- Marlize LombardMarlize LombardUniversity of Johannesburg
- and Katharine KyriacouKatharine KyriacouUniversity of Johannesburg
“Hunter-gatherer” refers to the range of human subsistence patterns and socio-economies since the Late Pleistocene (after about 126,000 years ago), some of which are still practiced in rare pockets across the globe. Hunter-gatherer research is centered on ethnohistorical records of the lifeways, economies, and interpersonal relationships of groups who gather field and wild foods and hunt for meat. Information collected in this way is cautiously applied to the Stone Age and Paleolithic archaeological records to inform on or build hypotheses about past human behaviors. Late Pleistocene hunter-gatherers possessed the behavioral, technological, and cognitive wherewithal to populate the globe. Hunter-gatherer groups are often relatively egalitarian regarding power and gender relationships. But, as is the case for all mammals, only females bear offspring. This biological reality has socioeconomic and behavioral implications when it comes to food supply. Whereas humans share the principles of the mammalian reproductive process, only humans evolved to occupy a unique cogni-behavioral niche in which we are able to outsmart other animal competition in the quest for survival on any given landscape.
Since early on in our history, women of our species gave birth to relatively large-brained offspring with considerable cognitive potential compared to that of other animals. Key to this development is the consumption of specific foods, which contain brain-selective nutrients such as omega-6 and omega-3 polyunsaturated fatty acids and trace elements including iron, iodine, copper, selenium, and zinc. Such nutrients are important for all peoples past and present. Ethnohistorical and nutritional evidence shows that edible plants and small animals, most often gathered by women, represent an abundant and accessible source of “brain foods.” This is in contrast to the “man the hunter” hypothesis where big-game hunting and meat-eating are seen as prime movers in the development of biological and behavioral traits that distinguish humans from other primates.
Hunter-Gatherer Women and Subsistence
“Man the hunter” and “his” ensuing contribution to the cogni-behavioral evolution of Homo sapiens has been much deliberated in terms of meat provision and eating as well as weapon use (e.g., Aiello and Wheeler 1995; Gärdenfors and Lombard 2018; Leonard et al. 2007; Lombard, 2019). How women’s subsistence behaviors acted upon our cognitive and behavioral development is discussed less, but of matching interest to the evolutionary anthropologist. What is more, the strict dichotomy between the activities of men and women, which often underpins subsistence models relating to human evolution, is at odds with ethnohistorical records that show a considerable overlap between the work of women and men (e.g., Hawkes 2001; Kent 1995; Panter-Brick 2002; Wadley 1998, 2013).
For example, both men and women fish in contemporary coastal foraging groups such as the Momega of Australia and Meriam of the Torres Strait Islands (Altman 1984; Bird and Bliege Bird 1997). The gathering of wild plants is typically an activity conducted by women in hunter-gatherer groups, but it is not unusual for men to do likewise. Ethnohistorical records show that Ju/’Hoan men in the Kalahari of southern Africa collect edible plants while tracking and hunting (Biesele and Barclay 2001) and Hiwi men in Columbia and Venezuela pick mangos when they are in season (Hurtado and Hill 1990).
With the exception of the Agta of the Philippines, modern-day hunter-gatherer women are seldom directly involved in weapon-assisted hunting (Noss and Hewlett 2001; Panter-Brick 2002). Nevertheless, they participate in a number of activities associated with the hunting of large and small game. In the desert regions of southern Africa, San women play a vital role in providing male hunters with information on the location and condition of potential prey. They may also accompany their husbands on hunting trips and assist them by acting as trackers (Biesele and Barclay 2001). Foraging women in southern and central Africa employ remote-capture techniques including traps and snares to catch small animals. In the forested regions of the Congo, women regularly take part in communal net hunts aimed at capturing small prey. Among the Mbuti, women act as beaters to drive small game into nets guarded by men. These roles are reversed among the Aka, where women engage in net hunting more frequently than (with or without) men (Bailey and Aunger Jr. 1989; Noss and Hewlett 2001). In Africa and Australia, small game such as mammals, birds, reptiles, rodents, insects, and shellfish are hand-collected by women without the assistance of men (Bliege Bird and Bird 2008; Lupo and Schmitt 2002; Panter-Brick 2002).
Despite this overlap in ethnohistorically recorded subsistence strategies practiced by women and men, there is a distinct pattern in the literature whereby women engage in more reliable activities with low variance and predictable returns, whereas men choose high-risk activities with potentially high rewards. There are two explanations for observed differences in men’s and women’s subsistence behaviors. One holds that their strategies are complementary (Gurven and Hill 2009; Hill and Hurtado 1996); the other is that they are geared toward different productive and reproductive goals (Bliege Bird and Bird 2008; Hawkes 1991; Scelza and Bliege Bird 2008). Within the framework of evolutionary ecology, subsistence strategies serve to maximize fitness through natural and sexual selection in different environmental contexts.
Hunter-Gatherer Production and Reproduction
Choosing between subsistence strategies that have different costs and benefits involves trade-offs between production and reproduction, which differ for men and for women. The environment influences the range of most productive tasks. For instance, hunting may be profitable for women in the forests of central Africa where small game is abundant and predictable, but not in more arid regions where game is widely dispersed. Furthermore, gathering wild plant foods may be highly productive and reliable in some parts of Africa but seasonally restricted in South America and Australia. Women may be able to meet all of their subsistence needs, and those of their children (and often children accompany them, collecting enough to feed themselves and younger siblings), in coastal or inland regions where plant foods and small prey are plentiful but may be more dependent on males where these foods are scarce (Hawkes and Bliege Bird 2002; Hurtado and Hill 1990: Noss and Hewlett 2001; Panter-Brick 2002).
Where male and female activities are seen as complementary, the sexual division of labor is regarded as a form of task specialization in which men and women pursue different subsistence strategies with the common goal of optimizing family or group production (often through the sharing of some foods) and securing a balanced omnivorous diet. Thus, men form cooperative and sharing partnerships with other males and engage in hunting to acquire large food packages that are rich in protein–lipid macronutrients and trace elements supposedly not found in plant foods collected by women.
Women usually avoid direct involvement in big-game hunting, as their participation would have a detrimental effect on child survival and reproductive success. Instead, they focus on less dangerous and physically demanding activities, compatible with childbearing and the caring of the family’s or group’s children. This pattern is evident among Ache and Hiwi foragers in South America, where men invest considerably more time in food procurement than women do and are the main providers. Hiwi and Ache men are active hunters who make successful kills 44 percent and 50 percent of the time, respectively, and share the meat with their families, neighbors, and hunting partners (Gurven and Hill 2009; Hurtado and Hill 1990).
Hunter-Gatherer Subsistence and Alloparenting
Alloparenting, a social phenomenon whereby individuals other than the biological parents support reproduction by sharing surplus food with parents to prevent shortfalls, is a defining feature of human societies (Gurven and Hill 2009; Hawkes et al. 1997; Hill and Hurato 2009). In Hiwi and Ache hunter-gatherer bands, extra-pair males are the main alloparental providers and help pair-bonded hunters compensate for deficits in women’s production. Hiwi and Ache women play a relatively minor role in subsistence by gathering edible wild plants that are available on a strictly seasonal basis and obtain less food than they require. Collected foods account for around 27 percent of the total diet among the Ache and only 5 percent among the Hiwi. Thus, women appear to be relatively dependent on men in the tropical forests inhabited by the Ache and even more so in the seasonally flooded grasslands occupied by the Hiwi (Gurven and Hill 2009; Hurtado and Hill 1990). Pronounced seasonal variation in the availability of gathered plant foods has also been inferred for Momega groups in Arnhem Land, Australia, increasing women’s dependence on males during certain times of the year (Altman 1984).
Hunter-gatherer women, however, often maintain strong cooperative partnerships with closely related females, usually mothers and sisters, to optimize household production. Where dependent offspring cannot be cared for by kinswomen, female foragers choose subsistence activities where returns and efficiency are not compromised by the presence of young children and may actively enlist their participation and help in the food quest (Hawkes et al. 1997; Scelza and Bliege Bird 2008). In some instances, post-reproductive women invest considerable time and energy in subsidizing their daughters’ reproductive and productive efforts by digging for large tubers, which have high nutritional yields but are located at considerable distances from camps and are difficult to extract and process (e.g., Hawkes et al. 1997).
The Hunter-Gatherer Subsistence Package
In most cases, women trade off large food package sizes in favor of greater reliability. Unlike male hunters, female foragers retain control over the final distribution of the foods they have collected (Hawkes et al. 2001). For example, women’s gathered plant foods provide the bulk of daily subsistence (60–80 percent) for the !Kung of the Kalahari Desert in southern Africa. Here, game meat is more prestigious and desirable but is successfully acquired less than 30 percent of the time and is not controlled by successful hunters (Lee 1968). In general, ethnohistorically recorded hunter-gatherer women pursue subsistence activities focused on relatively small-yielding and low-variance resources in order to minimize the risk of shortfalls and provide sufficient food for their immediate families.
Men, however, hunt large and unpredictable game as a political strategy aimed at maximizing their social currency by participating in competitive masculine displays, culminating in the sharing of prestigious food resources. Hunting is therefore seen as a form of costly signaling whereby males “show off” in order to gain status, attract women for pair bonding, and to attract other men to form alliance partnerships. Among the Ache and Meriam, for instance, men identified as accomplished big-game or turtle hunters, respectively, have higher rates of fertility and more mates than mediocre hunters. Proponents of the “show off hypothesis” argue that while hunted meat may yield considerable nutritional returns, these are too unpredictable and shared far too widely to secure adequate daily subsistence for the families of the hunters (e.g., Bliege Bird 2007; Hawkes and Bliege Bird 2002).
If reproductive success rather than efficient resource acquisition is the main goal of male foragers in many hunter-gatherer societies (Hawkes and Bliege Bird 2002; Smith 2004), then women engage in gathering and collecting to ensure the well-being of their children instead of doing so to attract mates. Women foragers consistently choose subsistence strategies with predictable returns that allow them to meet the subsistence needs of their households and effectively subsidize the men’s involvement in the high-risk, high-reward activity of hunting (Bliege Bird and Bird 2008; Hawkes 1991; Hawkes and Bliege Bird 2002).
Brain Foods for Mothers
In addition to requiring large amounts of energy, human brain development is based on the availability of adequate supplies of brain-selective nutrients. To develop and function in a healthy manner, the human brain requires specific nutrients during gestation and early infancy. Such brain-selective nutrients include omega-6 and omega-3 polyunsaturated fatty acids and micronutrients such as iron, iodine, copper, selenium, and zinc. Pregnant and lactating women have particularly high demands for certain polyunsaturated fatty acids and micronutrients to support fetal neurogenesis during gestation as well as optimal growth and development in infants. Very young children and rapidly growing adolescents also have increased requirements for some micronutrients, notably iron and zinc (Cunnane and Crawford 2014; De Souza et al. 2011). Maternal nutrition and access to foods containing these fatty acids and micronutrients during pregnancy and lactation are therefore critical to ensure healthy brain development in infants. Women’s access to foods containing large amounts of brain-selective nutrients would thus have been a significant nutritional challenge and constraint throughout human evolution (Cunnane and Crawford 2014).
The most basic omega-6 and omega-3 polyunsaturated fatty acid requirements in humans cannot be synthesized in adequate amounts and must be obtained through diet. Maternal deficiency in polyunsaturated fatty acids has been shown to have an adverse effect on neuronal development in utero (Al et al. 2000; De Souza et al. 2011; Innis 2000), and breast milk is an important source of polyunsaturated fatty acids for breastfeeding infants (Brenna et al. 2007; Carnielli et al. 2007). Thus, the consumption of foods that contain specific polyunsaturated fatty acids is essential for pregnant and lactating women (Cunnane et al. 2007; Plourde and Cunnane 2007), even though they may be able to synthesize such nutrients with greater efficiency than men and upregulate them during critical times (Bakewell et al. 2006; Burdge et al. 2003; Pawlosky et al. 2003).
Iron and iodine are two trace elements that also play an important role in brain growth and development, especially during gestation and an infant’s first eighteen postnatal months (Cunnane and Crawford 2003, 2014). Iron is essential for neurogenesis and differentiation of brain cells and specific brain regions. Deficiency in utero may impair the development of the central nervous system. Other adverse effects include alternations in brain morphology and impairment of auditory brainstem responses, motor function, as well as learning and memory (Beard 2008; Crichton 2013). During pregnancy, women’s iron requirements increase from 18 to 27 mg/day; this is more than three times the amount required by adult males. Iron losses are only partially offset by amenorrhea, or the cessation of menstrual bleeding during pregnancy, and food sources rich in dietary iron are needed. Iron requirements remain high in infants between the ages of seven and twelve months, which is a time of rapid neural development, and are also high during adolescence, especially in females at the onset of menarche (Beard 2008; Crichton 2013).
Other trace elements, namely, copper, selenium, and zinc, play more indirect roles in growth and neuronal development and are also classified as brain-selective nutrients (Cunnane and Crawford 2003, 2014). Copper and zinc are essential components of enzyme systems and proteins involved in various biochemical pathways in the human body. Zinc is also an absolute requirement for spermatogenesis, fetal growth, and embryonic development. Copper and especially zinc deficiency may result in slow or retarded growth in children and adolescents (Dwyer 2008; Grider 2013). Selenium plays an important role in metabolism and has antioxidant and anticarcinogenic properties (Combs Jr. 2013; Dwyer 2008).
Contrary to previous notions, the meat from game provided by hunters does not represent an ideal source of brain-selective nutrients, especially for women and children. Polyunsaturated fatty acids, and to a lesser extent, micronutrients, are not evenly distributed in the different edible tissues of terrestrial animals (Cordain et al. 2001). Most importantly, critical types of omega-3 polyunsaturated fatty acids are almost entirely restricted to certain fatty parts, notably the brains, organs, and bone marrow of animals (Kuipers et al. 2010; Kyriacou et al. 2014, 2016; Speth 2010). Liver tissue is also particularly rich in micronutrients such as iron, copper, and zinc (Kyriacou et al. 2014, 2016). The fatty acid and micronutrient-rich portions of a carcass are not equally divided among the different members of hunter-gatherer bands following a successful kill; people receive shares of different nutritional value and worth. Among the !Kung, for instance, hunters may consume the marrow fat, liver, and brains at the kill site; lean meat is more likely to be returned home for sharing with women and children (Speth 2010).
As an alternative to meat, some of the foods typically collected and controlled by hunter-gatherer women are potential sources of polyunsaturated fatty acids and brain-selective micronutrients. Plants, eggs, insects, and shellfish are good examples and serve as staple foods in many hunter-gatherer diets. Plant foods are quintessential gathered resources and represent an important source of energy in the form of carbohydrates and, in some cases, plant proteins and vegetable fats. They are also the starting point for all essential fatty acids in the human food chain (Brenna et al. 2009; Orr et al. 2013).
Gathered Plant Foods as a Source of Brain-Selective Nutrients
Nuts are a key component in the diets of many foraging societies and are rich in protein, fat, and polyunsaturated fatty acids (Goren-Inbar et al. 2002). Mongongo (Recinodendron rautenenni) and, to a lesser extent, marula (Sclerocaryabirrea caffra) nuts are a staple for !Kung hunter-gatherers living in the desert regions of Namibia, Botswana, and Angola. They contain more calories than other plant foods and are an important source of vegetable fat (Blurton Jones et al. 1994; Eaton et al. 1997). Mongongo nuts are foraged most intensively during the dry season (May to August) when other resources are scarce. Women travel to nut groves located at considerable distances from dry season camps; processing takes place after they return. Nuts are roasted over an open fire, and the edible kernel is extracted using a hammer and anvil. This is a time-consuming process in which children over the age of eight participate to maximize household returns (Blurton Jones et al. 1994; Hawkes 2001; Speth 2010).
The edible components of many indigenous plants found throughout the arid Sahel region of West Africa are important dietary staples and provide energy, polyunsaturated fatty acids, and trace elements (Glew et al. 1997; Lockett et al. 2000). Okra or lady fingers (Hibiscus esculentus) and African locust bean (Parkiia biglobosa) seeds and black plum (Vitex donania) fruit contain large amounts of polyunsaturated fatty acids (Lockett et al. 2000). Okra fruit and seeds are also good sources of zinc.
Several plants eaten by the nomadic Fulani people of northeastern Nigeria also have high concentrations of brain-selective micronutrients. For example, the bark of the baobab tree (Adansonia digitata), which is often given to infants to help them gain weight, contains large amounts of fat as well as copper, iron, and zinc. Common wild fig (Ficus thonningii), African locust bean, and drumstick or horseradish tree (Moringa oleifera) seeds are high in protein, fat, and the aforementioned trace elements. Tamarind seeds (Tamarindus indica), which are used to make a porridge typically consumed by pregnant women, and iron tree (Prospos africana) seeds contain large amounts of zinc (Glew et al. 1997).
Common purslane (Portulaca oleracea) grows wild in a number of different locations and environments in Europe, Asia, Africa, North America, and Australia. In modern times, it is grown as a potherb in parts of Europe and Asia and used in cooking and pickling in the Mediterranean and Middle East. This terrestrial plant has been identified as the richest vegetable source of certain polyunsaturated fatty acids. It is thought to have originated in the desert regions of the Middle East and India 4,000 years ago and is known to have been included in the diet of the ancient Romans and hunter-gatherers living in the Pacific Northwest (Kris-Etherton et al. 2000; Simopoulos 2004; Uddin et al. 2014).
Three wild Nordic berries, namely, blueberry (Vaccinium myrtillus), cloudberry (Rubuscha maemorus), and cowberry (Vaccinium vitisadaea), have also been found to contain large quantities of polyunsaturated fatty acids (Bere 2007). Conversely, a small range of berries (tick berry or Chrysanthemoides monilifera, tortoise berry or Nylandtia spinosa, and blue kuni-bush or Rhus glauca), fruits (sour fig or Carpobrotus edulis), seeds (cobra lily or Chasmanthe sp.), shoots (wild cauliflower or Trachyandra ciliata and Trachyandra revolute), and corms (slime lily or Albuca sp., bugle lily or Watsonia tabularis, cobra lily or Chasmanthe sp., and sword lily or Gladiolus sp.), indigenous to the Cape Fynbos biome of South Africa, contain measurable amounts of oleic, palmitic, and stearic acids, and in some cases also polyunsaturated fatty acids (Kyriacou et al. 2016); some of these, like the Watsonia lily bulb, were harvested by Stone Age hunter-gatherers at least since the beginning of the Holocene (e.g., Deacon 1976; Wadley 1998).
Gathered Animal Foods as a Source of Brain-Selective Nutrients
Egg yolk is one of the richest terrestrial sources of longer-chain polyunsaturated fatty acids, the specific composition of which is determined by the amounts of omega-3 polyunsaturated fatty acids in the diets of oviparous birds. The eggs of wild oviparous species form part of the diets of modern hunter-gatherers and are typically collected by women or both sexes (Lee 1979). Ostrich (Struthio camelus) eggs are frequently collected by !Kung women and men of the Kalahari. An ostrich egg yolk contains ~12 g/100 g of protein and ~5 g/100 g of fat and is an excellent source of iron (1.4 mg/100 g), copper (2.8 g/100 g), and zinc (1.0 mg/100 g). It also contains large amounts of omega-6 polyunsaturated fatty acids, as are found in the brain tissue of terrestrial vertebrates (Broadhurst et al. 2002; Kyriacou et al. 2016). Marine bird eggs are an excellent source of preformed longer-chain omega-3 polyunsaturated fatty acids (Broadhurst et al. 2002; Cunnane and Crawford 2014).
Terrestrial invertebrates are an important source of food for contemporary hunter-gatherers living in the warmer regions of Africa, Australia, Asia, and South and Central America. Insects are eaten throughout the year, during times of seasonal abundance, or when other animal foods are scarce. They serve as snacks for immediate consumption or as staple foods, especially among women and children. While several hundred species of insects are edible, caterpillars, grasshoppers, locusts, crickets, termites, and beetle grubs are the most frequently collected. These are all relatively large, abundant, and accessible food packages. In Africa and Australia, terrestrial invertebrates are usually gathered by women; they remain a favored and significant food source for many partially urbanized people of these continents (DeFoliart 1999; O’Dea et al. 1991). Edible insects are highly nutritious and are an excellent source of energy, trace elements, and polyunsaturated fatty acids (Ajai et al. 2013; Banjo et al. 2006; Marconi et al. 2002; Rumpold and Schluter 2013).
Caterpillars, soldier and winged termites, grasshoppers, and locusts consumed by hunter-gatherers in South America, such as the Yanomamo and Makiritare of Venezuela (Marconi et al. 2002), and by South African hunter-gatherers at the time of first contact with Europeans (Parkington 1977), as well as other indigenous populations throughout sub-Saharan Africa, are high in protein and fat. They represent an accessible source of these macronutrients, especially for women and when other forms of animal protein and fat are scarce (DeFoliart 1995, 1999; Kyriacou et al. 2016; Rumpold and Schluter 2013). Many of these edible insects are also rich in micronutrients and omega-6 and omega-3 polyunsaturated fatty acids.
Marine mollusks represent an accessible and reliable source of macronutrients, micronutrients, and polyunsaturated fatty acids for coastal communities. Many shellfish species contain protein and fat in similar quantities to lean meat from wild game animals, as well as brain-selective nutrients in considerably greater amounts (Kyriacou et al. 2016). Shellfish represent an important part of the traditional diet of coastal populations. For example, the Meriam of the Torres Strait Islands subsist on a combination of horticulture and traditional coastal foraging, including fishing, turtle hunting, and shellfish collecting (Bird and Bliege Bird 1997; Bliege Bird 2007). The latter includes a range of differently sized clams, conches, and gastropods. Shellfish gathering by Meriam men and women is usually highly selective, and undersized specimens are ignored and, if accidentally collected, discarded.
Similar behavior has been observed among the Anbarra coastal foragers living in Northern Australia (Meehan 1982), but here shellfish are usually collected by groups of women and girls. Intertidal foraging also remains an important part of the subsistence economy in several different regions in South Africa. Xhosa-speaking people living in the coastal region of the Eastern Cape Province supplement their maize-based diets with shellfish, including abalone, limpets, turban shells, winkles, and whelks (Lasiak 1992). Women in KwaZulu-Natal gather mussels, oysters, red bait, and limpets (Kyle et al. 1997a, 1997b).
Gathering Brain Foods through Deep Time
Apart from hunting, the gathering and consumption of brain-selective nutrients in all likelihood has a long history in our genus, but one that is difficult to trace. Information on the subsistence strategies of contemporary foragers has always informed reconstructions of prehistoric diets. When used with some caution, ethnographic analogies can help paleoanthropologists and archeologists to understand the role of gathered foods in human prehistory. For example, collected plant and animal foods are likely to have featured prominently in diets throughout the Stone Age of southern Africa.
Some of the earliest evidence for the exploitation of intertidal shellfish and other marine resources comes from Middle Stone Age sites along the southern shores of South Africa, a region characterized by highly productive coastlines (Klein and Steele 2013; Marean 2010a, 2010b; Parkington 2003). Intertidal shellfish represent an abundant and accessible source of protein, micronutrients, and polyunsaturated fatty acids (Kyriacou et al. 2014, 2016), supporting populations of early modern humans visiting or living at the coast since at least one hundred twenty thousand years ago. Eating these simple marine foods would have had considerable nutritional advantages, especially for women and children. Regular consumption may have had a cumulative effect in improving the reproductive fitness of individuals over multiple generations by ensuring proper neuronal development in utero and during early infancy, as well as enhancing child survival.
At some Middle Stone Age sites in southern Africa, marrow was intensively extracted by about seventy thousand years ago (e.g., Reynard et al. 2016). This behavior displays a “hunger” for the fatty marrow in bones, which contains the longer-chain omega-3 polyunsaturated fatty acids. Marrow exploitation has a long history in the human genus and was already practiced during the Early Pleistocene when it is argued that its consumption was subsidiary to the general benefits of carcass processing (e.g., Blumenschine et al. 1994; Lupo 2006).
Eggs would also have provided Stone Age gatherers with polyunsaturated fatty acids, iron, copper, and zinc. The inland site of Apollo 11 in Namibia provides evidence of some of the earliest known use of this resource, with more than seven thousand ostrich egg shell fragments from a context dated to about seventy thousand years ago (Vogelsang et al. 2010). Ostrich eggs are still considered a delicacy among Kalahari hunter-gatherers, and the ancient shell serves as evidence of their subsistence value through many millennia on the southern African landscape.
Edible wild plants would have provided some omega-6 and omega-3 polyunsaturated fatty acid requirements, as well as other essential micronutrients. From Mozambique, micro-botanical remains that are about one hundred fifty thousand years old suggest the consumption of seeds, legumes, caryopses, piths, underground storage organs, nuts, and mesocarps (Mercader 2009; Mercader et al. 2009). At Sibudu in KwaZulu-Natal (South Africa), there is ample preservation of carbonized seeds, nuts, and the stones of fruits (e.g., Sievers 2006). Anthropogenically deposited sedges from about seventy-seven thousand years ago is seen as evidence for the early use of plant-based “bedding” (Wadley et al. 2011). Abundant remains of the Cladium mariscus sedge (among the plants most likely to contain sufficient types of polyunsaturated fatty acids for biosynthesis) were recovered from layers dating between seventy-three thousand and thirty-nine thousand years ago, and a nutritional analysis of the plant’s nutlets and rhizomes indicates their potential as a food source at the site (Sievers 2015).
The role of hunter-gatherer women in bearing and caring for their large-brained, highly dependent infants, thus ensuring the survival of future generations, has always been acknowledged in models for human evolution. However, their equally important role in subsistence production is often overlooked in favor of male-dominated activities, notably big-game hunting. Maternal nutrition and access to foods containing large amounts of omega-6 and omega-3 polyunsaturated fatty acids and brain-selective micronutrients during pregnancy and lactation are critical for fetal neurogenesis and continued neuronal development in the first few months postpartum. It is apparent that foods typically collected by hunter-gatherer women met some, if not all, of these specific nutrient requirements.
The regular consumption of foods with brain-selective nutrients, which are collected predominantly by women in modern foraging societies, over succeeding generations may have contributed to the reproductive fitness and overall survival of prehistoric populations through deep time. Hunter-gatherer subsistence strategies and the associated gendered contributions are nuanced and variable. The ability to develop such flexible approaches to subsistence strategies would have had direct fitness consequences for early hunter-gatherer groups. Over time, this adjustable lifeway evolved to be so broad and flexible, allowing for the exploitation of most environments and resources, that it facilitated our successful spread across the globe (e.g., Kaplan et al. 2000; Lombard 2015, 2016). But behind the scenes of such behavioral flexibility, there is (among other things) a biological drive toward the gathering and consumption of brain-selective nutrients, and this need is critical during phases of gestation and lactation in women—today as in our hunter-gather past.
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