bluuebunny/crossref_metadata_2025 huggingface dataset:
The Evolution of Cooperation in an Ecological Context : An Agent-Based Model
Authors: Pepper John W. , Smuts Barbara B.
Published: November 2020

The social and behavioral sciences have a long-standing interest in the factors that foster selfish (or individualistic) versus altruistic (or cooperative) behavior. Since the 1960s, evolutionary biologists have also devoted considerable attention to this issue. In the last 25 years, mathematical models (reviewed in Wilson and Sober 1994) have shown that, under particular demographic conditions, natural selection can favor traits that benefit group members as a whole, even when the bearers of those traits experience reduced reproductive success relative to other members of their group. This process, often referred to as "trait group selection" (D. S. Wilson 1975) can occur when the population consists of numerous, relatively small "trait groups," defined as collections of individuals who influence one another's fitness as a result of the trait in question. For example, consider a cooperative trait such as alarm calling, which benefits only individuals near the alarm caller. A trait group would include all individuals whose fitness depends on whether or not a given individual gives an alarm call. If the cooperative trait confers sufficiently large reproductive benefits on the average group member, it can spread. This is because trait groups that happen to include a large proportion of cooperators will send out many more offspring into the population as a whole than will groups containing few, or no cooperators. Thus, even though noncooperators out reproduce cooperators within trait groups (because they experience the benefits of the presence of cooperators without incurring the costs), this advantage can be offset by differences in rates of reproduction between trait groups. Numerous models of group selection (Wilson and Sober 1994) show that whether cooperative traits can spread depends on the relative magnitude of fitness effects at these two levels of selection (within and between trait groups). In addition, there is a growing body of empirical evidence for the operation of group selection in nature (e.g., Colwell 1981; Breden and Wade 1989; Bourke and Pranks 1995; Stevens et al. 1995; Seeley 1996; Miralles et al. 1997; Brookfield 1998) and under experimental conditions (reviewed in Goodnight and Stevens 1997).
Be There Then : A Modeling Approach to Settlement Determinants and Spatial Efficiency Among Late Ancestral Pueblo Populations of the Mesa Verde Region, U.S. Southwest
Authors: Kohler Timothy A. , Kresl James
Published: November 2020

The archaeology of southwestern Colorado from A.D. 900 to 1300 presents a number of interesting problems, including population aggregation and abandonment. We report on an on-going project, implemented using the modeling libraries of Swarm, to model the settlement dynamics of this region, treating households as agents. Landscape detail includes an annual model of paleoproductivity, soils, vegetation, elevation, and water resource type and location. Individuals within households reproduce and die; households farm, relocate, and die; children within households marry and form new households. Household location is responsive to changing productivity (depleted in some scenarios) and, in some scenarios, water resources. Comparison of simulated settlement with the archaeological record highlights changes in the settlement and farming strategies between Pueblo II and Pueblo III times, including the increasing importance of water and sediment-control, and other alternatives to extensive dry farming. Our results suggest that degradation of the dry-farming niche may have contributed to these changes. This project began with a desire to understand why, during certain times in prehistory, most Pueblo peoples lived in relatively compact villages, while at other times, they lived in dispersed hamlets (Cordell et al. 1994). Our approach to this problem is based on a thread of accumulating research begun in the early 1980s when a dissertation from the University of Arizona by Barney Burns (1983) showed that it was possible to retrodict potential prehistoric maize yields in a portion of Southwest Colorado by combining prehistoric tree-ring records with historic crop-production records of local farmers. A few years later, Kohler et al. (1986; see also Orcutt et al. 1990) simulated agricultural catchment size and shape in a northern portion of the present study area, to arrive at the suggestion that avoiding violent confrontation over access to superior agricultural land was a major force in forming the villages that appeared in this area in the late A.D. 700s and again in the mid-800s.
The Political Impact of Marriage in a Virtual Polynesian Society
Authors: Small Cathy A.
Published: November 2020

Computer modeling, because it abstracts cultural processes and quantifies social variables, is often seen as contradictory to the rich qualitative rendering of culture that ethnography offers. In this chapter, I attempt to show that computer modeling and ethnography can go hand-in-glove. Using an agent-based model of Polynesian social dynamics, I demonstrate how simulation can aid an ethnographer in better understanding the ethnographic record, in this case, the relationship between marriage customs and stratification in Tonga. In a more abstract sense, I suggest that agent-based models, simulated over time, can elucidate the relationship between individual or group (human) decisions and the social structures which both result from and constrain those decisions. In so doing, simulation can provide new insights into the ethnographic record, edifying structural relationships, helping to generate explanations for phenomena, or pointing to the most fruitful places to go in the ethnographic record for new insights. Marriage in Polynesia both reflects and creates political fortunes by affecting the kinship and exchange relationships among lines, the pattern of chiefly alliances, and the transmission of rank over generations (Sahlins 1958; Biersack 1982; Huntsman 1975; Goldman 1970; Linnekin 1990; Shore 1976; Kaeppler 1971; Gailey 1987; Valeri 1972). The significance of marriage preferences or restrictions in the political process is often understood by historical example, that is by the advantages that accrued to particular lines or chiefs who enacted particular types of marriages. Thus, for instance, to understand Tongan "kitetama" marriage (where a man marries his mother's brother's daughter), Bott (1982:77) generalizes from particular examples of kitetama marriages, suggesting that this marriage custom strengthens a man's tie with his mother's people and, over time, serves to reinforce kinship and alliance ties over generations between a brother's and sister's lines. What we cannot tell from such an analysis is if this marriage form has any implications for the development and evolution of chiefdoms as a whole.
Island Biogeography in the Sea of Cortés II
Authors: Case Ted J. , Cody Martin L. , Ezcurra Exequiel
Published: November 2020

This updated and expanded A New Island Biogeography of the Sea of Cortés, first published nearly 20 years ago, integrates new and broader studies encompassing more taxa and more complete island coverage. The present synthesis provides a basis for further research and exploration in upcoming years of the biologically fascinating Sea of Cortés region. The Gulf region is increasingly being exploited, for its natural resources by way of marine fisheries, and for its stunning natural beauty by way of a burgeoning tourism industry. Further, the region's human population is increasing apace. It is appropriate, therefore, that this volume discusses these evolving circumstances, and the efforts of the Mexican government to regulate and manage them. The new Biogeography includes a section on the conservation issues in the Sea of Cortés, past accomplishments and conservation needs as yet outstanding. This book should be of strong interest to conservation biologists, ecologists, and evolutionary biologists more generally.
The Biological Environment of Lakes
Authors: Cohen Andrew S.
Published: November 2020

Biological processes form the basis for a rich source of information for paleolimnologists. Populations of organisms are sensitive to variations in their external environment, and this sensitivity can be recorded as proportional changes in fossil abundances, evolutionary change, or extinction. Variations in lake temperature or water chemistry below the threshold of geochemical archives would normally go unrecorded in lake deposits were it not for fossils capable of registering these changes. Biotic systems are also the most complex components of lake systems, involving numerous species, their interactions with each other, and with their external environment. As a result, the interpretation of lacustrine fossil records is rarely straightforward, and must be viewed in the context of complex ecological dynamics, unfolding against a background of environmental and evolutionary change. In this chapter we will consider the biotic structure of lakes from a paleolimnological perspective, focusing on organisms and ecological interactions likely to be preserved in a lake’s fossil record. A transect running downslope and offshore from the shoreline will almost invariably reveal a change in habitat and lake organisms (see figure 3.2). In the shallow, littoral zone, high rates of photosynthesis can normally be supported, as light is not a limiting factor for growth. A high diversity of autotrophic and heterotrophic (consuming) organisms is encountered here. Near the shoreline, a fringe of emergent or submerged macrophytes is often present, either attached to the substrate, or floating nearshore. These plants form a substrate for many attached (epiphytic) or crawling organisms. On wave-swept, rocky, or sandy coasts macrophytes may be absent, but abundant algae or photosynthetic bacteria may be present, attached to rock surfaces (epilithic), or adhering to sand grains. In the sublittoral zone, light penetration is reduced, and large macrophytic plants are absent, but lower levels of benthic primary production may persist from algal or bacterial growth. Although algae are frequently found below the photic zone, because of circulation or settling, they are not photosynthesizing under such conditions. In the aphotic, profundal zone food resources are provided exclusively through secondary productivity, consumption of settling detritus (or the organisms that feed on such detritus), and microbial food resources.
The Scientific Issues Associated with El Niño 1997-1998
Authors: Changnon Stanley A.
Published: November 2020

The development of a record large El Niño event and its ensuing major effects on the nation’s weather over an eight-month period created a scientific event of major proportions. Key science-related questions that developed during El Niño 97-98 included: • Who was issuing El Niño -based climate predictions and for what conditions? • What kinds of weather conditions were caused by El Niño ? • What types of impacts were being projected as a result of the El Niño weather? • How accurate and useful were the El Niño -based climate predictions? • How accurate were the oceanic predictions relating to the development, intensification, and dissipation of El Niño 97-98? • Was the record-size event caused by global warming? Answers to such questions define the scientific information transmitted to the public, the scientific community, and decision makers during the event. This assessment focused on the scientific information that appeared during the period from May 1997 to June 1998, but it also included information that appeared a few months after El Niño ended (i.e., into early 1999), since these issuances reflect the thoughts and findings generated by scientists during the event. Topics assessed included: (1) the sources of the scientific information, (2) how the information was interpreted and by whom, (3) the accuracy of what was presented by different sources, and (4) the scientific issues that emerged, some of which involved disagreements and/or caused potential confusion for decision makers and the public. Most of the information assessed herein was extracted from the Internet, newspaper stories, and scientific documents published during the June 1997-June 1998 period. What scientific information relating to El Niño 97-98 was measured? We assessed the presentations of the physical descriptions of El Niño and ENSO and the predictions, the predictions based on El Niño conditions of future seasonal climate conditions as well as the resulting physical and societal impacts, the verifications of the seasonal climate predictions, and other, more general information about El Niño 97-98 that emerged, such as its magnitude in comparison to past El Niño events and its possible relationship to other conditions, such as global warming.
Spatial Evolutionary Modeling
Authors: Krzanowski Roman M. , Raper Jonathan
Published: November 2020

Evolutionary models (e.g., genetic algorithms, artificial life), explored in other fields for the past two decades, are now emerging as an important new tool in GIS for a number of reasons. First, they are highly appropriate for modeling geographic phenomena. Secondly, geographical problems are often spatially separate (broken down into local or regional problems) and evolutionary algorithms can exploit this structure. Finally, the ability to store, manipulate, and visualize spatial data has increased to the point that space-time-attribute databases can be easily handled.
Vegetation of the Shortgrass Steppe
Authors: Lauenroth William K.
Published: November 2020

Two species are most characteristic of the vegetation of the shortgrass steppe: Bouteloua gracilis and Buchloë dactyloides. Both are perennial C4 grasses and are informally called shortgrasses. Technically, this means that they are both culmless grasses in which, for the majority of the tillers, the apical meristem remains at or near the soil surface and is protected by a succession of enveloping leaf sheaths for the entire growing season (Dahl, 1995; Dahl and Hyder, 1977). This morphological characteristic makes these two grasses well adapted to withstand turnover of aboveground organs as a result of intraseasonal drought or grazing by large generalist herbivores such as cattle. The current dominance of B. gracilis and B. dactyloides in the region is clear, but their ecological status has been controversial. In the earliest assessment of the vegetation of the Great Plains, Shantz and Zon (1924) mapped the western portion of the grasslands from the Canadian border to the panhandle of Texas as shortgrass or plains grassland, with B. gracilis as the characteristic species. However, Weaver and Clements ( 1938) argued t hat it h ad b een proved t hat Shantz a nd Zon’s shortgrass plains was not a climax plant community, but rather a disclimax as a result of overgrazing by livestock. Although these two views persist today, a 1964 map of the potential natural vegetation of the United States presented an alternative interpretation and a compromise between the views of Shantz and Zon (1924) and Weaver and Clements (1938). Küchler (1964) divided the large shortgrass area into a northern portion that is consistent with Weaver and Clements’s mixed prairie and a southern portion in which the potential vegetation is dominated by shortgrasses. Our definition of the shortgrass steppe is identical to Küchler’s (1964) Bouteloua–Buchloë vegetation type, except along the northern border. His Bouteloua–Buchloë type extends into the southeastern corner of Wyoming and the panhandle of Nebraska, but we draw the boundary between the shortgrass steppe and the northern mixed prairie at the Colorado–Wyoming border because of the sharp elevation gradient between the Colorado Piedmont and the High Plains that occurs at approximately the Colorado–Wyoming border, and the associated changes in both the environment and the vegetation (Lauenroth and Milchunas, 1992).
Attitudes and Technological Change
Authors: Lienhard John H.
Published: November 2020

We look into the mirror of our machines, but what do we really see when we look in that mirror? How does change occur in the context of the mirror? The mirror turns out to be a strange reflector. We do not see ourselves when we first look at a new machine because there is a time lag in the reflection. If you are a baby boomer or older, remember the first time you saw a computer. You felt neither need nor empathy for it. We cannot need what we have never experienced; yet that first glimpse initiated a long process. You have friends who still jitter about this new medium, wondering whether to accept the change it will bring into their lives or to keep dodging it. The need for transformation lies at our biological core, but we fear change nonetheless. The first computers I ever used were so large that they filled rooms, and we had to speak to them with punched cards. The simplest conversation could stretch into weeks. We would submit three-inch decks of cards, wait twenty-four hours, and be handed a five-hundred-page sheaf of nonsense output because a do-loop went mad when we misplaced a period. During the 1960s we began to compute things that had been beyond us a few years before; but even as we did we grew desperately frustrated. All we talked about was increasing the speed of calculation, but what we really needed was a more accurate mirror of our human nature. We finally began speaking directly to computers with keyboards during the 1970s. Then we realized we could compose text on the computer and print it out. Since the computer took no responsibility for organizing the text, we began to demand that word-processing logic be built into the computer. With the early 1980s, commercial software came on the market—canned sets of commands we could call up from the keyboard. Software now processed our words and laid our numbers out in spreadsheets. New programming languages removed more and more of the burden of speaking in the language of the machine.
Systems, Design, and Production
Authors: Lienhard John H.
Published: November 2020

No technology can be reduced to one invention or even to a cluster of inventions. The smallest component of any device, something so small as a screw, represents a long train of invention. Somebody conceived of a lever, someone else thought of a ramp, another person dreamed up a circular staircase. The simple screw thread merges all of those ideas, and it followed all of them. A contrivance made of more than one part is a system woven from those parts. Take a pair of scissors. It consists of just three correlated members—two blades with handles on one end and the bolt that holds them together. Each part represents a skein of invention, and the whole is a device with an efficacy that we would normally not see in the parts alone. System is a word that takes on new overtones in the modern engineering vocabulary. Yet the modern sense of the word is no different from the dictionary definition, “an assemblage with correlated members.” As machines become more complex, however, their systemic characters become increasingly important in the processes of conceiving, designing, and producing them. But the systemic nature of technology does not end with the particular device. Think for a minute about automobiles. An automobile engine is a large, complex system in itself, but it cannot be designed in isolation from the rest of the car. The engine, radiator, transmission, brakes, airconditioning, suspension, and much more all act in concert to get you to work or to play. And the systemic character does not stop there. The automobile interacts with life around it. Questions of service, noise, air pollution, parking, and pedestrian safety all come to rest on the shoulders of automobile makers. That particular assemblage of correlated members reaches even beyond the automobile and its immediate infrastructure. The finished automobile reshapes the society in which it moves. The layout of cities, the design of homes, and even the scaling of the nuclear family have been shaped to this exceedingly complex technology, and that process of change continues still.
Reasonable Use
Authors: Cumbler John T.
Published: November 2020

This book is a study of the impact of industrialization and urbanization on the environment of New England in general and the Connecticut River Valley in particular, and of the varied public responses the impact engendered. The narrative engages the reader with biographical vignettes woven into the larger narrative and crosses several historical fields by combining industrial, urban, environmental, legal, and political history.
Industrial Waste, Germs, and Pollution The Battle over Pollution
Authors: Cumbler John T.
Published: November 2020

In 1905, the state board of health for Connecticut looked back over the last half century and noted the tremendous change that had occurred. In the first half of the nineteenth century, “all the towns and cities in Connecticut were very rural in character, and nowhere were populations so dense from overcrowding as to affect the public health. Hence there was no conspicuous disparity in the salubrity of different towns.” As Connecticut industrialized and urbanized, disparity in the salubrity of different parts of the state increased. It became “an accepted fact, sustained by careful observation, that the death-rate was always higher in cities than in the country.” Although the pure past to which the Connecticut State Board of Health alluded may not have been as pure and healthful as it assumed, nonetheless, the board was correct in noting the increase in mortality in the industrial towns and cities that grew up over the century. Growing awareness of the “effect of environment and employment upon the prevalence o f . . . disease” created momentum for public action. The vision of an activist state promoting public health and protecting the citizens, particularly the “weak” and “poor,” from the vagaries of the market—whether those were represented by “foul” water or depleted resources—increasingly found support among other reformers. The urban industrial setting that made Connecticut’s cities so unhealthy also generated concerns overworking children, long working hours for women in the paid labor force, industrial diseases, and overcrowded tenements. Like the antipollution reformers, those who were concerned over these conditions increasingly looked to the state to legislate remedies. Laws that limited women’s working hours and child labor and that controlled the conditions of tenements found favorable hearings among legislatures attuned to an electorate demanding reform of the conditions they found in their daily lives. Environmental reformers—both public health activists and supporters of protection for fish—were important voices in this rising chorus that favored a more active state. The momentum for public action began in Massachusetts, the most industrialized and urbanized New England state, and spread to the other states of the region and ultimately to the entire nation.
New England, the Nation, and Us
Authors: Cumbler John T.
Published: November 2020

Sylvester Judd died in 1860 at seventy years of age, just before he completed his history of Hadley, Massachusetts. Judd had lived through the transformation of his community from a small rural village where people fished massive runs of salmon and shad each spring, to an industrial center seated on the banks of a polluted river. One of his motivations for writing his history was to capture that fast-disappearing older world. It was a world where lawyers, shopkeepers, journalists, and farmers (and Judd had been three of those four) knew how to cut timber, kill and clean a turkey, catch fish, butcher a pig, tend a garden, work an orchard, and make cider. By the time of Judd’s death, wood was sold already cut into cordwood or milled to clapboards, meat was butchered at the abattoir, and cloth was woven in mills. It was a world that could not be brought back through his history, but one that Judd hoped through his history might at least be remembered. On July 24, 1882, when Theodore Lyman went before the people of his district to run for Congress, he reminded them that when he was a boy (then, Judd was in his fifties), the region’s industry had already begun to grow, although many of the state’s residents were still rural farmers. Yet by the time Lyman ran for Congress, a majority of the people of Massachusetts found their homes and their jobs in towns and cities. The world that Judd saw fading in the 1850s was indeed a thing of memory for some of those listening to Lyman in 1882. New England of the 1880s was a place, as Lyman noted, of “manufacturing towns with . . . sickly smells.” Yet without this progress, according to him, New England would have remained a place of “a few grist-mills here and there and houses whose occupants raised such crops as they could from the scanty soil.” If, by 1882, the people of New England had lost their more direct contact with the resources of nature, for many, the romanticized memory of that intimacy lingered on.
Laodicea
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

Ancient Laodicea, once a thriving city, now lies in ruins, awaiting a more thorough excavation than it has so far received. Overshadowed by the more spectacular nearby site of Hierapolis (Pamukkale), Laodicea receives the occasional busload of tourists who stop to view the remains of this city that the book of Revelation imagined as having boasted, “I am rich, I have prospered, and I need nothing” (3:17). Laodicea is south of the modern village of Goncalï and north of the village of Eskihisar. The site is located on a plateau between two small rivers that are tributaries of the Lycus River. The Asopus River runs along the western part of the ancient city, while the Caprus River runs along the east. To visit the site, take the road from Denizli that leads to Pamukkale. Two different roads from the Denizli-Pamukkale highway lead to Laodicea, both of which are on the left and marked with a sign indicating the way to Laodicea. Laodicea is situated 10 miles from Colossae and 6 miles from Hierapolis. This area was a part of the region of Phrygia, although it was sometimes considered a part of Lydia or Caria. Pliny the Elder claims that Laodicea was built on the site of an earlier settlement known as Diospolis and later as Rhoas (Natural History 5.105). Because of its location near the Lycus River, the city was known as Laodicea ad Lycum in order to differentiate it from several other cities named Laodicea. Of particular importance to the commercial success of the city was its position at the junction of two roads—one that ran from the Aegean coast near Ephesus through the Meander River valley and on to the Euphrates, and another that ran from Pergamum to Sardis and then to Perga and Attalia (modern Antalya). Antiochus II, the Seleucid king (r. 261–246 B.C.E.), founded the city during the middle of the 3rd century B.C.E. He named the city in honor of his wife Laodice, whom he later divorced. After the Romans, with the aid of the Pergamene kingdom, defeated Antiochus III at Magnesia in 189 B.C.E., Laodicea came under the control of Pergamum.
Spatial Scale and Species Diversity: Building Species–Area Curves from Species Incidence
Authors: Lennon Jack J. , Kunin William Edward
Published: November 2020

This chapter is largely focused on the species–area relationship (SAR), although it may not seem so for much of the time. Bear with us; we will get there in the end. Our aim is to provide insights into how the relationship works, and how it is built. This leads us to take a rather reductionist approach, and to break down the SAR into its component parts. We will spend a substantial section of this chapter examining these pieces and their properties. We will then explore the logic by which the parts are reassembled, and will explore how biological and biogeographical properties of a system may affect the SAR. Before attempting this feat, however, we should begin with a brief discussion of the SAR itself, to explain why it is worth making such a fuss over. The SAR is, after all, only a simple graph: a plot of the number of species found in a sample as a function of the area sampled. Ecologists being an argumentative lot, we cannot even all agree on what this plot should look like; Gleason (1922, see also Williams 1964) argued that the absolute number of species should be plotted as a function of the logarithm of area, whereas Arrhenius (1921, see also Preston 1960) suggested that both species and area should be plotted logarithmically. Connor and McCoy (1979) found cases that fit both models, and two others besides (log species by untransformed area, and neither variable transformed). However it’s plotted, the SAR is not even a particularly attractive or elegant graph—at its best (!) it is simply a straight diagonal line within a tight scatter of datapoints on a rectangular plot. Hardly something to set the pulse racing. Yet the SAR is exciting stuff; that simple line encapsulates a great deal of information about the diversity of biological systems across a wide range of scales.
Toward a Unified Framework in Biodiversity Studies
Authors: Gosz James R. , Perevolotsky Avi
Published: November 2020

Biodiversity has been defined as the “full variety of life on Earth” (Takacs 1996). Because biodiversity refers to a fundamental property of ecological systems, it continues to develop as a scientific frontier for exploration and discovery. Ecological systems are a mixture, or diversity, of living and nonliving entities interconnected by a web of interactions. Biodiversity is a concept used to describe the number, variety, and organization of entities in the biosphere, or a unit of the biosphere, and their relationships to each other (Gaston 1996). More importantly, biodiversity includes consideration of processes that create and maintain variation in ecological systems (Groombridge 1992). Therefore, biodiversity is not simply about entities and taxonomy. Rather, biodiversity is concerned with the diversity of species within communities, the range of ecological processes within ecosystems, and the diversity of ecosystem processes across landscape mosaics (Heywood 1994, Levin 1997). A similar perspective on biodiversity is provided by Noss (1990), who applies the concept over hierarchical levels of organization ranging from the gene to the entire biosphere, and recognizes compositional, structural, and functional approaches to biodiversity. In contrast to this broad and comprehensive scope of biodiversity suggested above, researchers and conservationists often employ a narrow definition of biodiversity shaped by their values, interests, and goals. A more precise and more widely recognized interpretation of the scope of biodiversity is required in order to promote scientific research and to develop management programs (Christensen et al. 1996). The objective of this chapter is to build on the comprehensive framework for biodiversity proposed in the introduction (chapter 1, fig.1.1) and combine it with additional insights from the other chapters. The initial framework recognizes biodiversity to include four components, and one complex output. The components are the roster of entities, the number of each kind of entity, the nature and degree of difference between the entities, and the spatial or functional organization of the entities. The outcome is the effect of biodiversity on ecosystem processes. This framework enables us to (1) map, in a more unified way, the present achievements of research in the field of biodiversity, (2) understand the complexity of biodiversity, and (3) advance the scientific basis for biodiversity management.
Population Cycles of the Larch Budmoth in Switzerland
Authors: Turchin Peter , Briggs Cheryl J.
Published: November 2020

The population dynamics of the larch budmoth (LBM), Zeiraphera diniana, in the Swiss Alps are perhaps the best example of periodic oscillations in ecology (figure 7.1). These oscillations are characterized by a remarkably regular periodicity, and by an enormous range of densities experienced during a typical cycle (about 100,000-fold difference between peak and trough numbers). Furthermore, nonlinear time series analysis of LBM data (e.g., Turchin 1990, Turchin and Taylor 1992) indicates that LBM oscillations are definitely generated by a second-order dynamical process (in other words, there is a strong delayed density dependence—see also chapter 1). Analysis of time series data on LBM dynamics from five valleys in the Alps suggests that around 90% of variance in Rt is explained by the phenomenological time series model employing lagged LBM densities, R, =f(Ni-1,Ni-2,) (Turchin 2002). As discussed in the influential review by Baltensweiler and Fischlin (1988) about a decade ago, ecological theory suggests a number of candidate mechanisms that can produce the type of dynamics observed in the LBM (see also chapter 1). Baltensweiler and Fischlin concluded that changes in food quality induced by previous budmoth feeding was the most plausible explanation for the population cycles. During the last decade, the issue of larch budmoth oscillations was periodically revisited by various population ecologists looking for general insights about insect population cycles (e.g., Royama 1977, Bowers et al. 1993, Ginzburg and Taneyhill 1994, Den Boer and Reddingius 1996, Hunter and Dwyer 1998, Berryman 1999). These authors generally concurred with the view that budmoth cycles are driven by the interaction with food quality. A recent reanalysis of the rich data set on budmoth population ecology collected by Swiss researchers over a period of several decades, however, suggested that the role of parasitism is underappreciated (Turchin et al. 2002). Before focusing on the roles of food quality and parasitism in LBM dynamics, we briefly review the status of other hypotheses that were discussed in the literature on LBM cycles. First, the natural history of the LBM-larch system is such that food quantity is an unlikely factor to explain LBM oscillations.
Cell Migration
Authors: Saltzman W. Mark
Published: November 2020

Cell migration is crucial to the life of unicellular and multicellular organisms. Unicellular organisms migrate to find food and avoid predators; this migration can occur by swimming through a fluid, which is achieved by flagellar or ciliary beating (exemplified by E. coli or Paramecium, respectively), or crawling along a surface (as in amoebae). In multicellular organisms, migration of a particular cell population is often a component of complex multicellular behaviors including tumor invasion and metastasis, embryogenesis, angiogenesis, and immune responses. In both cases, the speed and pattern of migration are determined by the nature of the cell and by chemicals (both soluble and surface-bound) in the environment. Since cell migration is critical in the formation or regeneration of tissues, a clearer understanding of the dynamics of cell migration would greatly enhance our ability to design materials and processes for tissue engineering. Cell migration is a fundamental mechanism for forming of structures within developing embryos. Accordingly, the migration of cells during embryogenesis is under exquisite control; development of tissue structure and cell migration are interdependent. Chapter 3 discussed limb regeneration in salamanders, a process in which positional gradients of cell adhesion influence cell migration and, ultimately, tissue structure. Similarly, the rate and migration of myogenic cells from the somitic mesoderm is influenced by the presence of local signals in the form of diffusible factors and extracellular matrix composition. These local signals are also produced by cells, with the result that cells throughout the developing limb (which are present in a particular arrangement or tissue structure) control and coordinate the migration of myogenic cells by secretion of activating factors and expression or organization of extracellular matrix molecules. A better understanding of the mechanisms underlying cell migration in the embryo, and the strategies that nature uses to control migration, will almost certainly provide inspiration for tissue engineering. Cell migration underlies many important physiological functions in adults. For example, the immune system, with its widely dispersed ensemble of B and T cells, relies heavily on the coordinated migration of individual cells to patrol the body and to provide opportunities for cell–cell interaction.
Delivery of Molecular Agents in Tissue Engineering
Authors: Saltzman W. Mark
Published: November 2020

The previous chapter provided some examples of tissue engineering, in which cells that were isolated and engineered outside of the body are introduced into a patient by direct injection of a cell suspension, typically into the circulatory system. But the field of tissue engineering also points to treatments that are conceptually different from variations on cell transfusion technology; tissue engineering promises the regrowth of adult tissue structure through application of engineered cells and synthetic materials. In support of this broad claim, the field of tissue engineering can point to some initial successes. For example, synthetic materials are now available that accelerate healing of burns and skin ulcers. In addition, in vitro cell culture methods now allow the amplification of a patient’s own cells for cartilage repair or bone marrow transplantation. But major obstacles to the widespread application of tissue engineering remain. Tissue engineers have not yet learned how to reproduce complex tissue architectures, such as vascular networks, which are essential for the normal function of many tissues. In fact, the tissue engineering concepts that have been demonstrated in the laboratory to date involve arrangements of cells and materials into precursor tissues (or neotissues) that develop according to natural processes that are already present within the cells or the materials at the time of implantation. These methods may be suitable for production of some tissues in which either the structure is relatively homogeneous (such as cartilage, in which a tissue structure can reform after the implantation of chondrocytes into a tissue defect) or the structure develops naturally (such as in some tissue-engineered skin, in which the stratified epithelium develops naturally by culturing at an air–liquid interface). The engineering of many tissue structures—such as the branching architectures found in many tissues or the intricate network architecture of the nervous system—will probably require methods for introducing and changing molecular signals during the process of neo-tissue development. For example, it is well known that chemical gradients of factors known as morphogens induce the formation of structures during development; some of the attributes of morphogens were introduced in Chapter 3.
Digging to China
Authors: Wilshire Howard G. , Hazlett Richard W. , Nielson Jane E.
Published: November 2020

Americans like to buy things and own them—barbecues and refrigerators, computers and iPods, cars and bikes, boats and even private planes. Some folks make their appliances last a long time, but manufacturers rely on most people to buy new ones every five years or so. The few critics of our system sometimes charge that items from appliances and vehicles are designed to break down relatively quickly, to prod consumption along. Walking through a showroom or past shop windows, how many people stop to wonder where all the stuff comes from or what happens there? Here is the short answer: Nearly everything you use every day is based on minerals mined somewhere, often leaving behind disfigured land and a toxic mess. Materials still mined in the western United States include metals, particularly gold, iron, copper, zinc, and molybdenum—plus gypsum, borates, and other salts, and most cement ingredients. Mining is the prow of America’s consumer-propelled ship. Its whole purpose is to dig up resources for transformation to consumer goods. But the resources are nonrenewable, so mining progressively eliminates and eventually exhausts them. The processes of exploring for and exploiting mineral deposits consume vast resources also, especially water and energy. Natural processes spread mine pollution into water, soil, and air, at times killing all life in creeks, streams, and reservoirs. Geographer Lewis Mumford once estimated that “Mining’s effects on the earth are now on the same scale as hugely destructive natural forces.” He guessed the minimum amount of material moved by global mining operations at 28 billion tons in 1963—nearly twice the sediment all the world’s rivers carry annually. Determining just how much land may be affected by mine wastes, and how much farther the damage might spread, is more dif- cult. The massive scale of today’s mining operations dwarfs Mumford’s figure. The dominant U.S. mining law offers wide swaths of U.S. public lands to any and all comers, whether foreign or domestic (box 4.1).
No Habitat but Our Own
Authors: Wilshire Howard G. , Hazlett Richard W. , Nielson Jane E.
Published: November 2020

Americans tend to think of the western United States as open spaces and the east coast as urban and crowded. After all, the northeast corridor from Washington, DC to Boston, Massachusetts, exempli- es the modern “mega-conurbations” of cultural historian Lewis Mumford—”nearly unbroken belt[s] of residential and commercial development, dotted with isolated parklands but little actual countryside.” Ironically, the eastern urban centers melded together in imitation of Los Angeles, California, that haphazard collection of zoning-de- ant industrial-residential-commercial melanges. By now, Los Angeles’s cement-and-asphalt environment has become the very model of a modern human habitat and the nation’s poster child for suburban sprawl. In an attempt to emulate its glittery lifestyle, every prosperous American town has snaked strip developments out along major highways, spraying cheap commercial-residential urban–suburban developments in all directions. Supported and encouraged by enormous public investment in roads, highways, and other infrastructure, the sprawl constantly expands until it displaces all other land uses and human habitat becomes the dominant or only habitat. We seem to have little concept that clean environments, and clean air and water in particular, support the physical, mental, and economic health of human societies (see chapter 1). This is why environmental guru Paul Hawken and co-authors termed them “natural capital.” Sprawling urban–suburban habitats are not very healthy because they foul the air and make numerous contributions to water pollution. Developments are dominated by gas-belching automobiles, gas stations with leaky underground storage tanks, and asphalt roads and parking lots. Residential suburbs shed megatons of lawn fertilizers and pesticides into local streams and lakes. All these relatively uncontrolled chemical releases make cities and suburbs into sources of land, water, and air pollution, which damage both human health and livelihoods. Urban wastes come back to haunt us through our air and water and also come floating onto our beaches. Urban and suburban areas depend on nonurban areas for food, clean water and air, and raw and manufactured materials. Our Earth simply cannot support human life if urban growth continues wiping out all its agricultural land, isolating wildlife in limited preserves, taking clean water from rural areas, and spreading pollution from the mountains to the shore. All of these habitats people need for survival.
The Professional Schools
Authors: Keller Morton , Keller Phyllis
Published: November 2020

Harvard’s nine professional schools were on the cutting edge of its evolution from a Brahmin to a meritocratic university. Custom, tradition, and the evergreen memory of the alumni weighed less heavily on them than on the College. And the professions they served were more interested in their current quality than their past glory. True, major differences of size, standing, wealth, and academic clout separated Harvard’s Brobdingnagian professional faculties—the Graduate School of Arts and Sciences and the Schools of Medicine, Law, and Business— from the smaller, weaker Lilliputs—Public Health and Dentistry, Divinity, Education, Design, Public Administration. But these schools had a shared goal of professional training that ultimately gave them more in common with one another than with the College and made them the closest approximation of Conant’s meritocratic ideal. Harvard’s doctoral programs in the Graduate School of Arts and Sciences (GSAS) were a major source of its claim to academic preeminence. As the Faculty of Arts and Sciences became more research and discipline minded, so grew the importance of graduate education. A 1937 ranking of graduate programs in twenty-eight fields—the lower the total score, the higher the overall standing—provided a satisfying measure of Harvard’s place in the American university pecking order: But there were problems. Money was short, and while graduate student enrollment held up during the Depression years of the early 1930s (what else was there for a young college graduate to do?), academic jobs became rare indeed. Between 1926–27 and 1935–36, Yale appointed no Harvard Ph.D. to a junior position. The Graduate School itself was little more than a degree-granting instrument, with no power to appoint faculty, no building, no endowment, and no budget beyond one for its modest administrative costs. Graduate students identified with their departments, not the Graduate School. Needless to say, the GSAS deanship did not attract the University’s ablest men. Conant in 1941 appointed a committee to look into graduate education, and historian Arthur M. Schlesinger, Sr., “called for a thoroughgoing study without blinders.
A Plurality of Minorities
Authors: Keller Morton , Keller Phyllis
Published: November 2020

The triumph of meritocracy at Harvard had social as well as academic and intellectual consequences. It changed the ethnocultural and class structures of both the faculty and the student body. Jews in particular became a substantial, accepted part of the Harvard scene. And in more complex and ambivalent ways, Catholics, women, and African Americans gained in numbers, impact, and visibility. After World War II, meritocratic principles substantially overrode anti- Semitism in the admission of students and the appointment and promotion of faculty. An inquiry into the religious identification of Harvard College students in the mid-1950s revealed that 52 percent identified themselves as Protestants (about 15 percent of these Episcopalian), 12 percent as Catholics, 15 percent as Jews; 20 percent claimed no religious affiliation. Residual discrimination against Jewish applicants arguably lurked within an admissions policy that sought a Harvard class as diverse as possible in geographical origin, social background, and nonacademic talents. But the 1956 admission rate to Harvard from strongly Jewish feeder schools was (with the glaring exceptions of New York City’s Stuyvesant and Erasmus high schools) not too far below the overall Harvard acceptance rate of 43.3 percent of applicants. (Though it may be assumed that the academic record of these candidates was well above the norm.) After World War II, anti-Catholicism like anti-Semitism retreated to the margins of respectability. The religiously inclined Pusey had an ecumenical sympathy for Catholics, substantially reciprocated. And Catholics themselves became more ready to send their sons to Harvard. JFK’s election to the presidency in particular gave the University a cachet among them that all but obliterated the suspicion-ridden past. Catholic undergraduates, substantially greater in numbers than in the prewar years, felt more at home by the 1950s. In 1960 a Catholic Student Center opened adjacent to the campus, with Cardinal Cushing’s encouragement and assistance. The Current, a Catholic student magazine, concluded in the spring of 1963: “we are convinced that Catholics belong at Harvard.”