Category Archives: Peer Reviewed Article Review

Freeman Dyson on the origin of life

Recently I remembered that Freeman Dyson has this dissenting view on the origin if life. It’s a little hard to follow, but the basic idea is that life preceded DNA/RNA. It started as simple molecules that were able to metabolize, grow and evolve, but not able to replicate themselves efficiently. In other words, life without DNA. If I understand it correctly, this means DNA/RNA would have had to arise separately, perhaps as a virus that then infected the larger molecules and gave rise to modern cells. The most interesting implication, to me, is that this means life arose more than once. So life arising is not as rare an event as we might think. Maybe it happens relatively frequently under a range of conditions, and maybe Earth is not the only place it happens. Maybe it arises frequently, but it rarely gets off the ground. Dyson admits his theory is rejected or ignored by most biologists, but he insists it fits the facts. I was reading this abstract in Trends in Ecology and Evolution, which was a little over my head but reminded me of Dyson’s theory.

Despite recent progress, the origin of the eukaryotic cell remains enigmatic. It is now known that the last eukaryotic common ancestor was complex and that endosymbiosis played a crucial role in eukaryogenesis at least via the acquisition of the alphaproteobacterial ancestor of mitochondria. However, the nature of the mitochondrial host is controversial, although the recent discovery of an archaeal lineage phylogenetically close to eukaryotes reinforces models proposing archaea-derived hosts. We argue that, in addition to improved phylogenomic analyses with more comprehensive taxon sampling to pinpoint the closest prokaryotic relatives of eukaryotes, determining plausible mechanisms and selective forces at the origin of key eukaryotic features, such as the nucleus or the bacterial-like eukaryotic membrane system, is essential to constrain existing models.

 

 

Viktor Glushkov

Viktor Glushkov was a Soviet computer science who developed an idea for a cash-free, computer-controlled economic system. The theory is seductive because the idea was to improve information flows and feedback loops while reducing lag times. In other words, if you could collect perfect information and make it perfectly available, the economy could be perfectly efficient and in perfect balance. It didn’t work out, running into the crushing Soviet bureaucracy and technological limits. But in theory at least, the technology would be less of a constraint today.

Glushkov’s initial proposal included one particularly controversial provision. He envisioned that the new network would monitor all labor, production, and retail, and he proposed to eliminate paper money from the economy and to rely entirely on electronic payments. Perhaps Glushkov hoped that this idea would appeal personally to Khrushchev. The elimination of paper money evoked the Marxist ideal of money-free communist society, and it seemed to bring the Soviet society closer to the goal of building communism, promulgated by Khrushchev at the Twenty-Second Party Congress in 1961. The Academy president Keldysh, who was much more experienced in top-level bureaucratic maneuvers, advised Glushkov to drop the provision, for it would ‘only stir up controversy.’ Glushkov cut out this section from the main proposal and submitted it to the Party Central Committee under a separate cover. If ideology were to play any significant role in Soviet top-level decision-making, this was its best chance. Glushkov’s proposal to eliminate money, however, never gained support from the Party authorities.

emerald ash borer targets human arteries

The emerald ash borer is supposed to kill trees, not people. But this study found that heart attack risk for women went up 25% when all the trees were killed by this pest. Lessons learned – (1) contact with nature lowers stress in an urban environment, (2) people grieve for lost trees. So cities should plant trees and take care of them. Just not all the same kind of trees, which is a basic principle of resilience. Sure, cities have limited money to spend, but there is a public health case to be made for spending some of it on trees.

value of levees

This study seems to have had trouble finding any measurable economic value of levees, which is interesting.

The value of levee protection to commercial properties

Ecological Economics

Volume 119, November 2015, Pages 181–188

Levees have historically been a dominant approach to riverine flood control in the United States. Recent investigations have found many levees around the country are in substandard condition, however, and some communities are moving to upgrade and repair their levee systems. Little empirical work has examined how increasing flood protection from levees is valued. We present estimates of the capitalization of upgraded levee protection into commercial property prices in St. Louis County, Missouri. By using controls for surrounding land cover and coarsened exact matching to ensure close distribution between treatment and control on surrounding land cover, we attempt to isolate the price effect of the levee from agglomeration effects that may also be operating. We find that commercial properties protected by a 500-year levee do not have a statistically significant price discount as compared with properties not in a floodplain. We find the selling price of properties with levee protection to be higher (although also insignificant in many specifications) than those in a floodplain without levee protection.

the Environmental Kuznets Curve

Here’s a journal article with some discussion of the Environmental Kuznets Curve, which is the idea that a developing country’s environment will slowly degrade, then improve again. Having breathed and drank in a variety of countries, it is pretty clear to me that the concept applies to air and water pollution, but not to overall ecological footprint, wildlife habitat, or long-term stability of our atmosphere and oceans. I suspect that this is because air and water pollution are things people can understand – they affect health, safety, and property values in pretty obvious ways. Over time, economic development starts giving people some money, education, and leisure time, and they become more politically active, generating pressure to clean up the immediate human environment. But people don’t understand or don’t care about the long-term ecological issues as much, so the political pressure does not develop.

The main purpose of this paper is to present a theoretical model incorporating the concept of circular economic activities. We construct a circular economy model with two types of economic resources, namely, a polluting input and a recyclable input. Overall, our results indicate that the factors affecting economic growth include the marginal product of the recyclable input, the recycling ratio, the cost of using the environmentally polluting input and the level of pollution arising from the employment of the polluting input. Our analysis also shows that, contrary to the Environmental Kuznets Curve (EKC), environmental quality cannot be maintained or improved via economic growth. Instead, the improvement in environmental quality, as measured by a reduction in pollution, can only be achieved by an increase in the environmental self-renewal rate or the recycling ratio.

more on automation

The Economist has an article reviewing three recent papers on automation (i.e. robots, artificial intelligence) and employment. For two of the three papers, the bottom line is that automation has led to inequality in the past, because it means unemployment for some groups of people, but has led to overall economic growth and society-wide benefits in the longer term. The third paper, however, talks about the current exponential “explosion” of technological progress as a revolutionary development that cannot be compared to anything in the recent past. The last time anything like this happened was about 500 million years ago.

These are all open access, so I’ll put links to the papers below along with abstracts.

Autor, David H. 2015. “Why Are There Still So Many Jobs? The History and Future of Workplace Automation.” Journal of Economic Perspectives, 29(3): 3-30.

In this essay, I begin by identifying the reasons that automation has not wiped out a majority of jobs over the decades and centuries. Automation does indeed substitute for labor—as it is typically intended to do. However, automation also complements labor, raises output in ways that leads to higher demand for labor, and interacts with adjustments in labor supply. Journalists and even expert commentators tend to overstate the extent of machine substitution for human labor and ignore the strong complementarities between automation and labor that increase productivity, raise earnings, and augment demand for labor. Changes in technology do alter the types of jobs available and what those jobs pay. In the last few decades, one noticeable change has been a “polarization” of the labor market, in which wage gains went disproportionately to those at the top and at the bottom of the income and skill distribution, not to those in the middle; however, I also argue, this polarization is unlikely to continue very far into future. The final section of this paper reflects on how recent and future advances in artificial intelligence and robotics should shape our thinking about the likely trajectory of occupational change and employment growth. I argue that the interplay between machine and human comparative advantage allows computers to substitute for workers in performing routine, codifiable tasks while amplifying the comparative advantage of workers in supplying problem-solving skills, adaptability, and creativity.

Mokyr, Joel, Chris Vickers, and Nicolas L. Ziebarth. 2015. “The History of Technological Anxiety and the Future of Economic Growth: Is This Time Different?” Journal of Economic Perspectives, 29(3): 31-50.

Technology is widely considered the main source of economic progress, but it has also generated cultural anxiety throughout history. The developed world is now suffering from another bout of such angst. Anxieties over technology can take on several forms, and we focus on three of the most prominent concerns. First, there is the concern that technological progress will cause widespread substitution of machines for labor, which in turn could lead to technological unemployment and a further increase in inequality in the short run, even if the long-run effects are beneficial. Second, there has been anxiety over the moral implications of technological process for human welfare, broadly defined. While, during the Industrial Revolution, the worry was about the dehumanizing effects of work, in modern times, perhaps the greater fear is a world where the elimination of work itself is the source of dehumanization. A third concern cuts in the opposite direction, suggesting that the epoch of major technological progress is behind us. Understanding the history of technological anxiety provides perspective on whether this time is truly different. We consider the role of these three anxieties among economists, primarily focusing on the historical period from the late 18th to the early 20th century, and then compare the historical and current manifestations of these three concerns.

Pratt, Gill A. 2015. “Is a Cambrian Explosion Coming for Robotics?” Journal of Economic Perspectives, 29(3): 51-60.

About half a billion years ago, life on earth experienced a short period of very rapid diversification called the “Cambrian Explosion.” Many theories have been proposed for the cause of the Cambrian Explosion, one of the most provocative being the evolution of vision, allowing animals to dramatically increase their ability to hunt and find mates. Today, technological developments on several fronts are fomenting a similar explosion in the diversification and applicability of robotics. Many of the base hardware technologies on which robots depend—particularly computing, data storage, and communications—have been improving at exponential growth rates. Two newly blossoming technologies—”Cloud Robotics” and “Deep Learning”—could leverage these base technologies in a virtuous cycle of explosive growth. I examine some key technologies contributing to the present excitement in the robotics field. As with other technological developments, there has been a significant uptick in concerns about the societal implication of robotics and artificial intelligence. Thus, I offer some thoughts about how robotics may affect the economy and some ways to address potential difficulties.

The Secret of N.I.M.H.

I remember going to see the rats of N.I.M.H. way too young and being terrified (perhaps second only to my fear of the Wicked Witch of the West). Anyway, the secret is out…

Wong FK, Fei J-F, Mora-Bermúdez F, Taverna E, Haffner C, Fu J, et al. (2015) Sustained Pax6 Expression Generates Primate-like Basal Radial Glia in Developing Mouse Neocortex. PLoS Biol 13(8): e1002217. doi:10.1371/journal.pbio.1002217

The evolutionary expansion of the neocortex in mammals has been linked to enlargement of the subventricular zone (SVZ) and increased proliferative capacity of basal progenitors (BPs), notably basal radial glia (bRG). The transcription factor Pax6 is known to be highly expressed in primate, but not mouse, BPs. Here, we demonstrate that sustaining Pax6 expression selectively in BP-genic apical radial glia (aRG) and their BP progeny of embryonic mouse neocortex suffices to induce primate-like progenitor behaviour.

NIMH stood for “National Institute of Mental Health”. Which was, of course, secretly creating super-intelligent rats.

chemicals and cancer

I’ve tended not to obsess over chemicals and cancer, because I think there are other risks that are much higher and much more clearly proven (like the high odds of death every time you set foot in or anywhere near a motor vehicle, to give one example.) I also tend to accept some chemicals, like water disinfectants, food preservatives, drugs, even pesticides, as somewhat necessary evils – we actually know they have a downside, but they do more good than harm on balance. In a sense, it is a “luxury” that many of us avoid violence and infectious diseases long enough to get old and die of cancer. Cancer is at least to some extent a random phenomenon. That doesn’t mean we shouldn’t be looking for safer alternatives to these chemicals that do the same good. If we don’t look we won’t find them. And then, there are chemicals that are known to be harmful, and have no positive effects. Triclosan comes to mind. The companies using cynical fear-based marketing to force these on people should be punished.

All that aside, our food, water, air, and consumer products are full of chemicals, with the result that our bodies are full of chemicals. We don’t have good information on what most of them are doing to us, and especially what combinations of them may be doing to us. Here’s an interesting article that estimates what fraction of cancers are caused by chemicals in the environment, as opposed to lifestyle choices, genetics, and plain old bad luck.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety ‘Mode of Action’ framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.

CRISPR

Here’s some more info on CRISPR, a genetic engineering technique some people are saying will be revolutionary.

 The Bacterial Origins of the CRISPR Genome-Editing Revolution
Sontheimer Erik J. and Barrangou Rodolphe. Human Gene Therapy. July 2015, 26(7): 413-424. doi:10.1089/hum.2015.091.

Like most of the tools that enable modern life science research, the recent genome-editing revolution has its biological roots in the world of bacteria and archaea. Clustered, regularly interspaced, short palindromic repeats (CRISPR) loci are found in the genomes of many bacteria and most archaea, and underlie an adaptive immune system that protects the host cell against invasive nucleic acids such as viral genomes. In recent years, engineered versions of these systems have enabled efficient DNA targeting in living cells from dozens of species (including humans and other eukaryotes), and the exploitation of the resulting endogenous DNA repair pathways has provided a route to fast, easy, and affordable genome editing. In only three years after RNA-guided DNA cleavage was first harnessed, the ability to edit genomes via simple, user-defined RNA sequences has already revolutionized nearly all areas of biological science. CRISPR-based technologies are now poised to similarly revolutionize many facets of clinical medicine, and even promise to advance the long-term goal of directly editing genomic sequences of patients with inherited disease. In this review, we describe the biological and mechanistic basis for these remarkable immune systems, and how their engineered derivatives are revolutionizing basic and clinical research.

natural capital

Here’s a slightly novel take on natural capital, as a charged battery.

Human domination of the biosphere: Rapid discharge of the earth-space battery foretells the future of humankind

Earth is a chemical battery where, over evolutionary time with a trickle-charge of photosynthesis using solar energy, billions of tons of living biomass were stored in forests and other ecosystems and in vast reserves of fossil fuels. In just the last few hundred years, humans extracted exploitable energy from these living and fossilized biomass fuels to build the modern industrial-technological-informational economy, to grow our population to more than 7 billion, and to transform the biogeochemical cycles and biodiversity of the earth. This rapid discharge of the earth’s store of organic energy fuels the human domination of the biosphere, including conversion of natural habitats to agricultural fields and the resulting loss of native species, emission of carbon dioxide and the resulting climate and sea level change, and use of supplemental nuclear, hydro, wind, and solar energy sources. The laws of thermodynamics governing the trickle-charge and rapid discharge of the earth’s battery are universal and absolute; the earth is only temporarily poised a quantifiable distance from the thermodynamic equilibrium of outer space. Although this distance from equilibrium is comprised of all energy types, most critical for humans is the store of living biomass. With the rapid depletion of this chemical energy, the earth is shifting back toward the inhospitable equilibrium of outer space with fundamental ramifications for the biosphere and humanity. Because there is no substitute or replacement energy for living biomass, the remaining distance from equilibrium that will be required to support human life is unknown.