Home / 9.7: Ecological Anthropology

9.7: Ecological Anthropology

Man is the as part of nature as other living beings. Thus anthropologist must pay attention to natural settings of human being. Environment is natural setting which varies from place to place.

The ecological diversification of human species was significantly aided by cultural evolution in the form of tools, use of fire etc.

The features of environment is difficult to be changes or modified, human have sufficiently moulded & modifies its own behavior thus displaying to great extent adaptive behaviour.

Ecological Anthropology

Introduction –

  • It is a subfield of anthropology that studies the interaction of biotic & abiotic components of environment with human beings.
  • It is a branch of anthropology which is concerned with bio-cultural responses and processes that affect the survival, reproduction, development, longevity and spatial distribution of human populations
  • It studies the m/c of human adaptivity. It integrates findings from ecology, physiology, sociocultural anthropology, geography etc. Thus it is multidisciplinary study of the dynamic interface b/w humans & their socio-cultural & biophysical environments.

Development of Ecological Anthropology

  • Envrionemental Determinism
  • Natural Possibilism
  • term Ecology was coined in 1866 by Ernst Hackle.
  • Cultural Ecology – concept was given by Julian Steward (1950s), his multilinear theory of cultural evolution emphasis that cultural change is induced by adaption to env.
    • Acc. to him, Cultural ecology must be separate from biological ecology

All these approaches failed b/c they failed to recognize the biological concept of Ecosystem in which human relations are Mutualistic

  • Clifford Geertz was the first anthropologist to use to the concept of ecosystem in anthropology
    • Ecosystem concept emphasizes on Systems Approach
  • Later Andrew Voyada & Rapaport incorporated the priciple of biological ecology into the study of cultural ecology in order to make a single science of human ecology.
  • Their work gave impetus to Ecological Athropology
  • Over the period of time, this branch has included in it sphere various areas like human adaptation, ethno-ecology, sustainable development, population etc.

Scope of Ecological Anthropology

  • Influence of environment on man
    1. Cultural Ecology – Julian Steward says that,
      • some domains of culture have strong & direct relationship with environment which consitute cultural core
        • Ecological analogies could be used to explain cross cultural similarities only in this cultural core.
      • Other aspects of cuture have indirect relationship with the environement which is k/n as superstructures.
    2. Biological Adaptation – The Knowledge of anthropology can be used to understand existence of people in the harsh climate eg. hot desert, polar regions & area of high altitude.
    3. Ethno-Ecology – How people preserve & understand nature around them & how people use this knowledge to know about the surrounding.’
  • Influence of man on environment
    1. Environmental Degradation – Ecological anthropology has made an attempt to understand the problem of envrionment degradation (aroused due to overexploitation of natural resources) & came out with an innovative idea of sustainable development.

Relevance – help in understanding

  • of man environmental relationship
  • Development of cultures in different ecological settings
  • Bio-cultural adaptation m/c of humans towards climate conditions

Contemporary Significance

  • It has given idea of sustainable development which can promote the cause of env. & the interest of man as well
  • in creating awareness of race formation & racial differences.
  • It studies human adaption to harsh climate which can create awareness about human variation throughout the world which can help in combating racial arrogance, promoting health & nutrition
  • With the understanding of man-env. relationship, ecological anthropology can promote food security &consequently it can promote the health of masses.

Methods of Ecological Anthropology (Not)

Introduction – The research strategy of ecological anthropology is to study a wide range of human responses to environmental problems, to social constraints; and to past solutions of environmental problems. Little & Morren have succinctly expressed the strategy as “ecological anthropologiests are concerned with those cultural & biological responses, factors, processes and cycles that affect or are directly connected with the survival, reproduction, development, longevity or spatial position of people.”

Systems Analysis : Ecosystem Approach

  • Ecosystem quality leads naturally to use the systems analysis tec.
    • Ecosystems are self maintained & self regulationg.
  • It is useful b/c it begins with a holistic model of components & interrelation of an ecosystem, essentially a qualitative & descriptive process.
  • It provides a broad framework for analyzing empirical reality & for cutting across disciplinary boundaries.
  • It has similarity to Anthropological holism : A system is an integral whole & no part can be understood apart from the entire system.
  • Earlier ImpeE tus
    • Clifford Geertz
      • first anthropologist to argue , ecosystem as viable unit of analysis in cultural anthropology.
      • To explain Agricultural development historical & political factors must also be included.
    • Roy Rappaport & Andrew Vayda : Stongest impetus
      • prefer term ecological anthropology than cultural ecology
      • promoted the use of ecological & biological units
      • They showed that the behaviour of men toward each other, as well as toward nature, is part of the ecosystem.
  • Critics – Bennett argues the ecosystem approch doesn’t work well b/c it cann’t research the dynamic processes of institutions & the conscious processes of choice among alternative due to the complexity of the systems.

It is certainly premature to expect to expect the ecosystem perspective to resolve most of our questions about how humans adapt.

Close cooperation will be required b/w biological & behavioural scientists to generate an intergrated study of people in ecosytems.

Ethno-Ecological Approch

  • it is termed as Ethnoscience & it deals with the study of various culural perceptions of the world & how people order those perceptions through their given language.
  • It give rise to the subfields dealing with specific domains of culture,
    • Ethnobotany
    • Ethnozoology
    • Ehtnoecology
  • Its aim is to provide better understanding of how people perceive their environment & how they organize these perceptions.

Homostatis

  • Early thought
    • The tendency for biological systems to resist change & to remain in a state of equillibrium.
    • has led to overemphasis on static consideration & to an evaluation of man’s role as basically disruptive.
  • New thought
    • Homeostatis & dynamic equillibrium don’t imply changelessness.
    • They require constant adjustment of system parts & even some change in str.

Environment Change & Response

Introduction – Difference in environment can lead to population level differences, as individuals within the populations biologically adapt to local conditions. B/c of biological plasticity & adaptability, populations may phenotypically differentiate from one another without any underlying changes to the genotypes.

Thus human response to changes in environment can be studied at different levels

  1. Population Level ( here we see genotypic changes in relation to environment
  2. Individual Level – Ricklefs differentiates b/w various adjustments by individuals to changes in their env. They are
    1. Regulatory Adjustments – ex sea level to high altitude
    2. Accliamatory Adjustments – ex Tanning, ↑ RBC ; longer time
    3. Developmental Adjustments – not reversible ; but of limited value for short term env adjustments – child growing in high altitude → grow large lungs capacity ; not with adult

All three types operate by a process of negative feedback. This type of feedback seeks to maintain a stable relationship b/w organism & its surrounding.

Biological Plasticity

An ability on the part of individual to physiologically response to changes in the environment. This is obvious in poor environment ; For ex, if there is not enough food, an animal will become thinner

  • Stress – is taken as any factor that interferes with normal limits of operations. It is central to the study of adaptations.
  • The ability of organisms to respond physiologically (or) developmentally to environmental stresses is often referred to as plasticity
  • Genetic Plasticity – the ability of humans to mould themselves during developmental period to the prevalent env conditions.

Adaptation

Introduction – Adaptation are the response of an organism to the structural & functional  characteristics of its environment. These are multidimensional & Multi hierarchical & which result from

  • exposure to physical & chemical factors in the environment,
  • from interaction with other species &
  • from the interaction of individuals within the same species

Character of Adaptation

  • Irreversible Respones
  • Occurs during growth & development
  • They are adjustment to env. present during developmental period
  • Owing to greater plasticity of the individual during developmental period
  • It involve change in one or few gene
  • Adaptation happens through slow & gradual adjustments to the environment.
  • Different population of a species may be adapted differently to live in its environment. so that they are able to secure sufficient food, to protech & to produce successfully for maintaining the continutiy of the race.

Uniqueness of Human Adaptation : Genetic & Behavioural Transmission

  • Human ability differ signigicantly from lower forms in that the human ability is largely non genetic & a learnt behaviour whereas it is genetic & innate behaviour in case of lower animals.
  • But these are also transmitted to the next generation in the form of accumulated information. This process of transmission of accumulated information is major construct of culture & hence it is cultural behaviour that has significantly aided in the adaptation of population to diverse env.
  • Genetic mehcanisms also seem to have contributed to some extent in this adaptability. The genetic variation is expressed in biochemical, phyisological, immunogenetical & other aspects of functions.

Human adaptability, therefore, includes both a biological component & a cultural component.

Examples

  • An eskimo – has small limbs to prevent loss of heat whereas has normal truck length so that maximum metabolic energy is generated.
  • have cold genes → keep limbs warm & save from frost bite.
  • Child – High Altitude – Larger Lung Capacity

Some times it is difficult to classify an adjustment as acclimatization or genetic adaptation for eg.

  • dark skin colour : there is genetic adaptation in the melanin content of the skin & it shows acclimatization(genetic plasticity) effect too

Adaptability

the ability of individual organism to make positive anatomical or physiological changes after short or long term exposure to stressful environmental conditions.  The adaptability is manifested in both ter,

Multidimensional Nature of Human Adaptability

Hence, an holistic approch is needed that can describe such multifacet human adaptability – Ecological Anthropology.

Acclimatisation

Introduction -It refers to changes in physiological processes in response to changed environment.

Characteristics of Acclimatisation

  • It is always temp change & species wide i.e if individual reverts to original env., the changes vanish.
  • This characteristic adjustment is shown by all the individuals of a species.
  • As these are long historic process – it involve whole genetic system i.e organic str.
  • They occur when an external stimulus is parents for sufficient amount of time

Example – Acclimatisation for high altitude & heat stress is typical example of this category, Entire human species react similarly in such conditions.

Ex, Exercise – Muscles

Biocultural Adaptation

Introduction – Darwin’s observation of “struggle for existence” & survival of the fittest” means adaptation of  organism to a particular environment. It needs essentially biological modification. While in case of human the ability to learn (culture) plays crucial role in his adaption. 

Adaptation encompasses the physiological, cultural & genetic adaptations that allow individuals & populations to adjust to their env in which they live.

  • Biological Adjustment – Changes in the structural & physiological system of organism. eg. Changes in height, pigmentation, faical feature etc in response to particular physical env. Biological adjustment can be acclimatisation & adaptations
    • Acclimatisation (Whole genetic System) – Acclamatory Responses
      • Long term acclimatization : This is acquired ovet the years but is reversible under environmental changes
      • Seasonal Acclimatization : Such changes may be reversible during the annual cycle.
      • Short term Acclimatization : These are manifested in dialy or irregular responses to condition.
    • Adaptations (One or few genes) – Developmental Responses
      • Genetic Adaptation : Evolution of advantageous characteristics. eg. body, shape & size
      • Developmental Adaptation : The acquiring of appropriate response as an individual grows up in a particular env. eg. Europeans living in hot tropical areas.
  • Cultural Adjustment – Regulatory Responses ;
    • cultural adjustments human populations use methods & practices learnt from its ancestors over long period of time for its survival.i.e
      • Cultural Strategies
      • Psychological & Behavioural
      • Very rapid mode of adjustments
    • eg. use of cetain diet, dress, activity pattern, rituals etc are cultural adjustments.
    • Eg. Cultural responses enables human to survive & continue successfully in Arctic Circle, Kalahari Desert & in the mountain ranges of the Himalaya
      • Cultural behaviour eliminates the need the expected biological changes
      • However cultural adaptation may result into specific biological changes.

Conclusion – Thus human beings are not only equipped with inbuilt mech., but also his learning have enable him to coquer the forces of nature & continue his presence since time immemorial in almost every post of the planet earth.

Adaptations to Hot Desert /Arid Climate /Heat

Introduction – Human species developed in tropical Savannah type climate. So are capable of tolerating moderate heat & temp. of 30 ±5℃ is well tolerated. Problem arises when temp gets above 35℃.

The mean constant temp of human body is around 37℃/98℉.

Performance of any physical & mental tasks tends to decline at air temp above 28 ℃ & heat stress imposes a measurable metabolic cost on all human activities

Characteristics of Arid /Hot Desert Climate

  • < 100mm rainfall
  • Dry & random distribution of rainfall

Stress – Anything that disturbs the homeostasis, that is the equilibrium of body, is called stress. In case of hot condition .. 

  • Heat – Very High temp
  • Water
  • As warm blooded/ homeothermic, human body seeks to maintain a temp of around 37°C. Rise in body temp in ordinary circumstance can impair body activity. A 4-5° C rise can even cause permanent damage.

Adaptation to stressfull conditions such as Hot Climate by human beings takes place at physiological, genetic & cultural levels. It involves generation of less heat by the body & dissipation of heat as much as possible.

Biological Responses

The body seeks to continuously loss heat to the surrounding. This can be done by

  1. Acclimatisation (Physiological) – Mainly Sweating
    • Diminished pulse rate
    • Decrease in volume of urine
    • Decrease in salt conc. of sweat
    • Lower rectal temp.
    • In hot dry desert, heat loss occurs through evaporation resluting in loss of fluid & electorlytes.
      • in studies, water loss of 8 l/day has been found to be the avg. for young man. Body size is significant factor
      • However Salt excretion (electrolytes)decline over period of acclimatization.
    • Mechanism
  • Heat is first lessened by radition by vasodilator
  • Then if core temp doesn’t come down, hypothalamus is activated.
  • It is the most imp thermoregulatory organ located in brain.
  • If the heat load continues for some days, there is development of heat acclimatization with less sweating & lower core temp.
  • The heat acclimatization disappers if head load is removed.
  • Stages of Heat Tolerance
    1. Thermal Gradient
    2. Sweating in low vapor pressure
      • 1.5 million sweat glands on human skin
      • Sweat evaporates from surface & provides evaportive.
      • Lack of hair also ensure that evaporation takes place rapidly providing cooling effect.
      • small body – more heat tolerance b/c surface area for heat loss will be greater in relation to the heat producing mass of body
      • Long extremities will also be advantageous as these increase conductive & radiative cooling.
    3. By Thermal Gradient only in high vapor pressrue area
      • No loss through sweating but only through radition)
    4. Heat Acclimatization
      • Empirical studies in labs & field have shown that European, Australia, & S Africans, Bantu) initially differed in heat acclamatization. It is due to climate differences
      • But later most of these differenes disapper after heat acclimatication to higher level of stress
  • Heat tolerance also depends upon age. In infants, it is low due to non-activation of sweat glands. While from childhood to adulthood, it increase as surface area per unit of body mass ↓.
  • In Condition of high humidity sweating is ineffective
  • Adaptation (Genetic)- In some places of high level of humidity eg. Shores of red sea, tropica forest & shores of Persian Gulf . the sweating is of little or no use in cooling. Rather body shape & size of immense value
    • Bergman Rule (Body Size & Temp) : It state that individuals in warmer areas have lower body sizes that those of the same species in colder area. E.g Pygmies of tropical forest of Arica & South East Asia
      • Small Body produce less heat & large suface area to dissipate more → as body size decrease heat tolerance increases
    • Allen Rule (Body Shape & Temp) : It states that individuals in warmer areas have long body appendages than those of the same species in colder areas. Eg. Nitolics of Africa
      • long extremities like finger, toes, limbs & ears having larger surface area can dissipate large amount of heat from body.
    • Slender body with no fat

Cultural Response – Most Potent Weapon in Hands of Human Race

  • Houses Formation – Shelter
    • In hot desert : closed housing – inside temp cool during max day time heat & also are made up of high heat -reflective material & beneath the surface.
    • In hot wet env. : open housing to promote sweat evaporation
  • Clothing – Chamba Arabs of Sahara wear special clothing that blocks heat gain from environment.
    • In hot desert ; covered almost all of the body to reduce radiative heating
    • In hot wet env. ; minimal clothing to promote sweat evaporation.
  • Diet – high percentage of water in diet
  • Aridity – Normadic Acitivity
    • restrict physical activity during mid day in hot climates

Conclusion – Thus human being in the process of evolution has adapted itself to various degrees of hot climates thr biological & cultural responses so as to continue its race & survival .

Adaptation to High Altitude

Introduction – Since the atm pressure drops at high altitude → shortage of O2 to tissues ( hypoxia) ; & cold stress. Adaptation at high altitudes mainly means to adjust with low PO2. This adaptation takes place at Physiological, genetic & cultural level.

Biological Responses – The body needs to seek maximum O2 present in env. This can be done by –

  1. Acclimatisation (Physiological)
    1. Increased Breathing Rate & pulmonary ventilation – Hypoxic condition stimulate appropritate nervous centers(Medulla Oblongata -respiratory centre) to cause instant ↑  in breathing rate to 65 %
      • If person remains at high altitude, this rate ↑  5 folds
      • initially prevented b/c blowing off large amount of CO2 → change in blood alkalinity → suppresses the neural centers.
      • in few days this inhibitory effect resulting from low CO2 is removed & breathing rate ↑  5 folds
    2. Increased RBC (Polycythemia) & Hb
      • Hypoxia stimulate Kidneys to secrete erthropoietin → ↑  RBC count & hb level from 15g/dl to 22g/dl. & total blood volume ↑  by 20-30% hence net ↑  50% to 90%.
      • This ↑  in blood vol & hb is a slow process & evidenced after few weeks of accllinatization.
    3. Increased Lung Surface & residual volume
      • it means more O2 can diffuse to blood.
      • This is brought about by increased vol of lung due to increased breathing & expanded blood capillaries of lungs
    4. Increased Tissue Blood Supply
      • ↑  in cardic output & growth of additional capillaries in the tissues ensures increased tissue blood supply thus removing hypoxic condition.
    5. Cellular Acclimatisation
      • claimed that hypoxia causes ↑ in mitrochondria & some other cellular enzyme systems.
      • O2 inhaled is ulimately utilised by mitochondria for energy transduction.
    6. Shift of O2 dissociation curve to Right
      • At high altitude, diphosphoglyceric acid (DPG) it displaces O2 from HbO2
      • Hence HbO2 dissocaition becomes rapid & O2 readily available to tissues.
      • The O2 dissociation curve for the High landers is thus situated left to those of curve of low landers.
  1. Adaptation (Genetic) : The permanent inhabitants of high altitudes show adaptations
    1. Increased chest size – leads to  high ratio of ventilatory capacity to body mass. E.g Bods of Ladakh have more chest circumference than lowland Indians.
      • Sherpas of Nepal are exception, in them compensatory adaptations are found in blood.
    2. Decreased Body size → reduce the body mass, so that body can be supported by low O2 uptake.
    3. Smaller Size & weight of babies -this prevents the need for large supply of oxygen to large foetus. 
      1. High level of nutrition & care don’t come in the way.
      • Low birth weight – reduction in O2 demand
      • Delayed Growth – found in Andeans by Baker
        • Ethiopian Highlanders – exhibits faster growth rate than low landers (exception)
    4. Increased Right Side of Heart:  supply large amount of blood to lungs for oxygention
    5. Some physical attributes, such as shape of noe, skin color etc. are adaptive
      • Nose is shortened to reduce nasal passage way & nostril directed upward.
    6. capacity of their hb to extract O2 i.e combine with O2 at lower partial pressure of O2 (PO2)
      • PO2 saturation hb in high landers – 40mm of Hg
      • PO2 saturation hb in low landes – 100 mm of Hg
    7. Unique genetic Variations – e.g Tibetans have unique variants of EGLN1 & EPAS1 genes, key genes in the oxygen homeostasis system.

Cultural Response

  1. Diet is focused on maximum utilisation of glucose – Some highlanders in Brazil chew some herbal leafs so that Hb content in their blood is Increased  so helps in binding to more O2 & more availablitlity of O2
  2. Active lifesystle to build excercise tolerance
  3. High carbohydrate diet to provide energy
  4. Migration to lower altitudes during pregnancy -e.g as seen in Quechua Indians in Peru.

Conclusion –

  • Human adaptation to high altitude zones involves a combination of behavioural & physiological adaptations that have made it possible for populations to survive in this vertically zonated env.
  • The major constraint is hypoxia & numerous developmental adaptations are particularly valuable. An enlarged capillary bed, Polycythemia, decreased alvelolar arterial O2 gradient & other mechanisms are involved in facilitating survival in an O2 scarce env.

Case Studies

  • Maladaptations – Not all individuals native to high altitude adapt to hypoxia & some lose their adaptation. This is known as chronic mountain sickness & invoves loss of normal stimulation of breating.
  • Andeans – Baker studies them & wrote about them in his book, Man in the Andes (1976). He found that their children have low rates of physical growth than the lowland population.

Adaptation to Cold

Introduction – Adaptation to cold climate occurs through conservation & generation of heat by the body & it take place at physiological, genetic & cultural level.

Cold Stress in Human

  • Perhaps b/c of the tropical origin human have limited acclimatization responses to cold as compare to heat conservation & so rely more on cultural adaptation than biological adaptaions.
  • When the atm temp dips below 28°C, there is persistent heat loss from body to the surroundings.
  • Prolonged exposure can impair activity & may cause permanent damage.

The human body adjusts to such stress by the following

Biological Responses – the body seeks to reduce heat loss to the surrounding. This can be done by 

  1. Acclimatisation (Physiological Adaptation) – Cold Tolerance – By simulations conservation & generation of heat
    1. Conservation of heat – Temp. drops below 28℃ → Thermo receptos in skin → Hypothalamus in the brain → Vasocontriction & slow heart rate → reduced blood flow to extermities & skin → Heat conservation
      • Besides people try to reduce heat loss by folding their arms & legs which reduces surface area. Hence, conservation of heat is accomplished.
      • Narrowing down the blood vessels of extermities of the body, including skin whenever faced with a cold spell & succeded by its expansion Eg. immerising of finger in freezing water.
      • as less blood will flow & less heat loss.
    2. Generation of Heat
      • Adequate body heat is produced voluntarily through physical acitivity i.e through muscular activity.
      • Falling skin temp→ thermo receptors in the exposed surface of skin → Hypothalamus → involantary shivering → heat generation.
    • Cold tolerance also varies with age. Hanna (1976), after studying Highland Quechua Indians of Peru, showed that children have least tolerance. This is b/c of their low skin fold thickness & neurological development.
  2. Adaptation (Genetic)
    1. Cold Genes – A pair of gene that control how the body burn fat for warmth in the cold. Eg Greenland Inuit withlow European mixing, living in villages on the coast of Baffin Bay.
    2. Presence of the body hair which trap a layer of air.
    3. The body size & shape are of huge value to cold adaptation.
      • Bergman‘s Rule : Body size in colder regions ↑  b/c it results in  Increaseed mass in comparison to skin area, meaning less surface area. (B → Body Size)
        • Large body produces more metabolic heat & due to less surface area the heat is conserved
      • Allen’s Rule – it states that Individual in colder areas have large body appendages than those of the same species in warmer area. (A → Appendages)
    4. Subcutaneous fat in adipose tissue has low thermal conductivity & also in presence reduces surface area.
      • Eskimos living in Tundra region of canada & North pole have bulky body due to presene of subcutaneous fat

Cultural Adaptation

  • Nature of clothing – has helped humans survive below- freezing temperatures.
    • Eskimos use the clothing from Caribou’s fur which keeps them warm
  • Shelter – well Insulated housing e.g Igloos
    • North East Siberains such as Insuit live in specially built houses (made of of snow blocks) called lgloos where air pockets trapped in snow act as inslulators & keep the inside temp more than outside temp
  • use of fire – chief resource of early humans & still used by hunter-gathers of Bushmen of Kalahari.
    • Australian aborigines sleep naked around campfire & chew leaves of Duboisia & Tobacco containing alkaloid for warming their body.

Case Study – Population Differences In Whole Body Cooling:

  • A study comparing Australian aborigines with white people has been recorded.
  • Later on experiments on Bushman of South Africa was also conducted.
  • Such experiments show that Africans are best adapted against whole body cooling. They maintain higher temperature during freezing condition. Europeans are the second. Aborigines and inuits are the worst and their body temperature falls much tower, thus threatend by frostbite. Their limbs become numb during night and the fire that they use during ninht often hurn their

Adaption to Nutritional Stress & Nutritional Adaptation

Introduction – The capacity of a species to change itself to suit its natural environment is called adaptation.

Nutrition availability in Humans

  • Availability of nutritionally valuable food varieties varies according to geographical & environmental factors of a locale. Diff societies at diff ecological niches → diff type of food ; quantity & quality variable
  • Also Humans can utilise only the part of the energy available & that too in forms of convertible human types of nutrients. Viz proteins, carbohydrates, lipids etc. Poor nutrition can reduce immunity, increase sensitivity to diseases, and inhibit physical & mental development 
  • Thus, it becomes important for human population to evolve their own adaptive strategies depending on their nutritional requirements & locally available nutrition.
  • Nutritional Adaptation adaptation has two dimensions Biological & cultural.

Biological Adaptation

  • The basic metabolic rate (BMR) appears to be inherently high in populations having a good quality diet as compared to poorly nourished people.
  • Newman after considering human bodily adjustment to nutrition concluded that some human populations have adapted to levels of intake that would be fatal to others. Ability to stay on less food may be more general. We are aware that most populations of the world have been subjected to repeated famines resulting in development of adaptation in the special way.
  • Lactose tolerance: It refers to difficulty in digesting lactose in milk. Chinese have a higher rate of lactose intolerance as their cultural practices do not include the use of milk from domestic animal. In India the problem is rare.
  • People living in high altitude permanently are small in size. It can be attributed to the scarcity of food. Small body size requires less energy. Thus in this context small body size is valuable for survival.

Cultural Adaptations

  • Pig feasts in different communities supplement the requirements of protein in the diet.
  • People try to fulfil their nutritional requirements by combining plants and animals foods. Both are complements to each other. For ex essential amino acids in plant and animal foods complement each other.
  • Certain communities exchange food products among themselves to meet their nutritional requirements. The trade b/w pygmy hunters of central Africa & Bantu agriculturist provides a unique example of protein-carbohydrate trade.
  • Herding societies (Pastoralists) practise limited form of agriculture to supplement their food with carbohydrate, fibres, vitamin, minerals etc.

Conclusion: Thus it is seen that biological adaptations are complemented by cultural adaptations and human can survive in all sorts of environment irrespective of availability of food..

Adaptation to Nutritional Stress

  1. Hunters & Gatherers – They are known to have fairly nutritious diet & generally are not inflicted by nutritional stress. Lee (1979) studied the !Kung & found their diet to be quite diverse & balanced.
  2. Agriculturists & Pastoralists – they depend on cultivated plants & domesticated animals. E.g Polynesians derive their energy content from coconuts, taro & chicken

However, spread of diseases & other natural calamities have disturbed the balance of these populations in terms of their survival capacity.

  1. Modern Societies – Till the 20th century, many such societies suffered from nutritional stress due to disruption of traditional diets & introduction of new food items. But with increase in food production due to advanced agriculture, & modern technology like fortification & irradiation of food, nutritional stresses have declined. However poorer sections continue to suffer from malnutrition. Lifestyle changes have also resulted in nutritional stresses even in affluent sections. Preference for junk food, absence of balanced diets, & substance abuse have been the chief causes.

Conclusion – In present day, there are enough technological & educational solutions to end malnutrition & food shortage. Given the political will, especially on the part of affluent nations, this is not a distant dream 

Additional Information : Curiosity Corner

  • Habituation immerising of finger in freezing water. -The biological basis of habituation is very simple. The part of the body which is experiencing cold immediately sends impulses to the brain. The impulses are recorded in the special sensory cells of our skin which are specialised for thermal sensation. Brain interprets the sensation and accordingly responses are sent by return signals to the affected part for vasoconstriction. If this circuit is pressed for too long, the return signals from brain weakens. Once the cold stimulus to sensory cell is removed, the return signals from brain also stops. Adaptation to extremity cooling is, thus, simple biological phenomenon.

Allen’s & Bergmann’s Rule for Human Population

In the nineteenth century, two biologists, Carl Bergmann (1814-1865) and Joel Asaph Allen (1838-1921), looked at the relationship between body size and climate in a wide range of mammals. They found that within species, there were predictable relationships between body form and proportions and temperature.

Bergmann’s rule (1847) focuses on body size. He found that the colder the climate, the larger the body. Why? Because as volume increases, surface area decreases as a proportion of the volume. This would decrease the rate of heat dissipation through the surface, which helps to maintain a higher core temperature.

Allen’s rule (1877) focuses on the appendages of the body. For example, limbs should be longer relative to body size in warmer climates because that would help to dissipate heat, whereas shorter limbs in colder climates would conserve body heat.

Body forms of peoples living in some extreme environments are consistent with the rules. If we look at the Inuit in the Arctic and Nilotic peoples from East Africa, we see that the stocky, short-limbed Inuit body seems to be structured to conserve heat, whereas the long- limbed Nilotic body is designed to dissipate heat (Figure). Looking at a broad range of populations, there is a general. trend among humans for larger body size and greater sitting height (that is, body length) to be associated with colder Climates, whereas relative spans (fingertip to finger length divided by height) tends to be greater in warmer temperatures. Here natural selection could have been responsible for the body changes.