Adverse experiences in early life can exert powerful delayed effects on adult survival and health. Telomere attrition is a potentially important mechanism in such effects. One source of early-life adversity is the stress caused by competitive disadvantage. Although previous avian experiments suggest that competitive disadvantage may accelerate telomere attrition, they do not clearly isolate the effects of competitive disadvantage from other sources of variation. Here, we present data from an experiment in European starlings (Sturnus vulgaris) that used cross-fostering to expose siblings to divergent early experience. Birds were assigned either to competitive advantage (being larger than their brood competitors) or competitive disadvantage (being smaller than their brood competitors) between days 3 and 12 post-hatching. Disadvantage did not affect weight gain, but it increased telomere attrition, leading to shorter telomere length in disadvantaged birds by day 12. There were no effects of disadvantage on oxidative damage as measured by plasma lipid peroxidation. We thus found strong evidence that early-life competitive disadvantage can accelerate telomere loss. This could lead to faster age-related deterioration and poorer health in later life.

Anxiety disorders are among the most common mental illnesses, with huge attendant suffering. Current treatments are not universally effective, suggesting that a deeper understanding of the causes of anxiety is needed. To understand anxiety disorders better, it is first necessary to understand the normal anxiety response. This entails considering its evolutionary function as well as the mechanisms underlying it. We argue that the function of the human anxiety response, and homologues in other species, is to prepare the individual to detect and deal with threats. We use a signal detection framework to show that the threshold for expressing the anxiety response ought to vary with the probability of threats occurring, and the individual's vulnerability to them if they do occur. These predictions are consistent with major patterns in the epidemiology of anxiety. Implications for research and treatment are discussed. Can J Psychiatry. 2011;56(12):707-715. Clinical Implications• Understanding the evolved function of the anxiety response can aid in understanding why people's propensity to become anxious varies with their life circumstances and developmental history.• Theory predicts that the threshold for mounting an anxiety response should depend on the probability of dangerous events occurring in the current environment, and the vulnerability of the person to those events should they occur. Numerous epidemiologic findings relating to anxiety disorders can be integrated within this framework. Limitations• The evolutionary criteria for when a mechanism is functioning adaptively are different from the criteria for identifying when a psychiatric disorder is present.• Evolutionary thinking has not yet been used to develop new treatment strategies for anxiety disorders, although it may aid in understanding why existing ones are effective. Key Words: anxiety, anxiety disorders, emotions, signal detection theory, behavioural ecology, evolutionary medicineIt is not informative to study variations of behaviour unless we know beforehand the norm from which the variants depart. 1, p 109A nxiety disorders are among the most common mental illnesses, with huge attendant quality of life and financial costs. For example, during 12 months in [2001][2002]4.6% of Canadians had symptoms meeting DSM-IV diagnostic criteria for an anxiety disorder, 2 and, during the course of their lifetimes, around 28.8% of Americans are estimated to be affected. 3 Although treatments for anxiety exist, these currently have limited efficacy. For example, for GAD, antidepressants, though more effective than placebo, have a number needed to treat of 5.54, meaning nearly 6 patients need to be treated with the drugs to produce 1 more clinically significant symptomatic improvement than placebo.4 Only around 46% of GAD patients show a clinically significant response to psychological therapy. 5 The pervasiveness of anxiety disorders and their resistance to treatment suggest a need for a deeper understanding of the sources of anxiety. We argue that to make some pro...

Animals in a poor biological state face reduced life expectancy, and as a consequence should make decisions that prioritize immediate survival and reproduction over long-term benefits. We tested the prediction that if, as has been suggested, developmental telomere attrition is a biomarker of state and future life expectancy, then individuals who have undergone greater developmental telomere attrition should display greater choice impulsivity as adults. We measured impulsive decision-making in a cohort of European starlings (Sturnus vulgaris) in which we had previously manipulated developmental telomere attrition by cross-fostering sibling chicks into broods of different sizes. We show that as predicted by state-dependent optimality models, individuals who had sustained greater developmental telomere attrition and who had shorter current telomeres made more impulsive foraging decisions as adults, valuing smaller, sooner food rewards more highly than birds with less attrition and longer telomeres. Our findings shed light on the biological embedding of early adversity and support a functional explanation for its consequences that could be applicable to other species, including humans.

No abstract