Just reflecting on something I missed out of my review of Richard Dawkins’ autobiography – an interesting diversion that didn’t really fit into an already long post.
When I read it, I thought, “He’s having a giraffe – is it wise for him to be that certain?”
It’s the bit where he pretty much stakes his reputation as a scientist on his idea that the route of a giraffe’s recurrent laryngeal nerve is bad design, and is therefore evidence that the theory of evolution best fits the facts. Not only that, but he shackles a few other reputations to his concrete boots, and shuffles to the end of the pier. He refers in the book to the acclaimed TV appearance, where a few more scientists and students get to watch and participate in The Making of an Embarrassment.
Veterinary scientist Mark Evans acts as guide as a team of experts investigate the giraffe.
Creationists question how this extraordinary creature could have evolved such a long neck, but for evolutionary biologist Professor Richard Dawkins the anatomy of the world’s tallest animal provides some of the best arguments in favour of Darwinian natural selection.
For example, one nerve takes a huge detour up and down the long neck, from the voice box to the brain, via the chest – hardly the work of an `Intelligent Designer’. And, despite its length, the neck still only has seven vertebrae – the same number as almost all mammals, from mice to humans and whales.
But it’s no wonder the giraffe has the highest blood pressure of any animal; with a heart not much bigger than our own it must pump blood at high pressure around a towering body. It has evolved thick skin that acts as a natural ‘G-suit’ and a complex circulation system to avoid passing out when raising and lowering its head.
In fewer words, “This giraffe’s nerve is poor design, says confessedly poor designer”.
The thing that really stuck in my throat is the hypocritical value system that makes these case-closing assumptions, while at the same time accusing religious people of obstructing the progress of science by just answering ‘God did it’ to scientific questions. Then they have the nerve to claim to be ‘Bright’ bringers of knowledge and honest study. Just on that point alone, I’m choking and coughing.
In response to a question that could have led to more study, Dawkins answer ‘it’s a fish thing’ effectively says –
- It isn’t good design, it’s bad.
- I know, because like the lady says, it would be better going 2 inches than all that way. It shows what happens when a fish happens to get stretched into a giraffe over millions of years. Definitely.
- Because it’s bad design, and I know the fish thing is the answer, you needn’t look for anything else. Nothing to see here.
- If you look for something else, you’re wasting valuable research grants based on an evil and stupid world view. Did you not hear me Ted? It’s simple fish stretching, so it is.
Well, I don’t have a research grant or a reputation – I just have an dangerous world view and because of it, a stupid question:
What happens if a giraffe coughs while drinking?
To me, this is really interesting. I got the impression the guy at the end of the video had a similar curiosity, but he had to bow to Dawkins’ God-like knowledge of prehistoric fishes and their progeny. All sorts of questions spring out of this nerve detour:
- Giraffe blood pressure is really high – does that have a bearing on the detour past the heart?
- No – that’s silly – why would there be a connection between swallowing / voice and the heart?
- Do we understand everything that happens when a giraffe bends over to drink?
- As in communication cables, does length bring delay? Could that be a positive instead of a negative? Does length even matter in a nerve (probably not)?
- There must be more study & observation done on humans than giraffes – what happens when disease or accident messes with this signal? Are there unexpected side-effects?
- Is there a purely observation-based, non-ideological comment on this nerve?
- Is there a medically informative lesson from this giraffe that could help people who are ill?
I had this insatiable appetite for wonder thing going on, and my question was given a fig leaf of rationality by the last paragraph of the Channel 4 summary which talked of mechanisms that regulated the raising & lowering of the long neck below the heart level. What does the larynx do apart from make noises and swallow?
The most important role of the larynx is its protecting function; the prevention of foreign objects from entering the lungs by coughing and other reflexive actions. A cough is initiated by a deep inhalation through widely abducted (open) vocal folds, followed by the elevation of the larynx and the tight adduction (closing) of the vocal folds. The forced expiration that follows, assisted by tissue recoil and the muscles of expiration, blows the vocal folds apart, and the high pressure expels the irritating object out of the throat. Throat clearing is less violent than coughing, but is a similar increased respiratory effort countered by the tightening of the laryngeal musculature. Both coughing and throat clearing are predictable and necessary actions because they clear the respiratory passageway, but both place the vocal folds under great strain and can be catastrophic to a trained voice.
Another important role of the larynx is abdominal fixation, a kind of Valsalva maneuver in which the lungs are filled with air in order to stiffen the thorax so that forces applied for lifting can be translated down to the legs. This is achieved by a deep inhalation followed by the adduction of the vocal folds. Grunting while lifting heavy objects is the result of some air escaping through the adducted vocal folds ready for phonation.
Abduction of the vocal folds is important during physical exertion. The vocal folds are separated by about 8 mm (0.31 in) during normal respiration, but this width is doubled during forced respiration.
During swallowing, the backward motion of the tongue forces the epiglottis over the glottis’ opening to prevent swallowed material from entering the larynx which leads to the lungs; the larynx is also pulled upwards to assist this process. Stimulation of the larynx by ingested matter produces a strong cough reflex to protect the lungs.
So if a giraffe coughed with its head down below its heart, would it blow its head clean off? If coughing can ruin a singer’s voice, is all this extravagant length of nerve just to protect the rarely used voice function? Is the nerve’s connection with the vagus system part of an unobserved control network? Does it, as some have suggested, have a structural function to stop the heart rattling around?
That last one could even be an evolutionist’s reasonable question. Mostly, they’re the sort of questions only a faith-head like me would ask, so I’ll leave it here until someone studies my questions properly. If anyone has, please feel free to tell me.
Until then, I’ll make regular visits to the end of this pier, where Dawkins’ reputation waits in concrete boots for a real scientist to tip it over the end. My last post on this subject called us to pray for him – this one wonders whether being relieved of his vestigial reputation could be the start of his redemption.