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Label Detective: Are Bacteria ‘Ordinary Animals?’

By Kyle Lee-Crossett, on 17 October 2017

A few weeks ago, the Grant Museum opened a new exhibit, The Museum of Ordinary Animals: boring beasts that changed the world. As a detective of the mundane myself, I am a huge fan. But I’m particularly curious about the ordinary animals we can’t see.

Rather than focusing on a specific artefact label, I answer the title question by visiting two places in the Museum of Ordinary Animals exhibition that help raise questions about how things are organised and labeled in zoology more broadly.

Case notes: Bacteria are everywhere. As I mentioned in my previous post, we have 160 major species of bacteria in our bodies alone, living and working together with our organ systems to do things like digest nutrients. This is also happens with other animals — consider the ordinary cow, eating grass. Scientist Scott F. Gilbert tells us that in reality, cows cannot eat grass. The cow’s genome doesn’t have the right proteins to digest grass. Instead, the cow chews grass and the bacteria living in its cut digest it. In that way, the bacteria ‘make the cow possible’.

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The Ordinary Cow, brought to you to by bacteria. Credit: Photo by author

Scientifically speaking, bacteria aren’t actually ‘animals’; they form their own domain of unicellular life. But, as with the cow, bacteria and animals are highly connected. Increasingly, scientists say that the study of bacteria is ‘fundamentally altering our understanding of animal biology’ and theories about the origin and evolution of animals.

But, before we get into that, let’s go back to Charles Darwin (1809-1882). Darwin studied how different species of animals, like the pigeon, are related to each other, and how mapping their sexual reproduction shows how these species diversify and increase in complexity over time. This gets depicted as a tree, with the ancestors at the trunk and species diversifying over time into branches.

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Darwin’s Ordinary Tree of Pigeons. Photos by author

When scientists began to use electron microscopes in the mid-20th century, our ideas about what made up the ‘tree of life’ expanded. We could not only observe plants, animals, and fungi, but also protists (complex small things) and monera (not-so-complex small things). This was called the five kingdom model. Although many people still vaguely recollect this model from school, improved techniques in genetic research starting in the 1970s has transformed our picture of the ‘tree of life’.

It turns out we had given way too much importance to all the ordinary things we could see, when in fact most of the tree of life is microbes. The newer tree looks like this:

Credit: Wikipedia Commons

Credit: Wikipedia Commons

Now there are just three overarching domains of life: Bacteria, Eucarya (plants, animals, and fungi are just tiny twigs on this branch), and Archaea (another domain of unicellular life, but we’ll leave those for another day).

There’s a third transformation of the ‘tree of life’, and this one is my favourite. Since the 1990s, DNA technology and genomics have given us an even greater ability to ‘see’ the diversity of microbial life and how it relates to each other. The newest models of the tree look more like this:

Credit: Wikipedia Commons

Credit: Wikipedia Commons

This is a lot messier. Why? Unlike the very tiny branches of life (plants and animals) that we focused a lot of attention on early on in the study of evolution, most of life on earth doesn’t reproduce sexually. Instead, most microbes transfer genes ‘horizontally’ (non-sexually) across organisms, rather than ‘down’ a (sexual) genetic line. This creates links between the ‘branches’ of the tree, starting to make it look like….not a tree at all. As scientist Margaret McFall-Ngai puts it: ‘we now know that genetic material from bacteria sometimes ends up in the bodies of beetles, that of fungi in aphids, and that of humans in malaria protozoa. For bacteria, at least, such transfers are not the stuff of science fiction but of everyday evolution’.

Status: Are bacteria Ordinary Animals? We can conclusively say that bacteria are not animals. But, they are extremely ordinary, even if we can’t see them with the naked eye. In truth, they’re way more ordinary than we are.

 

 

Notes

As with the previous Label Detective entry, this post was deeply inspired by the book Arts of Living on a Damaged Planet, an anthology of essays by zoologists, anthropologists, and other scholars who explore how environmental crisis has highlights the complex and surprising ways that life on earth is tied together. Scott F. Gilbert and Margaret McFall-Ngai, both cited above, contribute chapters.

What’s a monkey, what’s a primate?

By Catryn Williams, on 8 October 2017

I have something to admit. Before starting my PhD researching the primate gut microbiome, I didn’t completely know the difference between the terms “monkey” and “primate”. Perhaps this is somewhat forgivable given that I was primarily a microbiologist, but I remember still feeling a sort of sneaky shame in googling the differences after I read the project title, like it was something I should definitely know.

This is a monkey (a Gibraltar macaque). Licensed under CC0 3.0.

This is a monkey (a Gibraltar macaque). Licensed under CC0 3.0.

As it turns out, the rules of what’s what in the primate tree are pretty simple once you know them. The evolutionary history of primates can be traced back to between 63 – 74 million years ago (MYA), and as they stand today can be divided into two main branches, named Strepsirrhini and Haplorrhini, which based on molecular studies are hypothesised to have branched away from each other around 64 MYA. Interestingly, the two groups are named after their noses, with Strepsirrhini meaning “wet-nosed” and Haplorrhini meaning “dry-nosed” and were called so by a French naturalist friend of Robert Grant, named Étienne Geoffroy Saint-Hilaire.

A simple primate evolutionary tree showing the major branchings. Strepsirrhini were formerly known colloquially as "prosimians", although this is an outdated term now. Licenced under CC0 1.0.

A simple primate evolutionary tree showing the major branchings. Strepsirrhini were formerly known colloquially as “prosimians”, although this is an outdated term now. Licensed under CC0 1.0.

Strepsirrhini primates (unsurprisingly) tend to have wet noses, as well as a more pointed, almost dog-like snout rather than the flatter faces of their Haplorrhini cousins, and are thought to be most similar in appearance to the first primates. The clades that make up the Strepsirrhini primates are the lemurs of Madagascar, the lorises from South East Asia and India, and the pottos and galagos (or bushbabies) of Africa. Until recently, tarsiers were also thought to belong to Strepsirrhini, however now they’ve been moved to the sister clade of Haplorrhini.

A selection of strepsirrhines spanning the whole clade. Licenced under CC0 3.0

A selection of strepsirrhines spanning the clade. Licensed under CC0 3.0

If you’ve been wondering up to this point where the monkeys are, you need look no further than the Haplorrhines. In terms of number of species, this clade is almost entirely monkeys. The major two branches within this clade are between Catarrhini (meaning “down-nosed”), or Old World monkeys and apes found across Africa and Asia, and Platyrrhini (meaning “flat-nosed”), or New Wold monkeys found in Central and South America.

A map showing the distribution of monkeys across the globe, with Old World monkeys coloured in red and New World monkeys coloured in orange. Licenced under CC0 3.0

A map showing the distribution of monkeys across the globe, with Old World monkeys coloured in red and New World monkeys coloured in orange. Licensed under CC0 3.0

Within the catarrhines, the apes, or Hominoidea, comprise gibbons, orang-utans, gorillas, chimpanzees and, of course, us. Apes are thought to have formed their own distinct clade from Old World monkeys (or Cercopithecoidea) around 29MYA, so if you wanted to get really technical, and you were the kind of person who happily accepts birds as being modern day dinosaurs, it wouldn’t be entirely wrong to say that apes are actually monkeys too.

An orang-utan in Borneo, Malaysia. Licensed under CC0 3.0.

An orang-utan in Borneo, Malaysia. Licensed under CC0 3.0.

So, hopefully the next time you get stuck wondering whether the primate you’re looking at is a monkey or not, you’ll be a little more clued in.

 

Lemurs: the Ghostly Primate?

By Josephine Mills, on 9 June 2017

Did you know lemurs are primates? In fact they are one of the oldest primates, known as prosimians, which evolved long before monkeys and apes. They belong to the suborder Strepsirrhini alongside other mostly insectivorous and nocturnal primates like bushbabies, lorises and pottos. Lemur-like primates appeared in Africa around 60 million years ago and crossed the sea to Madagascar shortly after – possibly via rafting on clumps of vegetation or trees. Madagascar, which had separated from the super continent Gondwanaland 100 million years earlier, continued to drift further from the African Coastline; this meant that no other primates were able to cross to its shores. Consequently Lemuriformes continued to evolve on Madagascar with no pressure from other primates and it is the only place where they survive today!

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Lemurs have a distinctive elongated nose seen here on a red ruffed lemur

Without this competition and predation lemurs evolved across the island’s distinct ecological niches, which range from dense forests, to lakes and open areas. There are over fifty different species of Malagasy lemur who all evolved from the same common ancestor, which makes variation in their behaviour particularly interesting. Lemurs have started to adopt behaviours previously associated solely with Haplorrhine primates (monkeys and apes!), including activity in the day, frugivory, and the formation of complex social groups. Lemur groups operate a matrilineal structure where power rests with adult females and their female children. This is due to the practice of female philopatry where females always remain in the group they were born in whereas males leave. This behaviour is relatively unusual within the primate world!

However Madagascar did not remain an untouched paradise for ever, with the arrival of arguably the most destructive and dangerous primate (guess who?) by boat around 2,000 years ago. As humans settled on the island they began to cause damage to lemur habitats and started to hunt them for food. This resulted in the extinction of several species of lemur including the giant lemurs Megaladapis and Archaeoindris. These megafaunal lemurs could reach the size of a gorilla but were slow moving and well adapted to their niche habitats making them easy prey. Some skeletal remains have been found with cut marks indicating butchery by humans.

Lemur’s unique evolution, far from the pressures of living alongside other competing primates, has allowed them to expand their evolutionary niches. One great example of this is new sightings of them being active both during the day and night. This newly observed behaviour has been called ‘cathemeral’, literally meaning around the clock, indicating the ability to distribute activity throughout the 24-hour period. This is very unusual in primates but has now been documented in four species of lemur on Madagascar; it is observed elsewhere in some populations of South American owl monkeys Aotus azarii (Fernandez-Duque et al. 2001; Tattersall 2008). Interestingly being most active during the day (Diurnality) is seen as a fundamental transition in primate evolution; the move into the light associated with larger group size and gregarious social behaviour (Donati et al. 2013).

However lemurs are traditionally nocturnal; the name ‘lemur’ derives from the Latin ‘lemures’ meaning ghost or spirit, perhaps linked to their spooky call and haunting stare seen reflecting from the dense Malagasy forests at night. The lemur’s gaze looks distinctive in the dark due to a biological feature unique to nocturnal animals, the tapetum lucidum, a reflective layer present behind the eye that maximises any available light. This provides a key advantage to nocturnal species, both predator and prey. Look closely and you can even see it on your family cat! The presence of this adaptation in many lemur species suggests that it was a characteristic shared by their common ancestor.

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I know these are cats, but you get the idea! (Photo credit: Awwwcats)

 

So if lemurs have this specialised nocturnal adaptation why are we seeing them active during the day? This unusual change in several different species of lemur presents quite a conundrum and several adaptive factors have been suggested that may have been influential (see Curtis and Rasmussen 2006 for more info):

  • Temperate control: Being able to spread their activity throughout the day and night allows lemurs to avoid extremes of temperature; on cooler days they can feed and forage in the day and vice-versa on hot days. In this way they would save energy otherwise used to regulate their body temperature.
  • Maximising digestion time: Extremely folivorous (leaf eating) lemurs may improve their digestion by being active at different times.
  • Predator avoidance: Lemurs may have adopted cathemerality to avoid their main predator the Fossa (you may remember these scary critters from the movie Madagascar); a highly specialised and dangerous nocturnal predator.

Contrasting non-adaptive hypothesis

  • An evolutionary disequilibrium: This theory proposes that cathemerality is only seen when a distinct ecological pressure is lifted putting a primate population into an evolutionary disequilibrium. Proposed by Van Schaik and Kappeler (1996) who suggest that lemurs can be active during the day due to removal of their diurnal predators by the recent mass megafaunal extinction events in Madagascar.

Overall the idea of an evolutionary disequilibrium is not well supported as there are distinct adaptive benefits to cathemerality; equally lemurs have a stable relationship with their main predator: the fossa. It appears that cathemerality is closely linked to predation and may provide other physiological benefits, but it is particularly interesting when re-evaluating the evolution of diurnal behaviour. In this way it emphasises the complex and diverse process that influence primate evolution and how there is not a pan-explanation for how certain behaviours appear. It also reminds us that when interpreting primate evolution new previously unseen things are happening all the time. Here’s where if I was going to bore you I’d link it back to Neanderthals but I won’t… Instead a picture of me hanging out with red ruffed lemur… and do check out the lemur specimens in the Grant Museum!

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Red ruffed lemur at Artis Zoo in Amsterdam

 

References:

Curtis, D., Rasmussen, M. A. (2006). The evolution of cathemerality in primates and other mammals: a comparative and chronoecological approach. Folia Primatologica 77: 178-193

Donati, G., Santini, L., Razafindramanana, J., Boitani L., Borgognini-Tarli, S. (2013). (Un-)expected nocturnal activity in ‘diurnal’ Lemur Catta supports cathermarlity as one of the key adaptations of the lemurid radiation. American Journal of Physical Anthropology 150: 99-106

Fernadez-Duque, E., Rotundo, M., Sloan, C. (2001). Density and population structure of owl monkeys (Aotus azarai) in the Argentinean Chaco. American Journal of Primatology 53: 99-108

Tattersall, I. (2008). Avoiding commitment: cathemerality among primates. Biological Rhythm Research 39: 213-228

Van Schaik, C. P., Kappeler, P. M. (1996). The social systems of gregarious lemurs: lack of evolutionary convergence with anthropoids due to evolutionary disequilibrium? Ethology 102: 915-941

Normativity November: Defining the Archaeological Normal

By Stacy Hackner, on 23 November 2016

This post is part of QMUL’s Normativity November, a month exploring the concept of the normal in preparation for the exciting Being Human events ‘Emotions and Cancer’ on 22 November and ‘The Museum of the Normal’ on 24 November, and originally appeared on the QMUL History of Emotions Blog.

DSC_0745by Stacy Hackner

 

The history of archaeology in the late 19th and early 20th centuries can be read as the history of European men attempting to prove their perceived place in the world. At the time, western Europe had colonized much of the world, dividing up Africa, South America, and Oceania from which they could extract resources to further fund empires. Alongside this global spread was a sincere belief in the superiority of the rule of white men, which had grown from the Darwinian theory of evolution and the subsequent ideas of eugenics advanced by Darwin’s cousin Francis Galton: not only were white men the height of evolutionary and cultural progress, they were the epitome of thousands of years of cultural development which was superior to any other world culture. According to their belief, it was inevitable that Europeans should colonize the rest of the world. This was not only the normal way of life, but the only one that made sense.

In modern archaeology, we let the data speak for itself, trying not to impose our own ideas of normality and society onto ancient cultures. One hundred years ago, however, archaeology was used as a tool to prove European superiority and cultural manifest and without the benefit of radiocarbon dating (invented in the 1940s) to identify which culture developed at what time, Victorian and Edwardian archaeologists were free to stratify ancient cultures in a way that supported their framework that most European=most advanced. “European-ness” was defined through craniometry, or the measurement and appearance of skulls, and similar measurements of the limbs. Normality was defined as the average British measurement, and any deviation from this normal immediately identified that individual as part of a lesser race (a term which modern anthropologists find highly problematic, as so much of what was previously called “race” is culture).

In my research into sites in Egypt and Sudan, I’ve encountered two sites that typify this shoehorning of archaeology to fit a Victorian ideal of European superiority. The first is an ancient Egyptian site called Naqada, excavated by Sir William Matthew Flinders Petrie in the 1890s. Petrie is considered the founder of modern, methodological archaeology because he invented typology – categorizing objects based on their similarity to each other. As an associate and friend of Galton and others in the eugenics circle, he applied the same principle to categorizing people (it’s likely that his excavations of human remains were requested by Galton to diversify his anthropometric collection). Naqada featured two main types of burials: one where the deceased were laid on their backs (supine) and one where the deceased were curled up on their side (flexed). Petrie called these “Egyptian” and “foreign” types, respectively. The grave goods (hand-made pottery, hairpins, fish-shaped slate palettes) found in the foreign tombs did not resemble any from his previous Egyptian excavations. The skeletons were so markedly different from the Egyptians – round, high skulls of the “Algerian” type, and tall and rugged – that he called them the “New Race”. Similarities, such as the burnt animal offerings found in the New Race tombs, present in Egyptian tombs as symbolic wall paintings, were obviously naïve imitations made by the immigrants. However, the progression of New Race pottery styles pointed to a lengthy stay in Egypt, which confused Petrie. Any protracted stay among the Egyptians must surely have led to trade: why then was there an absence of Egyptian trade goods? His conclusion was that the New Race were invading cannibals from a hot climate who had completely obliterated the local, peaceful Egyptian community between the Old and Middle Kingdoms.

Of course, with the advent of radiocarbon dating and a more discerning approach to cultural change, we now know that Petrie had it backwards. The New Race are actually a pre-Dynastic Egyptian culture (4800-3100 BC), who created permanent urban agricultural settlements after presumably thousands of years of being semi-nomadic alongside smaller agricultural centres. Petrie’s accusation of cannibalism is derived from remarks from Juvenal, a Roman poet writing centuries later. It also shows Petrie’s racism – of course these people from a “hot climate” erased the peaceful Egyptians, whose skulls bear more resemblance to Europeans. In actuality, Egyptian culture as we know it, with pyramids and chariots and mummification, developed from pre-Dynastic culture through very uninteresting centuries-long cultural change. Petrie’s own beliefs about the superiority of Europeans, typified by the Egyptians, allowed him to create a scientific-sounding argument that associated Africans with warlike-invasion halting cultural progression.

The second site in my research is Jebel Moya, located 250 km south of the Sudanese capital of Khartoum, and excavated by Sir Henry Wellcome from 1911-1914. The site is a cemetery that appears to be of a nomadic group, dating to the Meroitic period (3rd century BC-4th century AD). The site lacks the pottery indicative of the predominant Meroitic culture, therefore the skulls were used to determine racial affiliation. Meroe was seen as part of the lineage of ancient Egypt – despite being Sudanese, the Meroitic people adopted pyramid-building and other cultural markers inspired by the now-defunct Egyptian civilization. Because many more female skeletons were discovered at this site than male, one early hypothesis was that Jebel Moya was a pagan and “predatory” group that absorbed women from southern Sudanese tribes either by marriage or slavery and that, as Petrie put it, it was “not a source from which anything sprang, whether culture or tribes or customs”. Yet, the skulls don’t show evidence of interbreeding, implying that they weren’t importing women, and later studies showed that many of the supposed female skeletons were actually those of young males. This is another instance of British anthropologists drawing conclusions about the ancient world using their framework of the British normal. If the Jebel Moyans weren’t associating themselves with the majority Egyptianized culture, they must be pagan (never mind that the Egyptians were pagan too!), polygamous, and lacking in any kind of transferrable culture; in addition, they must have come from the south – that is, Africa.

Sir Henry Wellcome at the Jebel Moya excavations Credit: Wellcome Library, London.

Sir Henry Wellcome at the Jebel Moya excavations
Credit: Wellcome Library, London.

These sites were prominent excavations at the time, and the skeletons went on to be used in a number of arguments about race and relatedness. We now know – as the Victorian researchers reluctantly admitted – that ruggedness of the limbs is due to activity, and that a better way to examine relatedness is by examining teeth rather than skulls. However, the idea of Europeans as superior, following millennia of culture that sprung from the Egyptians and continued by the Greeks and Romans, was read into every archaeological discovery, bolstering the argument that European superiority was normal. Despite our focus on the scientific method and attempting to keep our beliefs out of our research, I wonder what future archaeologists will find problematic about current archaeology.

Sources

Addison, F. 1949. Jebel Moya, Vol I: Text. London: Oxford University Press.

Baumgartel, E.J. 1970. Petrie’s Naqada Excavation: A Supplement. London: Bernard Quaritch.

Petrie, W.M.F. 1896. Naqada and Ballas. Warminster: Aris & Phillips.

On the Origin of Pokémon Species

By Arendse I Lund, on 27 July 2016

Arendseby Arendse Lund

Last week, I was in the Grant Museum of Zoology when a cry came that a Pokémon had been spotted! Mobiles out, the visitors advanced on the creature and succeeded in capturing it. Surrounded by zoological specimens meticulously collected over centuries, here were people amassing their own digital collection of creatures. From a mouse that shoots lightning bolts to a shellfish that poisons with its lick, these creatures, collectively called Pokémon, take a variety of forms and all have different abilities. Many of these Pokémon are based on real animals.

TapirFor example, take Drowzee: These psychic Pokémon eat dreams and are based on the chiefly nocturnal tapirs, animals indigenous to tropical America and Southeast Asia. Tapirs have short legs and the Malayan tapirs are two-toned just like their virtual counterparts; they also have long, flexible snouts which allow them to grab foliage beyond their reach and even act as a snorkel when swimming. The Japanese word for tapir, baku, refers to both the zoological animal and a spirit in folklore which consumes dreams—just like its Pokémon counterpart.

PangolinAnother example are Sandslash, which have long claws for burrowing, feature brown quills covering their bodies, and will roll into a ball in order to defend themselves from attack. These Pokémon take their inspiration from the pangolin, which are sometimes referred to as scaly anteaters. However, they are more closely related to giant pandas. The name derives from the Malay word pengguling, meaning “something that rolls up.” They have overlapping keratin scales armoring their backs, with tails strong enough to hang from trees, and a tongue that, when extended, is longer than its body. These incredible creatures are found in Asia and Africa but are sadly the most trafficked animals in the world.

DugongThen there’s Seel, which evolves into Dewgong. In these two Pokémon, everything’s in the names: The former is based off of a seal and the latter a dugong. In appearance, dugongs are similar to manatees but both male and female dugongs grow two tusks—this is reflected in its adorable Pokémon counterpart. The semi-nomadic dugongs’ habitat extends throughout the Indo-West Pacific but they mostly stay in the bays around Australia; their conservation status is listed as vulnerable due to overdevelopment of the coastal areas and excessive fishing. Dugongs derive their name from the Malay word duyung, meaning “lady of the sea” and the species is possibly the origin of the mermaid myth.

There are many more examples of the real-life basis for Pokémon: axolotl for Mudkip, tadpoles for Poliwag, and racoons for Zigzagoon, to name just a few. The creator of Pokémon, Satoshi Tajiri, was heavily influenced by the type of creatures he found while insect collecting as a child. He used to sneak out into rice paddies and look under rocks for beetles. In a 1999 interview, he bemoaned the disappearance of those paddies and said of his love for the outdoors, “As a child, I wanted to be an entomologist. Insects fascinated me. Every new insect was a wonderful mystery. And as I searched for more, I would find more. If I put my hand in a river, I would get a crayfish. Put a stick underwater and make a hole, look for bubbles and there were more creatures.” These findings influenced many of the creatures that would make up the Pokémon world.

As both the Grant and Petrie Museums are PokéStops, it’s great to see people encouraged to check out the museum collections as they pursue their Pokémon. Perhaps most fascinating of all, these virtual Pokémon collections now spark conversations with strangers over techniques and the best places to acquire rarer species in a strikingly similar way to amassing physical collections of any sort.

And any avid collector, be it of stamps or insects, can understand the lure of the Pokémon slogan: “Gotta catch ‘em all!”

Did we evolve to run?

By Stacy Hackner, on 5 January 2015

By Stacy Hackner

A few years ago, spurred by my research on just how deleterious the sedentary lifestyle of a student can be on one’s health, I decided to start running. Slowly at first, then building up longer distances with greater efficiency. A few months ago, I ran a half-marathon. At the end, exhausted and depleted, I wondered: why can we do this? Why do we do this? What makes humans want to run ridiculous distances? A half-marathon isn’t even the start – there are people who do full marathons back-to-back, ultra-marathons of 50 miles or more, and occasionally one amazing individual like Zoe Romano, who surpassed all expectations and ran across the US and then ran the Tour de France.[i] Yes, ran is the correct verb – not cycled.

I’ve met so many people who tell me they can’t run. They’re too ungainly, their bums are wobbly, they’re worried about their knees, they’re too out of shape. Evolution argues otherwise. There are a number of researchers investigating the evolutionary trends for humans to be efficient runners, arguing that we are all biomechanically equipped to run (wobbly bums or not). If you have any question whether you can or can not run, just check out the categories of races in the Paralympic Games. For example, the T-35 athletics classification is for athletes with impairments in ability to control their muscles; in 2012, Iiuri Tsaruk set a world record for the 200m at 25.86s, which is only 6 seconds off Bolt’s world record at 19.19 and 4 seconds off Flo-Jo’s womens record (doping aside). 2012 also saw the world record for an athlete with visual impairment: Assia El Hannouni ran 200m in 24.46.[ii] You try running that fast. Now try running with significant difficulty controlling your limbs or seeing. If you’re impressed, think about these athletes the next time you say you can’t run.

Paralympic_athlete

Paralympian Scott Rearden. Wikimedia Commons.

Let’s think about bipedalism for a bit. Which other animals walk on two legs besides us? Birds, for a start, although flight is usually the primary mode of transport for all except penguins and ostriches. On the ground, birds are more likely to hop quickly than to walk or run. Kangaroos also hop. Apes are able to walk bipedally, but normally use their arms as well. Cockroaches and lizards can get some speed over short distances by running on their back legs. However, humans are different as we always walk on two legs, keep the trunk erect rather than bending forward as apes do, keep the entire body relatively still, and use less energy due to stored kinetic energy in the tendons during the gait.[iii] Apparently we can group our species of strange hairless apes into the category “really weird sorts of locomotion” along with kangaroos and ostriches.

Following this logic, Lieberman et al point out that a human could be bested in a fight with a chimp based on pure strength and agility, can easily be outrun by a horse or a cheetah in a 100m race, and have no claws or sharp teeth: “we are weak, slow, and awkward creatures.”[iv] We do have two strokes in our favor, though – enhanced cognitive capabilities and the ability to run really long distances. Our being awkwardly bipedal naked apes actually helps more than one would think. First, bipedalism decouples breathing from stride. Imagine a quadruped running – as the legs come together in a gallop, the back arches and forces the lungs to exhale like a bellows. Since humans are upright, the motion of our legs doesn’t necessarily affect our breathing pattern. Second, we sweat in order to cool down during physical exertion. (In particular, I sweat loads.) Panting is the most effective way for a hairy animal to cool down, as hair or fur traps sweat and doesn’t allow for effective convection (imagine standing in a cool breeze while covered in sweat – this doesn’t work for a dog.) But it’s impossible to pant while running. So not only are humans able to regulate breathing at speed, but we can cool down without stopping for breath.

From a purely skeletal perspective, there is more evidence for the evolution of running. Human heads are stabilized via the nuchal ligament in the neck, which is present only in species that run (and some with particularly large heads), and we have a complex vestibular system that becomes immediately activated to ensure stability while running. The insertion on the calcaneus (heel bone) for the Achilles tendon is long in humans, increasing the spring action of the Achilles.[v] Humans have relatively long legs and a huge gluteus maximus muscle (the source of the wobbly bum). All of these changes are seen in Homo erectus, which evolved 1.9 million years ago.[vi]

H. erectus skeleton with adaptations for running (r) and walking (w). From Lieberman 2010.

H. erectus skeleton with adaptations for running (r) and walking (w). From Lieberman 2010.

The evolutionary explanation for this is the concept of endurance or persistence hunting. In a hot climate, ancient Homo could theoretically run an animal to death by inducing hyperthermia. This is also where we come full circle and bring in the cognitive capabilities of group work. A single individual can’t chase an antelope until it expires from heat stroke because it’ll keep going back into the herd and then the herd will scatter. But a team of persistence hunters can. If persistence hunting is how humans (or other Homo species) evolved to be great at long distance running, that’s also the why humans developed larger brains: the calories in meat generated an excess of calories that allowed nourishment of the great energy-suck that is the brain. However, persistence hunting is a skill that mostly went by the wayside as soon as projectile weapons (arrowheads and spears) were invented, possibly around 300,000 years ago. Why? Because humans, due to our large brains, are very inventive, but also very lazy. Any expenditure of energy must be made up for by calories consumed later, at least in a hunting and gathering environment – so less energy output means less energy input; a metabolic balance. Thus we have the reason why humans can run, but also why we don’t really want to. (As an aside, some groups such as the Kalahari Bushmen practiced persistence hunting until recently, although they had projectile weapon technology, probably because of skill traditions and retaining cultural practices. Humans are always confounding like that.)

Which brings up another point: gathering. As I’ve written before, contemporary hunter-gatherers like the Hadza rely much more on gathering than hunting. Additionally, it is possible that the first meat eaten by Homo species was scavenged rather than hunted. There is no such evolutionary argument as endurance gathering. If ancient humans spent much more time gathering, why would we evolve these particular running mechanisms? As with many queries into human evolution, these questions have yet to be answered. Either way, it’s clear that humans have a unique ability. Your wobbly bum is, in fact, the key to your running. Another remaining question is why we still have the desire to continue running these ridiculous distances – a topic for a future post, perhaps.

Sources

[i] http://www.zoegoesrunning.com

[ii] Check out all the records at http://www.paralympic.org/results/historical

[iii] Alexander, RM. Bipedal Animals, and their differences from humans. J Anat, May 2004: 204(5), 321-330.

[iv] Lieberman, DE, Bramble, DM, Raichlen, DA, Shea, JJ. 2009. Brains, Brawn, and the Evolution of Human Endurance Running Capabilities. In The First Humans – Origins and Early Evolution of the Genus Homo (Grine, FE, Fleagle, JG, Leakey, RE, eds.) New York: Springer, pp 77-98.

[v] Raichlen, DA, Armstrong, H, Lieberman, DE. 2011. Calcaneus length determines running economy: implications for endurance running performance in modern humans and Neandertals. J Human Evol 60(3): 299-308.

[vi] Lieberman, DE. 2010. Four Legs Good, Two Legs Fortuitous: Brains, Brawn, and the Evolution of Human Bipedalism. In In the Light of Evolution (Jonathan B Losos, ed.) Greenwood Village, CO: Roberts & Co, pp 55-71.

Movement Taster – Movement in Premodern Societies

By Stacy Hackner, on 14 May 2014


engaging

The following is a taster for the Student Engagers’ Movement event taking place at UCL on Friday 23 May. Stacy, a researcher in Archaeology, will be discussing movement through the lens of biomechanics.

by Stacy Hackner

Imagine you’re in the grocery store. You start in the produce section, taking small steps between items. You hover by the bananas, decide you won’t take them, and walk a few steps further for apples, carrots, and cabbage. You then take a longer walk, carefully avoiding the ice cream on your way to the dairy fridge for some milk. You hover, picking out the semi-skimmed and some yogurt, before taking another long walk to the bakery. This pattern repeats until you’re at the checkout.

What you may not realize is that this pattern of stops and starts with long strides in between may be intrinsic to human movement, if not common to many foraging animals. A recent study of the Hadza, a hunting and gathering group in Tanzania, shows that they practice this type of movement known as the Lévy walk (or Lévy flight in birds and bumblebees). It makes sense on a gathering level: you’ve exhausted all your resources in one area, so you move to another locale further afield, then another, before returning to your base. When the Hadza have finished all the resources in an area, they’ll move camp, allowing them to regrow (for us, this is the shelves being restocked). This study links us with the Hadza, and the Hadza with what we can loosely term “ancient humans and their ancestors”.

Diagram of a Levy walk.

Diagram of a Levy walk. Credit Leif Svalgaard.

It’s unsurprising that the Hadza were used to examine the Lévy walk and probabilistic foraging strategies. As they are one of the few remaining hunter-gatherer groups on the planet, they are often used in scientific studies aiming to find out how humans lived, ate, and moved thousands of years ago, before the invention of agriculture. The Hadza have been remarkably amenable to being studied by researchers investigating concepts including female waist-to-hip ratios, the gut microbiome, botanical surveys, and body fat percentage. Tracking their movement around the landscape using GPS units is one of the most ingenious!

Much of the theoretical background to my work is based on human movement around the landscape. The more an individual moves, the more his or her leg bones will adapt to that type of movement. Thus it is important to examine how much movement cultures practicing different subsistence strategies perform. The oft-cited hypothesis is that hunter-gatherers perform the most walking or running activity, and the transition to agriculture decreased movement. An implicit assumption in this is that males, no matter the society, always performed more work requiring mobility than females. This has been upheld in a number of archaeological studies: between the Italian Late Upper Paleolithic and the Italian Neolithic, individuals’ overall femoral strength decreased, but the males decreased more; over the course of the Classical Maya period (350-900 AD), the difference in leg strength between males and females decreased, solely due a reduction in strength of the males. The authors posit that this is due to an economic shift allowing the males to be free from hard physical labour.

However, I take issue with the hypothesis that females always performed less work. The prevailing idea of a hunting man settling down to farm work while the gathering woman retains her adherence to household chores and finding local vegetables is not borne out by the Hadza. First, both Hadza men and women gather. Their resources and methods differ – men gather alone and hunt small game while women and children gather in groups – but another GPS study found that Hadza women walk up to 15 km per day on a gathering excursion (men get up to 18 km). 15 km is not exactly sitting around the camp peeling tubers. Another discrepancy from bone research is the effect of testosterone: given similar levels of activity, a man is likely to build more bone than a woman, leading archaeologists to believe he did more work. Finally, hunting for big game – at least for the Hadza – occurs rarely (about once every 30 hunter-days, according to one researcher) and may be of more social significance than biomechanical, and berries gathered account for as many calories as meat; perhaps we should rethink our nomenclature and call pre-agricultural groups gatherer-gatherers or just foragers.

For a video of Hadza foraging techniques, click here.

For a National Geographic photo article, click here.

 

Sources

Marchi, D. 2008. Relationships between lower limb cross-sectional geometry and mobility: the case of a Neolithic sample from Italy. AJPA 137, 188-200.

Marlowe, FW. 2010. The Hadza: Hunter-Gatherers of Tanzania. Berkeley: Univ. California Press.

O’Connell, J and Hawkes, K. 1998. Grandmothers, gathering, and the evolution of human diets. 14th International Congress of Anthropological and Ethnological Sciences.

Raichlen, DA, Gordon, AD, AZP Mabulla, FW Marlowe, and H Pontzer. 2014. Evidence of Lévy walk foraging patterns in human hunter–gatherers. PNAS 111:2, 728-733.

Wanner, IS, T Sierra Sosa, KW Alt, and VT Blos. 2007. Lifestyle, occupation, and whole bone morphology of the pre-Hispanic Maya coastal population from Xcambó, Yucatan, Mexico. IJO 17, 253-268.

Question of the Week: Why is brain coral shaped like a brain?

By Lisa Plotkin, on 12 March 2014


Ruth Blackburn #1By Ruth Blackburn

The aptly named brain coral is a dome-shaped member of the family Faviidae which has distinct sinuous valleys (that’s the wibbly ridgey bits that look like the surface of a brain).

So why the dome shape?  This is largely driven by the position of the coral within the reef: brain coral is found in shallow parts of reef at a depth of about 1-15 metres. At this depth there is substantial wave action, which corals with a compact spheroid shape are much more resilient to than those with thin antler-like projections.

Brain coral from the Grant Museum collection.

Brain coral from the
Grant Museum collection.

The sinuous valleys on the surface of the brain coral can also be explained.  These mark the areas in which polyps – soft bodied marine creatures – are most densely found.  Polyps are able to secrete calcium carbonate (just like the scale that builds up in your kettle) to form a hard and protective exoskeleton that it can live in: this exoskeleton is what you actually see when you visit the Grant Museum.

Taxonomies of Bones and Pots – The Petrie Pops up at the Grant Museum

By Niall Sreenan, on 10 March 2014

Niall_small

 

TAXONOMIES OF BONES AND POTS: THE PETRIE POPS UP AT THE GRANT MUSEUM

On the 13th of February, objects and ideas from the Petrie Museum of Egyptian Archaeology “popped-up” in the neo-Victorian surrounds of the Grant Museum of Zoology in an event that sought to explore some of the ways in which archaeologists and biologists both engage in the act of classification and taxonomy. I attended this event in the guise of ‘Student Engager’, with the intention of sharing with visitors my own research on Darwinian evolution and literature. More on this later, but for now, it is perhaps a good idea to examine the procedure of taxonomy itself, as it relates specifically to biology and archaeology.

Taxonomy (from the Greek ‘taxis’ meaning ‘order and ‘nomos’ meaning ‘knowledge’) refers broadly to the act of (unsurprisingly) the ordering of knowledge and to the examination of the principles that underlie these logically ordered schemata. It is this process of ordering that the proponents of both ancient Egyptian archaeology and zoology practice – albeit in subtly different ways.

Taxonomy in biology, as we understand it now, is widely considered to derive from the work of the Swedish 18th Century naturalist Carolus Linnaeus. His seminal work in taxonomy, most famously given expression in Systema Naturae (1735), has bequeathed to us a method of biological classification, the finer details of which are now scientifically inaccurate, that to some extent lives on in popular thought (think of the game “Animal, Plant, or Mineral”) and whose basic outline persists in biology to this day. Linnaeus divided the natural world into three distinct types or ‘Kingdoms’, animal, plant, and mineral, and divided each of these into classes, with those categories dividing in turn into orders, familiesgenera, and species.

Regnum Animale – Systema Naturae
Click to zoom

Today, biological classification requires a more complex, nuanced system, in which there are six ‘kingdoms’, subsumed under the category of three ‘domains’ of life and take into account another category of life within this schema, the phylum. Moreover, the Linnaen classificatory system has given way to the Darwinian ‘Tree of Life’ as the dominant visual representation of the natural world, as evidenced by the current exhibition in the British Library that examines the nature of the visual representation of science: one installation in particular allows us to explore with touchscreen techonology, in great detail, the natural world through navigating this ‘Tree of Life’ and has a profoundly disorienting effect on our image of our human selves as the centre or pinnacle of the natural world. Homo sapiens in this model occupy an obscure, diminutive branch amongst the great, entangled, and monstrously abundant foliage of other species.

‘Tree of Life’ – Origin of Species, 1859

Yet despite the insistence of the dynamic, non-hierarchical schema of the Darwinian ‘Tree of Life’, the basic hierarchical ranking of Linnaean taxonomy persists (necessarily) in contemporary biology. Without this “ordering” of knowledge, with its embedded hierarchies and rankings, biological classification would be a disordered chaos. How then does this taxonomic procedure play out in other fields, distinct from biology?

While the significance of taxonomy is evident (and its history well known) in biology, the taxonomic aspects of archaeology are perhaps not as widely appreciated. The case of Flinders Petrie, the founder of the Petrie Museum of Egyptian Archaeology at UCL, provides us with a particularly apposite opportunity to excavate the function and significance of taxonomic classification in archaeology. Amongst Petrie’s most crucial contributions to archaeology are his schematic, chronological sequences of ancient Egyptian pottery. Petrie, faced with an abundance of predynastic pottery, collected along the Nile at various locations, needed a method of placing these pots in chronological order. Unlike the distinctly un-scientific methods of some of Petrie’s predecessors for whom the act of archeology was partially mythic in its reconstruction of the past, Petrie paid specifically close attention to the morphology of the objects with which he was faced and treated these morphologies as, what we call today, data-sets. Based on the assumption that the morphologies of pottery changed over time (in an almost evolutionary fashion), Petrie was able, via a complex mathematical process, to systematize and sequence the chronological order creating, in effect, a taxonomical method of dating pots. Both Petrie’s skill as a mathematician and diligence as an archaeologist is underlined here as, today, this statistical approach is undertaken using computers only – the complex arithmetic required simply taking too long for humans. The consequences of Petrie’s methodology – what is now called seriation – on the discipline of archaeology were and still are profound. The process is an important method in contemporary archeology and, in particular, it revolutionized our understanding of the timeline of Egyptian history, all through his taxonomic analysis of pottery.

https://twitter.com/LatentLaziness/status/434023358943207424

It was these very histories and methods of taxonomy in biology and archaeology that provided the crucial link between the Petrie and Grant Museums, and in turn provided the subject matter and theme of the event which I attended. Visitors were invited to engage in a number of taxonomic activities: reconstructing the shattered sequence of Flinders Petrie’s classification of pots, re-connecting and correctly identifying the scattered skeletal remains of a gorilla, and placing ancient Egyptian pots in their correct chronological order. These acts of reconstruction and identification, of the re-assembling of broken sequences and structures, stress the importance of taxonomy and classification in both biology and archaeology – disciplines whose methods, goals, and data-sets overlap in the fields of anthropology and osteo-archaeology. Moreover, it invites the participant to engage in the very ordering of knowledge out of disorder that underlies the procedure of taxonomy (albeit without the complex statistical mathematics). By the same token, taking part in a re-construction allows us to consider the implications of breaking up and disrupting these structure, of the deconstruction of systems of ordered classification.

My own research as a PhD student in UCL explores the way in which reading the work of Charles Darwin can provide us with new critical and theoretical insight into works of literature – and how reading works of literature have a reciprocal effect on our readings of Darwin. I referred to the Darwinian ‘Tree of Life’ earlier in this blog and it is to this I return now. Previously, I suggested that the tree model of life provided us with a more nuanced and dynamic method of ‘ordering’ our knowledge of the natural world than that of the Linnaean classificatory system. This view of the natural world, I stated, was profoundly decentring: homo sapiens are removed from our self-appointed place at the top of the hierarchy of species. And yet, does Linnaeus specifically place humans at the top of a hierarchy? Looking at the table of species published in Systema Naturae, there is a distinct echo of the deliberate subordination of all animals to the supremacy of man that has occurred in older visual and conceptual models of the natural world. Linnaeus’ table puts us (‘anthropomorpha’) at the top of the table, bestowing us with the title of “Number 1”. This repeats the schema that has been passed down through Western thought since Aristotle in the Scala Naturae, or the “Chain of Being” in which humans existed only below God in the grand hierarchy of all species. In this context, Darwin’s arboreal structuring of the natural world, with the human race being afforded no greater a position than a mouse or a mollusc is defiantly radical, shunning the accepted wisdom of all naturalist and biological thought since Ancient Greece. Moreover, the categories in Darwin’s model of life, the taxonomic leaves that sit upon the branches of genetic connection, are themselves unstable and subject to constant change.

Chain of Being – Rhetorica Christiana 1579

 

Darwin himself, writing in The Origin of Species in 1859 wrote:

 

“Naturalists try to arrange the species, genera, and families in each class, on what is called the Natural System. But what is meant by this system? Some authors look at it merely as a scheme for arranging together those living objects which are most alike, and for separating those which are most unlike; or as an artificial means for enunciating, as briefly as possible general propositions …”

 

Darwin, it seems, wishes to question the very substance and authority of this natural system, inaugurated by Linnaeus. For him, it is a necessary evil – an unwanted and ‘artificial’ ossification of the dynamism and change inherent in biological life that is nevertheless required for order and brevity in biology.

 

Yet, he goes further in his critique of classificatory systems:

 

“…we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species…”

 

The term species for Darwin is an arbitrary linguistic imposition on an organic form that by definition is never stable and always in a state of flux. He, like those who criticize the worst vagaries of cultural, linguistic, and philosophical postmodernism, sees in this biological relativism something to be maligned – a state of existential flux that results only in the melancholia of unstable and incomplete knowledge. Yet, in this he sees the prospect of an end to a “vain search”: the search for “essence”, linguistic, philosophical, and biological. Rather, Darwin would assert, we should instead attend to the ‘entangled bank’ of differences, to which he refers towards the end of Origin of Species, that make up the natural world rather than vainly trying to categorise and essentialise all of organic existence.

What if anything, does this literary critical digression of mine have to do with the taxonomical procedures of Flinders Petrie? Or, indeed, with his chronological series of pots? It might be worth asking, instead, what do Petrie’s series of pots tell us about the humans that made them? Or indeed about the relationship these humans had to the form of the pots that they created? It is my job as a literary critic to focus on ‘difference’ in literature and art; to attend in detail to the specific and subjective detail of single works of culture and their relationships with history, with other works of art, with texts, and with the individuals that created them. Taxonomy, the ordering of knowledge, on the other hand has a tendency to subordinate difference at the hands of “order”. On an instrumental level, this ordering process is vital for biology to operate – we could not simply throw our hands up give in to the desire to say that, say, tigers are contingent and temporary balls of matter in a state of constant flux and, therefore, should not be named! Yet, when it comes to the creative products of human hands and minds, there is an ethical dimension that should be attended to: to subordinate difference in art and culture is to subordinate individual difference in human life.

Francis Galton, a cousin of Darwin, and a colleague and acquaintance of Petrie, who worked at UCL in the early 20th C saw in the science of taxonomy, underlined by a misreading of Darwinian evolution and heredity, the potential to categorise and order human society according to his terms. He differentiated between the European races and the ‘lower races’ of man, creating, in effect, a taxonomy of human life. Not only is this scientifically incorrect, but the very act of naming and of creating order in doing so does a violence to those whom it names – restricting their existence to a category in which variance and difference within that group cannot be registered and asserting an unquestioned hierarchy of races, similar to that of the Systema Naturae. A distinctive passage from Galton’s work Hereditary Genius elucidates his views on the hierarchies of life:

“The natural ability of which this book mainly treats, is such as a modern European possesses in a much greater average share than men of the lower races. There is nothing either in the history of domestic animals or in that of evolution to make us doubt that a race of sane men may be formed who shall be as much superior mentally and morally to the modern European, as the modern European is to the lowest of the Negro races”

Galton is considered to have inaugurated the pseudo-scientific practice of eugenics, a discipline which espoused the improvement of human ‘stock’, the creation of a ‘race of sane men’, through selective breeding and other methods, the very name of which, today, can only be used in pejorative terms due to its racist foundations and invidious implications in the 20th Century.

These are the dangers of taxonomy when applied, misguidedly and without reflection, to human culture. Certainly, it is not my argument that taxonomy or order is inherently wrong. It was, however, my intention at the event held in the Grant Museum on the 13th of February to try and disrupt and disorder the usual ways in which we think about taxonomy in all fields.

Interestingly, Darwin, a scientist, like Galton, gives us an elegant means of resisting the worst vagaries of taxonomical essentialism. However it is only through a detailed and sensitive reading of Darwin’s writing that this can emerge from his texts. In other words, in order to see Darwin as holding ambivalent and philosophically interesting views on taxonomy and classification, it was necessary to ignore the taxonomical classification of Darwin as “Scientist” and “Biologist” and instead attend to the specific literary detail of his work.

Works cited and further reading (in no particular order):

Charles Darwin, On the Origin of Species, ed. by Gillian Beer, New edition (OUP Oxford, 2008).

Francis Galton, Hereditary Genius, (London: Macmillan, 1892).

Debbie Challis, The Archaeology of Race: The Eugenic Ideas of Francis Galton and Flinders Petrie, (London: Bloomsbury, 2013)

Michel Foucault, The Order of Things, (London: Routledge, 1989)

Sexual Conflict in Nature and Museums: Specimen Ratios and Duck Genitalia

By Suzanne M Harvey, on 18 November 2013

Suzanne Harvey #2by Suzanne Harvey

 

 

 

 

 

 

 

 

The Duck Penis Controversy of 2013 is well known amongst science bloggers, evolutionary anthropologists and Fox News viewers alike [1]. Now, the time has come for the worlds of museum collections and duck genitalia to collide.

There are some interesting facts about duck penises. For example, they measure a third of the length of the duck’s body, and they cannot become erect outside of the female duck’s vagina (or, as we will find out later, a man made substitute created in the name of science)[2]. Probably most surprising of all, duck penises are corkscrew shaped. However, in March 2013, Fox News conducted a poll in which 89.14% of respondents agreed that the research that brought us these fascinating facts was a waste of public money. At a time when funding for basic science research is becoming more and more difficult to obtain, I disagree with 89.14% of Fox News respondents. And as is so often the case, by clicking on links that come up in a search for ‘penis’, we miss the fact that the most interesting findings of this research come from the vagina. The duck penis controversy not only gives us the opportunity to talk about research, but also the curious bias towards male specimens in museums.

Specimen Ratios and Sexual Dimorphism

Duckling

Duckling preserved in fluid.
Research sugests 97% are of
ducklings are voluntarily
conceived despite
forced copulations.
Photograph: Grant Museum
of Zoology. 

 

On first arrival at the Grant Museum of Zoology, or indeed most natural history museums, it’s not obvious that the vast majority of specimens on display are male. But why is this the case? One possible explanation is the sexual dimorphism present in many species – the fact that males and females often look different, either in colouring or size [3]. Specifically, males are often larger than females due to competition for mates and sexual selection, and thus make more impressive specimens for display. Perhaps the most obvious example of sexual dimorphism at the Grant is the giant deer at the entrance to the museum, with his imposing 3.6m wide antlers.

It’s also been suggested that male animals were seen as a greater challenge and a more impressive trophy for the Victorian hunters who collected zoological specimens [4] – an acquisition policy that would not be used by the modern day Grant Museum! As well as this unavoidable bias in the specimens on display, some of the most popular blogs on this site have focused on the penis. With the onset of the duck penis controversy, we now have an opportunity to redress this balance, and assess the value of duck genitalia research from a more feminine perspective…

Corkscrews, Angles and Dead Ends: Welcome to the Duck Vagina

That ducks have corkscrew shaped penises is obviously a fact worth knowing, but surely the more interesting question is why do ducks have corkscrew shaped penises? The answer comes from sexual conflict. Forced copulations are common in ducks, presenting an evolutionary problem for females who only want to mate with high quality males of their choice. Females are rarely able to physically resist forced copulations, so in order to control the father of their offspring, their genitalia have evolved an elaborate structure that effectively prevents unwanted suitors from fathering offspring.

Here’s where the research comes in. By creating four substitute duck vaginas from glass tubes (one straight, one twisting in the same direction as a penis, one twisting in the opposite direction from the penis, and one with a sharp bend) researchers were able to assess which shape effectively prevents ducks from depositing semen at the site of fertilisation. The actual duck vagina is a combination of a sharp angle, and a anti clockwise spiral that twists in the opposite direction to the penis. As confirmed by the experiment, this makes it very difficult for males to inseminate females. The female must solicit males with a particular posture in order to make fertilisation likely, therefore gaining control over which males they breed with. In fact, while forced copulations are common, only 3% result in fertilisation.

Duck Vaginas

Glass substitute duck vaginas. A combination of
the two examples on the right most closely represents
an actual duck vagina. Photograph: adapted from
Brennan et al. 2009.

Ducks then are an example of the males and females of a species evolving equally elaborate genital anatomy under the pressures of sexual conflict and sexual selection. There are certainly some impressive male specimens in the Grant Museum, but those giant antlers and corkscrew penises did not evolve without the female of the species.

 

 

 

 

 

 

Suzanne Harvey is a PhD student in Biological Anthropology, working on social interactions and communication in wild olive baboons. She is also a teaching assistant on the UCL Arts and Sciences BASc, a new interdisciplinary degree, and can be found on twitter @suzemonkey.

 

References

[1] Yong, Ed. (2009). Ballistic penises and corkscrew vaginas – the sexual battles of ducks. Not Exactly Rocket Science. http://scienceblogs.com/notrocketscience/2009/12/22/ballistic-penises-and-corkscrew-vaginas-the-sexual-battles/

[2] Brennan, P., Clark, C., & Prum, R. (2009). Explosive eversion and functional morphology of the duck penis supports sexual conflict in waterfowl genitalia. Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.2139

[3] Machin, R. (2008). Gender Representation in the Natural History Galleries at the Manchester Museum. Museum and Society 6(1) 54-67. ISSN 1479-8360.

[4] Shamloul, R., El-Sakka, A., & Bella, A. J. (2010). Sexual selection and genital evolution: an overview. Journal of Sexual Medicine (7): 1734–1740.