About

Eva Garrett is an Assistant Professor in the Department of Anthropology at Boston University. She is co-PI of the Sensory Morphology and Genomic Anthropology Lab and has a broad interest in the evolution of sensory systems in primates, with a particular focus on the sense of smell and pheromone detection. Her research integrates morphology, genomics, and paleontology to understand how humans and their closest relatives have evolved their unique sensory adaptations. She works with her postdoctoral scholar and UROP students to create digital models of primate crania, both extant and fossil, to measure bony correlates of the vomeronasal organ, which provides estimates of genes related to pheromone detection. Her work has demonstrated that only a recent branch of the primate tree, including apes and Old World monkeys, has reduced reliance on pheromone detection in favor of vision, contrary to earlier hypotheses about primate evolution.

Research topics

• Biology
• Ecology
• Computer Science
• Neuroscience
• Zoology
• Anatomy
• Aerospace engineering
• Cognitive science
• Paleontology
• Materials science
• Nanotechnology
• Psychology
• Engineering
• Evolutionary biology

Selected publications

• Human subsistence and signatures of selection on chemosensory genes

  Communications Biology · 2023 · 7 citations

  • Biology
  • Ecology
  • Evolutionary biology

  Chemosensation (olfaction, taste) is essential for detecting and assessing foods, such that dietary shifts elicit evolutionary changes in vertebrate chemosensory genes. The transition from hunting and gathering to agriculture dramatically altered how humans acquire food. Recent genetic and linguistic studies suggest agriculture may have precipitated olfactory degeneration. Here, we explore the effects of subsistence behaviors on olfactory (OR) and taste (TASR) receptor genes among rainforest foragers and neighboring agriculturalists in Africa and Southeast Asia. We analyze 378 functional OR and 26 functional TASR genes in 133 individuals across populations in Uganda (Twa, Sua, BaKiga) and the Philippines (Agta, Mamanwa, Manobo) with differing subsistence histories. We find no evidence of relaxed selection on chemosensory genes in agricultural populations. However, we identify subsistence-related signatures of local adaptation on chemosensory genes within each geographic region. Our results highlight the importance of culture, subsistence economy, and drift in human chemosensory perception.

  PublisherOA PDFDOI

• Particle deposition and sensory drive

  Evolutionary Anthropology Issues News and Reviews · 2020 · 2 citations

  Senior authorCorresponding
  • Computer Science
  • Neuroscience
  • Computer Science

  The mutualism between chemical cues emitted into the air and variations in how primates respond to them using olfaction has demonstrated aspects of species-specific adaptations. Building on this mutualism we can look at particle deposition as another means to understanding how various environments may have elicited biological changes that enable efficient communication. Research on particle movement and deposition within the nasal cavity is largely based on questions about health as it relates to drug delivery systems and overall olfactory function in modern humans. With increased access to 3D models and the use of computational fluid dynamic analysis, researchers have been able to simulate site-specific deposition, to determine what particles are making it through the nasal cavity to the main olfactory epithelium, which ultimately leads to processing in the olfactory bulb. Here we discuss particle deposition research, sensory drive and their potential applications to evolutionary anthropology.

  PublisherDOI

• Fruit scent and observer colour vision shape food-selection strategies in wild capuchin monkeys

  Nature Communications · 2019-06-03 · 56 citations

  articleOpen access

  The senses play critical roles in helping animals evaluate foods, including fruits that can change both in colour and scent during ripening to attract frugivores. Although numerous studies have assessed the impact of colour on fruit selection, comparatively little is known about fruit scent and how olfactory and visual data are integrated during foraging. We combine 25 months of behavioural data on 75 wild, white-faced capuchins (Cebus imitator) with measurements of fruit colours and scents from 18 dietary plant species. We show that frequency of fruit-directed olfactory behaviour is positively correlated with increases in the volume of fruit odours produced during ripening. Monkeys with red-green colour blindness sniffed fruits more often, indicating that increased reliance on olfaction is a behavioural strategy that mitigates decreased capacity to detect red-green colour contrast. These results demonstrate a complex interaction among fruit traits, sensory capacities and foraging strategies, which help explain variation in primate behaviour.

  PublisherOA PDFDOI

• De-Scent with Modification: More Evidence and Caution Needed to Assess Whether the Loss of a Pheromone Signaling Protein Permitted the Evolution of Same-Sex Sexual Behavior in Primates

  Archives of Sexual Behavior · 2019-11-18 · 3 citations

  letterSenior author
  PublisherDOI

• Effects of agricultural transitions on the evolution of human sensory systems

  OpenBU (Boston University) · 2017-04-01

  article

  The transition from hunting and gathering to agricultural food production, beginning
\naround 10,000 years ago, represents a dramatic shift in how people acquire and process
\nfood. These shifts to agriculture resulted in major changes in human environments and
\nbiology. For example, previous studies have identified selective effects of agriculture in
\nmany genes, such as those involved in lactose and starch metabolism, as well as immune
\nfunction. In other primates and non-primate mammals, sensory systems are often tightly
\nlinked to foraging strategy, such that dietary changes are associated with changes in the
\ngenes involved in taste, olfaction, and color vision. In this study, we investigated how the
\nshift to agriculture, a major change in foraging strategy, influenced the evolution of
\nhuman sensory genes. We used targeted capture methods to sequence 898 genes
\n(encoding taste receptors, olfactory receptors, and cone photopigments) and 71 neutral
\nintergenic regions in 165 individuals from two distinct geographic regions: Uganda and
\nthe Philippines. In each region, we sampled two hunter-gatherer populations and a
\nneighboring agricultural population, thus allowing us to compare sensory genes between
\nhunter-gatherer and paired agricultural populations across two independent transitions to
\nagriculture. We employed allele frequency-based tests (FST, population branch statistics,
\nand bayenv2) to identify candidate functional variants across sensory genes that may
\nreflect subsistence strategy adaptations. Preliminary results suggest that subsistence
\nstrategy influenced subtle shifts of allele frequencies in functional variants in at least two
\nbitter taste receptor genes and thirteen olfactory receptor genes in populations from both
\nUganda and the Philippines.

  Publisher

• Evolution of the primate vomeronasal system: fossil evidence from the Fayum

  OpenBU/Boston University Institutional Repository (Boston University) · 2017-04-01

  article1st authorCorresponding

  Extant primates vary dramatically in the presence and development of the vomeronasal system (VNS), which largely detects social pheromones and anti-predator chemosignals. While the strepsirrhine VNS resembles most mammals, haplorhines either have derived VNS traits with ambiguous effects on vomeronasal function, or have lost the system entirely. While a reduced reliance on vomeronasal olfaction in haplorhines is inferred, few studies have addressed VNS variation in extinct primates to examine the timing and context of the loss of this system. We have previously identified an osteological correlate of the vomeronasal organ, the vomeronasal groove (VNG), which allows us to implement a paleontological approach toward understanding primate VNS evolution. We investigated cranial material of fossil primates for the presence or absence of a VNG using microCT scans. The VNG was present in a broad temporal and taxonomic range of primate fossils, including plesiadapiforms, adapiforms, omomyoids, crown platyrrhines, stem anthropoids, and stem catarrhines. Notably the VNG persists as a relatively small gutter in the stem catarrhine Aegyptopithecus zeuxis, but is absent in advanced stem catarrhine Saadanius hijazensis, and the Miocene cercopithecoid Victoriapithecus. We estimate that VNG loss occurred between 30-28ma, based on our sample. These dates complement estimates for the accelerated rate of deleterious mutations, and loss of function, in the TRPC2 pheromone transduction gene in catarrhines between 40-25ma. Further exploration of the VNG in fossil primates will lead to a more thorough understanding of past sensory environments and their ultimate effects on sensory specializations of extant lineages.

  Publisher

• Was There a Sensory Trade-off in Primate Evolution? The Vomeronasal Groove as a Means of Understanding the Vomeronasal System in the Fossil Record

  CUNY Academic Works (City University of New York) · 2015-01-01 · 43 citations

  article1st authorCorresponding

  Primates have remarkable visual adaptations compared to most other mammals, long explained as associated with a trade-off with olfaction (smell). However, as more information comes to light on the role of olfaction in primate behavior it becomes apparent that olfaction is not a trivial sense. Even humans use smell to communicate, albeit in subtle ways, and the olfactory systems of the lemurs and lorises are very well-developed. Olfaction, however, is actually comprised of two distinct systems - the main olfactory and vomeronasal systems. These two systems overlap in many functions, but the main olfactory system is considered fairly generalized while the vomeronasal system is responsible for detecting odors specifically related to reproduction and predator avoidance. The vomeronasal system is incredibly variable in primates, being well-developed in the lemurs and lorises (strepsirhines) and absent in Old World monkeys and apes (catarrhines). Such variation does imply relaxed selection pressure to maintain a functional vomeronasal system in catarrhines, perhaps in response to gains in visual specialization. The goal of this dissertation is to investigate that evolutionary scenario using a multifaceted approach. A combined approach of comparing histology of the vomeronasal organ (the peripheral organ of the vomeronasal system) and computed tomography of the cranium is used to reveal variation in the vomeronasal organ across primates and to relate the soft-tissue organ to hard-tissue correlates. Indeed, the cartilage that surrounds the soft-tissue vomeronasal organ leaves a distinct impression on the nasal floor, which is here termed the "vomeronasal groove". To assess the utility of inferring biological function from gross dimensions of the vomeronasal organ and its groove, vomeronasal organ length is compared to the number of genes underlying vomeronasal olfaction. To test whether or not the main olfactory system is evolving in tandem with the vomeronasal system, a hard-tissue correlate of the main olfaction (area of the cribriform plate) is compared to the number of genes encoding main olfaction. Results indicate that main olfaction and vomeronasal olfaction are affected by evolution differently and that vomeronasal organ length when adjusted for body size has a strong statistical relationship with the proportion of functional vomeronasal receptor genes across mammals. To test whether or not phylogenetic history, ecology, and reproduction strategies affect the evolution of the vomeronasal organ in primates, size-adjusted vomeronasal groove length is compared across related categories. Mating categories, probably reflecting sexual selection, appear to drive variation in vomeronasal groove length in lemurs and lorises, while color vision phenotypes appear to drive variation in the tarsiers, monkeys, and apes. The acquisition of trichromatic color vision in Old World monkeys and apes is associated with vomeronasal organ loss, but trichromatic color vision does not appear to be a primary driving force of vomeronasal organ reduction in other primates. The acquisition of high visual acuity, rather, appears to affect initial reduction in length of the vomeronasal groove in crown haplorhines. Fossils representing various "stages" of primate evolution show presence of the vomeronasal groove, and the presence of this groove in the recent ancestors of Old World monkeys and apes suggest that the vomeronasal organ was not lost until crown catarrhines (the group containing Old World monkeys and apes) diverged from all other primate lineages. High visual acuity, routine trichromatic color vision, environments with increased visibility, and changes in social dynamics could have shifted the way in which socio-sexual information was perceived in some primates, increasing the priority of visual and main olfactory signals over vomeronasal signals. Thus, a strict "trade-off" may not have occurred as much as a "reallocation" of sensory information from the vomeronasal system to vision and main olfaction.

  Publisher

• Strong links between genomic and anatomical diversity in both mammalian olfactory chemosensory systems

  Proceedings of the Royal Society B Biological Sciences · 2014-04-09 · 72 citations

  articleOpen access1st author

  Mammalian olfaction comprises two chemosensory systems: the odorant-detecting main olfactory system (MOS) and the pheromone-detecting vomeronasal system (VNS). Mammals are diverse in their anatomical and genomic emphases on olfactory chemosensation, including the loss or reduction of these systems in some orders. Despite qualitative evidence linking the genomic evolution of the olfactory systems to specific functions and phenotypes, little work has quantitatively tested whether the genomic aspects of the mammalian olfactory chemosensory systems are correlated to anatomical diversity. We show that the genomic and anatomical variation in these systems is tightly linked in both the VNS and the MOS, though the signature of selection is different in each system. Specifically, the MOS appears to vary based on absolute organ and gene family size while the VNS appears to vary according to the relative proportion of functional genes and relative anatomical size and complexity. Furthermore, there is little evidence that these two systems are evolving in a linked fashion. The relationships between genomic and anatomical diversity strongly support a role for natural selection in shaping both the anatomical and genomic evolution of the olfactory chemosensory systems in mammals.

  PublisherOA PDFDOI

• The Vomeronasal Complex of Nocturnal Strepsirhines and Implications for the Ancestral Condition in Primates

  The Anatomical Record · 2013-11-19 · 64 citations

  article1st authorCorresponding

  This study investigates the vomeronasal organ in extant nocturnal strepsirhines as a model for ancestral primates. Cadaveric samples from 10 strepsirhine species, ranging from fetal to adult ages, were studied histologically. Dimensions of structures in the vomeronasal complex, such as the vomeronasal neuroepithelium (VNNE) and vomeronasal cartilage (VNC) were measured in serial sections and selected specimens were studied immunohistochemically to determine physiological aspects of the vomeronasal sensory neurons (VSNs). Osteological features corresponding to vomeronasal structures were studied histologically and related to 3-D CT reconstructions. The VNC consistently rests in a depression on the palatal portion of the maxilla, which we refer to as the vomeronasal groove (VNG). Most age comparisons indicate that in adults VNNE is about twice the length compared with perinatal animals. In VNNE volume, adults are 2- to 3-fold larger compared with perinatal specimens. Across ages, a strong linear relationship exists between VNNE dimensions and body length, mass, and midfacial length. Results indicate that the VNNE of nocturnal strepsirhines is neurogenic postnatally based on GAP43 expression. In addition, based on Olfactory Marker Protein expression, terminally differentiated VSNs are present in the VNNE. Therefore, nocturnal strepsirhines have basic similarities to rodents in growth and maturational characteristics of VSNs. These results indicate that a functional vomeronasal system is likely present in all nocturnal strepsirhines. Finally, given that osteological features such as the VNG are visible on midfacial bones, primate fossils can be assessed to determine whether primate ancestors possessed a vomeronasal complex morphologically similar to that of modern nocturnal strepsirhines.

  PublisherDOI

• The Vomeronasal Organ of New World Monkeys (Platyrrhini)

  The Anatomical Record · 2011-11-01 · 53 citations

  articleOpen access

  Although all platyrrhine primates possess a vomeronasal organ (VNO), few species have been studied in detail. Here, we revisit the microanatomy of the VNO and related features in serially sectioned samples from 41 platyrrhine cadavers (14 species) of mixed age. Procedures to identify terminally differentiated vomeronasal sensory neurons (VSNs) via immunolabeling of olfactory marker protein (OMP) were used on selected specimens. The VNO varies from an elongated epithelial tube (e.g., Ateles fusciceps) to a dorsoventrally expanded sac (e.g., Saguinus spp.). The cartilage that surrounds the VNO is J-shaped or U-shaped in most species, and articulates with a groove on the bony palate. Preliminary results indicate a significant correlation between the length of this groove and length of the VNO neuroepithelium, indicating this feature may serve as a skeletal correlate. The VNO neuroepithelium could be identified in all adult primates except Alouatta, in which poor preservation prevented determination. The VNO of Ateles, described in detail for the first time, had several rows of VSNs and nerves in the surrounding lamina propria. Patterns of OMP-reactivity in the VNO of perinatal platyrrhines indicate that few or no terminally differentiated VSNs are present at birth, thus supporting the hypothesis that some platyrrhines may have delayed maturation of the VNO. From a functional perspective, all platyrrhines studied possess structures required for chemoreception (VSNs, vomeronasal nerves). However, some microanatomical findings, such as limited reactivity to OMP in some species, indicate that some lineages of New World monkeys may have a reduced or vestigial vomeronasal system.

  PublisherOA PDFDOI

Frequent coauthors

• Timothy D. Smith

  Slippery Rock University

  24 shared

• Michael E. Steiper

  New York Consortium in Evolutionary Primatology

  12 shared

• Kunwar P. Bhatnagar

  University of Louisville

  12 shared

• Edward E. Morrison

  Auburn University

  9 shared

• John C. Dennis

  9 shared

• Christopher J. Bonar

  9 shared

• Anne M. Burrows

  Duquesne University

  9 shared

• Natalie K. Steckler

  University of Florida

  6 shared

Labs

• Sensory Morphology and Genomic Anthropology LabPI

Education

• Ph.D., Anthropology

  The Graduate Center, CUNY

  2015