Chapter 13

A round cross section of a long bone suggests that the bone will:

have equal strength in all directions.

superfoods

Cereal grains, such as rice, corn, and wheat, that make up a substantial portion of the human population's diet today.

periosteal reaction

Inflammatory response of a bone's outer covering due to bacterial infection or to trauma.

nonheme iron

Iron—found in lentils and beans—that is less efficiently absorbed by the body than is heme iron.

True or False? In the ancient world, dentistry was mostly nonexistent, and cavities grew until the teeth fell out or, in some instances, people with cavities died from secondary infections.

True

True or False? Tooth size is under stronger genetic control than is bone size, and as a result, tooth size is less affected by the environment.

True, and as a consequence, humans' teeth had much less room to grow, resulting in the remarkable increase in crowded and poorly occluded teeth

Humans shifted from _________ for their food to _____________ their food.

foraging, foraging

How did the increase in size and density of the population during the Holocene, especially when the population remained in place, affect people's health?

humans began to live in conditions crowded and unsanitary enough to support pathogens.

Porotic Hyperostosis and Cribra Orbitalia

(a) In porotic hyperostosis, which results from anemia, the cranial bones become porous as the marrow cavities expand from the increased production of red blood cells. (b) Anemia can also give the eye orbits a porous appearance, called cribra orbitalia.

The archaeological record suggests that farming began in southeastern Turkey by _________ yBP or so.

10,500 By 8,000 yBP, early agricultural communities had sprung up across a vast swath extending from the eastern side of the Mediterranean across an arch-shaped zone of grasslands and open woodlands known as the Fertile Crescent. Once domestication developed, within a short time villages sprang up; some of these villages developed into cities.

iron deficiency anemia

A condition in which the blood has insufficient iron; may be caused by diet, poor iron absorption, parasitic infection, and severe blood loss.

What is the best example of a negative affect of rapid population growth?

As towns and cities began to compete for increasingly limited resources (e.g., arable land for crops), organized warfare developed. Interpersonal violence has a long history in human evolution, going back at least to Neandertals, in the late Pleistocene. But the level of violence in pre-Holocene hominins was nothing compared with the organized warfare of early civilizations in southwest Asia, Central America, and South America or with the medieval wars in Europe, where up to thousands of people were killed. The consequences of environmental degradation, like those of extreme population growth, are well documented by historians and ecologists for recent human history. This degradation actually has a much more ancient origin, beginning with plant and animal domestication around 10,000 yBP. For much of the region surrounding the Mediterranean, especially the Levant, landscapes have been substantially transformed and degraded. Dense settlement based on agrarian economies has contributed to soil erosion, making it increasingly difficult to produce food. Around 6000 BC, a number of large towns in the eastern Mediterranean were abandoned, probably due to a period of climate drying. Contributing to the abandonment was human activity, however, such as overgrazing with goats, which resulted in damaging erosion. Likewise, the recent collapse of coastal ecosystems worldwide clearly had its start in overfishing—especially in that of large vertebrates (e.g., whales) and of shellfish—beginning thousands of years ago. one primary force behind the reduction in biodiversity is expanding human population size. He predicts that if left unchecked, the population will outstrip the arable land available to produce the plants and animals consumed by humans. Thus, the increased food supply that resulted from the agricultural revolution in the Holocene could, in the not-too-distant future, lead to a food crisis.

Neolithic

The late Pleistocene/early Holocene culture, during which humans domesticated plants and animals.

domestication

The process of converting wild animals or wild plants into forms that humans can care for and cultivate.

One of the most obvious ways of assessing the impact of nutritional change in the Holocene is by looking at the growth of _______ and of _____.

bones and teeth

Evidence shows that hunter-gatherers have quite ______ workloads. Anthropologists realized that workload depended highly on:

diverse; the local ecology and the kinds of foods being eaten. For example, in how they acquire plants and animals, people living in the tropics differ greatly from people living in the arctic.

Animals were domesticated around the world, beginning with _____ at about _______ yBP. Some 7,000-8,000 years later, goats, sheep, cattle, and pigs were domesticated. These animals were important in Asia and later Europe, but domesticated ______ were far more fundamental to the growing human populations' survival.

dogs, 15,000, plants

cribra orbitalia

pathological feature of spongy bone invading the eye socket that occurs in the interior upper surface of the eye sockets

the foods we eat and the manner in which they are prepared tremendously influence our ____________ ______________.

physical appearance. The relationship between food and morphology is well illustrated by the major anatomical changes throughout human evolution. As discussed in chapter 10, the massiveness of the late australopithecines' face and jaws was clearly linked to the hard foods those hominins ate, such as seeds. Generating the power to chew hard foods required large masticatory muscles (and their bony support). Thus, the well-developed sagittal crests of some later australopithecines—such as Australopithecus aethiopicus—are adaptations related to chewing. Over the course of human evolution following the australopithecines, the face and jaws have continuously reduced in size and robusticity, reflecting a general decrease in the demand placed on the jaws and teeth as culture became increasingly complex and foodstuffs changed.

Rice and other cereal grains are now aptly called:

superfoods

Archaeological evidence and genetic studies of domesticated plants indicate that prior to becoming agricultural at the end of the Pleistocene, people living in southwestern Asia began to intensively harvest the grains of ________ and _________ wild ancestors.

wheat's and barley's Within 1,000 or so years following this combined practice of exploiting wild grains and foraging, sometime around 11,500 yBP, people began to manipulate plants' growth cycles. This manipulation was probably based on the simple observation that some seeds falling to the ground grew into new plants.

True or False? Climate change will result in more rainforests as a result of warming temperatures.

False. Climate change will likely lead to desertification of areas that are now productive.

True or False? Treponematosis is associated with a venereal disease brought to the New World by Christopher Columbus.

False. This pathology predates Columbus in the US Southwest.

Archaeologists are learning that domesticated plants served as both a food staple and a source of drink, especially _________ drink.

alcoholic. In China, for example, chemical analysis of residue inside ceramic vessels shows that perhaps as early as 8,000 yBP grapes and rice were fermented for wine.

All domesticated plants have nutritional drawbacks. Because they are carbohydrates, they promote ______ _______, commonly known as tooth decay or "cavities"

dental caries

Deficiencies in dental _________ are one of the most important nonspecific stress indicators.

enamel

masticatory-functional

hypothesis states that change in skull form represents a response to decreased demands on the chewing muscles—temporalis and masseter—as people shifted from eating hard-textured wild foods to eating soft-textured agricultural foods, such as millet..

The pattern of bone changes in the New World prior to the late 1400s suggests a ___________ syphilis, one passed not by sexual contact but by casual contact, such as by a mother holding her child

nonvenereal

Temperature Changes and Plant Domestication

(a) Over the last 120,000 yBP, as this timeline shows, Earth's temperature has fluctuated substantially. Around 11,000 yBP, a rapid warming trend created new habitats favorable for plant domestication. (b) The first grains were the wild ancestors of the domesticated varieties we know today. The wild ancestor of maize (right) is teosinte (left). (c) Domestication began with humans' harvesting of wild plants using late Paleolithic technology, such as this tool, an antler handle with stone microblades inserted into it.

How did agriculture affect human living circumstances?

1) Agriculture (and associated population increase) resulted in population sedentism and crowding. Accumulation of waste and increased transmission of microbes owing to crowding provided the conditions conducive to the spread and maintenance of infectious disease. 2) Agricultural foods shifted nutrition from a generalized diet to one focused on carbohydrates and poorer-quality protein. 3) In most settings, agriculture caused a decline in workload/activity.

What are the most important forces shaping human biology today?

1) Global warming is altering the environment. If left unchecked, it potentially will threaten food production and have continued negative impacts on health. 2) Population increase is placing a burden on our resources and well-being. 3) Population increase and associated crowding leads to poor sanitation and enhances the spread of existing and newly emerging infectious diseases.

When, where, and why did agriculture first develop?

1) The Holocene epoch—the most recent 10,000 years—was not a static period in human evolution or in biological change generally. During this time, Homo sapiens dramatically altered their diets to include for the first time domesticated plants and domesticated animals. 2) The earliest agriculture occurred in the eastern Mediterranean (the Levant). It arose in at least 10-11 other centers independently around the world. 3) Plant and animal domestication may have arisen to feed the ever-increasing human population beginning in the Neolithic.

Are we still evolving?

1) There is abundant evidence of continued evolution in humans and other organisms. 2_ Little can be said about future evolution. If environmental circumstances (global warming, for example) continue in their predicted direction, almost certainly conditions eliciting evolutionary change will occur.

How did agriculture affect human biological change?

1) Wherever the shift from foraging to farming occurred, quality of diet declined owing to a decrease in the breadth of diet and a reduction in the nutritional quality of foods eaten. 2) Poorer-quality diets led to a decline in health as foragers became farmers. 3) The shift from hard foods to soft ones resulted in a generally shorter and rounder cranial vault, along with a smaller face and smaller jaws. The bone supporting the teeth reduced in size faster than the teeth reduced. As a result, humans now have many more orthodontic issues requiring the artificial straightening of teeth. 4) Decreased workload/activity resulted in a general tendency toward increased gracilization of the skeleton. 5) The decline in health did not affect human populations' reproductive performance worldwide. For much of human evolution, population size was likely well under 1 million, but it perhaps grew to several million by the close of the Pleistocene. Today, the human population exceeds 7 billion people.

dental caries

A disease process that creates demineralized areas in dental tissues, leading to cavities; demineralization is caused by acids produced by bacteria that metabolize carbohydrates in dental plaque.

treponematoses

A group of related diseases (venereal syphilis, yaws, endemic syphilis) caused by the bacteria Treponema, which causes pathological changes most often to the cranium and tibiae.

The Good and Bad of Agriculture

Advantages Support for larger numbers of people Creation of surplus food Long-term food storage, especially of grains Disadvantages: Increased demands on the environment (land degradation) Pollution Conflict between populations competing for the same lands Loss of wild species through overhunting Decline of biodiversity Health costs and quality-of-life implications

How are humans affecting the evolution of other organisms.

Bacteria associated with horrific infections have developed resistance to antibiotics, such as penicillin and tetracycline. Today, hospitals report that bacteria such as Staphylococcus aureus are almost always resistant to penicillin. The evolution of new, antibiotic-resistant strains of Mycobacterium tuberculosis is a big part of the dramatic rise in human deaths from this disease—more than 3 million people die per year. Other human-influenced evolution is also reported in a range of other organisms. For example, fish are evolving slower growth and thinner bodies owing to overfishing. Salmon males are under strong selection for smaller size, and they are returning to the sea earlier to increase their survival. These are but a few of the many examples of the pervasive evolution resulting from human presence and activity. Thus, the natural world is rapidly changing, in large part due to humans. These changes are anthropogenic.

True or False? Hunter-gatherers spend most of the day working very hard and have little leisure time.

False. Lee and DeVore's work, and that of others, showed that modern hunter-gatherers living in Africa have a lot of leisure time and spend relatively few hours of the day in the food quest.

True or False? Nutrition has no impact on infection.

False. Studies of living populations have shown nutrition and infection have a synergistic relationship: poor nutrition worsens the infection, and vice versa; essential nutrition is used to fight the infection and is taken away from the growth process. Despite such complications, anthropologists have found these indicators to be very informative about the history of stress both in individuals and in populations.

At least two factors probably brought about this agricultural revolution.

First, environments changed, bringing about new conditions—local climates and local ecologies—suited to the domestication of plants and of animals. Second, almost everywhere agriculture developed, human population increased at the same time. Domestication, especially of plants, produced more food per unit area of land than had hunting and gathering—more people could be fed from the same amount of land. In addition, agriculture provided food that could be stored for long periods

Why were agriculturists smaller than Huber-Gatherers

For some groups shorter height might have been the biological result of adopting agriculture, but for other groups it might have been an adaptation to reduced resources since smaller bodies require less food. However, all the human populations whose height decreased due to stress also experienced elevated infectious disease loads, anemia, malnutrition, and other factors indicating that a smaller body does not confer an adaptive advantage. These people were smaller but not healthier.

How do scientists know how hard or how easy a hunter gatherer's lifestyle was?

Highly physically active people's bones tend to be larger and more developed than those of not so physically active people. Borrowing from how engineers measure the strength of building materials—such as the "I" beam used in the construction of a bridge or of a house—physical anthropologists have developed a means for assessing the robusticity of bone cross sections. Based on the simple premise that material placed farther away from an axis running down the center of the bone is stronger than material placed closest to the axis, it has become possible to look at the degree of bone development and determine by empirical means how bone strength has changed over the course of human evolution to the present.

Labor, Lifestyle, and Adaptation in the Skeleton-- Hunter-Gatherers vs Agriculturalists

Hunter-Gatherers: Bones with higher second moments of area Larger, more robust bones More osteoarthritis Agriculturalists: Bones with lower second moments of area Smaller, less robust bones Less osteoarthritis

Probably the single most visible characteristic associated with the shift from foraging to farming is the:

Increase in population size. Called the Neolithic demographic transition, this shift from low birthrate to high birthrate resulted in a rapid increase in the world's population. The greater number of births was brought about by a reduced period of weaning. The availability of grains cooked into soft mushes and fed to infants made it possible to wean infants earlier in their lives. With earlier weaning, spacing between births reduced, and mothers were able to produce more offspring.

How did Agriculture affect Iron intake?

Iron—specifically, heme iron—enters the body easily through meat-eating since meat does not require processing in the stomach and since the amino acids from the digestion of meat promote iron absorption. Iron from plants—nonheme iron—is not as readily available because various substances in plants inhibit iron absorption (see the above discussion on corn). Citric acid found in various fruits, however, may promote iron absorption. Some authorities believe that iron deficiency is rarely caused by dietary stress and is more often related to nondietary factors. Parasitic infections, for example, are a primary cause of iron deficiency anemia in many regions of the globe. One such infection, hookworm disease, is caused when someone inhales or ingests hookworm larvae.

Was plant and animal domestication a one-time event, first occuring in one place and spreading globally, or did it evolve independently in many regions?

It started in 11 independent regions around the world. Out of these primary centers, the idea spread through a process of diffusion in some areas and through the movement of agricultural people in others. The process evolved slowly in some areas and fast in others. Eventually, every inhabitable continent except Australia saw the change.

If agriculture had such negative effects on health, how did it have an adaptive advantage over hunting-gathering?

One documented fact about the Holocene is that during this time human fertility greatly increased. That women gave birth to more babies was likely made possible by the reduced spacing out of births in agricultural groups. Simply, because women were settled and not spending time moving about the landscape, they could bear children more frequently. Therefore, a population with a reduced quality of life might still have very high fertility. Agriculture's positive side is that it provides both more calories per unit of land and the resources for population increase. And evolution dictates that organisms, including humans, engage in behaviors that increase the potential for and outcome of reproduction.

As towns and cities began to compete for increasingly limited resources:

Organized warfare developed

_________ has fed more people since its domestication than any other plant. It now accounts for half the food consumed by 1.7 billion people in the world whose diets include it and more than 20% of all calories consumed by humans today.

Rice

Different domesticated plants promote tooth decay at varying rates. ______ does not seem to cause it to the same extent as other domesticated plants. ______ causes it considerably.

Rice, Corn Once post-AD 800 populations in eastern North America had adopted corn agriculture, the frequency of their dental caries rose dramatically

Soft food and biological change

The shift to agriculture and the eating of softer foods resulted in biological changes to the face, jaws, and teeth of modern people. Although not universal, some tendencies characterized the skulls and teeth of hunter-gatherers and of agriculturalists. Hunter-Gatherers: Long cranial vault Large, robust mandible Large teeth Few malocclusions Much tooth wear Agriculturalists: Short skull Small, gracile mandible Small teeth Many malocclusions Little tooth wear

Besides treponematoses, what other infectious disease likely affected Holocene populations worldwide?

The skeletal indicators of tuberculosis are widespread in parts of the New World, of the Old World, and of Australia. Other modern diseases made possible by overcrowding include, but are not limited to, measles, mumps, cholera, smallpox, and influenza. Some of these diseases have an Old World origin, but the New World was hardly a disease-free paradise before their introduction.

True or False? Today, the high numbers of people with orthodontic problems—malocclusions ranging from simple overbite to very poorly aligned teeth—contrast sharply with the few such problems found in ancient hominins and throughout much of prehistory.

True. Malocclusion is a clearly negative result of humans' eating soft foods. A positive result is that our teeth have very little wear since eating soft foods places less stress on the chewing surfaces.

True or False? Bone size, shape, and density are affected by the stresses applied to the bones, but tooth number, shape, and size are primarily determined by genes.

True. Since earlier hominins did not undergo a wholesale shift to very mushy foods, evolution never had an "opportunity" to coordinate growth patterns of bone and teeth, which might have resulted in fewer negative consequences.

True or False Treponematosis is associated with an infectious disease that is passed between people with regular casual contact.

True. While this disease is related to sexually transmitted syphilis, this form is not transmitted sexually. Because it was contracted through casual contact, like a mother holding her child, it could have been spread more rapidly.

World Population

Until 10,000 yBP and the advent of agriculture, population remained constant, numbering less than 10 million people. After the agricultural revolution, however, population skyrocketed.

A misperception shared by the public and anthropologists is that with the appearance of essentially modern Homo sapiens in the late Pleistocene, human biological evolution ground to a halt. That is, many think that humans stopped evolving biologically once they became modern, in the Upper Paleolithic. Why are they wrong?

We are still undergoing all of the forces of evolution. Consider, do some people have more children than others. If there is a genetic cause for that then we are seeing natural selection. Do people with very different ancestries mate and have offspring? That's gene flow. Are some people having fewer offspring than others due to random chance? That's genetic drift. And all of us have several mutations.

Domesticated plants have nutritional value, of course, but they also present a range of negative nutritional consequences. For example:

corn is deficient in the amino acids lysine, isoleucine, and tryptophan; and a person who does not receive the right amount of even one amino acid will neither grow normally nor develop properly. In addition, vitamin B3 (niacin) in corn is bound chemically, and corn contains phytate, a chemical that binds with iron and hampers the body's iron absorption. Grains such as millet and wheat contain very little iron. Rice is deficient in protein and thus inhibits vitamin A activity.

Bone comparisons—from hunter-gatherers' to later agriculturalists' to modern peoples'—show a remarkable __________ in size.

decline. In general, the reduction in human bone size represents an overall evolutionary trend in the last 20,000 yBP. Thanks to the increasing tool complexity and greater cultural sophistication, the biological changes came about as physical strength was replaced with technology. Ruff's studies of human remains from around the world indicate that the reduced bone mass reflects about a 10% decrease in body weight during this period.

Millions of years have passed since the split between the nonhuman apes and Homo sapiens. Many of the evolutionary changes that have occurred are still relevant today and will likely be relevant to our future. What are some of the most important evolutionary changes that happened during the Neolithic period?

degradation of the environment including climate change development of technology increased importance of culture as an adaptive mechanism

Like most other technological innovations, agriculture spread by:

diffusion out of the primary centers, usually for very long distances. Corn, for example, spread from its primary center in Mexico (probably in the lowland tropics) to the American Southwest. Eventually, corn agriculture reached North America's Atlantic coast about 1,000 yBP. The spread occurred not through people carrying corn but through people describing their agricultural successes to neighbors, those neighbors telling their neighbors, and so forth, until the idea spread for thousands of miles over a series of generations.

______ temperatures and loss of ________ cover increase the breeding of mosquitoes, which in turn help spread pathogens such as those associated with malaria.

higher, land

Up until around 10,000 yBP or so—humans had acquired all their food through:

hunting and gathering They hunted, trapped, fished, and otherwise collected animals big and small, terrestrial and aquatic; and they collected a huge variety of plants. During the later Pleistocene, they began to intensively exploit fish and shellfish, in oceans, lakes, streams, and so on. In the final centuries of that epoch, at the key environmental transition from the Pleistocene's cold and dry climate to the Holocene's warm and wet climate, people began to control animals' and plants' growth cycles, through a process anthropologists call domestication. Eventually, humans replaced nearly all the wild animals and wild plants in their diets with domesticated animals and domesticated plants.

During the Holocene, especially in agricultural settings, crowding seems to have produced __________ and _____________. Any kind of injury to the outer surface of bone can cause a __________ ___________, or bone buildup, which is sometimes combined with an abnormal expansion of a bone's diameter. The reaction is caused by localized infection, such as from the so-called staph bacteria, Staphylococcus aureas. The infection essentially stimulates new bone growth, hence the swollen appearance

illnesses and injuries, periosteal reaction

Tooth crowding and malocclusion

improper fit of the upper and lower teeth, sometimes called underbite or overbite

What do dietary reconstructions of past societies by archaeologists and studies of living agrarian populations in different settings indicate?

that agriculturalists' diets tend to overemphasize one plant or a couple of them, such as rice in Asia, wheat in Europe and temperate Asia, corn in the Americas, and millet or sorghum in Africa. Thus, many groups, especially in the later Holocene, received poor nutrition from an increasingly narrow range of foods.

Some infections identified on bones from Holocene populations have a specific pattern that suggests the diseases that caused them. These bone deformation are caused by a group of diseases called ________________, which include venereal syphilis, nonvenereal (also called endemic) syphilis, and yaws.

treponematoses