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The Visible Ape Project: A free, comprehensive, web‐based anatomical atlas for scientists and veterinarians designed to raise public awareness about apes



The Visible Ape Project (VAP) is a free online platform providing unprecedented access to a suite of resources designed to comprehensively illustrate and educate about the anatomy of our closest relatives, the apes. It contains photographs, magnetic resonance images, and computed tomography scans, as well as three-dimensional models that can be manipulated to explore homologies and variations in soft and hard tissues in hylobatids, orangutans, gorillas, chimpanzees, and bonobos. Based at Howard University, a historically black university, it aims to reach communities underrepresented in anthropology and evolutionary biology, providing educational materials appropriate for K-12 and college classrooms in both English and Spanish. Accordingly, VAP incorporates outreach activities to disseminate science and promote awareness of apes, forming partnerships with veterinarians and conservationists in Africa and Asia. In this paper, we present an introduction to the website to illustrate how this accessible, evolving resource can support evolutionary anthropology and related disciplines.
The Visible Ape Project: A free, comprehensive, web-based
anatomical atlas for scientists and veterinarians designed to
raise public awareness about apes
Nicole Barger
| José Saúl Martín
| Eve K. Boyle
| Marli Richmond
Rui Diogo
Anatomy Department, Howard University
College of Medicine, Washington, District of
Center for the Advanced Study of Human
Paleobiology, The George Washington
University, Washington, District of Columbia
Anthropology, The George Washington
University, Washington, District of Columbia
Biology Department, University of Aveiro,
Aveiro, Portugal
Nicole Barger, Anatomy Department, Howard
University, College of Medicine, Washington,
Funding information
NSF-BCS Excellence in Research Grant, Grant/
Award Number: 1856329
The Visible Ape Project (VAP) is a free online platform providing unprecedented
access to a suite of resources designed to comprehensively illustrate and educate
about the anatomy of our closest relatives, the apes. It contains photographs, mag-
netic resonance images, and computed tomography scans, as well as three-
dimensional models that can be manipulated to explore homologies and variations in
soft and hard tissues in hylobatids, orangutans, gorillas, chimpanzees, and bonobos.
Based at Howard University, a historically black university, it aims to reach communi-
ties underrepresented in anthropology and evolutionary biology, providing educa-
tional materials appropriate for K-12 and college classrooms in both English and
Spanish. Accordingly, VAP incorporates outreach activities to disseminate science
and promote awareness of apes, forming partnerships with veterinarians and conser-
vationists in Africa and Asia. In this paper, we present an introduction to the website
to illustrate how this accessible, evolving resource can support evolutionary anthro-
pology and related disciplines.
anatomy, awareness, biological anthropology, human evolution, muscles, outreach, STEM
Human evolutionary biology cannot be understood without
referencing our closest relatives, the apes. These can be divided into
lesser apes (hylobatids, including gibbons and siamang) and great apes,
including orangutans, gorillas, bonobos, and common chimpanzees.
Evolutionary anthropology arose as a discipline largely through the
exercise of comparing humans and apes, e. g., their anatomy, locomo-
tion, and behavior. Today, we understand that the markedly distinct
phenotypes characterizing each ape species result from only minor
variation in the protein coding genome.
Yet, considerable effort has
been spent cataloguing ape genomic variation through public data-
bases, while resources on ape anatomy remain available only to a pro-
portionately smaller number of specialists. The open-source platforms
that do exist, like MorphoSource (, provide
excellent access to raw data but do not provide detailed information
about anatomical structures or homologies for most specimens, partic-
ularly soft tissues such as muscles, nerves, and blood vessels, or ana-
tomical variation. Given the rare and precious nature of ape samples,
resources required to further interrogate these data are often expen-
sive and less accessible. In fact, a major problem of texts focusing on a
single species, or even a single specimen as in some previous atlases,
is that they often do not illustrate homologies across apes nor varia-
tions within a certain ape genus, while papers addressing homologies
are largely limited in their anatomical scope. The paucity of informa-
tion on soft-tissues is exemplified by the fact that, of the soft-tissues
catalogued in the human in Nomina Anatomica,
only 10% have been
well described in apes.
This complicates efforts not only to translate
Received: 29 March 2021 Accepted: 13 April 2021
DOI: 10.1002/evan.21896
Evolutionary Anthropology. 2021;111. © 2021 Wiley Periodicals LLC. 1
variations in genotype to anatomical phenotype but also to isolate
morphological correlates of behavioral phenotypes unique to the
human lineage, for example, bipedalism, complex tool use, or lan-
More broadly, it encumbers instruction in human evolutionary
biology, especially in challenging pedagogical environments outside of
universities where active learning is key.
The Visible Ape Project (VAP) ( is a
major project funded by NSF-HBCU-EiR (Historically Black Colleges
and Universities - Excellence in Research) with various related aims.
One is to fill this scientific gap by providing a common, intuitive, web-
based, public reference atlas presenting two-dimensional (2D) and
three-dimensional (3D) resources for visualizing ape anatomy
(Figures 16), including musculoskeletal, cardiovascular, nervous, and
digestive systems. All great ape generacommon chimpanzees (Pan
troglodytes), bonobos (Pan paniscus), gorillas (Gorilla gorilla), and orang-
utans (Pongo pygmaeus)are included in addition to gibbons
(Hylobates sp.) and siamang (Symphalangus syndactylus). Drawing on
FIGURE 1 The Visible Ape Project provides multiple ways to
view anatomical information for each ape. For example, for
chimpanzee crania, we provide MRIs (top), 3D models of the
musculature and skull (upper left and right), detailed soft tissue and
osteological photographic atlases (middle left and right), and artists'
illustrations (bottom left)
FIGURE 2 3D models can be
manipulated in the webpage (left).
Use scroll to zoom and left click and
hold to rotate; small numbers on
musculoskeletal models refer to
individual muscles. 3D models are
designed to facilitate comparison of
homologous structures across species
(right). Some models incorporate
multiple species to simplify comparing
variation across ape species (upper
right). In these models, large numbers
identify species. Models of human
anatomy may be used to address
evolutionary variation between
humans and apes (lower right)
FIGURE 3 The Visible Ape Project contains rare developmental
specimens. CT-based 3D models, like these neonatal and adult
gorillas, can be used to appreciate skeletal variation through
the expertise of an international group of collaborators,
VAP is
the first freely available, detailed multispecies ape anatomical atlas. As
such, it should prove an essential tool for researchers seeking to iden-
tify and analyze homologous anatomical regions across hominoids,
substantially increasing information available for these rare species.
To bridge to human anatomy and evolutionary biology, VAP includes
3D anatomical models of Homo sapiens, designed to complement, and
in a way inspired by, the Visible Human Project (https://www.nlm.nih.
gov/research/visible/visible_human.html). Integrating this diverse data
under one framework, VAP is positioned to be a transformative tool
for research in evolutionary anthropology and related fields like
genomicsincluding research about the links between phenotype and
genotypedevelopmental biologyincluding information about ape
fetuses, neonates, infants, juveniles/subadults and adultsanatomy,
systematics, biomechanics, physiology, and neuroscience.
A second, major aim of VAP is to help educators in STEM fields
increase scientific literacy in human evolutionary biology and raise
public awareness and appreciation of our diverse and imperiled evo-
lutionary relatives. The Visible Human Project recognized that 3D
anatomical models greatly improve the understanding of anatomical
concepts in education.
That project has proven extremely useful to
the scientific community and popular with the general public, unde-
rscoring the utility of this approach. VAP capitalizes on this empha-
sis, incorporating 3D anatomical models to provide a more intuitive
format for understanding the relationship between anatomical struc-
tures presented in 2D atlases (Figure 1) and for visualizing homolo-
gies across hominoids (Figure 2). This, in turn, highlights that, despite
the ecological and morphological diversity of hominoid species, the
gross internal anatomy of apes is strikingly similar, in general, to that
of humans. This has two important implications for the general pub-
lic: it emphasizes that we evolved from apes, promoting inclusion in
STEM disciplines related to biological and human evolution, and
stresses that apes are very similar to us on the inside and thus
deserve to be respected and protected. As such, it has pragmatic
value as a pedagogical tool in K-12, university, and graduate educa-
tion, including veterinary training, as well as a tool for scientific dis-
semination to underrepresented communities in the United States
and globally.
FIGURE 4 Accessing the
resources is simple. (1) From the
explore page on the header, (2) select
the species and visualizations of
interest, (3) which will present the
visualization tool and the View
button. Clicking on the View button
will take you to the visualization of
interest. The bottom half of the image
details the visualization tools
currently available and their
associated resources
Based at Howard University, the most renowned HBCU (histori-
cally black colleges and universities), VAP especially aims to increase
engagement with and participation in anthropology and biology by
groups that are underrepresented in these fields, particularly African-
American and Latina/o communities.
To reach broader audiences
within and outside of the United States, many resources are pres-
ented in both Spanish and English. Providing free resources appropri-
ate for K-12 education can help to increase early educational
exposure to these concepts across diverse communities in the US and
globally, promoting and extending the scope of audiences interested
in our discipline. VAP includes STEM outreach to further advance
this goal.
In its first year (March 2020 to March 2021), the VAP website
hosted approximately 6,000 visits in total from over 60 countries
representing all inhabited continents (Figure 7). VAP was accessed by
users across the globe and in nearly all US states (43 states and the
District of Columbia). Designed to be inclusive to Spanish-speaking
communities, it has received high use in Spanish-speaking countries
and states with large Latina/o populations (e.g., California,
New York, Texas, and Florida). Academic institutions accessing
resources were diverse, including universities, museums, and com-
munity colleges. Many of these visits have already led to practical
outcomes, for example, veterinarians using VAP data in US
zoos, conservationists in ape sanctuaries in Africa establishing
outreach collaborations, and science dissemination projects that
kids. Below we present a brief overview of the site and its
resources to formally introduce VAP to researchers and educators
FIGURE 5 The site incorporates a diverse array of illustrations. For individual species, some illustrations reveal the association between hard
and soft tissues (upper left) or provide detailed illustrations incorporating anatomical terminology (lower left). Inter-species illustrations (upper and
lower right) indicate shared and derived features across ape species
in evolutionary anthropology, comparative anatomy, and related
fields of science.
2.1 |Collection
VAP collates anatomical resources obtained from long-term
projects detailing homologous hard and soft-tissues across ape
augmenting them with complementary open-source
data. It integrates magnetic resonance images (MRI), photographic
data, 3D models based on computed tomography (CT) scans, and 2D
and 3D renderings by anatomists and anatomical illustrators (Table 1;
Figures 16). Currently, there are 642 anatomical resources from
56 individual nonhuman apes, including 9 bonobos, 17 chimpanzees,
8 gorillas, 10 orangutans, 9 gibbons, and 3 siamang (Table 2) and
20 resources representing humans for a total of 662. The site contains
537 cadaver dissection photographs, 53 anatomical illustrations,
48 3D musculoskeletal models, 10 3D CT whole skeleton models, one
3D CT of the cardiovascular system, and 13 brain, head, and neck
MRIs. Developmental stages span fetal (n=2), neonate (n=4), infant
(n=7), juvenile/subadult (n=6), and adult (n=34) periods (Table 2;
Figure 3). It includes 30 males, 22 females, and 4 apes of unknown
sex (CT models). All cadaver specimens were obtained after their nat-
ural death from zoos or research institutes. Atlas images are full color
and were taken at high resolution (36.3 M) with a Nikon D-800 cam-
era equipped with micro and macro lenses, providing clear visualiza-
tion of fine detail. Most dissections were performed on fresh frozen
specimens to ensure optimal preservation of soft tissues. CT scans of
ape cadavers were mainly performed using a Somatom multislice Sen-
sation 64 CT-system at the University of Vallidolidcourtesy of Fran-
cisco Pastoror were obtained from MorphoSource (Table 2). MRIs
were collected in vivo and were sourced from the National Chimpan-
zee Brain Resource (, provided courtesy of
J. K. Rilling.
3D models of whole skeletons were created with
Avizo 7.1.0 (ThermoFisher, Inc.) from CT data from ape cadavers,
stored as PLY files, and cleaned with Geomagic 2017 (3D Systems).
3D muscle reconstructionsdone by coauthor J. S. Martinare based
primarily on dissections from atlases authored by Diogo and col-
(Table 1) as well as on work from other groups
obtained through comprehensive literature review
to approximate
what is the most typical phenotypic configuration for each species. In
the 3D editor Zbrush (Pixologic, Inc.), sculpting tools (brushes) were
used to build and transform all surface elements of the musculoskele-
tal system. To build organized and uniform 3D structures, a dynamic,
interactive mesh subdivided into polygons was sequentially updated
to recalculate polygons that were initially deformed, achieving a com-
pact base allowing continuity and detail improvement until the correct
form was reached. A standard color was added and elements such as
light, shadow, material, and position were configured before render-
ing. Each render act as a photographof the model, an accurate sci-
entific illustration as it was drawnin 3D. This method was
FIGURE 6 CT scan of a siamang injected with radiopaque
material to reveal the cardiovascular system, from the Museums at
the Royal College of Surgeons
FIGURE 7 The Visible Ape Project is accessed by users across the globe and in nearly all US states. Designed to be inclusive to Spanish-
speaking communities, it has received high use in Spanish-speaking countries and states with large Latina/o populations (e.g., CA, NY, TX, and FL)
successively used to achieve realistic 3D musculoskeletal models of
heads, upper, and lower limbs.
2.2 |Nomenclature
Anatomical structures are defined based on extensive, long-term
analyses of homologies across ape species published by Diogo and
colleagues in several atlases.
Latin terms similar to those
used in modern human anatomy
are used to label musculoskeletal
structures. English names are provided when Latin does not easily
To facilitate access by diverse users, the interface is designed to be
easily navigated by researchers and members of the public.
Anatomical resources may be accessed from the EXPLORE link on our
webpage banner (Figure 4). Use the left drop-down menu, SEARCH
BY SPECIES, to select the species of interest and the right menu, SEA-
RCH BY VISUALIZATION TOOL, to further refine the results. To
access each resource, select the orange View button. A quick naviga-
tion menu is also provided in the footer. A description of each
resource currently in the archive follows.
3.1 |Atlas photographs
Each species is documented in over 70 atlas photographs (Figure 4).
Clicking on View for each tool provides an overview of the photo-
graphs organized by anatomical region: Head and Neck, Upper Limb,
Lower Limb, and Trunk. Left clicking on an individual photograph
increases the image to full size. Each image includes the names of
major anatomical features with lines indicating their position on the
gross specimen and anatomical orientation.
TABLE 1 Inventory of resources
Species Media HN UL LL T W Total
Bonobo MRIs 2 2
Illustrations 3 5 2 10
Photographs 25 67 56 12 160
3D model 2 2 2 1 7
Chimpanzee MRIs 2 2
Illustrations 3 4 2 9
Photographs 35 23 14 6 78
3D model 3 2 2 0 3 10
Gorilla MRIs 2 2
Illustrations 2 3 1 6
Photographs 27 46 20 36 129
3D model 3 2 2 0 2 9
Orangutan MRIs 3 3
Illustrations 2 3 1 6
Photographs 31 21 36 8 96
3D model 3 2 2 0 1 8
Gibbon MRIs 2 2
Illustrations 1 1 1 3
Photographs 14 10 38 12 74
3D model 2 2 2 0 1 7
Siamang 3D model 2 2
Human MRIs 2 2
Illustrations 3 6 4 13
3D model 2 0 1 0 2 5
Species comparison Illustrations 2 3 1 6
3D model 9 1 1 11
Grand total 662
Non-human ape total 642
Abbreviations: C, cranium; UL, upper limb; LL, lower limb; T, thorax; W, whole body.
TABLE 2 List of apes and associated anatomical resources on the current website build. Visualization type: OA, osteological atlas; STA, soft
tissue atlas; 3DS, 3D skeleton model; 3DM, 3D muscle model; 3DC, 3D cardiovascular model. Source Institution: AMNH-M, American Museum of
Natural History via MorphoSource; AZ, Antwerp Zoo; BV, Bioparc Valencia; CMN, Canadian Museum of Nature; DU, Duquesne University; HU,
Howard University; NCBR, National Chimpanzee Brain Resource; PFA, Primate Foundation of Arizona; RSCOM, Museums at the Royal College of
Surgeons; VU, Valladolid University; YPM-M, Yale Peabody Museum via MorphoSource; YNPRC, Yerkes National Primate Research Center. ARK
identifiers are provided for data accessed on
Name Age group Sex Species Visualization Source institution/copyright
CMS GG1 Adult Male Gorilla gorilla STA, 3DM CMN
Neonate Male Gorilla gorilla 3DS, OA, STA, 3DM VU/BV
KEKLA Juvenile Male Gorilla gorilla MRI NCBR
KINYANI Subadult Female Gorilla gorilla MRI NCBR
VU GG1 Adult Female Gorilla gorilla STA, 3DM VU
VU GG2 Adult Female Gorilla gorilla OA, STA, 3DM VU
VU GG3 Adult Male Gorilla gorilla STA, 3DM VU
YPM MAM 014998 Unknown Unknown Gorilla gorilla 3DS YPM-M ark:/87602/m4/M56407
Infant Male H. gabriellae STA, 3DM VU
Adult Male H. gabriellae STA, 3DM VU
M-201742 Unknown Male H. hoolock 3DS AMNH ark:/87602/m4/M25860
Adult M H. klossii 3DM VU
BUDDY Adult Male H. lar MRI NCBR
CLEO Adult Female H. lar MRI NCBR
GWU HL1 Juvenile Female H. lar STA, 3DM GWU
Adult Male H. lar STA, 3DM HU
Adult Male H. muelleri STA, 3DM DU
ARJU Adult Unknown Pan paniscus OA AZ
ANO Fetus Female Pan paniscus STA, 3DM AZ
BOSONDJO Adult Male Pan paniscus MRI NCBR
ETJE Infant Male Pan paniscus STA, 3DM AZ
FOYO Infant Male Pan paniscus STA, 3DM AZ
JASIRI Juvenile Female Pan paniscus STA, 3DM AZ
KIDOGO Adult Male Pan paniscus STA, 3DM AZ
LOREL Adult Female Pan paniscus MRI NCBR
M-202870 Subadult Male Pan paniscus 3DS AMNH-M ark:/87602/m4/M38741
GWU-ANT PT1 Adult Female Pan troglodytes STA, 3DM GWU
GWU-ANT PT2 Adult Female Pan troglodytes STA, 3DM GWU
HU PT1 Infant Male Pan troglodytes STA, 3DM HU
MARV Adult Male Pan troglodytes MRI NCBR
MARY Adult Female Pan troglodytes MRI NCBR
PFA 1009 Adult Female Pan troglodytes STA, 3DM PFA
PFA 1016 Adult Female Pan troglodytes STA, 3DM PFA
PFA 1051 Infant Female Pan troglodytes STA, 3DM PFA
PFA 1077 Infant Female Pan troglodytes STA, 3DM PFA
Infant Male Pan troglodytes STA, 3DM PFA
PTN1 Neonate Male Pan troglodytes 3DS VU
RCSOM/OH/W099 Fetus Unknown Pan troglodytes 3DS, CT RCS OH
Adult Male Pan troglodytes STA, 3DM VU
Adult Male Pan troglodytes STA, 3DM VU
Adult Female Pan troglodytes OA, 3DM NCBR
YERKESU Adult Male Pan troglodytes STA, 3DM YNPRC
3.2 |3D models
3D models of hard and soft tissues are provided for each species
Table 2). Models of the musculature are separated into head and
neck, upper limb, and lower limb for each species (Figure 4). They
incorporate a numbering system to identify muscles visible on the
model surface (Figure 2). Clicking the View button will open a
form Sketchfab ( Click on the model to
load it. Once loaded, left click and hold to rotate the model or use
scroll to zoom in and out (Figure 2). The right mouse button can
be used to pan, changing the position of the model. Model
meshes can be downloaded in .obj or .ply format from the FILE
the upper right corner of the screen. They can also be directly
accessed from our Sketchfab page:
3.3 |Scientific illustrations
Detailed line drawings primarily illustrating myological anatomy are
available for each ape (Figure 5). These drawings present anatomy in a
way that is easy to parse, visually, and many are color-coded to help
discriminate muscle groups.
3.4 |MRIs and CTs
We currently profile MRIs for one male and one female per species
(Figure 4). Selecting View opens these two MRIs in the same browser
page. Clicking on the MRI will start the navigation. Clicking on the
image or the left arrow advances forward in the image stack and
the right arrow, backward. We provide a variety of CT scans, mostly
of skeletons, but also of a vessel injected body of a siamang (Figure 6).
Raw data can be accessed through the FILE DOWNLOADS AND
DATASETS menu option (Figure 8).
3.5 |Inter-species comparisons
While separate browser pages can be used to compare species, the
website also incorporates several visualizations that include multiple
species accessible via the INTER-SPECIES option on the pull-down
menu in SEARCH BY SPECIES. Some 3D myological models incorpo-
rate multiple species to facilitate direct comparison (Figure 2), while
many scientific illustrations indicate the relationship between groups
of muscles and specify known variation across hominoids (Figure 5).
3.6 |Educator resources
Under the Resources page, the Educator Resourcesbutton provides
the primary material meant for education, including several lesson
TABLE 2 (Continued)
Name Age group Sex Species Visualization Source institution/copyright
YPM MAM 015939 Adult Male Pan troglodytes 3DS YPM-M ark:/87602/m4/M58004
GWU PP1 Adult Male Pongo pygmaeus STA, 3DM GWU
HATI Adult Female Pongo pygmaeus MRI NCBR
HU PP1 Neonate Male Pongo pygmaeus STA, 3DM HU
MENTUBAR Juvenile Male Pongo pygmaeus MRI NCBR
MOLEK Adult Male Pongo pygmaeus MRI NCBR
PPN1 Neonate Male Pongo pygmaeus 3DS VU
VU PA1 Adult Female Pongo abelli OA VU
VU PA2 Adult Female Pongo abelli OA VU
VU PP1 Adult Female Pongo pygmaeus STA, 3DM VU
VU PP2 Adult Female Pongo pygmaeus OA, STA, 3DM VU
Adult Male Symphalangus syndactylus STA, 3DM DU
M-202326 Unknown Unknown S. syndactylus 3DS AMNH ark:/87602/m4/M24479
RSCOM-OH-W098 Neonate Unknown S. syndactylus 3DC RSCOM
Uncatalogued specimen.
Originated from the Bioparc Fuengirola.
Yerkes Regional Primate Center number YN87-134.
Originated from the Cleveland MetroParks Zoo.
Originated from the Fundaci
on Mona.
Originated from the Zoo-Aquarium of Madrid.
plans for using the site tools to explore evolutionary and developmen-
tal anatomy. Each provides a lesson and an answer key in Spanish and
in English. Additionally, a glossary of evolutionary and anatomical
terms can be accessed from the resources tab in both languages. An
informational overview of each ape, explaining the species' habitat,
conservation status, behavior, lifespan, locomotor habits, and size, is
accessible from the home page. These summaries are succinct and
designed to be easily understood by young readers. Because illustra-
tions and models are suitable for younger children, we expect the site
to be useful for educators in diverse environments. Atlas material is
also designed to augment instruction in human evolutionary biology.
3D models are freely available and are saved in a format that is com-
patible with 3D printers. Additional models with no numbering are
included and could be used to test anatomical concepts. Sketchfab-
hosted material can be viewed in virtual reality to provide an alterna-
tive, hands onexperience.
The website is built with various audiences in mind: researchers, stu-
dents, and educators from K-12 to higher education, people who are
responsible for the health and well-being of primates, conservationists
that aim to promote awareness of apes, and the general public, includ-
ing underprivileged and underrepresented minorities in Western
countries and rural communities in African and Asian countries.
Because VAP is the sole free 2D and 3D atlas of extant ape anatomy
documenting homologies and variations across genera of all major ape
groups, it should aid anthropologists and biologists who rely on com-
parative anatomy to make inferences about extinct taxa. For example,
VAP could inform models of fossil hominoid musculature which
require the use of methods like the extant phylogenetic bracket
artistic reconstructions based on such models. Comprehensive data
on soft tissues will similarly be valuable in systematic biology. Evolu-
tionary developmental biologists can better understand developmen-
tal variation across the hominoid clade, directly comparing apes at
different developmental stages within and between species. Hypothe-
ses about the significance of genetic variation observed over hominin
evolution and about the links between the phenotype and genotype
can be better interrogated with phenotypic information catalogued in
VAP, as the know genotypes of each ape can be studied/compared
with the phenotypes illustrated in the VAP. Broadly, we believe VAP
benefits researchers from any field who wish to perform comparative
and evolutionary studies of apes, including humans, that require ana-
tomical precision.
VAP resources should aid teachers and students of general biol-
ogy, biological anthropology, comparative anatomy, mammalogy, and
zoology. Active learning can promote better understanding of ana-
tomical concepts,
but few students have the opportunity to appreci-
ate ape anatomy through gross dissection, given the limited
availability of ape cadavers and infrastructure required. VAP attempts
to overcome this barrier by making the information widely available to
students, teachers, and the general public. Our educational resources
have already been accessed by universities and community colleges.
During the COVID-19 pandemic, we shared them with local elemen-
tary school students and their families through a virtual event with
the DC outreach organization, Turning the Page (https:// To educate the broader public, we introduced
visitors at the National Museum of Natural History to VAP. In Portu-
gal, the governmental ciencia-viva (live-science) project will use
printed 3D models to promote awareness of both our evolution and
ape conservation. Several African-American students in the College of
FIGURE 8 From the FILE
menu item, raw radiographic image
series and 3D mesh files can be
Medicine and undergraduate students in the Biology Department of
Howard University have been actively engaged in the project, with
the aim of bridging the gap between medical education and human
evolutionary biology which can hinder medical appreciation of varia-
tions, anomalies, and pathology of human structures.
Other vital groups VAP is designed to support are veterinarians
and other caretakers of apes, both wild and captive. Currently, there
are limited resources to understand ape anatomy in the detail needed
to inform medical procedures or evaluate injuries. Surgeons at George
Washington University and Hospital are already using our 3D models
and 2D photographs to undertake hand surgery of an orangutan at
the Smithsonian. Moreover, we will engage in collaborative activity
with the Gorilla Doctors of the Mountain Gorilla Veterinary Project in
Rwanda. Thus, the suite of information provided by VAP will aid the
care and management of both captive and wild apes. In this regard,
VAP could contribute both to the health of individual apes in addition
to broader conservation efforts. So far, it can be said that in just
1 year, the VAP has been particularly active and successful in terms of
its applications and outreach.
Within academia, VAP's applications and goals concern the promotion
of research and development in evolutionary anthropology, compara-
tive biology, and other fields to open avenues for interaction and col-
laboration by providing free access to extensive documentation of
ape anatomy. For the general public, we hope to increase literacy in
evolutionary anthropology by providing free access to material for
education and exploration. A major objective of VAP is to increase
awareness of the remarkable similarities between ourselves and our
closest living relatives who risk extinction. Showing how similar
humans and apes are can draw attention to our close relationship with
other apes, highlighting the need for their conservation. Finally, we
are committed to increasing representation of historically underrepre-
sented groups in evolutionary anthropology. African-Americans are
especially underrepresented in ecology and evolutionary biology (EEB)
departments, receiving less than 2% of all PhDs awarded in EEB
related subfields in 2014.
Lack of exposure to evolutionary concepts
has been associated with a lower sense of belonging in EEB among
African-American students, while Latina/o students also report lower
exposure to evolutionary biology relative to their white counter-
Thus, VAP's broader benefits to public education, providing a
free, accessible platform to explore human evolutionary biology, may
be magnified in these groups. As a research project of Howard Uni-
versity, a premier MSI (minority serving institution), VAP incorporates
and is, in part, built by African-American undergraduate students who
are profiled on the Our Teampage. Moreover, this resource in evo-
lutionary anthropology will be housed permanently at Howard Univer-
sity, reinforcing the position of this HBCU within EEB research and
the association of MSIs with work in EEB. We aim to be inclusive of
mono- and bilingual Spanish speakers. Strikingly, last year,
approximately a third of all non-US visitors to VAP were from coun-
tries where Spanish is the primary language. Within the United States,
many users were located in states which have large Latina/o
populations like California, New York, and Texas (Figure 7). Ultimately,
we would like to make VAP open to contributions from diverse
research communities to comprehensively represent anatomical varia-
tion among the apes and to encourage its use in educational outreach
globally and in underserved communities in the United States.
We envision VAP to be a living documentof ape anatomy, increas-
ing in breadth over time. In the first year, we have focused on building
visualizations primarily of the musculoskeletal system, with some atlas
pages devoted to soft tissues like those of the digestive system. Our
current objective is to address the nervous system, including the
nerves of the body and the brain, while continuing to expand
the available musculoskeletal visualizations, and to incorporate raw
CT and MRI scans in the site. Plans are in place to perform more
detailed dissections and 3D renderings of the arteries, veins, and
nerves. We are partnering with the American Museum of Natural His-
tory to perform whole body CT and MRI scans. These scans, in addi-
tion to scans used to create some of the skeletal models for the site,
will be made freely available to researchers through the download
page. We would like to pursue in-person outreach within the
Washington, DC, public, private, and charter school systems and hope
to expand the scope of this work, especially through collaborations in
Rwandan and other African communities living near ape habitats.
Additionally, we plan to hold workshops to increase visibility of VAP
among relevant professional organizations, for example, the American
Associations of Physical Anthropologists, Anatomists, and Zoo Veteri-
narians. We are also establishing partnerships with conservationists
and ape sanctuaries in Africa and Asia. In fact, one of the main objec-
tives for the next year is to have much more visibility and activity in
non-Western countries, something that we could not fully engage in
yet because of the current pandemic.
This work is funded by the NSF-BCS Excellence in Research Grant
#1856329. We thank collaborators who have provided materials for
the website: Drs. Francisco Pastor, Bernard Wood, Julia Molnar,
Carina Phillips, Vance Powell, Josep Potau, Felix de la Paz and Laura
Martínez-Íñigo, our student contributors: Latonya Aaron, Boyani
Moikobu, Tah-jai Sharpe, and Alexander Pru˚cha, and our partners: the
American Museum of Natural History, Antwerp University and Zoo,
Icahn School of Medicine at Mt. Sinai, Royal College of Surgeons, Uni-
versity of Valladolid, University of Antwerp, and the George
Washington University. Ape silhouettes in figures are from PhyloPic
(, attributed to
T. Michael Keesey and Tony Hisgett (chimpanzee: Figure 1) and Gar-
eth Monger (orangutan: Figure 4).
The data that support this study are openly available from the Visible
Ape Project at and Morphosource at (see Table 2 for direct links).
Nicole Barger
Rui Diogo
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[6] Pobiner B. 2016. Accepting, understanding, teaching, and learning
(human) evolution: Obstacles and opportunities. Am J Phys Anthropol
[7] Barger N, Stefanacci L, Schumann CM, et al. 2012. Neuronal
populations in the basolateral nuclei of the amygdala are differentially
increased in humans compared with apes: A stereological study.
J Comp Neurol 520:30353054.
[8] Barger N, Hanson KL, Teffer K, Schenker-Ahmed NM,
Semendeferi K. 2014. Evidence for evolutionary specialization in
human limbic structures. Front Hum Neurosci 8:227.
[9] Boyle EK, Mahon V, Diogo R. 2020. Muscles lost in our adult primate
ancestors still imprint in us: On muscle evolution, development, varia-
tions, and pathologies. Curr Mol Biol Reports 6:3250.
[10] Diogo R, Wood B. 2012. Comparative anatomy and phylogeny of pri-
mate muscles and human evolution, Boca Raton, FL: CRC Press.
[11] Diogo R, Potau JM, Pastor JF, et al. 2013. Photographic and descrip-
tive musculoskeletal atlas of orangutans, Boca Raton, FL: CRC Press.
[12] Diogo R, Potau JM, Pastor JF. 2013. Photographic and descriptive
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[13] Ackerman MJ. 1998. The visible human project. Proc IEEE 86:
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[15] Diogo R, Potau JM, Pastor F. 2010. Photographic and descriptive
musculoskeletal atlas of gorilla, Boca Raton, FL: CRC Press.
[16] Diogo R, Potau JM, Pastor JF, et al. 2012. Photographic and descrip-
tive musculoskeletal atlas of gibbons and siamangs (hylobates), Boca
Raton, FL: CRC Press.
[17] Rilling James K., & Insel Thomas R. 1999. Differential expansion of neu-
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spective using magnetic resonance imaging. J Hum Evol 37:191223.
[19] Rilling JK, Seligman RA. 2002. A quantitative morphometric compara-
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Nicole Barger is project manager of the Visible Ape Project at Howard
University and Assistant Research Professor in Anthropology at The
George Washington University, affiliated with the Center for the
Advanced Study of Human Paleobiology. Her research addresses
comparative and developmental variation in ape brains through an
evolutionary anthropological framework.
José Saúl Martín is a biologist and scientific illustrator with experience
in biological and anatomical illustrations for papers, guides, and scien-
tific communication projects. He provided 3D illustrations for the Visi-
ble Ape Project. He is currently a master's student in applied biology
with a specialization in scientific illustration at Aveiro University in the
Scientific illustration laboratory (lic dBio).
Eve K. Boyle is currently an AAAS Science & Technology Policy Fel-
low serving at the National Science Foundation. As a postdoctoral fel-
low at Howard University in 2019 to 2020, she was the first project
manager for the Visible Ape Project. She is an evolutionary anthropol-
ogist with expertise in informal science education, public engagement,
project management, and broadening participation activities.
Marli Richmond serves as the Visual Designer for the Visible Ape Pro-
ject. She combines a research background in biological anthropology
with training in user experience design, user interface design, and
education-based media development. Marli created and implemented
the website's primary design system and digital strategy.
Rui Diogo, Associate Professor at Howard University, is a multi-
awarded researcher known for his multidisciplinary approach to
address broader societal issues using state-of-the-art empirical data.
He participated in about 150 papers and 20 books, including Learning
and understanding human anatomy and pathologyand Evolution
driven by organismal behavior,often listed among the top-10-best
2017 evolutionary books.
How to cite this article: Barger N, Martín JS, Boyle EK,
Richmond M, Diogo R. The Visible Ape Project: A free,
comprehensive, web-based anatomical atlas for scientists and
veterinarians designed to raise public awareness about apes.
Evolutionary Anthropology. 2021;111.
Full-text available
How the neural structures supporting human cognition develop and arose in evolution is an enduring question of interest. Yet, we still lack appropriate procedures to align ages across primates, and this lacuna has hindered progress in understanding the evolution of biological programs. We generated a dataset of unprecedented size consisting of 573 time points from abrupt and gradual changes in behavior, anatomy, and transcription across human and 8 non-human primate species. We included time points from diverse human populations to capture within-species variation in the generation of cross-species age alignments. We also extracted corresponding ages from organoids. The identification of corresponding ages across the lifespan of 8 primate species, including apes (e.g., orangutans, gorillas) and monkeys (i.e., marmosets, macaques) reveal that some biological pathways are extended in humans compared with some non-human primates. Particularly, the human lifespan is unusually extended relative to studied nonhuman primates demonstrating that very old age is a phase of life in humans that does not map to other studied primate species. More generally, our work prompts a reevaluation in the choice of a model system to understand aging given very old age in humans is a period of life with a clear counterpart in great apes. Significance Statement What is special about the duration of human development and aging has been an enduring source of interest. A significant hurdle in identifying which biological programs are unusually extended in humans is the lack of standardized approaches with which to align ages across species. We harnessed temporal variation in behavior, transcription, and anatomy to align ages across the lifespan of primates. These data reveal which biological programs are conserved, and which are modified. Harnessing time points across scales of study guides the choice of model systems to understand disease progression, and can be used to enhance care of great apes, many of which are critically endangered.
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The study of evolutionary developmental pathologies (Evo-Devo-Path) is an emergent field that relies on comparative anatomy to inform our understanding of the development and evolution of normal and abnormal structures in different groups of organisms, with a special focus on humans. Previous research has demonstrated that some muscles that have been lost in our ancestors well before the evolution of anatomically modern humans occasionally appear as variations in adults within the normal human population or as anomalies in individuals with congenital malformations. Here, we provide the first review of fourteen atavistic muscles/groups of muscles that are only present as variations or anomalies in modern humans but are commonly present in other primate species. Muscles within the head and neck and pectoral girdle and upper limb region include platysma cervicale, mandibulo-auricularis, rhomboideus occipitalis, levator claviculae, dorsoepitrochlearis, panniculus carnosus, epitrochleoanconeus, and contrahentes digitorum manus. Within the lower limb, they include scansorius, ischiofemoralis, contrahentes digitorum pedis, opponens hallucis, abductor metatarsi quinti, and opponens digiti minimi. For each muscle, we describe their synonyms, comparative anatomy among primates, embryonic development, presentation and prevalence as a variation, and presentation and prevalence as an anomaly. Research on the embryonic origins of six of these muscles has demonstrated that they appear early on in normal human development but usually disappear before birth. Among the eight muscles in the upper half of the body, mandibulo-auricularis is, to our knowledge, present in humans only as a variation, while the other seven muscles can be present as either a variation or an anomaly. All six muscles of the lower limb are present only as variations, and to our knowledge have not been described in anomalous individuals. Interestingly, although these muscles conform to most definitions of what constitutes an atavism—i.e., they were lost in our adult ancestors and now appear in some adult humans—some of them are seemingly present in more than 2% of the normal population. Therefore, they might actually constitute polymorphisms rather than variations. The research summarized here therefore emphasizes the need of future studies of the evolution, development, and prevalence of soft tissue variations and anomalies in humans, not only for the understanding of our evolutionary history but also of our phenotype and pathologies.
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African Americans and other ethnic minorities are severely underrepresented in both graduate education and among the professoriate in ecology and evolutionary biology (EEB). In the present research, we take a social psychological approach to studying inclusion by examining interrelationships among challenges to inclusion, the sense of belonging, and interest in pursuing graduate education in EEB. We conducted a survey of African American (N = 360), Latino/a/Hispanic (N = 313), White (N = 709), and Asian/Asian American (N = 524) college undergraduates majoring in science, technology, engineering, and math fields and used the results to test several interrelated hypotheses derived from our theoretical model. Compared to Whites, ethnic minorities were more likely to experience challenges to inclusion in EEB (e.g., less exposure to ecology, fewer same-race role models, discomfort in outdoor environments). Challenges to inclusion were associated with a decreased sense of belonging in EEB educational contexts. Finally, experiencing a low sense of belonging in EEB educational contexts was associated with lower interest in pursuing graduate education in EEB. Sense of belonging in EEB was especially low among African Americans relative to Whites. We discuss the implications of the study results for educational interventions.
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This book challenges the assumption that morphological data are inherently unsuitable for phylogeny reconstruction, argues that both molecular and morphological phylogenies should play a major role in systematics, and provides the most comprehensive review of the comparative anatomy, homologies and evolution of the head, neck, pectoral and upper limb muscles of primates. Chapters 1 and 2 provide an introduction to the main aims and methodology of the book. Chapters 3 and 4 and Appendices I and II present the data obtained from dissections of the head, neck, pectoral and upper limb muscles of representative members of all the major primate groups including modern humans, and compare these data with the information available in the literature. Appendices I and II provide detailed textual (attachments, innervation, function, variations and synonyms) and visual (high quality photographs) information about each muscle for the primate taxa included in the cladistic study of Chapter 3, thus providing the first comprehensive and up to date overview of the comparative anatomy of the head, neck, pectoral and upper limb muscles of primates. The most parsimonious tree obtained from the cladistic analysis of 166 head, neck, pectoral and upper limb muscle characters in 18 primate genera, and in representatives of the Scandentia, Dermoptera and Rodentia, is fully congruent with the evolutionary molecular tree of Primates, thus supporting the idea that muscle characters are particularly useful to infer phylogenies. The combined anatomical materials provided in this book point out that modern humans have fewer head, neck, pectoral and upper limb muscles than most other living primates, but are consistent with the proposal that facial and vocal communication and specialized thumb movements have probably played an important role in recent human evolution. This book will be of interest to primatologists, comparative anatomists, functional morphologists, zoologists, physical anthropologists, and systematicians, as well as to medical students, physicians and researchers interested in understanding the origin, evolution, homology and variations of the muscles of modern humans. Contains 132 color plates.
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Questions about our origin as a species are universal and compelling. Evolution-and in particular human evolution-is a subject that generates intense interest across the world, evidenced by the fact that fossil and DNA discoveries grace the covers of major science journals and magazines as well as other popular print and online media. However, virtually all national polls indicate that the majority of Americans strongly reject biological evolution as a fact-based, well-tested, and robust understanding of the history of life. In the popular mind, no topic in all of science is more contentious or polarizing than evolution and media sources often only serve to magnify this polarization by covering challenges to the teaching of evolution. In the realm of teaching, debates about evolution have shaped textbooks, curricula, standards, and policy. Challenges to accepting and understanding evolution include mistrust and denial of science, cognitive obstacles and misconceptions, language and terminology, and a religious worldview, among others. Teachers, who are on the front lines of these challenges, must be armed with the tools and techniques to teach evolution in formal education settings across grades K-16 in a straightforward, thorough, and sensitive way. Despite the potentially controversial topic of human evolution, growing research is demonstrating that a pedagogical focus on human examples is an effective and engaging way to teach core concepts of evolutionary biology. Am J Phys Anthropol 159:S232-S274, 2016. © 2016 Wiley Periodicals, Inc.
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Increasingly, functional and evolutionary research has highlighted the important contribution emotion processing makes to complex human social cognition. As such, it may be asked whether neural structures involved in emotion processing, commonly referred to as limbic structures, have been impacted in human brain evolution. To address this question, we performed an extensive evolutionary analysis of multiple limbic structures using modern phylogenetic tools. For this analysis, we combined new volumetric data for the hominoid (human and ape) amygdala and 4 amygdaloid nuclei, hippocampus, and striatum, collected using stereological methods in complete histological series, with previously published datasets on the amygdala, orbital and medial frontal cortex, and insula, as well as a non-limbic structure, the dorsal frontal cortex, for contrast. We performed a parallel analysis using large published datasets including many anthropoid species (human, ape, and monkey), but fewer hominoids, for the amygdala and 2 amygdaloid subdivisions, hippocampus, schizocortex, striatum, and septal nuclei. To address evolutionary change, we compared observed human values to values predicted from regressions run through (a) non-human hominoids and (b) non-human anthropoids, assessing phylogenetic influence using phylogenetic generalized least squares regression. Compared with other hominoids, the volumes of the hippocampus, the lateral nucleus of the amygdala, and the orbital frontal cortex were, respectively, 50, 37, and 11% greater in humans than predicted for an ape of human hemisphere volume, while the medial and dorsal frontal cortex were, respectively, 26 and 29% significantly smaller. Compared with other anthropoids, only human values for the striatum fell significantly below predicted values. Overall, the data present support for the idea that regions involved in emotion processing are not necessarily conserved or regressive, but may even be enhanced in recent human evolution.
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The present publication reviews the broader evolutionary implications of our long-term study of primate musculature. It summarizes the implications of the study for our understanding of the use of myological characters for phylogenetic reconstruction, for assessing the importance of homoplasy and reversions in evolution, and for our understanding of Dollo's law, the notion of 'direction' in evolution, the common myth of human complexity, the tempo and mode of primate and human evolutionary history, adaptive radiations, the notion that 'common' equals 'primitive' and the influence of morphogenesis on the variability of head, neck, pectoral and upper limb muscles. Among other results our study shows that myological characters are useful for phylogenetic reconstruction. The results also stress the importance of homoplasy and of evolutionary reversions in morphological evolution, and they provide examples of reversions that violate Dollo's law due to the retention of ancestral developmental pathways. They also show that contrary to the idea of a 'general molecular slow-down of hominoids' the rates of muscle evolution at the nodes leading to and within the hominoid clade are higher than those in most other primate clades. However, there is no evidence of a general trend or 'directionality' towards an increasing complexity during the evolutionary history of hominoids and of modern humans in particular, at least regarding the number of muscles or of muscle bundles. The rates of muscle evolution at the major euarchontan and primate nodes are different, but within each major primate clade (Strepsirrhini, Platyrrhini, Cercopithecidae and Hominoidea) the rates at the various nodes, and particularly at the nodes leading to the higher groups (i.e. those including more than one genus) are strikingly similar. Our results also support, in general terms, the assumption that 'common is primitive' and they lend some support for the 'vertebrate-specific model' in the sense that during the divergent events that resulted in these four major primate clades there was more emphasis on postcranial changes than on cranial changes. Our study of primates does not, however, support suggestions that the distal structures of the upper limb are more prone to variation than the proximal ones, or that the topological origins of the upper limb muscles are more prone to evolutionary change than their insertions.
The Visible Human Project data sets are designed to serve as a common reference point for the study of human anatomy, as a set of common public-domain data for testing medical imaging algorithms, and as a testbed and model for the construction of image libraries that can be accessed through networks. The data sets are being applied to a wide range of educational, diagnostic, treatment planning, virtual reality, artistic, mathematical, and industrial uses by more than 800 licensees in 27 countries. But key issues remain in the development of methods to link such image data to text-based data. Standards do not currently exist for such linkages. Basic research is needed in the description and representation of image-based structures and in the connection of image-based structural-anatomical data to text-based functional-physiological data. This is the larger, long-term goal of the Visible Human Project: to link the print library of functional-physiological knowledge with the image library of structural-anatomical knowledge transparently into one unified resource of health information
Orangutans, together with chimpanzees and gorillas, are our closest living relatives. This book, which is the first photographic and descriptive musculoskeletal atlas of the genus Pongo, adopts the same format as the photographic atlases of Gorilla, Pan and Hylobates previously published by the same authors.