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To celebrate the 204th birthday of the father of modern biology, the Horniman Museum’s Rachel Jennings gave a talk last night at the Albert Arms about the depth and breadth of Charles Darwin’s work.

Darwin investigated everything: from the changing face of geological formations to the effects of piano music on earthworms. Though he is most known for his Origin of Species by means of Natural Selection, this is by no means the only thing he published. We have amassed a large body of data since Darwin’s day including entire new disciplines such as genetics. How have Darwin’s predictions held up? What did he get right and what was Darwin wrong about?

In the Origin, Darwin agreed with the naturalists of his day in concluding that the vast variety of pigeon breeds were descended from a single common ancestor: Columba livia. This was conclusively proved last week when a genetic study was done on a number of pigeon breeds. The study also found that the mutation which causes feathers to grow in the wrong direction – seen in the Old German Owl Pigeon or Indian Fantail Pigeon, has also arisen only once and has been selected repeatedly by breeders.

Keeping with the domestic breeding theme, Darwin studied the various breeds of domestic dog and came to the conclusion that they were too different to have come from a single wild species – that there must have been some crossing of multiple wild dogs to produce the canine spectrum from Chihuahua to St. Bernard.
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Subsequent studies have demonstrated, based on genetics and morphological character analyses, that all the breeds of dog do indeed stem from the Grey Wolf (‘African Pitbull’ aside). Darwin would probably have been delighted to hear that he was wrong in his conclusion as he once said that a single origin of dogs would lend great weight to his theory.

During his travels Darwin encountered many unusual plants and animals. Not least of which was Angraecum sesquipedale, or Darwin’s Orchid.
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Darwin’s Orchid image taken from Wikimedia Commons. Reproduced under a Creative Commons licence.

When he saw it, Darwin predicted that there would be an animal somewhere nearby adapted to feeding from it – one with a tongue long enough to reach the nectar. When he first said it, his contemporaries scoffed. The discovery of Xanthopan morgani, or “Morgan’s Sphynx” fulfilled that prediction.

On the subject of peacocks: Darwin reportedly was sickened by the sight of a peacock’s tail (he was in very poor health anyway though, so we won’t hold it against him). His explanation for the tail was to attract a mate – the larger and more spotted the tail, the more likely the male would pass on his genes. The actual situation is somewhat more complicated: for starters, removing eye spots did indeed reduce mating success but adding them seemed to have no significant effect. The peacock caused quite a stir in the question and answers round – an animal evolving a handicap to prove its prowess? What other examples are there of this? To which Paolo promptly wheeled out the human penis (thankfully metaphorical): Humans have the largest penis to body ratio of any primate and also have no bone supporting it. A male who can still get it up despite the odds stacked against him (stress, et al) is clearly worth mating with.

In The Ascent of Man, Darwin wrote: “An American monkey, after getting drunk on brandy, would never touch it again, and thus is much wiser than most men”. Darwin was wrong about the monkeys – as demonstrated by a study of a population of Vervet Monkeys on the island of St. Kitts. In the study, the monkeys could be divided into four groups: the teetotal group, representing about 10-15% of the population; the social drinkers, around 65%, drink more in the evenings – largely female; the steady drinkers, around 15% of the population, drink more in the mornings; and the binge drinkers, 5% of the population whose alcohol consumption per kg per day exceeds the fatal dose in humans! The theory is that an affection for alcohol may be linked to the ability to locate ripe fruit. Rachel is not convinced:

In conclusion: Darwin was a very gifted naturalist and very thorough researcher. We should celebrate the advancement of collected data and the ways in which Darwin has been corrected over time. If we try to sanctify the memory of Darwin into a figure who made no mistakes we not only give future naturalists an impossible role model, we also create a symbol out of the man instead of letting the integrity of his body of work stand for itself.

That’s all for now. Come along on the 11th next month when we will be discussing the marriage of art & science. http://pubsci.co.uk/

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