iiinova — where your digital self keeps evolving

Kai Caspar @nomascus.bsky.social · 24/09/2026

For the record: The @mammalbiology.bsky.social anniversary meeting in Berlin last week has been an amazing experience but I simply cannot do it justice here. Incredibly proud to be part of this community.

Specimens of some shrews native to the Oder valley close to Berlin

Berlin victory column, illuminated at night and visited during an urban bat excursion

Dinosaur hall with sauropod skeletal mounts at the Natural History Museum, Berlin

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Kai Caspar @nomascus.bsky.social · 24/09/2026

In Frankfurt today for a collection visit - and the Messel exhibition is promoted by perhaps the most attractive Gastornis reconstruction I've seen so far.

Gastornis walking though the Messel forest. Shown as a rather lean bird with grey plumage and widely exposed blue facial skin. Artist unknown.

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Kai Caspar @nomascus.bsky.social · 13/09/2026

One of the most beautiful of all mammals, to me at least - Goodfellow's tree kangaroo from Papua New Guinea. Photo taken last week at Rostock Zoo. 🧪🦘

Zoo-housed Goodfellow's tree kangaroo rearing up to grasp leaves.

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Kai Caspar @nomascus.bsky.social · 04/09/2026

Female pileated gibbon enjoying some cooked meat at Zoo Schwerin.

Close-up of a gibbon handling food. Relaxed facial expression.

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Kai Caspar @nomascus.bsky.social · 19/08/2026

One of my favourite works in all of the primatological literature. The orangutan is great but my highlight will always be the iconic type illustration of the Javan gibbon, which was scientifically named in this book.

Detailed drawing of a Javan gibbon by Audebert walking upright (as they do) and facing the viewer. The artist drew a stuffed animal that is still in the collection of the Paris Natural History Museum and is considered the holotype specimen of this species.

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Kai Caspar @nomascus.bsky.social · 09/08/2026

How do gibbons view human and congeneric faces? New gibbon eye tracking work by Uchikoshi et al., again showing its indeed feasible, even for old individuals (> 50 years). We need more such data to contextualize findings on model species. 🦍🧪 www.animalbehaviorandcognition.org/article.php?...

Heatmap plots illustrating on which part of the face gibbons focus when they look at photos from other gibbons and humans. The eye region is preferred, but more so when congeneric pictures are viewed.

Taken from Uchikoshi, M., Yu, L., & Hattori, Y. (2026). Gibbons (Hylobates spp.) show increased attention to eyes when viewing conspecific faces: An eye-tracking study. Animal Behavior and Cognition, 13(3), 228-238. https://doi.org/10.26451/abc.13.03.02.2026

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Kai Caspar @nomascus.bsky.social · 07/08/2026

Excellent sketch of a naked mole-rat from Weber's "Die Säugetiere"(2nd edition, 1928), showing why the name is actually a misnomer: The body is covered in sensory hairs, crucial for picking up tactile cues for orientation. 🧪

Stylized sketch of a naked mole-rat highlighting the many sensory hairs covering the whole body

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Kai Caspar @nomascus.bsky.social · 29/06/2026

New study on pathways of tool use learning in zoo-housed hornbills, an understudied group that does not habitually use tools in the wild. 🧪 www.sciencedirect.com/science/arti...

Graphical abstract from the paper showing the apparatus used to examine tool use learning in hornbills

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Kai Caspar @nomascus.bsky.social · 19/06/2026

How salient is human eye appearance compared to that of other primates? This excellent new study by Perea-García et al. suggests that under some conditions, chimp-like eyes actually have a signalling advantage. 🧪 www.cambridge.org/core/journal...

Model from the Perea-Garcia et al. study wearing a dark lens to mimic chimp-like eyes on the left and her natural eyes on the right (note that different from chimps, the model has a grey iris color).

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Kai Caspar @nomascus.bsky.social · 06/06/2026

Now visiting the Macrauchenia at Krefeld Zoo.

Zoo sign for camels, resembling an extinct South American ungulate

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Kai Caspar @nomascus.bsky.social · 28/05/2026

Last chance for early bird registrations - come join us in Berlin! My students and I will present new data from undergrad projects and collabs on some fascinating species, incl. okapi (!), river dolphins (!!) and wood mice (!!!)

Skeleton of a Ganges River dolphin and model of an Amazon River dolphin in the Prague Natural History Museum (both relevant to work presented at the DGS meeting)

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Kai Caspar @nomascus.bsky.social · 22/05/2026

A couple years ago I purchased these figures from an Etsy (?) shop. I simply cannot remember where I got them from, but they are great and I occasionally use them for teaching. Any ideas who might have crafted them and whether these/similar models are still sold?

Grey figurines of Deinotherium and Nothritheriops

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Kai Caspar @nomascus.bsky.social · 20/05/2026

Our phylogenetic analysis suggests that pigmentation is greater in species with large eyes and lower in nocturnal lineages. No effect of latitude was found (but see our discussion on that). All in all, this suggests that photoprotective demands are crucial determinants of eye pigmentation. (4/5)

Figure from preprint showing that peri-iridal brightness is negatively correlated with eye size.

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Kai Caspar @nomascus.bsky.social · 20/05/2026

Primate data suggest that a critical function of peri-iridal pigment is UV protection. The eye’s exposure to UV correlates with latitude and increases with eye size and day time activity. We checked effects of these variables on peri-iridal brightness across 62 (non-primate) mammal species. (3/5)

Figure from https://onlinelibrary.wiley.com/doi/10.1111/brv.70033: Eye appearance of primates originating from different latitudes

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Kai Caspar @nomascus.bsky.social · 20/05/2026

New preprint, building on the thesis of my former undergrad @cstreitferdt.bsky.social: doi.org/10.64898/202... We present evidence that conjunctival pigmentation (peripheral to the iris) in terrestrial mammals is importantly driven by demands of UV protection. Quick thread 🧵1/5.

Phylogenetic tree of 62 terrestrial mammals from the preprint. Bar length indicates eye size, bar color approximates brightness of peri-iridal tissues.

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Kai Caspar @nomascus.bsky.social · 18/05/2026

It finally arrived in print: The recent Mammalian Biology Special Issue on African mole-rats dedicated to the late Stan Braude - one of the pioneers of research on wild naked mole-rats. Complete issue: link.springer.com/journal/4299...

Cover photo, showing portraits of Stan Braude and impressions of various mole-rat species

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Kai Caspar @nomascus.bsky.social · 04/05/2026

Description of a new species of blind mole-rat (Spalax lyapunovae sp. nov. ) from the northern Caucasus (photo by Oleg V. Brandler) vertebrate-zoology.arphahub.com/article/1809...

Photo of a male blind mole-rat of the newly described species on a meadow. Photo by Oleg V. Brandler

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Kai Caspar @nomascus.bsky.social · 29/03/2026

Finally: A thorough anatomical description of the enigmatic pseudo-anteater Eurotamandua from the Messel pit based on CT data. Futher evidence is provided that this charismatic animal is a stem-pangolin. link.springer.com/article/10.1...

The original fossil of Eurotamandua from the Messel exhibition at the Darmstadt Natural History Museum.

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Kai Caspar @nomascus.bsky.social · 13/03/2026

Another great 3D-printed model created by students - the inner ear endocast of a hummingbird. 👂🏻

3D-printed endocast of a hummingbird inner ear with tiny hummingbird toy figure on the right

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Kai Caspar @nomascus.bsky.social · 06/03/2026

The last 3 weeks I spent teaching a special new course on bird ecology & behavior: From phylogeny to neurology & behavioral observations; visiting birds in the field, collections, zoos, & labs. Only possible thanks to dedidacted students & support from many excellent colleagues - awesome experience!

Bird skeletons in a museum collection. Cassowary in focus.

3D-printed endocast of a nightjar. Segmented by students as part of the course.

Brain of a Nile crocodile - as the extant sister group to birds, crocodilians featured prominently in the course.

Hyacinth macaw taking a bath at Wuppertal zoo.

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Kai Caspar @nomascus.bsky.social · 14/02/2026

This has been a fun integrative study very long in the making co-led by @sabinebegall.bsky.social and HA expert Delphine del Marmol (not on Bluesky). Always a pleasure to return to the mole-rats! (8/8)

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Kai Caspar @nomascus.bsky.social · 14/02/2026

In any case, the idea of increased skin elasticity in burrowing mammals is not supported. Has elasticity been confused with skin looseness (adherence to underlying muscles) in the past? Perhaps, but whether skin looseness is remarkable in burrowers also needs to be tested (not trivial to do) (7/8)

Ansell's mole-rat, held by a human. Loose skin on the back is obvious. Photo by Sarah M. Wilms.

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Kai Caspar @nomascus.bsky.social · 14/02/2026

We also performed size exclusion chromatography to determine HA polymer size in Ansell’s mole-rat, comparing it with naked mole-rats and guinea pigs. We find the mole-rat HA to be moderately elongated across tissues – but not super-sized. (5/8)

Plot showing size distribution of hyaluronan molecules in the skin o Ansell's mole-rat (AMR), naked mole-rat (NMR) and guinea pig (GP).

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Kai Caspar @nomascus.bsky.social · 14/02/2026

The skin of the naked mole-rat is actually very stiff – and can endure (relatively) enormous mechanical stress, as tensile tests revealed. We argue that this relates to nakedness, since the lack of pelage allows the dermal collagen network to be more extensive and resilient. (4/8)

Maximum stress the skin can endure in a number of rodent taxa. The naked mole-rat is an outlier, combining high resilience with thin skin.

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Kai Caspar @nomascus.bsky.social · 14/02/2026

However, this finding proved hard to replicate by other labs and whether mole-rat skin biomechanics are actually special was never even tested. Using cutometry we find: It is not, when compared to laboratory rodent species. (3/8)

Cutometric comparison of subterranean (blue) and surface-dwelling (red) rodent taxa. The higher R8, the greater the skin's ability to recover its initial conformation (elasticity).

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Kai Caspar @nomascus.bsky.social · 14/02/2026

Do subterranean mammals have hyper-elastic skin thanks to super-sized hyaluronan (HA) polymers? We challenge this popular idea in a new preprint, presenting the first skin elasticity measurements of burrowing rodents & HA size profiles for Ansell’s mole-rat (1/8) 🧪 www.biorxiv.org/content/10.6...

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Kai Caspar @nomascus.bsky.social · 25/01/2026

Another bit on eye-sight: I've put together a plot on visual acuity in birds and mammals. Interestingly, corvids seem to have acuity that is a lot better than expected for their eye size/passerines in general. Is anyone aware of structural peculiarities of corvid eyes that might explain that? 🧪🪶

Scatter plot with eye sight acuity (measured in cycles per degree) on the y-axis and eye diameter (in mm) on the x-axis.
Birds tend to have higher acuity than mammals at a given eyesight, except anthropoid primates (monkeys and apes) that outperform most birds, except for a few raptors. Some birds of prey (falcons, eagles) exhibit the highest recorded acuity. Corvids cluster between other birds and anthropoids, showing higher acuity than would be expected.

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Kai Caspar @nomascus.bsky.social · 13/12/2025

Finally out: There are good arguments to recognize three species of surprisingly distinct naked mole-rats. The one species kept in labs and zoos worldwide (pictured below) is now Heterocephalus ansorgei - the other two have so far barely been studied. 🧪 www.nature.com/articles/s42...

Kenyan naked mole-rat (Heterocephalus ansorgei) in a lab.

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Kai Caspar @nomascus.bsky.social · 29/10/2025

The mammalogy course had luck with the marsupials at Zoo Duisburg today. Devils, koalas, macropods, wombats ...

Photo of a common wombat walking through the autumn leaf litter

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Kai Caspar @nomascus.bsky.social · 14/10/2025

Dancing crested gibbons made it into National Geographic! The individual shown in the article (Polly) actually features in our study - which you can find here: link.springer.com/article/10.1...

Photo of a NatGeo article on gibbon dance, discussing the study by Coye et al. Female Nomascus leucogenys is shown, photographed by Joel Sartore

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Kai Caspar @nomascus.bsky.social · 06/09/2025

A couple of snapshots from Plzen Zoo today

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Kai Caspar @nomascus.bsky.social · 01/09/2025

Just visited Lucy and the Dikika child in Prague. Icons.

Photo of the front of Prague's National Museum with an Australopithecus banner

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Kai Caspar @nomascus.bsky.social · 18/08/2025

Broad in scope but strikingly concise, highly accessible, and nuanced - go get this book if you have even the slightest interest in birds and/or vertebrate brain evolution. I will use it a lot. Congrats @evoneuro.bsky.social! #neuroskyence 🧪

Picture of a copy of "Bird Brains and Behavior" by Striedter & Iwaniuk: https://mitpress.mit.edu/9780262552738/bird-brains-and-behavior/

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Kai Caspar @nomascus.bsky.social · 04/08/2025

Close-up of a male Bornean orangutan I met at the zoo last week. Different from their Sumatran relatives, Bornean orangs have strongly pigmented eyes. The iris is surrounded by an arcus senilis. In humans, these lipid deposits may form at an old age but manifest a lot earlier in many other primates.

Close-up of eyes and nose of a Bornean orangutan

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Kai Caspar @nomascus.bsky.social · 26/07/2025

We are currently testing highly underrated and understudied colobus monkeys for @manyprimates.bsky.social at Zoo Krefeld. It's a start - but ManyPrimates needs more colobines (and gibbons) for fair representation!

Colobus monkey (Colobus guereza) approaching a two-choice set up to test for its ability to infer the hiding location of a bait by exclusion.

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Kai Caspar @nomascus.bsky.social · 25/07/2025

New comparative study by Sulser & McPhee on anatomical proxies of sensory ecology in tenrecs and otter shrews, featuring some nice CT visualizations of the trigeminal nerve 🧪 www.nature.com/articles/s42...

CT renders of the brains and trigeminal nerves of iodine-stained tenrec specimens. Taken from Sulser & MCPhee (2025): https://www.nature.com/articles/s42003-025-08489-8

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Kai Caspar @nomascus.bsky.social · 20/06/2025

Will be worth the wait, I guess ... 🧪

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Kai Caspar @nomascus.bsky.social · 17/06/2025

Bizarre bird phylogeny still on display at Augsburg Zoo.

Phylogenetic tree of birds, with orders placed essentially at random.

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Kai Caspar @nomascus.bsky.social · 26/05/2025

Always a treat - Heinrich Harder's (restored) palaeoart pieces at Zoo Berlin's aquarium building. Only today I noticed that the dorsal spines of the Edaphosaurus are not depicted to support a sail here.

Murals and reliefs showing Ichthyosaurus, Stegosaurus, Pteranodon, Triceratops, Edaphosaurus and Claosaurus

Murals and reliefs depicting Meiolania, Pareiasaurus, ammonites, and other prehistoric critters

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Kai Caspar @nomascus.bsky.social · 15/05/2025

We point to photoprotection, sexual selection, genetic drift & non-referential signaling as non-mutually exclusive factors that might have driven the evolution of peri-iridal pigmentation. Many of these ideas were sparked by research inspired by the CEH. It has an important legacy either way. 10/11

Low-latitude primates (incl. humans) have darker peri-iridal tissues, probably an adaptation to counter damaging UV radiation. Figure from Perea-García et al. (2025)

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Kai Caspar @nomascus.bsky.social · 15/05/2025

We recommend to leave the CEH behind and focus on other avenues of research to understand how peri-iridal tissue color evolved in primates – there’s huge diversity that requires an explanation and that the CEH stands no chance to make sense of. 9/11

Phylogenetic tree of anthropoid primates, illustrating the diversity of peri-iridal pigmentation. From Perea-García et al. (2025)

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Kai Caspar @nomascus.bsky.social · 15/05/2025

3) Evidence that human eye appearance is superior to e.g. chimps’ when it comes to signalling gaze is slight and not available for naturalistic settings. In fact, chimps’ eye gaze is well visible from 10s of meters away and their eyes are the most conspicuous feature of their faces. 7/11

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Kai Caspar @nomascus.bsky.social · 15/05/2025

2) Peri-iridal color differs between human populations. Low-latitude populations, which are traditionally underrepresented in this line of research, can have notable pigmentation. 6/11

Figure from Perea-Garcia et al. (2025) - eyes of diverse humans, showing a spectrum of peri-iridal pigmentations. Photos were taken my Marios Forsos, Juan Perea-García, and Gunther Deichmann.

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Kai Caspar @nomascus.bsky.social · 15/05/2025

1) Extensive peri-iridal depigmentation has evolved multiple times in non-human primates. Both at individual and species level, humans are not unique. Here’re just a couple of examples. 5/11

Figure from Perea-García et al. (2025) comparing peri-iridal brightness in humans, Southern pig-tailed macaques, and Golden langurs

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Kai Caspar @nomascus.bsky.social · 15/05/2025

Due to the whites of the eye, humans have a uniquely communicative gaze. Other primates have dark eyes, hiding their gaze from conspecifics. We cooperate, they compete. Common knowledge – right? Yes, but it’s incorrect, as we argue in our new paper 🧵🧪1/11 onlinelibrary.wiley.com/doi/10.1111/...

Human eye on top, squirrel monkey eye below. Little of the peri-iridal tissues are exposed in the squirrel monkey, which is now understood to derive from simply scaling constraints and human adaptations to horizontal scanning. There is no evidence for social cognition being tied to such differences in eye appearances.

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Kai Caspar @nomascus.bsky.social · 04/05/2025

Visited the Piesberg (Osnabrück) today - hunting for fossil plants with @kpg13.bsky.social

Carboniferous deposits at Piesberg, Osnabrück,

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Kai Caspar @nomascus.bsky.social · 19/04/2025

Strangely, habitual aerial urination is only known from Amazon river dolphins, documented from various populations. Is it unique to them or just underreported in other lineages (as implied by this palaeoart piece by @joschuaknuppe.bsky.social)? As always, more data is needed … 8/9

Drawing of the extict sperm whale Eophyseter engaging in aerial urination. Art by Joshua Knüppe.

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