147 Maximum Ape

Contingency is a fundamental concept in evolution. Chance events and the vagaries of history set animals along evolutionary trajectories that are less optimal strategies, and more strategies that make the most of a bad situation.  As the immortal Christopher Hitchens so simply put:

Even with all the advantages of retrospect, and a lot of witnesses dead and gone, you can’t make your life look as if you intended it or you were consistent. All you can show is how you dealt with various hands.

We know from experience the role contingency plays in each of our lives. At times*, it can outweigh the relentless driving force of adaptive evolution. Indeed, chance events may be our best explanation for why there are so many different types of animals and plants on this planet; without contingency we would likely be looking at a much more depauperate, uniform world.

For one thing we would not have snooker. For those US readers, snooker is basically gentleman’s pool. Matches can last several days, waistcoats and bow-ties are compulsory, and a butler is present to polish the balls. Do yourself a favor and google it. I spent my undergraduate days in Sheffield, the home of world snooker. Aptly named ‘the Crucible’, Sheffield’s premier snooker hall is filled with as much drama and intrigue as any theatrical show. The city comes alive during world championship season, with the excitement on the streets reaching fever-pitch levels. Frankly, to see that many people take something so silly, so seriously, is life-affirming. I like all sport for that reason, but as an evolutionary biologist, snooker lends a special appeal to me as it is the the most perfect physical embodiment of primate evolution.

No other animals on earth could even attempt snooker. Only several key innovations, unique to the history of primates, make snooker possible. Most obviously, in order to reach the table, one must affect an upright posture. This is not trivial. Most animals require all limbs for balance. Bears and horses can rear up on their hind legs temporarily, but certainly not for the 72 hours required to make it through the grueling 35 frame final in South Yorkshire.

Not only does an upright posture allow us to see the table, it also frees up our hands to hold the cue. Incidentally, freeing up the hands is our best guess for why we stood up in the first place, although then it was for picking berries off the forest floor, rather than phenomenal break-building. Of course, being upright is necessary but not sufficient. In order to deftly sink colors and control the cue ball, one also requires precision grip. The opposable thumb is another adaptation that arose to improve our ability to manipulate food, but again we can co-opt that adaptation (very common in evolution by the way) to different purposes.

So now we have the tools to physically play the game, but we have several adaptations to go before we can actually comprehend what we are doing, i.e. be any good at the game. For instance, it would behoove us to know what balls we were aiming at, and thus color vision seems a rather important prerequisite for snooker**. Even in pool, when the balls are numbered, the issue is not circumvented because the ability to count requires the final primate adaptation we will discuss.

We are a self-aggrandizing bunch, and our species will take any opportunity to laud it over the rest of the animal kingdom with our big brains. It is true that our cognitive abilities are the primary trait that set us apart from other species, and certainly without such processing power, we would not be tearing up the pool halls anytime soon. The main power that our big brains bestow upon us is that of foresight. Very few animals can look past the here and now, to predict future outcomes, or make plans. In order to be even remotely competent at something like snooker requires being able to at least guess where the balls are going to end up after you hit them. This seems pretty easy to us, but as I say, most animals do not have such clairvoyance. In addition, as alluded to previously, big brains are required for counting to any substantial number. With 147 points available on the table at the start of a frame, mathematical skills are as important for snooker as they are for darts. The games we play…

 

*mass extinction events are the most obvious example

**having said this, I have fond memories of my maternal grandparents glued to the professional snooker on a black-and-white television set! Adds an extra challenge for the spectator I guess, but it didn’t make any sense to me then, and it doesn’t make any sense to me now. 

GMOs? GTFO!

You really think bananas used to just grow naturally in the forest? GTFO!

We’ve been modifying organism’s genes since the agricultural revolution. Somewhat belatedly (12,000 years hence), people are beginning to voice concerns about genetically modified organisms. For those people, I have bad news; genetic modification is practically the definition of domestication. We select crops and livestock for desirable traits, from large udders in dairy cows, to high-yield maize, and seedless fruit*. Although farmers prior to 1866 didn’t know the mechanisms behind what they were doing, they were doing it nonetheless. Without genetically modified organisms, civilization would not exist.

So why the recent bruhaha? My thoughts come straight from the school of my namesake, the incomparable George Orwell. George Orwell was a staunch advocate of language, and provided one of the gloomiest foretelling of what would happen were we to lose it. The ministry’s prime weapon was language, either to incite violence and ill-will, or to placate citizens into a languid stupor.

We live in the information age, where everybody is too busy and overwhelmed with data to evaluate things outside of their field of expertise in any depth. Thus, we all must make snap judgments concerning the world around us. In other words, we must judge books by their covers. This is why language is more important today than it ever has been. If we had infinite time to research topics, or canvas expert opinion, the choice words used in incendiary headlines (or provocative tweets, if you want me to be current) would pale into insignificance. However, if these headlines are the only things that people read, the language means everything.

Politicians know the power of language, and hence they talk about ‘military conflicts’, because war has become rather taboo, and ‘enhanced interrogation’, because as a society we agree torture is wrong. As Orwell puts it:

“Political language is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind.”

My favorite** of these political deceptions has to be ‘waterboarding’. Drowning someone to make them confess to any crime you put before them is morally reprehensible, but I might consider going waterboarding myself on the weekend; sounds like fun for all the family! It would be rather amusing if it was not so sinister. When you begin to realize that every word that comes out of a politician’s mouth is carefully calibrated to trick the public into going along with any despicable, harebrained scheme they concoct, it ceases to be just an interesting psychological novelty. Again, Orwell knew the severity of the problem:

“if thought corrupts language, language can also corrupt thought.”

Just as the right words can convince the unsuspecting public of just about anything, the wrong words can generate mass outrage and mob opposition to rather benign concepts. Enter ‘Genetically Modified Organisms’. I’m an evolutionary biologist by trade, and would wager my training in genetics is more appreciable than the average person. Even I however, will admit that it sounds like something out of a horror film. ‘Genetic Modification’ conjures up images of mad scientists messing around with radioactive waste, giant spiders with wings, or even some kind of zombie apocalypse. The steadfast resistance to an idea without having the slightest notion of what that idea entails is lamentable. We mustn’t let imagined fears brought on by a revulsion to scary words jeopardize the progress of civilization. We risk losing one of the best chances of feeding the planet due to a knee-jerk reaction from people who lack even a basic understanding of agriculture, let alone molecular biology.

Unless scientists pay closer attention to the psychology of language, future technological and scientific advances will continue to fall by the wayside under the weight of public disapproval. If politicians are manipulating language to satisfy their own self-interests, and preying on people who lack the time to investigate spurious claims, we must do the same. We were on the right path when we talked about ‘golden rice’, but we dropped the ball sometime in the 1990’s. GMO’s may sadly be a lost cause, but I implore scientists to learn from the witless tricksters in power, and fight fire with fire.

Okay, that seems like enough words, hopefully they are the right ones.

 

*It seems unlikely that nature would devise an organism that could not reproduce on its own now doesn’t it? And of course, when I say unlikely, I mean ridiculous.

**perhaps favorite isn’t the right word…

Serengeti: Endless Pains

Every year, more than a million wildebeest, accompanied by similarly colossal herds of zebra, march across the plains of east Africa. Like swarms of locusts, they devour everything in sight, and adopt a nomadic lifestyle in their continual search for fresh grazing land. This infamous migration represents one of the greatest natural spectacles on the earth, but all is not as it seems in the Garden of Eden. The conception of the Serengeti as a pristine wilderness, untouched by mankind, is a lie. More specifically, it is a carefully calculated piece of British propaganda, a vestige of the most powerful empire in human history, that is in dire need of revision. Just like the Garden of Eden, there were people here once. For over two centuries, Maasai pastoralists used the ‘endless plains’ to graze their livestock, feed their families, and make a living. As an aside, there are so many parallels between this story and events following European arrival in the New World as to be nauseating. See if you can spot them all!

The Germans reached that part of the rift valley in the 19th century, but never took to it. The British arrived on the scene just before the first world war, at a time when the Serengeti looked less like ‘The Lion King’, and more like a scene from the Wild West. Cattle everywhere, and not a fence in sight. Clearly a ‘tragedy of the commons’ situation, that befell most European attempts at shared resources, had been avoided by these savages. But it wasn’t long before things started to take a turn for the worse. In less than a decade, British travelers had nearly extirpated lions from the area, leading to cries* of “well this simply won’t do, whatever will we shoot now?”. Desperate to retain their grizzly pastimes, the British attempted to enact protective legislation to conserve the area’s natural resources… so that they could keep on obliterating them. Unfortunately, for the Brits at least, it is difficult to ring-fence an area and control the activities that can occur if people already live there. The conflict rages to this day, as indigenous Amazonian tribes are displaced in the name of ‘progress’. It doesn’t matter whether you are forcing people off their lands for natural resource protection, or natural resource extraction. It’s not Kosher either way.

Luck came in the form of everybody’s favorite founder of fascism, the crackpot dictator, Benito Mussolini. Mussolini had grand plans for Italy’s imperial gains, particularly Abyssinia (modern day Ethiopia), and dispatched over 700,000 troops to the horn of Africa at the height of his power. Salient to our narrative, is what those soldiers brought with them. Rinderpest is a viral disease that causes fever, diarrhea, and eventually death of several ungulate species. The literal translation from German, ‘cattle plague’, tells you all you need to know. Thankfully, following a decades-long global eradication scheme, the disease was declared extinct in the wild in 2011, but in its day, Rinderpest caused unimaginable devastation.

When the bovine plague reached the great plains of East Africa, that was all she wrote. The cows died, the families starved, and the Maasai population plummeted. Just what the British were waiting for! Forcible eviction of a peoples from there land is an easier sell when there aren’t that many of them. Indeed, one can make the argument (and believe me they did), that you are actually doing these famine-stricken, jobless, impoverished people a favor by moving them. Such is the hubris of white privilege. In true ‘Trail of Tears’ fashion, the farmers were marched across the landscape, and told to set up shop 50 miles to the south in the Ngorongoro highlands**. Once the people problem had been dealt with, Serengeti National Park was established in 1951 to commemorate the coronation of Queen Elizabeth II. How lovely. Today, British tourists can experience an unrivaled level of guilt, as they traipse through Elizabeth’s ‘park’, the highest peaks of which offer stunning views over Victoria’s Lake…

Oh god, I need to stop before I punch somebody.

 

*albeit muted, on account of the plum-filled mouths.

**they were subsequently ousted from their new home in the mid-seventies, for fear that they might scare tourists, and again in the eighties, just for fun at this point, and even in this century (2006), the Tanzanian government are delivering ultimatums to tribal elders to get out the way or be pushed.

Rattled Nerves?

The only thing more terrifying than knowing you are within striking distance of a rattlesnake, is not knowing you are within striking distance of a rattlesnake.

Anecdotally, rattlesnakes across the United States are becoming more and more reluctant to rattle, and I for one hope it’s true, because the purported reason is deliciously ironic with a healthy dollop of comeuppance thrown in for good measure. Even if it is not true, it provides a nice framework for introducing concepts of evolutionary theory to a wider audience, and brings attention to chronic acts of animal cruelty that still take place to this day. Thus for this essay, I shall accept the premise.

The story goes that rattlesnakes are falling silent because of a century-long, nationwide extermination effort that has effectively driven the remaining survivors into hiding. ‘Rattlesnake Roundups’ date back to 1939, and were originally devised as a benign educational fair at which the public could learn about these elusive and often misunderstood creatures. Since their conception, the main goal has always been to prevent snakebites and reduce incidents of human-wildlife conflict. In recent years however, roundups have transformed into a grotesque circus that culminates in the slaughter of literally hundreds of thousands* of animals each year, in a macabre display of Man’s domination of nature.

Justification for the killings often comes via an extremely exaggerated account of the risk that rattlesnakes pose to pets, livestock, and children. Alternative reasons must exist however, otherwise I would expect to see ‘mosquito roundups’ or ‘automobile roundups’ undertaken with similar (if not greater) enthusiasm. Sufficed to say, these do not exist, and hence I am led to conclude that the persecution of snakes simply stems from bad PR.

Something akin to religious fervor grips people when it comes to snakes. Indeed religion may be partly responsible for their bad image in the western world. In Judeo-Christian mythology, snakes are always the ‘bad guys’, and the Old Testament may have sealed the fate of snakes much the same way that Jaws did for sharks**. Public attitudes can be changed with concerted outreach efforts and targeted educational programs, but progress can be slow when you are fighting a tide of fear and misinformation.

Thankfully, the heyday of roundups is behind us, but despite many states banning the events, and global condemnation of the wanton killing, annual fairs still take place in Texas, Oklahoma, Kansas, New Mexico, Pennsylvania, Alabama and Georgia. Public support for such events is waning, but in many cases, the damage has already been done; rattlesnake populations have been decimated, and some species have required state and federal protection to try to curb declines.

Even if populations recover however, the iconic, spine-tingling buzz of the old west may be a thing of the past. While the rattle serves as an excellent deterrent for large grazers (historically Bison, nowadays cattle) with its ‘don’t tread on me’ message, it proves to be their undoing when it comes to people. To a trained rounder-upper, the rattle serves as a beacon, with the message roughly translated as: ‘here I am, come kill me’. It is argued therefore, that the US has been partaking in a massive artificial selection experiment. By preferentially killing the most conspicuous snakes, we have been unwittingly selecting for sneaky snakes that avoid detection, who in turn, survive to produce baby snakes that are equally adept at not getting caught.

The end result is rattlesnakes that don’t rattle, and a group of people achieving the exact opposite of what they initially set out to accomplish. It is much more likely you will step on a rattlesnake if it does not alert you to its presence. I told you the irony was delectable.

Unfortunately, we do not have data on the incidence of rattling from before the age of roundups, and thus it very difficult to discern whether any change has actually taken place. But as I alluded to at the beginning of this essay, whether it is true or not makes little difference to me. Far more important is that people understand how nature works. Even for the staunchest creationist, it is difficult to argue with the logical steps of the evolutionary argument. The direction of selection is so intuitive that even a child could understand the mechanisms involved, and indeed it floods the imagination with a childlike wonder as to what else is being driven down some serendipitous evolutionary trajectory as a result of human folly.

Some dispute the anecdotes, and claim rattlesnakes rattle as much as they always have. For my rebuttal, I shall return to the Bible, that highlights how lessons can be learned from stories even if they are not true. If the notion of silent snakes spurs people to condemn animal cruelty and/or think about the natural world more deeply, I think I would be happy to perpetuate the myth.

 

* exact numbers unknown due to reluctance amongst event organizers to provide figures.

**and they say kids don’t read anymore!

Egret Meets West

Originally restricted to central Africa, cattle egrets (Bubulcus ibis) now occupy every continent on the planet barring Antarctica. Less than 50 years after their arrival to North America, cattle egrets have taken over every US state and now outnumber all other egrets and herons combined. It appears that cattle egrets achieved this feat all on their own*, and have displayed similar population explosions following introductions to Australia and Europe.

As their name suggests, cattle egrets have close ties to livestock grazing, and  agricultural expansion in the 20th century has been attributed to their spread and success. But less clear, and perhaps even more mindbogglingly impressive than flying non-stop across an ocean, is how rapidly cattle egrets have conjured up entirely novel migration routes on reaching new lands.

Some cattle egrets from the original batch in tropical Africa do not migrate at all! I must admit, I was skeptical when I first heard this story. It has become clear that evolution can operate on the same timescale as ecological processes, but for something as complicated and multifaceted as migration?! Apparently so.

It has been posited that the first arrivals to North America learnt by example, following native heron flocks along their long-established migration routes. Seems plausible; at least now we are only trying to explain a phenomenon rather than a miracle. But even still, this requires that the birds have remarkably flexible behavior, and it is thought the unpredictable movements of the Cape buffalo that they originally followed gave them the prior training (pre-adapted in fancy terminology) to make migration decisions on the fly.

Besides, even if we assume all colonizers originate from those birds that did exhibit migratory behavior in their home range, the pathways used to get from Ghana to Algeria will likely be of little use in navigating from Florida to Brazil, or anywhere else for that matter. This is self-evident. It is also evident in the environmental cues that different flocks of birds respond to and the directions they move. For example, African birds move from a cooler summer climate to a warmer winter environment; in contrast Australian birds move from balmy Queensland in the summer to a much cooler wintering range across New Zealand and Tasmania. Similarly, egrets in western Africa and India use rainfall to orient themselves to the seasons and move at the right time, whereas birds in the Americas are though to respond to temperatures alone. With each tidbit of new information, the story becomes more and more incredible, and indeed there are still many more questions than answered.

Cattle egrets are one of the few winners in the rise of man; I advocate we learn from their success, and use that knowledge to improve the chances of the myriad losers.

 

*with the exception of Hawaii, people brought them there.

Atrazine – The A to Z of Herbicide Woes

Midwestern frogs are mysteriously changing sex, Floridian alligators are being born with small penises, and mass fish die-offs are becoming commonplace. What is going on?
Whatever it is, don’t drink the water!

The commercial application of herbicides and pesticides has contaminated our environment to an extent hitherto unimaginable. Chief amongst the chemicals in the limelight is atrazine, one of the most widely used herbicides globally. Atrazine is most commonly applied to crop fields, however it is highly mobile, particularly in water, and has been detected in non-trivial concentrations up to 200 miles from where it was initially sprayed. Mimicking a nuclear explosion, atrazine enters the environment as an initial localized explosion, spreads across the landscape far beyond ground-zero, and persists with a slow half life much like radioactive decay. Thus even natural areas distant from agricultural operations (in either time or space) are not safe from the subsequent fallout. Of greatest concern is atrazine’s ability to stimulate the overproduction of estrogen; the production of too much estrogen causes all sorts of problems in reproductive physiology and can increase the risk of certain cancers. Emasculated crocs and three-legged frogs are just a taste of the harm that exposure can cause, and hint at the indiscriminate nature of atrazine’s destruction.

As is typical, people didn’t really care about this issue until it became clear the same issues may be manifest in human beings. Most differences between us and frogs (or alligators for that matter) are largely superficial, and our underlying physiology is remarkably similar. As such we would expect the effects of atrazine to be comparable, and indeed that is what we see. Sterility, feminization, and certain cancers have all been posited as human health risks to atrazine exposure. Contaminated drinking water should be cause for universal concern, however it is the workers (mostly from minority backgrounds) toiling away in the fields and the factories interacting directly with these chemicals who are exposed to the highest concentrations and most at risk. Thus, unregulated herbicide use is not only bad environmental policy, it is discrimination, pure and simple. Thankfully many nations and governing bodies have banned the use of atrazine. Even if we curtail atrazine use immediately however, adverse health effects may persist long into the future, potentially even passed down into generations that have had no direct exposure to the drug. A growing body of evidence links genital deformities in male babies to atrazine exposure of the mother (or even the grandmother!). We should all be a lot more worried.

It begs the question: why didn’t anyone test this chemical before rolling it out onto the market? Were there no environmental impact assessments? No clinical studies?

One would assume that the government takes responsibility in screening and approving chemicals for commercial use, but in fact, it is the manufacturing companies themselves that conduct virtually all of the safety testing. Such an honor system would be fine if we were dealing with a tea and biscuits donation box, but this is big business! I shall remind everyone of the recent Volkswagen emissions scandal. There is no honor among thieves… or CEOs apparently. When there is profit to be made, companies are happy to deceive consumers, even in matters concerning public health. It is important to bear in mind that this is not liberal rhetoric, this is economics 101. Any company that does not put the dollar first will be out-competed and driven into bankruptcy. In modern society we often consider our species as impervious to the the laws of nature, that we have somehow risen above the dog-eat-dog existence of ‘wild’ animals. This may harbor some truth for the individual, but at the level of the organization, in a capitalist free-market system ‘survival of the fittest’ plays out with the ruthless efficiency.

The scariest facet of this entire story, is that we are only looking at one chemical. One chemical out of hundreds of commercially used products. Atrazine is not special; it is simply the one we know most about. There is nothing to say that its detrimental impacts are somehow atypical or unrepresentative. Thus when we take atrazine and extrapolate out to evaluate to combined effects of all commercially used herbicides, the potential scale of the damage is terrifying. If that isn’t enough, most herbicides are actually purchased as a chemical cocktail, including a myriad of additional compounds that receive even less scrutiny than the herbicides themselves! As an example, surfactants, chemicals that facilitate the dispersal of an herbicide through water, are likely to pose as great a risk to aquatic communities of fishes and amphibians as that posed by the herbicide itself. Yet such extraneous ingredients remain largely unregulated.

I’m not one for conspiracy theories, but if I had to pick one*, I would be inclined to sit with the anti-Fluoride group, yelling at people (and traffic) about the poisoned water whilst simultaneously listing all the things in Coca-Cola that will probably also kill you. Water, water everywhere, nor any drop to drink. In this ‘chemical age’, you no longer have to be stranded at sea to appreciate the mariner’s sentiment.

 

*and they do rather amusingly seem mutually exclusive; I have sat and listened to a self-proclaimed UFO abductee lampooning Loch Ness monster sightings… go figure.

Epidermis Epidemic

Is there anything more soul-crushing than the image of The Rat-Pack, or any other crooner from the golden age of singers performing to an empty concert hall? Sinatra, baring his soul, with nothing but his echo reverberating off the bare walls in reply. The power of the artistry on display becomes heightened, as the emotional content of the lyrics is starkly juxtaposed with the futility of the performance. And perhaps there is an additional sullen reminder of the heights of the past.

In music this happens at venues the world over, as popular tastes change and musical styles go in and out of vogue; in frogs this happens at wetlands across the globe as audiences are decimated by a deadly fungal pathogen, and lonely males are left to lament into the void. The now infamous Chytrid fungus has wreaked havoc across all continents except Antarctica, and continues to shows no signs of curtailing its cataclysmic rise. Chytrid originated in Asia, and was transported across the globe most likely via the pet and commercial trades of amphibians. Affecting the majority of the 6000 frog species on earth, Chytrid is one of the most generalist diseases known to man. The very trait that defines amphibians is there downfall; porous skin provides no barrier to the fungal spores, and individuals are slowly suffocated as the disease enshrouds their bodies. Populations’ crash, and the once-heard lively midnight choruses become lonely plaintiff cries.

Even if the pathogen does not get every last frog, populations will be left decimated, and teetering on the brink of disappearing altogether. This phenomena, the heightened risk of blinking out at low numbers, is referred to as the ‘small population paradigm’. A multitude of reasons, struggling to find mates, low genetic diversity, and natural catastrophes, help to stack the odds against the recovery of small populations even if the original threat (Chytrid in our case) is eradicated. Eventually every singer gives up the ghost, entire species blink out, and both the songs and admiring masses are consigned to the annals of history. In the frog world, final curtains have fallen at least 200 times in our lifetime, likely considerably more. Potential solutions do not come easy, and I offer none. I know for certain however that without action, a silent night will leave us mourning.

Desert Island Risks

Picture it. A tropical paradise, blonde sands calmly caressed by the cool blue, a gentle ocean breeze brings salt and seaweed to the nostrils, and unseen birds bring a sweet melodious symphony to the ear. But there is trouble in paradise. Indeed, your presence in such a place is reason enough to be worried. The propensity of human beings to explore every inch of this planet, traversing back and forth with wanton abandon, has dire consequences for all other life on this planet, particularly islands.

Islands may seem distant and immaterial, but these microcosms are home to some of the most precious wildlife on Earth. There are thousands of islands, each one a world in miniature. Just because life on islands have so little room to move, does in no way mean that life on islands is any less complex, intricate, and unfathomable than life on the mainland. Even a cursory glance at some of the weird and wonderful, almost mythical creatures on islands: Komodo dragons, moas, pygmy elephants, reveals this truth. Indeed, island inhabitants face unique pressures that provide opportunities for life to experiment and evolve. Their inherent isolation is what makes each island unique, and the diversity generated inspires awe and fascination for island-life.

It is this same isolation however, that makes islands so inherently vulnerable. Islands are the geographical equivalent of immune systems that have yet to be exposed to infection. They lack the acquired defences to combat illness, and hence the fallout from exposure to novel diseases is often fatal. In the 21st century islands are sick, and we are to blame. However, human beings are not the disease in this analogy. Like mosquitoes, acting unknowingly as a vector for the real nasties, malaria, dengue, zika, we are in turn merely vectors for the real pathogens: cats and rats.

First some ‘soil-yourself’ statistics:
– Half of all known extinctions in human history have occurred on islands.
– 90% of all bird extinctions have occurred on islands.
– Rats and cats are responsible for 130 island extinctions, and threaten at least 600 more.

With so many species succumbing to rather mundane predators, it begs the question: ‘don’t these island critters know an enemy when they see one?’ And the answer is, somewhat surprisingly, ‘no’. Or more accurately perhaps, ‘at least not anymore’. Fear is an adaptive trait, useful for avoiding predators and undue risks. However fear is an extremely costly trait, and hence animals on islands with no natural predators tend to lose their fear rather quickly. Stories abound of Dodos practically walking into the cooking pots of Dutch sailors and Galapagos finches feeding from the hand of Darwin; not so much fish in a barrel as birds on an island. Lack of fear therefore, is the characteristic that makes islanders so endearing and so endangered.

Unfortunately, the situation is going to get worse before it gets better. People are only becoming more numerous and more mobile. It is now possible to fly halfway round the world in less than 16 hours. It is now possible to book a package holiday to Tristan da Cunha. Nowhere is safe, nowhere too remote to avoid the ongoing pandemic. We are oversized mosquitoes, transmitting life-threatening moggies to every corner of the globe. We are orchestrating a transition from desert island to deserted island.

Picture it. A tropical paradise, blonde sands calmly caressed by the cool blue, a gentle ocean breeze brings rotting carcasses and cat shit to the nostrils, an eerie unnatural silence fills the ear. Fuck that for a laugh.

Them Bullfrog Blues

Have you ever woke up with them bullfrogs on your mind?
I got the bullfrog blues and I can’t be satisfied,
Mexico got ‘em,
Japan got ‘em,
Cuba got ‘em,
Jamaica got ‘em too,
I got the bullfrog blues and I can’t be satisfied,
Italy got ‘em,
France got ‘em,
Brazil got ‘em,
the Netherlands got ‘em too
I got the bullfrog blues and I can’t be satisfied,
Canada got ‘em,
China got ‘em,
Brazil got ‘em,
And Columbia got ‘em too,
I got the bullfrog blues and I can’t be satisfied,
Uruguay got ‘em,
Venezuela got ‘em,
Argentina got ‘em,
And South Korea got ‘em too.

When the original version of this superb pre-war blues was penned by William Harris in 1928, bullfrogs had yet to be transplanted by humans outside of their native range in eastern North America. I have necessarily modified the lyrics accordingly, but the sentiment remains the same. Today, bullfrogs are found on every continent besides Antarctica, and thus it is not just the bluesmen of the Deep South that have bullfrogs on their minds. To me, the two pertinent questions are How has this happened? and Why does it matter? The first is simple, the second multifaceted, subject to personal bias, and can only be briefly touched upon in a single blog post*.

The short answer to the question of how this situation arose is: people. The slightly longer answer is: people… obviously. More informatively, bullfrogs have both been introduced accidentally, as stowaways or hitchhikers, and purposefully, with the intention of farming them for their meaty (and I’m told tasty) legs. Despite the mechanism, the end result is the same; an animal is now where it’s not supposed to be. The myriad consequences of these artificial dispersal events are still being quantified, but we have been witnessing the detrimental impacts of bullfrogs for decades and it is truly terrifying to extrapolate out from the irreparable damage caused by a single species to the carnage posed by biological invasions generally. We have only documented the tip of the iceberg when it comes to the impact of invasive species, but it is patently clear that if we do not divert our course, this thing is big enough to sink us.

Ecosystems are intricate interwoven fabrics, such that you cannot alter one aspect without having knock-on effects that percolate throughout the rest of the . Herein lies the destructive power of invasive species. Their impacts are often so far-reaching they are near-impossible to predict, and have only begun to be quantified. The most intuitive impacts of invasive organisms are those directly experienced by closely related species through competition; i.e. if bullfrogs are introduced, something has to make way. A loose ‘one in, one out’ policy was elegantly described by Bob MacArthur and E.O. Wilson studying island communities. This delicate balancing act however, assumes that the system in question exists in a serene, idyllic state of equilibrium. Invasive species are by definition a severe disruption to the equilibrium, and tend to exert a much more damaging influence on local fauna, typically leading to more of a ‘one in, many out’ situation. Indeed with bullfrogs, this is what we see the world over.

Common toad (Bufo bufo) with in strings of toadspawn | Erkr ten-Paar (Bufo bufo) beim Laichen, die schwarzen Punkte sind die Eier in der Laichschnur

Native frog communities likely tell stories of bullfrogs akin to those yarns spun by Romans of Visigoths**. Standing 20cm long, weighing 1.5kg, they will eat anything that fits in their mouth, from spiders to sparrows. Their tadpoles are toxic, allowing them to breed in virtually any body of water, and circumventing any population regulation from predatory fish. They arrive, they establish, and they multiply. Unimpeded, they reek havoc on competitors and prey alike. Direct impacts such as these are well understood and receive the majority of attention from scientists studying invasive species. Interestingly in the case of bullfrogs however, and the role they play in global amphibian declines, indirect effects are of much greater concern.

American bullfrogs are thought to be responsible for the rapid spread of a deadly fungal pathogen that threatens % of all frog species with extinction. Chytrid routinely makes mainstream news and has already led to the decimation of frog populations in several continents. Bullfrogs are one of the few amphibian species that are seemingly immune to the fungus, but can still carry and transmit the pathogen. Perhaps then, our analogy should not be the Roman-Visigoth clashes of antiquity, but that of the European conquest of the Americas. Far more indigenous people died as a result of diseases brought over on Spanish and Portuguese ships than direct fighting with Conquistadors. Similarly, an indigenous frog does not even have to encounter the invader to suffer as a result of its arrival.

When I first introduce kids to the topics of evolution and natural selection, the concept of ‘survival of the fittest’ inevitably draws the same astute question: why is there so much diversity? This is an excellent question that, for the most part, baffles scientists. Explaining patterns of diversity is a major branch of the biological sciences, and answers to date are largely underwhelming in their explanatory power and often mindbogglingly complex. Critics have a much easier time of it. If what you say is true, the doubters assert, why isn’t there one species that out-competes all others? Why isn’t there just one frog, the fittest, most well-adapted frog that drives all others to extinction? Perhaps soon there will be.

*Especially one that is already running too long on account of the inclusion of made-up lyrics to a song that no-one but me has heard. To those who complain that this tune is too long and repetitive, I wholeheartedly agree. It is depressing that we have let the situation develop into such a sorry state of affairs. But I have bad news. The global invasion of bullfrogs across the globe is far from complete; by the end of the decade, we will almost certainly be able to add a couple more verses. Indeed, in my haste I forgot to include the UK, my homeland; we have them there too.

**The Visi- in Visigoths actually means west, so it is a fitting analogy to the amphibian invader in the western hemisphere terrorizing the longstanding civilizations of the Old World.

Evolution in the Anthropocene

Welcome to the Unnatural Histories blog!
It will feature stories spanning the breadth of the animal kingdom (maybe some plant stuff as well), documenting the often unintentional influences of human beings on the natural world.

Life is an interwoven tapestry, a majestic work of art, both through time and across space. In our struggle for self preservation, we tug at the threads of life and distort the carefully crafted images therein. In doing so we threaten our own existence, for humanity is very much a part of this intricate fabric. There is still time before life is in tatters, but we have already left an indelible mark. By studying the tears and inkblots inflicted by human civilization we learn something of the structure of nature, how things are put together. We also gain insight into how best to preserve and possibly restore such a marvelous composition.