Olfactory Orientation and Navigation in Humans.

Although predicted by theory, there is no direct evidence that an animal can define an arbitrary location in space as a coordinate location on an odor grid. Here we show that humans can do so. Using a spatial match-to-sample procedure, humans were led to a random location within a room diffused with two odors. After brief sampling and spatial disorientation, they had to return to this location. Over three conditions, participants had access to different sensory stimuli: olfactory only, visual only, and a final control condition with no olfactory, visual, or auditory stimuli. Humans located the target with higher accuracy in the olfaction-only condition than in the control condition and showed higher accuracy than chance. Thus a mechanism long proposed for the homing pigeon, the ability to define a location on a map constructed from chemical stimuli, may also be a navigational mechanism used by humans

Naris deformation in Darwin’s finches: Experimental and historical evidence for a post-1960s arrival of the parasite Philornis downsi

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).The rate of evolution depends on the strength of selection, which may be particularly strong for introduced parasites and their naive hosts. Because natural selection acts on phenotypes and because parasites can alter host phenotype, one fruitful starting point to measure the impact of novel pathogens is to quantify parasite-induced changes to host phenotype. Our study system is Darwin’s finches on Floreana Island, Galápagos Archipelago, and the virulent fly larvae of Philornis downsi that were first discovered in Darwin’s finch nests in 1997. We use an experimental approach and measure host phenotype in parasitized and parasite-free chicks in Darwin’s small ground finch (Geospiza fuliginosa). Beak size did not differ between the two treatment groups, but naris size was 106% larger in parasitized chicks (∼3.3 mm) versus parasite-free chicks (∼1.6 mm). To test if P. downsi was present prior to the 1960s, we compared naris size in historical (1899–1962) and contemporary birds (2004–2014) on Floreana Island in small ground finches (G. fuliginosa) and medium tree finches (Camarhynchus pauper). Contemporary Darwin’s finches had significantly larger naris size (including extreme deformation), whereas historical naris size was both smaller and less variable. These findings provide the first longitudinal analysis for the extent of P. downsi-induced change to host naris size and show that Darwin’s finches, prior to the 1960s, were not malformed. Thus natural selection on altered host phenotype as a consequence of P. downsi parasitism appears to be contemporary and novel

Evolutionary Psychology and Mental Health

AN EVOLUTIONARY PERSPECTIVE revolutionized our understanding of behavior over a generation ago, but most mental health clinicians and researchers still view evolution as an interesting or even threatening alternative, instead of recognizing it as an essential basic science for understanding mental disorders. Many factors explain this lag in incorporating new knowledge, but the most important may be the clinician’s pragmatic focus on finding ways to help people now. Evolutionary researchers have not found a new treatment for a single mental disorder, so why should mental health clinicians and researchers care about evolutionary psychology (EP)? This chapter attempts to answer that question. The greatest value of an evolutionary approach is not some specific find- ing or new therapy, but is instead the framework it provides for uniting all aspects of a biopsychosocial model. Perhaps equally valuable is the deeper empathy fostered by an evolutionary perspective on life’s vicissitudes. An evolutionary perspective does not compete with other theories that try to explain why some people have mental disorders and others do not. Instead, it asks a fundamentally differ- ent question: Why has natural selection left all humans so vulnerable to mental disorders? At first, the question seems senseless. Natural selection shapes mecha- nisms that work, so how can it help us understand why the mind fails? It is also difficult to see how it is useful to know why we are vulnerable. Who cares why all humans are vulnerable to depression, when the goal is to help the individual who is depressed here and now? Surmounting these conceptual hurdles is a challenge that requires time and effort. Researchers and clinicians will make the effort when they know what evolution offers to the understanding of mental disorders.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145726/1/Nesse - 2015 - Evolutionary Psychology and Mental Health.pdfDescription of Nesse - 2015 - Evolutionary Psychology and Mental Health.pdf : Chapte

Data from: The Beagle collections of Darwin's finches (Geospizinae)

No description availabl

Data from: Adaptive divergence in Darwin's small ground finch (Geospiza fuliginosa): divergent selection along a cline

We examine here, in a single year (2005), phenotypic divergence along a 560-m elevation gradient in Darwin's small ground finch (Geospiza fuliginosa) in the Galápagos Islands. In this sample, four composite measures of phenotypic traits showed significant differences along the 18-km geographical cline extending from lowlands to highlands. Compared with lowland birds, highland birds had larger and more pointed beaks, and thicker tarsi, but smaller feet and claws. Finches in an intervening agricultural zone had predominantly intermediate trait values. In a second, mark–recapture study we analyse selection on morphological traits among birds recaptured across years (2000–2005) in lowland and highland habitats. Birds were more likely to survive in the highlands and during the wet season, as well as if they had large beaks and bodies. In addition, highland birds exhibited higher survival rates if they had small feet and pointed beaks – attributes common to highland birds as a whole. Lowland birds were more likely to survive if they possessed the opposite traits. Selection therefore reinforced existing morphological divergence, which appears to reflect local adaptation to differing resources during the predominantly drought-ridden conditions that characterized the 5-year study. Alternative explanations – including genetic drift, matching habitat choice, deformation by parasites, and the effects of wear – received little or no support