult reproductive strategies. Specifically, we review the Ache data in light of speciational and cross-cultural variation in developmental rates and infant-care practices. Two factors are suggested that appear to explain this variation, the environmental distribution of economically relevant resources and the hazards to which young are exposed.
... Magdalena Hurtado Kim Hill Hillard Kaplan Jane Lancaster. ... las comunidades indigenas: Vari... more ... Magdalena Hurtado Kim Hill Hillard Kaplan Jane Lancaster. ... las comunidades indigenas: Variantes en la lucha antituberculosa en situationes dificiles, selva y archipelagos. Manuscript, Comisiónde Control de la UICTER, Hospital Nuestra Señora del Pino, Las Palmas, España ...
How did humans sleep before the modern era?
Because the tools to measure sleep under natural
cond... more How did humans sleep before the modern era? Because the tools to measure sleep under natural conditions were developed long after the invention of the electric devices suspected of delaying and reducing sleep, we investigated sleep in three preindustrial societies [1–3]. We find that all three show similar sleep organization, suggesting that they express core human sleep patterns, most likely characteristic of pre-modern era Homo sapiens. Sleep periods, the times from onset to offset, averaged 6.9–8.5 hr, with sleep durations of 5.7–7.1 hr, amounts near the low end of those industrial societies [4–7]. There was a difference of nearly 1 hr between summer and winter sleep. Daily variation in sleep duration was strongly linked to time of onset, rather than offset. None of these groups began sleep near sunset, onset occurring, on average, 3.3 hr after sunset. Awakening was usually before sunrise. The sleep period consistently occurred during the nighttime period of falling environmental temperature, was not interrupted by extended periods of waking, and terminated, with vasoconstriction, near the nadir of daily ambient temperature. The daily cycle of temperature change, largely eliminated from modern sleep environments, may be a potent natural regulator of sleep. Light exposure was maximal in the morning and greatly decreased at noon, indicating that all three groups seek shade at midday and that light activation of the suprachiasmatic nucleus is maximal in the morning. Napping occurred on <7% of days in winter and <22% of days in summer. Mimicking aspects of the natural environment might be effective in treating certain modern sleep disorders.
American journal of human biology : the official journal of the Human Biology Council
The large human brain, the long period of juvenile dependence, long life span, and male support o... more The large human brain, the long period of juvenile dependence, long life span, and male support of reproduction are the co-evolutionary result of the human niche based on skill-intensive techniques of resource accrual. The regulation of fertility under traditional conditions is based upon a co-evolved psychology and physiology where adjustments of investment in offspring depend upon the returns to skill and mortality hazards. When all wealth is somatic, the hormonal system controlling ovulation and implantation translates income into genetic descendants. In modern society the existence of extra-somatic wealth is a critical condition to which our evolved proximate physiological mechanisms do not respond. However, psychological mechanisms regulating parental investment in offspring quality may lead to greater and greater investment in own and offspring education, a smaller desired family size, a delay in the onset of reproduction, and a reduction in the total numbers of offspring produced. This delay in reproduction can cause many individuals to produce fewer children than desired because fecundity falls during the reproductive part of the life course. As more individuals in a society follow this pattern, more will fail to reach their desired family size. At the same time the effective use of birth control decreases the numbers of families producing more children than desired. Below replacement fertility can result. Predictions from this model were tested using data from the National Survey of Families and Households and the Albuquerque Men study. Am.
Reciprocity is a vital feature of social networks, but relatively little is known about its tempo... more Reciprocity is a vital feature of social networks, but relatively little is known about its temporal structure or the mechanisms underlying its persistence in real world behavior. In pursuit of these two questions, we study the stationary and dynamical signals of reciprocity in a network of manioc beer (Spanish: chicha; Tsimane': shocdye') drinking events in a Tsimane' village in lowland Bolivia. At the stationary level, our analysis reveals that social exchange within the community is heterogeneously patterned according to kinship and spatial proximity. A positive relationship between the frequencies at which two families host each other, controlling for kinship and proximity, provides evidence for stationary reciprocity. Our analysis of the dynamical structure of this network presents a novel method for the study of conditional, or non-stationary, reciprocity effects. We find evidence that short-timescale reciprocity (within three days) is present among non-and distant-kin pairs; conversely, we find that levels of cooperation among close kin can be accounted for on the stationary hypothesis alone. Entropy 2013, 15 4933
Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studie... more Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studies have examined their interactions. We measured changes in salivary oxytocin, testosterone and cortisol among Tsimane' men returning home after hunting, an ancient context of male status competition, parental investment and cooperation. Contra normal diurnal rhythm, oxytocin increased relative to baseline and this increase was positively associated with duration of the hunt and change in testosterone, but not cortisol, social context, hunting outcome or physical activity. The concurrent increase in endogenous peripheral oxytocin and testosterone is unexpected given their opposing independent effects on social cognition and behaviour, and has not been observed before. We discuss the potential significance of these effects for the biology of pair-bonding, parenting and social foraging in humans and other species.
This study reports the results of research into infant development among the Ache of eastern Para... more This study reports the results of research into infant development among the Ache of eastern Paraguay. The Ache were full time hunter-gatherers until the mid-1970s and now practice a mixed economy of settled agriculture and mobile foraging in the forest. Data on infant development and infant care in foraging societies are critical to an understanding of the factors that have shaped the evolution of human infancy and parental care strategies. The Denver Developmental Screening Test (DDST) was administered to 32 children between the ages of 2 months and 4 years. We found that, although Ache children did not differ from American children on the personal-social sector of the test, they showed significant delays in the acquisition of linguistic, fine-motor and gross-motor skills. This difference was most dramatic with respect to gross-motor development; Ache children are more than a year behind their American counterparts 3 years of age. We interpret these results in terms of traditional practices of infant care among the Ache and attempt to relate those practices to their subsistence ecology and to adult reproductive strategies. Specifically, we review the Ache data in light of speciational and cross-cultural variation in developmental rates and infant-care practices. Two factors are suggested that appear to explain this variation, the environmental distribution of economically relevant resources and the hazards to which young are exposed.
... Magdalena Hurtado Kim Hill Hillard Kaplan Jane Lancaster. ... las comunidades indigenas: Vari... more ... Magdalena Hurtado Kim Hill Hillard Kaplan Jane Lancaster. ... las comunidades indigenas: Variantes en la lucha antituberculosa en situationes dificiles, selva y archipelagos. Manuscript, Comisiónde Control de la UICTER, Hospital Nuestra Señora del Pino, Las Palmas, España ...
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Papers by Hillard Kaplan
Because the tools to measure sleep under natural
conditions were developed long after the invention
of the electric devices suspected of delaying and
reducing sleep, we investigated sleep in three preindustrial
societies [1–3]. We find that all three show
similar sleep organization, suggesting that they
express core human sleep patterns, most likely characteristic
of pre-modern era Homo sapiens. Sleep
periods, the times from onset to offset, averaged
6.9–8.5 hr, with sleep durations of 5.7–7.1 hr,
amounts near the low end of those industrial societies
[4–7]. There was a difference of nearly 1 hr between
summer and winter sleep. Daily variation in
sleep duration was strongly linked to time of onset,
rather than offset. None of these groups began sleep
near sunset, onset occurring, on average, 3.3 hr after
sunset. Awakening was usually before sunrise. The
sleep period consistently occurred during the nighttime
period of falling environmental temperature,
was not interrupted by extended periods of waking,
and terminated, with vasoconstriction, near the nadir
of daily ambient temperature. The daily cycle of temperature
change, largely eliminated from modern
sleep environments, may be a potent natural regulator
of sleep. Light exposure was maximal in the
morning and greatly decreased at noon, indicating
that all three groups seek shade at midday and that
light activation of the suprachiasmatic nucleus
is maximal in the morning. Napping occurred
on <7% of days in winter and <22% of days in summer.
Mimicking aspects of the natural environment
might be effective in treating certain modern sleep
disorders.
Because the tools to measure sleep under natural
conditions were developed long after the invention
of the electric devices suspected of delaying and
reducing sleep, we investigated sleep in three preindustrial
societies [1–3]. We find that all three show
similar sleep organization, suggesting that they
express core human sleep patterns, most likely characteristic
of pre-modern era Homo sapiens. Sleep
periods, the times from onset to offset, averaged
6.9–8.5 hr, with sleep durations of 5.7–7.1 hr,
amounts near the low end of those industrial societies
[4–7]. There was a difference of nearly 1 hr between
summer and winter sleep. Daily variation in
sleep duration was strongly linked to time of onset,
rather than offset. None of these groups began sleep
near sunset, onset occurring, on average, 3.3 hr after
sunset. Awakening was usually before sunrise. The
sleep period consistently occurred during the nighttime
period of falling environmental temperature,
was not interrupted by extended periods of waking,
and terminated, with vasoconstriction, near the nadir
of daily ambient temperature. The daily cycle of temperature
change, largely eliminated from modern
sleep environments, may be a potent natural regulator
of sleep. Light exposure was maximal in the
morning and greatly decreased at noon, indicating
that all three groups seek shade at midday and that
light activation of the suprachiasmatic nucleus
is maximal in the morning. Napping occurred
on <7% of days in winter and <22% of days in summer.
Mimicking aspects of the natural environment
might be effective in treating certain modern sleep
disorders.