Last year, when I covered the Wildlife on One episode "Uninvited Guests", I mentioned an episode called "Amazon Assassin" that I remembered being pretty darned peculiar, and lamented the then-elusiveness of said episode. Elusive no more, however - "Amazon Assassin" recently emerged from hiding, so the time has finally come to dig in and get to grips with how peculiar.
"Amazon Assassin" first aired on BBC1 on 16th July 2003. At this point, Wildlife on One had been a fixture of the BBC's programming for more than thirty seasons; alas, it did not have much longer to go, and the series' twilight years were among the most fascinating for some of the more experimental tactics it engaged in in an effort to keep the format fresh. "Be An Animal", which aired the previous summer, centred around the playthrough of a fictitious video game in which the player was required to make choices that, for the computer simulations' real-life counterparts, could mean the difference between life and death. It was hard to envision a freakier direction for Wildlife on One, but "Amazon Assassin" gave it a run for its money in assuming an approach that was every bit as novel. This film demonstrates how similar techniques to those used in forensic science can be applied in studying animal behaviour, and does so by adopting the format of a good old-fashioned murder mystery. The skeletal remains of a sloth have been uncovered from the rainforest floor; the skeleton itself seems unusually intact, suggesting that it was not devoured by a large predator likely to have given the carcass a more thorough mangling. Close examination of the bones determines that the sloth was young and healthy, ruling out old age and disease as potential causes of death. Likewise, the absence of any broken bones would appear to confirm that the sloth was not the victim of a fatal fall. The probability points increasingly to foul play - presumably, the sloth was done in by one of its fellow jungle dwellers, but who? The problem is that none of the blemishes detected on the sloth's bones seem entirely consistent with any one Amazon predator's style of killing. Can we piece together everything we know about the complex web of life in the rainforest to deduce how that final, deadly scenario played out for our three-toed friend and with it, the identity of the elusive sloth slayer with whom it had the misfortune of tangling? As with any riveting whodunnit, our investigation is wont to lead us into some truly unexpected and unsettling territory.
"Amazon Assassin" was actually the second installment in a conceptual two-parter - before it, we had "African Assassin" (not currently on The Internet Archive, but give it time), which applied the same formula to an act of carnage on the grasses of the savannah, the victim in this instance being a baby Thompson's gazelle. David Attenborough gave a run-down of several prominent predators who could potentially have done the deed, before DNA testing revealed that the gazelle was, in fact, killed by an animal previously framed as being above suspicion (although perhaps it would not surprise you if you'd remembered one of the scenarios from "Be An Animal"). Reaction to the two episodes was presumably very positive, because an entire spin-off series, Animal Crime Scene Investigation, was commissioned in 2005 (regrettably, I largely missed out on that one, although I am aware that two of the episodes were straight-up remakes of "African Assassin" and "Amazon Assassin", padded out with an extra fifteen minutes' worth of material). The whole enterprise was presumably conceived in response to the popularity of contemporary CBS series CSI: Crime Scene Investigation, and while it certainly was an inventive mash-up, there is a degree of philosophical incompatibility between the two genres that "Amazon Assassin" intermittently struggles to overcome. Crime dramas such as CSI are rooted in ideas about moral boundaries, the inherent abhorrence in transgressing such boundaries and the necessity of bringing any and all transgressors to justice, concepts that obviously don't apply when scrutinising how the animal world functions. In reconceptualising the sloth's story to fit the familiar narrative patterns of a whodunnit, "Amazon Assassin" ends up adopting terminology that would be huge no-nos in a more conventional wildlife documentary - the sloth is described as an "innocent victim", while one of the top suspects, the harpy eagle, is tagged a "sloth serial killer". To an extent, this is a necessary evil in keeping with the genre it's aping - even the term "murder" carries uneasy overtones of human judgement - and while it's evident that the CSI homages are intended to be more than a little tongue-in-cheek (we get shots of the supposed "crime scene", complete with police barricade tape), it is nevertheless rather jarring to hear the words "sloth serial killer" coming from a voice as authoritative as Attenborough's. But then, to get too hung up on this point would detract from the real purpose of the documentary, which is to teach us about the complexities of life in the Amazon, and of the numerous challenges to which the sloth and sloth predators alike have risen in order to carve out a living therein. It's easy enough to dismiss the whodunnit angle as a hollow gimmick designed to hook viewers who might be indifferent toward more conventional approaches, but it does offer a very unique and effective perspective - by emphasising the blind spot in our narrative understanding, it increases the immediacy and menace of the situation, attuning our awareness to the hidden perils we otherwise might have overlooked. No better way for us to appreciate the multitude of hazards lurking within that dense Amazon greenery than for us to match our mental wits against it. On top of which, if you can allow for a little artistic licence, the whodunnit approach is, simply put, a whole lot of fun.
In this case, the victim is one that should have little difficulty eliciting our sympathies - the unassuming sloth has endeared itself to many a human heart, mass appeal that I've no doubt can be at least partly attributed to it being the specimen in the animal kingdom to most closely resemble a Jim Henson puppet, with its gangling limbs, prominent nose and comically extended neck (comprising more bones than a giraffe's, Attenborough informs us). Furthermore, it's a species that has mastered extreme slovenliness as a survival technique, and that too is a magnet for human admiration and envy alike. The sloth sleeps for twenty hours a day (expending minimal energy allows it to thrive on a diet of low-nutrient leaves - more accurately, poisonous, low-nutrient leaves, which its slow-brewing digestive system makes simple work of), it only ventures down to the ground either to shit or to move between trees, and during the rainy season it enhances its camouflage technique by developing green mold all over its fur (which also houses a huge variety of parasites). In Attenborough's words, "The sloth must make an unattractive meal - it's all insects, fur and giant fermenting gut." Is there a single thing not to love about this living Muppet? There are, of course, limitations to how far the way of slothfulness can take you, as our sloth's sorry story demonstrates. A sloth's two key weaknesses are a) its inability to regulate its body temperature, meaning that it must intermittently break its camouflage to bask in the sunlight and b) if ambushed by a predator while on the ground, it's as good as defenceless. Attenborough surveys the various jungle killers with the means to exploit these vulnerabilities, and measures up how their respective methods compare to the state of our decomposed sloth.
In visualising how these prospective attacks would play out, the episode runs into a few obvious technical limitations - it rarely has actual footage of the pertaining scenarios, so most visualisations are reliant on creative editing (you'll rarely see the sloth in the exact same frame as each predator) or clever use of props (look closely, and you'll notice that a stuffed sloth endures an awful lot of abuse throughout this film). Some of these recreations are more effective than others, the least convincing involving a certain piscine predator (see below), but then if you think that sloths are so endearing, odds are that you don't want to see a documentary comprised of nothing but scenes of genuine sloth slaughter. A little chintziness is welcome in taking the edge off.
The sloth is at its safest when it's in its element, clinging statically to a branch suspended way above the forest floor. It's not a guarantee, however, so Attenborough begins by looking at the hunters that might have poached it from up high:
- Harpy Eagle: Earlier, I scoffed at the idea of this bird being labelled a "sloth serial killer". Regardless, I can comprehend why it, out of all of the suspects, received such a loaded and macabre title - its preferred raw materials for building its nest are a) branches and b) the bones of its victims. Very Buffalo Bill, no? The intact nature of the skeleton indicates that our sloth was not eaten by a harpy eagle; the lack of breakages likewise suggests that the sloth was not dropped by an eagle while en route to its nest.
- Human: The indigenous people of the Amazon hunt tree-dwelling mammals by felling them with poisoned blow darts. Attenborough points out that this technique is more effective at bringing down monkeys than sloths - a sloth's grip can be locked so tightly that it could continue to dangle from the treetops even with a poisoned dart lodged in its torso - but if it was successful, then the sloth should certainly expect to break a few bones on the way down. Already this isn't looking very probable.
Due to the lack of broken bones, Attenborough proposes it more likely that this sloth was ambushed while traversing the forest floor. Canopy hunters are eliminated, and we instead look to those predators that operate at the ground level:
- Army Ants: These tiny but tenacious killers generally target other invertebrates, although a sloth is one of the few mammals incapable of outrunning them; it's well-covered, however, by its thick hide and long coarse coat, which the ants' teeth would have difficulty penetrating.
- Jungle Rattlesnake: Has the right teeth for the job, although the sloth's skeleton shows no signs of deterioration from venom.
- Jaguar: Described by Attenborough as our prime suspect, although deer are this cat's preferred prey and it is less likely to target a sloth during seasons in which their numbers are plentiful. In the breeding season (December to May) a pregnant female might broaden her diet to include sloth.
With that in mind, Attenborough suggests that it would fruitful to study the skeleton for evidence of when the sloth was killed, and it's here that we really get the opportunity to marvel at the proficiency of the forensic techniques and what they can tell us. Roots growing between the bones are telltale signs that the sloth has been dead for several months, which pinpoints the time of the killing back to the wet season, when the forest floor would have been covered with flood water. Even more remarkably, forensic tests for microscopic algae known as diatom can indicate whether our sloth was a victim of drowning; diatom are present in the sloth's bone marrow, confirming that it was indeed dragged to a watery grave. Mystery solved? Not really - the sloth is a very capable swimmer; if anything, it makes the process of transferring from tree to tree easier, as a sloth can move three times as quickly in the water as on land. Once again, it seems that another creature sealed our sloth's fate, one adept at handling a more aquatic domain. This revelation looks to be a real game-changer for our investigation. Land predators are eliminated as suspects, and our attention instead turns to a whole new line-up of prospective water assassins:
- Amazon River Dolphin, aka Boto: These guys have crocodilian jaws and, as per the local folklore, a predilection for shape-shifting in order to pick up human women. Their taste in cuisine swings predominantly toward fish, however, so sloth is presumably off the menu.
- Giant Otter: The concept of an otter the size of a wolf is...a little nightmarish, admit it. Fortunately, they too are unlikely to deviate from their primarily fish-based diet.
- Anaconda: Every ophidiophobic's worst nightmare. A sloth would indeed be a viable meal for the world's largest and most powerful snake. What's less probable is that the sloth's skeleton would be able to withstand the snake's method of killing - by squeezing the life from its prey - without anything giving way.
- Electric Eel: I think this episode aired somewhere near the time that Hula Hoops were threatening to unleash these beady-eyed bruisers into the UK waterworks. The eel is no sloth hunter, but could potentially deliver a shock in self-defence if it were accidentally stepped on. Attenborough emphasises that it's unlikely, but not out of the question.
- Arowana: This fishy foe seems an unlikely candidate for sloth carnage - primarily, it's an insect eater, and hunts by leaping out of the water and picking its prey off of overhead branches. Adults can grow to be two feet in length, however, and some pretty unexpected artefacts have been uncovered from the guts of individual specimens - including two baby sloths in one instance. As Attenborough observes, "to hunt one sloth might be seen as a freak occurrence. To hunt two is the pattern of a killer." Sounds convincing enough, only the visuals used to accompany this sequence somewhat undercut the menace with their borderline comical shoddiness; footage of an arowana leaping is juxtaposed with that of a sloth lowering itself, and it is a stretch to envision any kind of connection between the two.
- Piranha: Another fishy foe, and one whose fearsome reputation certainly precedes it - although Attenborough implies that this reputation may be at least partially exaggerated. Nevertheless, this is our first lead in which we have actual physical evidence to go on, and not just speculation. The sloth's skeleton is covered in tiny indentations resembling the bite marks of piranhas, indicating that the fish at least had a hand in picking clean the sloth's carcass. Contra the barrage of popular myths surrounding the piranha's voracious killing habits, Attenborough considers it unlikely that a school of piranhas would attack a healthy sloth - and besides, there are signs of greater bite marks in the sloth's skeleton still, suggesting that it was mauled by a larger predator before the fish got to it. Our search continues.
- Caiman: The jaws on these crocodilians are certainly large and impressive, and could potentially have poached a passing sloth - however, the caiman's blunt and rounded teeth are inconsistent with the bite marks on our sloth's skeleton.
- Bull Shark: Sharks have been found in the Amazon river, with the bull shark in particular being detected as far as 3,000 miles along. It specialises in shallow water attacks and, Attenborough tells us, is responsible for a higher number of human fatalities than either the great white or the tiger shark. Attenborough dangles this alluring theory only to abruptly pull the rug from under us; the odds of a sloth and shark encountering one another in the Amazon, he assures us, are so miniscule as to effectively render this entire trail of thought moot. Better stick to less laboured scenarios.
At this point, Attenborough admits that we have a problem. We've eliminated all potential suspects, so clearly something went awry with our detective work. Our only recourse now would be to retrace our steps and to consider where we might perhaps have underestimated any of our past candidates.
It turns out that our investigation made not just one, but two missteps. The first of these was in ruling out the possibility of a canopy ambush on the grounds that the sloth had no broken bones...for if it landed in the water it might not have broken any. The second was in automatically eliminating all land-dwelling predators upon learning that the sloth was killed during the wet season. In an environment that spends a significant portion of the year covered in flood, it shouldn't surprise us that land predators, much like the sloth, aren't perturbed by a little water. We had, previously, skimmed over at least one suspect that could handle all three domains - the jaguar is both an excellent swimmer and climber. And those large bite marks on the sloth's skeleton are indeed consistent with a jaguar attack.
Whereas "African Assassin" used the classic whodunnit device of the betrayal, with the killer being someone whom we were, up until the end, led to believe we could trust, "Amazon Assassin" plants its own twist in that of the double bluff - Attenborough had explicitly advertised the jaguar as our most probable candidate, and perhaps we are reflexively inclined to direct our suspicions elsewhere upon hearing those words. After all, the familiar pattern of the whodunnit dictates that prime suspects are ordinarily red herrings. The real clue, however, is in how easily Attenborough allows himself to become sidetracked in reviewing our supposed prime suspect. This is a deliberate tactic designed to misdirect the viewer into assuming that the killer must be more aquatically-inclined. Pay close attention, and you may pick up on a loose thread that Attenborough seems initially content to leave dangling. We are told that the jaguar is a "fickle villain" and that so long as there are ample deer about it will generally ignore sloths, although a pregnant female may deviate in order to supplement her diet. The implicit suggestion, which Attenborough does not at first pursue, is that there may also be periods where the deer population dips, in which case the sloth might find itself a greater target. This is finally addressed at the episode's climax - during the wet season, when the forest becomes flooded, the deer will move on to dryer terrain, but the jaguar may remain and sustain itself in their absence by catching fish, or by venturing into the canopy and taking on arboreal prey...which is how our sloth and its killer would have encountered one another.
The evidence points to the jaguar having dealt the fatal blows, but not actually having eaten the sloth. So what happened exactly? Attenborough speculates that the jaguar would have attacked and mauled the sloth in the treetops - yet while the jaguar can cope with heightened hunting, it isn't as specialised at it as bringing down prey on land, and will inevitability knock some of its would-be meals into the waters below. In which case, to the piranhas the spoils.
With that, we can close the book on our mysterious sloth killing. Attenborough suggests that this might be seen as a "rainforest conspiracy", with a whole multitude of factors combining to engineer the sloth's destruction - the real message being that life in the Amazon (or any natural environment) is complicated, and that animal lives will intersect and interdepend in surprising ways. He concludes by anticipating what new insights into animal behaviour we might gain from the increasing sophistications of forensic science.
Finally, to answer a question I posed in my coverage of "Uninvited Guests", does "Amazon Assassin" have it licked in the quirkiness arena? Honestly, I'm not sure. As offbeat as the wildlife whodunnit's approach is, "Uninvited Guests" has an understated warmth to its weirdness, and I'm inclined to give that the edge. But now that I've touched on it, that "Be An Animal" installment was also seriously odd, and might be an even worthier contender still. That episode currently survives in little bits and pieces on BBC Earth's official YouTube channel (again, beware if you don't want to have "African Assassin" indirectly spoiled for you), but until I can find it in its entirety, I'm not going to make a judgement. Let the jury stay out another day.
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