Welcome to the last article in my little series on Inside Nature’s Giants (see part I, part II and part III first). The final, fourth episode looked at giraffes (or, specifically, Rothschild’s giraffe Giraffa camelopardalis rothschildi, or G. rothschildi if you prefer). For me this was the most impressive episode; partly because they covered just about everything you could think of, and partly because I haven’t seen inside a giraffe before. Graham Mitchell was on-hand as their giraffe expert (is this the same Graham Mitchell who also publishes on crocodile farming?). They showed us the enormous, yellow nuchal ligament [see adjacent CG image, and dissection shown below. Images © Channel 4], the neck musculature, the lungs (again, very bizarre), the anatomy and role of the tongue, the enormous, phenomenally thick-walled heart, the tightly adhering leg skin, the dense lower limb bones, the vasculature associated with the skin blotches, the capillary network at the base of the brain (this prevents high-pressure blood from the heart rushing in and damaging the brain), and more. That’s a lot of detail.
If you know anything about giraffes and hypotheses about their evolution, you’ll know that experts have argued over which pressure was more important in directing the evolution of the incredible neck. The ‘traditional’ hypothesis – if there is such a thing – is that the long neck evolved in response to competition avoidance. This was challenged by Simmons & Scheepers (1996) who argued that the role of the neck in sexual selection might have been more important in shaping its evolution. This is the ‘necks for sex’ hypothesis. Their arguments were contested by Cameron & du Toit (2007) who showed that competition avoidance and access to elevated foliage is of major importance to giraffes (Cameron actually starred in this episode). I was mightily impressed to see all of this featured!
Perhaps the most memorable scene involved the dissection of the recurrent laryngeal nerve: the branch of the vagus nerve that travels from the brain to the larynx. Rather than going directly for all of 50 mm or so, it needlessly travels all the way down to the heart, loops round the aorta, and then comes all the way back up to the larynx. This is more pronounced in a giraffe than any other living animal, of course. This is illogical ‘bad design’ and apparently the result of historical legacy: in the earliest vertebrates, the nerve was taking the most direct route, but once necks evolved the nerve found itself in the middle of a complex vascular junction, and had to remain tangled with the aorta even when the aorta and the brain became widely separated. ‘Bad design’, whatever it means and whatever significance you want to give it, is great fun, and does demonstrate the contingent nature of evolution. Featuring the recurrent laryngeal nerve of the giraffe was, I feel, an excellent move.
Mistakes, Dawkins and… will there be more?
Inevitably, a few little mistakes, or points of contention, made it into the series. Elephant tusks are not canines, as stated, but actually deciduous incisors (Tassy 1987), and baleen whales were said to use the low-frequency noises they create to detect distant fish shoals via echolocation. It has indeed been suggested on occasion that baleen whales might employ crude echolocation, but last I heard this was only a speculation and required confirmation. Let me know if you know otherwise!
It was great to see so many ‘relevant’ people featuring in the respective episodes but, personally, I didn’t see much point to the Richard Dawkins bits: his role in the series was essentially superfluous, as we already had anatomists and other specialists telling us all about the anatomy. His main role seemed to note repeatedly that – even while organisms ‘look designed’ – it is blind evolution alone that has done the designing, and that there is no designer in the true sense. This served, I suppose, as a smackdown to creationist bullshit, but was it really needed? I’m not a fan of religion, but I’m not really a fan of Dawkins either: as some people have already noted in the comments, the fact that he’s generally taken to be synonymous with hardline godlessness will put off many of the people who would likely benefit from exposure to the evidence for evolution.
Anyway, there we have it. Tons of information: essential revision and/or practical demonstration for those with some anatomical knowledge, and a fascinating and compelling introduction for a whole new audience. Bold, fantastically done, and surprisingly comprehensive, I think that Inside Nature’s Giants really was outstandingly good, and well done and congrats to everyone involved. The big question is: will there be more? Of course, I don’t know, but I note that the series is referred to as ‘series 1′ on the Channel 4 website. Fingers crossed. There are more giant animals that could be dissected for TV – I’m thinking big sharks, ostriches and leatherback turtles – but there’s also the exciting possibility that small and medium-sized animals could be discussed too, perhaps with CG being used to make them look big and exciting. The anatomy of small critters is often just as incredible and bizarre as that of giant animals, if not more so, but of course we forget this because we’re fascinated by size. If you liked Inside Nature’s Giants as much as I did, you should perhaps consider registering your thoughts at Channel 4. I often feel that television is, increasingly, vacuous crap and that owning a TV set is a complete waste of time. Events like Inside Nature’s Giants make me feel that things aren’t so bad after all.
For more on giraffes see…
- Dammit, and I sooo loved the ‘necks for sex’ hypothesis
- Tet Zoo picture of the day # 6 (on giraffe skulls)
- Giraffe vs plane
- Giraffe-killing lions exploit paved roads
- Yet another bizarre and unfortunate giraffe death
- Sleep behaviour and sleep postures
- Death by lightning for giraffes, elephants, sheep and cows
Refs – –
Cameron, E. Z. & du Toit, J. T. 2007. Winning by a neck: tall giraffes avoid competing with shorter browsers. The American Naturalist 169, 130-135.
Simmons, R. E. & Scheepers, L. 1996. Winning by a neck: sexual selection in the evolution of giraffe. The American Naturalist 148, 771-786.
Tassy, P. 1987. A hypothesis on the homology of proboscidean tusks based on paleontological data. American Museum Novitates 2895, 1-18.