Glycine decarboxylase deficiency causes neural tube defects and features of non-ketotic hyperglycinemia in mice.

Glycine decarboxylase (GLDC) acts in the glycine cleavage system to decarboxylate glycine and transfer a one-carbon unit into folate one-carbon metabolism. GLDC mutations cause a rare recessive disease non-ketotic hyperglycinemia (NKH). Mutations have also been identified in patients with neural tube defects (NTDs); however, the relationship between NKH and NTDs is unclear. We show that reduced expression of Gldc in mice suppresses glycine cleavage system activity and causes two distinct disease phenotypes. Mutant embryos develop partially penetrant NTDs while surviving mice exhibit post-natal features of NKH including glycine accumulation, early lethality and hydrocephalus. In addition to elevated glycine, Gldc disruption also results in abnormal tissue folate profiles, with depletion of one-carbon-carrying folates, as well as growth retardation and reduced cellular proliferation. Formate treatment normalizes the folate profile, restores embryonic growth and prevents NTDs, suggesting that Gldc deficiency causes NTDs through limiting supply of one-carbon units from mitochondrial folate metabolism

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Law, Biology, and Property: A New Theory of the Endowment Effect

Recent work at the intersection of law and behavioral biology has suggested numerous contexts in which legal thinking could benefit by integrating knowledge from behavioral biology. In one of those contexts, behavioral biology may help to provide theoretical foundation for, and potentially increased predictive power concerning, various psychological traits relevant to law. This Article describes an experiment that explores that context. The paradoxical psychological bias known as the endowment effect puzzles economists, skews market behavior, impedes efficient exchange of goods and rights, and thereby poses important problems for law. Although the effect is known to vary widely, there are at present no satisfying explanations for why it manifests when and how it does. Drawing on evolutionary biology, this Article provides a new theory of the endowment effect. Briefly, we hypothesize that the endowment effect is an evolved propensity of humans and, further, that the degree to which an item is evolutionarily relevant will affect the strength of the endowment effect. The theory generates a novel combination of three predictions. These are: (1) the effect is likely to be observable in many other species, including close primate relatives; (2) the prevalence of the effect in other species is likely to vary across items; and (3) the prevalence of the endowment effect will increase or decrease, respectively, with the increasing or decreasing evolutionary salience of the item in question. The authors tested these predictions in a chimpanzee (Pan troglodytes) experiment, recently published in Current Biology. The data, further explored here, are consistent with each of the three predictions. Consequently, this theory may explain why the endowment effect exists in humans and other species. It may also help both to predict and to explain some of the variability in the effect when it does manifest. And, more broadly, the results of the experiment suggest that combining life science and social science perspectives could lead to a more coherent framework for understanding the wider variety of other cognitive heuristics and biases relevant to law

Law, Biology, and Property: A New Theory of the Endowment Effect

Recent work at the intersection of law and behavioral biology has suggested numerous contexts in which legal thinking could benefit by integrating knowledge from behavioral biology. In one of those contexts, behavioral biology may help to provide theoretical foundation for, and potentially increased predictive power concerning, various psychological traits relevant to law. This Article describes an experiment that explores that context. The paradoxical psychological bias known as the endowment effect puzzles economists, skews market behavior, impedes efficient exchange of goods and rights, and thereby poses important problems for law. Although the effect is known to vary widely, there are at present no satisfying explanations for why it manifests when and how it does. Drawing on evolutionary biology, this Article provides a new theory of the endowment effect. Briefly, we hypothesize that the endowment effect is an evolved propensity of humans and, further, that the degree to which an item is evolutionarily relevant will affect the strength of the endowment effect. The theory generates a novel combination of three predictions. These are: (1) the effect is likely to be observable in many other species, including close primate relatives; (2) the prevalence of the effect in other species is likely to vary across items; and (3)the prevalence of the endowment effect will increase or decrease, respectively, with the increasing or decreasing evolutionary salience of the item in question. The authors tested these predictions in a chimpanzee (Pan troglodytes) experiment, recently published in Current Biology. The data, further explored here, are consistent with each of the three predictions. Consequently, this theory may explain why the endowment effect exists in humans and other species. It may also help both to predict and to explain some of the variability in the effect when it does manifest. And, more broadly, the results of the experiment suggest that combining life science and social science perspectives could lead to a more coherent framework for understanding the wider variety of other cognitive heuristics and biases relevant to law

Using an Evolutionary Approach to Improve Predictive Ability in Social Sciences: Property, the Endowment Effect, and Law

From the perspective of other disciplines, evolutionary approaches more often provide explanation and coherence than they help to solve discrete problems. We believe that more examples of the latter sort will help both with disciplinary synthesis and with the advance of knowledge. Here we describe a 20-year arc of research to demonstrate the problem-solving utility of an evolutionary perspective by focusing, as a case study, on a particular cognitive bias – the endowment effect – that has implications for law. Legal systems often assume that humans make decisions that are substantively rational, consistent, and aimed at maximizing their own wellbeing. But prevalent cognitive biases disrupt this, showing that humans consistently make decisions that seem to violate rationality and/or their own best interests. And despite decades of research, there has been little progress in understanding why these biases exist. We are among the scholars who have converged on the idea that many cognitive biases may have evolved as adaptations to pre-modern conditions, the evolutionarily sudden changes from which often leave them mis-matched to current conditions, prompting us to situationally irrational outcomes. Here, we discuss our data testing hypotheses derived from this perspective in both humans and nonhuman primates and consider how it has advanced our understanding of both the endowment effect narrowly and cognitive biases generally – including those relevant to law and policy

Predicting Variation in Endowment Effect Magnitudes

Hundreds of studies demonstrate human cognitive biases that are both inconsistent with “rational” decisionmaking and puzzlingly patterned. One such bias, the “endowment effect” (also known as “reluctance to trade”), occurs when people instantly value an item they have just acquired at a much higher price than the maximum they would have paid to acquire it. This bias impedes a vast range of real-world transactions, making it important to understand. Prior studies have documented items that do or do not generate endowment effects, and have noted that the effects vary in magnitude. But none has predicted any of the substantial between-item variation in those magnitudes across a large and novel set of items. Working from evolutionary theory, we derived six factors that predicted 52% of the between- item variation in magnitudes for a novel set of 24 items. These results deepen understanding of both the causes of and patterns in endowment effects. More broadly, they suggest that many other cognitive biases may be similarly approached, and potentially linked by a common theoretical framework

Chimpanzee Autarky

Background: Economists believe that barter is the ultimate cause of social wealth—and even much of our human culture—yet little is known about the evolution and development of such behavior. It is useful to examine the circumstances under which other species will or will not barter to more fully understand the phenomenon. Chimpanzees (Pan troglodytes) are an interesting test case as they are an intelligent species, closely related to humans, and known to participate in reciprocal interactions and token economies with humans, yet they have not spontaneously developed costly barter. Methodology/Principle Findings: Although chimpanzees do engage in noncostly barter, in which otherwise value-less tokens are exchanged for food, this lack of risk is not typical of human barter. Thus, we systematically examined barter in chimpanzees to ascertain under what circumstances chimpanzees will engage in costly barter of commodities, that is, trading food items for other food items with a human experimenter. We found that chimpanzees do barter, relinquishing lower value items to obtain higher value items (and not the reverse). However, they do not trade in all beneficial situations, maintaining possession of less preferred items when the relative gains they stand to make are small. Conclusions/Significance: Two potential explanations for this puzzling behavior are that chimpanzees lack ownership norms, and thus have limited opportunity to benefit from the gains of trade, and that chimpanzees\u27 risk of defection is sufficiently high that large gains must be imminent to justify the risk. Understanding the conditions that support barter in chimpanzees may increase understanding of situations in which humans, too, do not maximize their gains

Squirrel Monkeys’ Response to Inequitable Outcomes Indicates a Behavioural Convergence Within the Primates

Although several primates respond negatively to inequity, it is unknown whether this results from homology or convergent processes. Behaviours shared within a taxonomic group are often assumed to be homologous, yet this distinction is important for a better understanding of the function of the behaviour. Previous hypotheses have linked cooperation and inequity responses. Supporting this, all species in which inequity responses have been documented are cooperative. In this study, we tested this hypothesis by investigating the response to inequity in squirrel monkeys, which share a phylogenetic Family with capuchin monkeys, but do not cooperate extensively. Subjects exchanged tokens to receive food rewards in conditions in which the level of effort required and reward received varied. Squirrel monkeys did not respond negatively to inequity. However, the monkeys were sensitive to the variation present in the task; male subjects showed a contrast effect and, as in previous studies, subjects were more sensitive to differences in reward in the context of a task than when rewards were given for free. Taken with other results, these results support the hypothesis that a negative response to inequity evolved convergently in primates, probably as a mechanism for evaluating outcomes relative to one’s partners in cooperative species

The Endowment Effect in Orangutans

The endowment effect is the tendency to, seemingly irrationally, immediately value a possessed item more than the opportunity to acquire the identical item when one does not already possess it. Although endowment effects are reported in chimpanzees (Brosnan, Jones, Lambeth, Mareno, Richardson, & Shapiro, 2007) and capuchin monkeys (Lakshminarayanan, Chen, & Santos, 2008), both species share social traits with humans that make convergence as likely an evolutionary mechanism as homology. Orangutans (Pongo spp.) provide a unique insight into the evolution of the endowment effect, along with other apparently irrational behaviors, because their less frequent social interactions and relatively more solitary social organization distinguishes them from the more gregarious apes, allowing a test of evolutionary homology. In the present study, we used pairs of both food and non-food objects, as in an earlier test on chimpanzees (Brosnan et al., 2007). We established the apes’ preferences in forced-choice tasks, then tested whether they showed an endowment effect in an exchange task, in which subjects were given one of the objects, followed by the option to exchange it for the other. Here, we report the first evidence of the endowment effect in a relatively less social primate, the orangutan. This indicates that this behavior may have evolved as a homology within the primates, rather than being due to convergent social pressures. These findings provide stronger evidence for the hypothesis that at least one bias, the endowment effect, may be common in primates and, potentially, other species