Sexual Division of Labor (Evolutionary Perspective)
Encyclopedia
The sexual division of labor (SDL) is defined as the delegation of different tasks between males and females. Among human foragers, males and females target different types of foods and share them with each other for a mutual or familial benefit. In some species, males and females eat slightly different foods, while in other species, males and females will routinely share food-but only in humans are these two attributes combined. The few remaining hunter-gatherer populations in the world serve as evolutionary models that can help explain the origin of the sexual division of labor. Many studies on the sexual division of labor have been conducted on hunter-gatherer populations, such as the Hadza-a hunter-gatherer
population of Tanzania
.
; however, trade-off differences do exist between sexes. Females are likely to benefit most from parental effort because they are certain which offspring are theirs and have relatively few reproductive opportunities, each of which is relatively costly and risky. In contrast, males do not have an absolute certainty of paternity, but may have many more mating opportunities bearing relatively low costs and risks. Though not every hunter-gatherer population pinpoints females to gathering and males to hunting (most notably the Aeta
and Ju'/hoansi), the norm of most current populations divide the roles of labor in this manner. Natural selection
is more likely to favor male reproductive strategies that stress mating effort and female strategies that emphasize parental investment
. As a result, women have been relegated to the low-risk task of gathering vegetation
and underground storage organs that are rich in energy to provide for themselves and offspring. Since women provide a reliable source of caloric intake, men are able to afford a higher risk of failure by hunting animals.
This classic theory of natural selection positing a difference in male and female reproductive strategies has recently been reexamined, with an alternate theory being proposed that promiscuity was encouraged among women and men alike, causing uncertainty among males of the paternity of their offspring, allowing for group cooperation in raising all offspring due to the possibility that any child could be the descendant of a male, similar to observations of the closest relative of humans, the bonobo
. Moreover, recent archaeological research done by the anthropologist and archaeologist Steven Kuhn from the University of Arizona suggests that the sexual division of labor did not exist prior to the Upper Paleolithic and developed relatively recently in human history. The sexual division of labor may have arisen to allow humans to acquire food and other resources more efficiently.
s by targeting different foods so that everyone in the household benefits. Females may target foods that do not conflict with reproduction and child care, while males will target foods that females do not gather, which will reduce variance in daily consumption and provide a broader diet for the family. Foraging
specialization in particular food groups should increase skill level and thus foraging success rates for targeted foods.
functions mainly to provide an honest signal of the underlying genetic quality of hunters, which later yields a mating advantage or social deference. Females tend to target the foods that are most reliable, while men tend to target difficult-to-acquire foods to “signal” their abilities and genetic quality. Hunting is thus viewed as a form of mating or male-male status competition, not familial provisioning
. Recent studies on the Hadza have revealed that men hunt mainly to distribute food to their own families rather than sharing with other members of the community. This conclusion suggests evidence against hunting for signaling purposes.
that benefits the household; thus, foraging behavior of males will appear optimal at the level of the family. If a hunter-gatherer man does not rely on resources from others and passes up a food item with caloric value, it can be assumed that he is foraging at an optimal level. But, if he passes up the opportunity because it is a food that women routinely gather, then as long as men and women share their spoils, it will be optimal for men to forgo the collection and continue searching for different resources to complement the resources gathered by women.
in early Homo may have created problems of food theft from women while food was being cooked. As a result, females would recruit male partners to protect them and their resources from others. This concept, known as the theft hypothesis, accommodates an explanation as to why the labor
of cooking is strongly associated with the status of women. Women are forced to gather and cook foods because, otherwise, they will not acquire food otherwise and access to resources is critical for their reproductive success
. On the contrary, men do not gather because their physical dominance allows them to scrounge cooked foods from women. Thus, women’s foraging and food preparation efforts allow men to participate in the high-risk, high-reward activities of hunting. Females, in turn, become increasingly sexually attractive as a means to exploit male interest in investing in her protection.
and assessing horizontality and verticality, and a female advantage in spatial memory. The sexual division of labor has been proposed as an explanation for these cognitive differences. This hypothesis argues that males needed the ability to follow prey over long distances and to accurately target their game with projectile technology, and, as a result, male specialization in hunting prowess would have spurred the selection for increased spatial and navigational ability. Similarly, the ability to remember the locations of underground storage organs and other vegetation would have led to an increase in overall efficiency and decrease in total energy expenditure since the time spent searching for food would decrease. Selection on behaviors that increase hunting success and energetic efficiency would bear a positive influence on reproductive success
. However, recent research suggests that the sexual division of labor developed relatively recently and that gender roles were not always the same in early-human cultures, contradicting the theory that each sex is naturally predisposed to different types of work.
Some researchers, such as Cordelia Fine
, argue that available evidence does not support a biological basis for gender roles.
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...
population of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
.
Man the hunter vs. woman the gatherer
Both men and women have the option of investing resources either to provision children or to have additional offspring based on life history theory. Males and females monitor costs and benefits of each alternative to maximize reproductive fitnessFitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
; however, trade-off differences do exist between sexes. Females are likely to benefit most from parental effort because they are certain which offspring are theirs and have relatively few reproductive opportunities, each of which is relatively costly and risky. In contrast, males do not have an absolute certainty of paternity, but may have many more mating opportunities bearing relatively low costs and risks. Though not every hunter-gatherer population pinpoints females to gathering and males to hunting (most notably the Aeta
Aeta
The Aeta , Agta or Ayta are an indigenous people who live in scattered, isolated mountainous parts of Luzon, Philippines. They are considered to be Negritos, who are dark to very dark brown-skinned and tend to have features such as a small stature, small frame, curly to kinky afro-like textured...
and Ju'/hoansi), the norm of most current populations divide the roles of labor in this manner. Natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
is more likely to favor male reproductive strategies that stress mating effort and female strategies that emphasize parental investment
Parental investment
In evolutionary biology, parental investment is any parental expenditure that benefits one offspring at a cost to parents' ability to invest in other components of fitness...
. As a result, women have been relegated to the low-risk task of gathering vegetation
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
and underground storage organs that are rich in energy to provide for themselves and offspring. Since women provide a reliable source of caloric intake, men are able to afford a higher risk of failure by hunting animals.
This classic theory of natural selection positing a difference in male and female reproductive strategies has recently been reexamined, with an alternate theory being proposed that promiscuity was encouraged among women and men alike, causing uncertainty among males of the paternity of their offspring, allowing for group cooperation in raising all offspring due to the possibility that any child could be the descendant of a male, similar to observations of the closest relative of humans, the bonobo
Bonobo
The bonobo , Pan paniscus, previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee...
. Moreover, recent archaeological research done by the anthropologist and archaeologist Steven Kuhn from the University of Arizona suggests that the sexual division of labor did not exist prior to the Upper Paleolithic and developed relatively recently in human history. The sexual division of labor may have arisen to allow humans to acquire food and other resources more efficiently.
Provisioning household
The traditional explanation of the sexual division of labor finds that males and females cooperate within pair bondPair bond
In biology, a pair bond is the strong affinity that develops in some species between the males and females in a pair, potentially leading to breeding. Pair-bonding is a term coined in the 1940s that is frequently used in sociobiology and evolutionary psychology circles...
s by targeting different foods so that everyone in the household benefits. Females may target foods that do not conflict with reproduction and child care, while males will target foods that females do not gather, which will reduce variance in daily consumption and provide a broader diet for the family. Foraging
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
specialization in particular food groups should increase skill level and thus foraging success rates for targeted foods.
“Show-Off” / Signaling hypothesis
The “show‐off” hypothesis proposes that men hunt to gain social attention and mating benefits by widely sharing game. This model proposes that huntingHunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
functions mainly to provide an honest signal of the underlying genetic quality of hunters, which later yields a mating advantage or social deference. Females tend to target the foods that are most reliable, while men tend to target difficult-to-acquire foods to “signal” their abilities and genetic quality. Hunting is thus viewed as a form of mating or male-male status competition, not familial provisioning
Provisioning
In telecommunication, provisioning is the process of preparing and equipping a network to allow it to provide services to its users. In NS/EP telecommunications services, "provisioning" equates to "initiation" and includes altering the state of an existing priority service or capability.In a...
. Recent studies on the Hadza have revealed that men hunt mainly to distribute food to their own families rather than sharing with other members of the community. This conclusion suggests evidence against hunting for signaling purposes.
SDL and optimal foraging theory
Optimal foraging theory (OFO) states that organisms forage in such a way as to maximize their energy intake per unit time. In other words, animals behave in such a way as to find, capture, and consume food containing the most calories while expending the least amount of time possible in doing so. The sexual division of labor provides an appropriate explanation as to why males forgo the opportunity to gather any items with caloric value- a strategy that would seem suboptimal from an energetic standpoint. The OFO suggests that the sexual division of labor is an adaptationAdaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
that benefits the household; thus, foraging behavior of males will appear optimal at the level of the family. If a hunter-gatherer man does not rely on resources from others and passes up a food item with caloric value, it can be assumed that he is foraging at an optimal level. But, if he passes up the opportunity because it is a food that women routinely gather, then as long as men and women share their spoils, it will be optimal for men to forgo the collection and continue searching for different resources to complement the resources gathered by women.
Cooking and the sexual division of labor
The emergence of cookingCooking
Cooking is the process of preparing food by use of heat. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic, and cultural traditions. Cooks themselves also vary widely in skill and training...
in early Homo may have created problems of food theft from women while food was being cooked. As a result, females would recruit male partners to protect them and their resources from others. This concept, known as the theft hypothesis, accommodates an explanation as to why the labor
Manual labour
Manual labour , manual or manual work is physical work done by people, most especially in contrast to that done by machines, and also to that done by working animals...
of cooking is strongly associated with the status of women. Women are forced to gather and cook foods because, otherwise, they will not acquire food otherwise and access to resources is critical for their reproductive success
Reproductive success
Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. A more correct definition, which incorporates inclusive fitness, is the...
. On the contrary, men do not gather because their physical dominance allows them to scrounge cooked foods from women. Thus, women’s foraging and food preparation efforts allow men to participate in the high-risk, high-reward activities of hunting. Females, in turn, become increasingly sexually attractive as a means to exploit male interest in investing in her protection.
Sexual division of labor and the evolution of sex differences
Many studies investigating the spatial abilities of men and women have found no significant differences, though metastudies show a male advantage in mental rotationMental rotation
Mental rotation is the ability to rotate mental representations of two-dimensional and three-dimensional objects.-Introduction:Mental rotation is somewhat localized to the right cerebral hemisphere. It is thought to take place largely in the same areas as perception...
and assessing horizontality and verticality, and a female advantage in spatial memory. The sexual division of labor has been proposed as an explanation for these cognitive differences. This hypothesis argues that males needed the ability to follow prey over long distances and to accurately target their game with projectile technology, and, as a result, male specialization in hunting prowess would have spurred the selection for increased spatial and navigational ability. Similarly, the ability to remember the locations of underground storage organs and other vegetation would have led to an increase in overall efficiency and decrease in total energy expenditure since the time spent searching for food would decrease. Selection on behaviors that increase hunting success and energetic efficiency would bear a positive influence on reproductive success
Reproductive success
Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. A more correct definition, which incorporates inclusive fitness, is the...
. However, recent research suggests that the sexual division of labor developed relatively recently and that gender roles were not always the same in early-human cultures, contradicting the theory that each sex is naturally predisposed to different types of work.
Some researchers, such as Cordelia Fine
Cordelia Fine
Cordelia Fine is an Australian academic psychologist and writer. She is the author of two books on neuroscience, several book chapters and numerous academic publications...
, argue that available evidence does not support a biological basis for gender roles.
Evolutionary perspective
Based on the current theories and research on the sexual division of labor, four critical aspects of hunter‐gatherer socioecology led to the evolutionary origin of the SDL in humans: (1) long‐term dependency on high‐cost offspring, (2) optimal dietary mix of mutually exclusive foods, (3) efficient foraging based on specialized skill, and (4) sex‐differentiated comparative advantage in tasks. These combined conditions are rare in nonhuman vertebrates but common to currently-existing populations of human foragers, which, thus, gives rise to a potential factor for the evolutionary divergence of social behaviors in Homo.See also
- Hunter-gathererHunter-gathererA hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...
- Division of laborDivision of labourDivision of labour is the specialisation of cooperative labour in specific, circumscribed tasks and likeroles. Historically an increasingly complex division of labour is closely associated with the growth of total output and trade, the rise of capitalism, and of the complexity of industrialisation...
- EvolutionEvolutionEvolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
- AdaptationAdaptationAn adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
- Natural selectionNatural selectionNatural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....