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In her new book, The Mantle of the Earth, geographer Veronica della Dora explains how Earth9s mantle has provided a capacious metaphor for the terrain that sustains human life and the manner in which it is imagined and investigated. This is a metaphor that thrives on the lifting of veils and the piercing of interiors, as well as the "warp and weft" of a web of life and the weaving together of social and physical phenomena into narratives that convey the rich texture of this environment.

Immunogenomics The human thymus is the organ responsible for the maturation of many types of T cells, which are immune cells that protect us from infection. However, it is not well known how these cells develop with a full immune complement that contains the necessary variation to protect us from a variety of pathogens. By performing single-cell RNA sequencing on more than 250,000 cells, Park et al. examined the changes that occur in the thymus over the course of a human life. They found that development occurs in a coordinated manner among immune cells and with their developmental microenvironment. These data allowed for the creation of models of how T cells with different specific immune functions develop in humans. Science , this issue p. [eaay3224][1] [1]: /lookup/doi/10.1126/science.aay3224

Telomeres are the protective end-complexes at the termini of eukaryotic chromosomes. Telomere attrition can lead to potentially maladaptive cellular changes, block cell division, and interfere with tissue replenishment. Recent advances in the understanding of human disease processes have clarified the roles of telomere biology, especially in diseases of human aging and in some aging-related processes. Greater overall telomere attrition predicts mortality and aging-related diseases in inherited telomere syndrome patients, and also in general human cohorts. However, genetically caused variations in telomere maintenance either raise or lower risks and progression of cancers, in a highly cancer type–specific fashion. Telomere maintenance is determined by genetic factors and is also cumulatively shaped by nongenetic influences throughout human life; both can interact. These and other recent findings highlight both causal and potentiating roles for telomere attrition in human diseases.

Animal Culture Cultural transmission of information occurs when individuals learn from others with more experience or when individuals come to accept particular modes of behavior as the local norm. Such information transfer can be expected in highly social or long-lived species where contact and time for learning are maximized and are seen in humans (see the Perspective by de Waal ). Using a network-based diffusion analysis on a long-term data set that includes tens of thousands of observations of individual humpback whales, Allen et al. (p. 485 ) show that an innovative feeding behavior has spread through social transmission since it first emerged in a single individual in 1980. The “lobtail” feeding has passed among associating individuals for more than three decades. Van de Waal et al. (p. 483 ), on the other hand, used a controlled experimental approach in vervet monkeys to show that individuals learn what to eat from more experienced individuals within their social group. Not only did young animals learn from observing older animals, but immigrating males switched their food preference to that of their new group.

Modern technology and modern medical practice have evolved over the past decades, enabling us to enhance and extend human life to an unprecedented degree. The two books under review examine this phenomenon from remarkably different perspectives. Mark O9Connell9s To Be a Machine is an examination of transhumanism, a movement characterized by technologies that seek to transform the human condition and extend life spans indefinitely. Haider Warraich9s Modern Death is a physician9s well-referenced account of modern medicine9s approach to death. Despite their differences, both books advocate for retaking personal control over death. Neither vision is trivial, and both encourage further introspection and deliberation.

Harvard psychologist Steven Pinker calls Robert Trivers "one of the great thinkers in the history of Western thought." Stuart West, a professor of evolutionary biology at Oxford, recently described Trivers as "one of the most influential evolutionary biologists since Charles Darwin." And in 1999, Time named Trivers one of the 20th century9s 100 greatest thinkers and scientists. In the 1970s, Trivers penned a series of landmark papers that have been cited thousands of times and opened up the study of human relationships to biology. Looking at interactions between friends, lovers, and parent and child, he helped to lay the foundations for sociobiology, or a "Darwinian social theory," as he called it. Then he disappeared from view, only to reemerge in the 1990s. His latest effort, a book called The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life, might well introduce him to a larger audience.

OriginsWhat is the future of evolution? In the final essay in Science 's series in honor of the Year of Darwin, Carl Zimmer explores the subject of human-driven evolution. Since Darwin's day, humans have gained an unprecedented influence over our own evolution. At the same time, our actions, be it causing climate change, modifying the genomes of other organisms, or introducing invasive species, are creating new sources of natural selection on the flora and fauna around us. If there's one thing that's certain, it's that humans, like other living things, will continue to evolve; medical advances and other changes to human life have not stopped natural selection, nor will they in the future.

Secord surveys the reception of eight books published in the United Kingdom around 1830 that "offered comprehensive perspectives on science and its meaning for human life."

[Figure][1] CREDIT: INGA SPENCE/ALAMY In their Policy Forum “End the deadlock on governance of geoengineering research” (15 March, p. [1278][1]), E. A. Parson and D. W. Keith recognize the environmental and policy risks posed by geoengineering methods and lay out a course of action to address them. They argue that a void in international governance of research exists and that geoengineering operations are subject to no international legal control. They further assess no progress in defining the boundary between small and large activities. In fact, relevant guidance does exist. The 1977 Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques—the so-called ENMOD Convention—is an international agreement that already governs aspects of geoengineering. The Convention was the result of a several-year policy development, set in motion by interest in the national security implications of geoengineering. The U.S. government investigated geoengineering techniques ([ 1 ][2]) and used weather modification (cloud seeding) as a weapon during the Vietnam War in the late 1960s and early 1970s ([ 2 ][3]). The Convention, recognizing the issue of scale, prohibits weapons uses that would have “widespread, long-lasting, or severe” effects. An agreed Understanding specifies that, for the purposes of the Convention, these terms refer to an area of several hundred square kilometers, a duration of months or about a season, and severity as “serious or significant disruption or harm to human life, natural and economic resources or other assets” ([ 3 ][4]). Parties commit to the “fullest possible” exchange of relevant information on peaceful geoengineering and to feasible international scientific and economic cooperation. If geoengineering research, let alone experiments or possibly operations, is to proceed, the ENMOD Convention and its negotiating history provide precedents and information. The need for a moratorium on geoengineering for weapons purposes is moot. The authors' discussion of a social bargain recognizes the importance of “international norms of cooperation and transparency.” Arms control already applies to geoengineering: Fortunately, one cooperative norm is already in place. 1. [↵][5]1. S. Weart , “The Discovery of Global Warming: Climate Modification Schemes” (2011); [www.aip.org/history/climate/RainMake.htm][6]. 2. [↵][7]1. D. Shapley , Science 184, 1059 (1974). [OpenUrl][8][FREE Full Text][9] 3. [↵][10]Federation of American Scientists, Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (1980); [www.fas.org/nuke/control/enmod/text/environ2.htm][11]. [1]: pending:yes [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #xref-ref-1-1 "View reference 1 in text" [6]: http://www.aip.org/history/climate/RainMake.htm [7]: #xref-ref-2-1 "View reference 2 in text" [8]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DShapley%26rft.auinit1%253DD.%26rft.volume%253D184%26rft.issue%253D4141%26rft.spage%253D1059%26rft.epage%253D1061%26rft.atitle%253DWeather%2BWarfare%253A%2BPentagon%2BConcedes%2B7-Year%2BVietnam%2BEffort%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.184.4141.1059%26rft_id%253Dinfo%253Apmid%252F17736187%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6MzoiUERGIjtzOjExOiJqb3VybmFsQ29kZSI7czozOiJzY2kiO3M6NToicmVzaWQiO3M6MTM6IjE4NC80MTQxLzEwNTkiO3M6NDoiYXRvbSI7czoyNDoiL3NjaS8zNDAvNjEzMi81NDguMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30= [10]: #xref-ref-3-1 "View reference 3 in text" [11]: http://www.fas.org/nuke/control/enmod/text/environ2.htm

George Bugliarello, a creative engineer, outstanding researcher, and dedicated educator, died on 18 February at age 83, in New York. His range of interests and expertise transcended many disciplines, including civil engineering, biomedical engineering, urban development, science policy, water resources, and environmental science. His vision of the role of science, innovation, and education, coupled with a passion for turning his vision into reality, is reflected in today's urban communities, forged through academic and industry interactions in ways that spur economic growth and societal well-being, while respecting the quality of human life and the environment.

Biologists and the Promise of American Life From Meriwether Lewis to Alfred Kinsey. Philip J. Pauly. Princeton University Press, Princeton, NJ, 2000. 329 pp. $29.95, £18.95. ISBN 0-691-04977-7. Examining the social history of biology in the United States, Pauly argues that scientists coupled their researches to their desires to improve plants, animals, and human life and thus build a nation of "prosperous, liberal, secular, and humane" people.

In his Editorial “Twilight for the Enlightenment?” (8 Apr., p. 165), Donald Kennedy makes an interesting ethical argument in defense of (presumably embryonic) stem cell research. By pointing out that beliefs regarding the beginning of a human life are not universal, the author implies that there is no basis for restricting research in the area. If one were to use this yardstick of universal objection to determine when research becomes unethical, it follows that even the infamous medical experiments of the Nazis might pass muster. Rather than being the exclusive domain of Christian fundamentalists, concern over the ethical implications of embryonic stem cell research is widespread and is an area of academic interest ([1][1]). I respectfully submit that the author could more effectively support his position by discussing the point of true contention: when human life begins. Certainly the author would not deny his adversaries the skepticism that he so strongly advocates? 1. [↵][2]1. S. Holm , Bioethics 16, 493 (2002). [OpenUrl][3][CrossRef][4][PubMed][5][Web of Science][6] [1]: #ref-1 [2]: #xref-ref-1-1 "View reference 1 in text" [3]: {openurl}?query=rft.jtitle%253DBioethics%26rft.volume%253D16%26rft.spage%253D493%26rft_id%253Dinfo%253Adoi%252F10.1111%252F1467-8519.00307%26rft_id%253Dinfo%253Apmid%252F12472110%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [4]: /lookup/external-ref?access_num=10.1111/1467-8519.00307&link_type=DOI [5]: /lookup/external-ref?access_num=12472110&link_type=MED&atom=%2Fsci%2F309%2F5731%2F51.3.atom [6]: /lookup/external-ref?access_num=000178502900002&link_type=ISI

Finch and Crimmins ([ 1 ][1]) hypothesized that “decreased inflammation during early life has led directly to a decrease in morbidity and mortality resulting from chronic conditions in old age.” Various early-life factors have been shown to affect late-life mortality ([ 2 ][2], [ 3 ][3]).

The completion of the human genome sequence is, without question, a crowning achievement in biology. The commemorative issues of [ Science ][1], 16 February, and Nature , 15 February, provide superb chronicles of this event and I, for one, will keep them as mementos of the occasion. However

Heals all manner of ailments, unlimited quantities, tailor-made for you. … No, it's not an advertisement for snake oil but may represent the promise of stem cells—cells that have the potential to produce various cell types that make up the body and might therefore provide replacements for tissues damaged by age, trauma, or disease. But the work raises numerous questions as well: Can such promise be true? What is the ethical cost of such developments? Who will fund the necessary R&D? This special issue takes a look at these questions. The Reviews begin with Watt and Hogan's (p. [1427][1]) description of what's currently known about stem cells. As the authors note, some stem cells are pluripotent: essentially blank slates that are ready when called on to differentiate into any cell type. But, as described by Slack (p. [1431][2]), stem cells of certain tissues, such as epithelial structures, must fit in with existing tissue architecture. In a related Report, Meng et al. (p. [1489][3]) describe progress in the search for stem cells that give rise to sperm. A particular surprise has been the discovery of stem cells in unexpected places. As reviewed by Gage (p. [1433][4]), the adult central nervous system, long thought not to contain cells capable of dividing, in fact harbors stem cells. Such cells may help treat Alzheimer's and Parkinson's disease. In addition, as discussed by Weissman (p. [1442][5]), hematopoietic stem cells from bone marrow may one day provide transplants to replace blood and immune cells. The very blankness of stem cells has turned out to be a surprise as well: The right signals can send some adult stem cells down unexpected paths of differentiation. Van der Kooy and Weiss (p. [1439][6]) discuss theories about the origins and development of this remarkable plasticity. With these developments come great ethical challenges. Certain stem cells that show therapeutic potential are derived from early embryos or from fetal germ cells. As shown in a series of Viewpoints, opinions vary widely about whether the potential benefits outweigh the ethical costs of using such cells. To Young (p. [1424][7]), the answer is clearly yes. But, as Perry notes (p. [1423][8]), the use of such cells involves ethical issues that must be considered with great respect for the sanctity of human life. Reflecting the issue's complexity, policies of various governing bodies also vary. Lenoir (p. [1425][9]) presents a European perspective. Finally, the News component of this special issue includes three stories. One addresses the issue of whether adult stem cells can provide cells for all kinds of tissues, thereby relieving the ethical quandary posed by the use of embryonic or fetal cells. The second looks at the companies now going into the stem cell business, and the third deals with the lessons that 10 years of fetal cell transplants for treatment of Parkinson's disease might provide for the stem cell work. Whatever the scientific and ethical uncertainties, as Frankel notes in the Editorial (p. [1397][10]), we must move with all due consideration, but without unnecessary delay, toward the answers so that the promises and benefits of stem cells can be effectively explored. [1]: /lookup/doi/10.1126/science.287.5457.1427 [2]: /lookup/doi/10.1126/science.287.5457.1431 [3]: /lookup/doi/10.1126/science.287.5457.1489 [4]: /lookup/doi/10.1126/science.287.5457.1433 [5]: /lookup/doi/10.1126/science.287.5457.1442 [6]: /lookup/doi/10.1126/science.287.5457.1439 [7]: /lookup/doi/10.1126/science.287.5457.1424 [8]: /lookup/doi/10.1126/science.287.5457.1423 [9]: /lookup/doi/10.1126/science.287.5457.1425 [10]: /lookup/doi/10.1126/science.287.5457.1397

Temperature bears an importance to man far beyond the mere matter of his hour-to-hour comfort. In some places it lays a heavy, stagnating hand over his life and holds him to a vegetative existence; in others, it generates an energy and progressiveness which drives him forward with irresistible impetus. Its effects begin even before he is conceived, for the metabolic vigor of parental germ cells at the time of their union exerts a potent influence over the entire course of the new life. Without favorable temperatures, neither individual nor nation can develop innate potentialities to the full. The human body is essentially a combustion machine that functions only as its cells release energy by burning the foodstuffs taken in. For every unit of combustion energy transformed into work-output by our bodies, three or four similar units must be dissipated as waste heat. Failure of such dissipation to keep pace with heat production in the body may mean heat stroke and death within a few hours. The waste heat of combustion thus becomes one of the body's most important excretory products. Following several weeks of difficulty in dissipation waste heat, physical and mental activity declines, and there is a drop in the combustion rate. A lowered total combustion rate means less energy for thought and action, as well as less waste heat to be dissipated. Physical and mental characteristics thus change, from the dynamic and pushing, to a more passive type; personal initiative gives way to a desire for security. That these are basic changes in the individual's metabolic make-up is evidenced by equally profound alterations in such body functions as growth, rate of development, resistance to infection, and thought capacity. When difficult heat loss induces a lowered combustion rate in the cells, growth slows down and may be completely halted, even though an ample food supply be available; onset of puberty and maturity is progressively delayed and ability to reproduce is reduced or completely obliterated, although matings go on freely; resistance to bacterial invasion is impaired, especially for those respiratory infections in which the white blood cells (phagocytes) provide the first and main line of the body's defense-system; and, finally, ability to solve problems is greatly impaired. Proper ease of body heat-loss means just the opposite—a fast growing, early maturing, highly fertile individual, with a keen mentality and good ability to fight infectious disease. These statements are by no means hypothetical but are based upon well authenticated statistical findings on man and on experimental animals under controlled conditions. They show up in the laboratory, under natural climatic differences, and during the wide seasonal swings in middle temperature latitudes. Climatic temperature differences, whether brought about by latitude or altitude, are potent factors in human life, and so also are the wide seasonal temperature swings of the earth's middle latitudes. The fortunate nations of the earth are those located where the body's waste heat can be lost readily. Man is in reality a pawn of the environmental forces encompassing him, being pushed forward to a vantage point at one time or held in lethargic bondage at another. Here is a challenge of the first magnitude—can human intelligence find an effective answer? If not an answer, then it should at least comprehend the forces at work and the major significance of their effects.

SEVERAL years ago a discussion was carried on in one of the London newspapers on that interminable but always interesting question as to what is the best definition of a gentleman. Various answers were suggested by different contributors. Some were in the form of citations from our noblest literature-one, as I recall, was given in the words of St. Paul, another was taken from Shakespeare, a third from Emerson. The one generally acknowledged to be the most effective was, however, phrased in the picturesque vernacular of modern sport. A gentleman, so this answer ran, is a man who plays the game. As this lingers in the memory it brings a growing sense of broader implications. The definition, evidently, only gives a new turn to the old thought that human life is like a great game that man plays with the world. We recall the striking words in which an illustrious master of modern science once brought this thought to bear upon the problem of education

The minimum amount of water necessary to sustain human life is calculated. The water needed to produce a pound of meat is 25 times the amount needed to produce a pound of vegetables or grain. The amount of water now being used to sustain the American standard of living is computed. The number of people the American land could feed if all the rainfall in the country were totally utilized is calculated. It is estimated that the country could accomodate 50 million more people bringing the total population to 230 million before there would be any decrease in the present standard of living. This figure will have been reached by the year 2000.