In The Blink Of An Eye: How Vision Sparked The Big Bang Of Evolution

In The Blink Of An Eye: How Vision Sparked The Big Bang Of Evolution

Andrew Parker

Language: English

Pages: 264

ISBN: 0465054382

Format: PDF / Kindle (mobi) / ePub


About 550 million years ago, there was literally an explosion of life forms, as all the major animal groups suddenly and dramatically appeared. Although several books have been written about this surprising event, known as the Cambrian explosion, none has explained why it occurred. Indeed, none was able to. Here, for the first time, Oxford zoologist Andrew Parker reveals his theory of this great flourishing of life. Parker's controversial but increasingly accepted "Light Switch Theory" holds that it was the development of vision in primitive animals that caused the explosion. Drawing on evidence not just from biology, but also from geology, physics, chemistry, history, and art, In the Blink of an Eye is the fascinating account of a young scientist's intellectual journey, and a celebration of the scientific method.

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they existed, they did exhibit a variety of lifestyles. We know this from the shapes of the life forms themselves and from their trace fossils - footprints and their equivalents. The Cambrian was once described as a peaceful time, but we have now established this is not true. In fact we know now that predators existed even before. In the Precambrian there were jellyfish pulsating through mid-water, and relatives of the Portuguese man-of-war floating on the surface. Any creature that accidentally

fossil community, one really can be more specific. The presence of photosynthetic algae in a fossil assemblage indicates that this community lived under reasonable levels of sunlight, placing the extinct environment within the photic zone - between the ocean surface and around 90 metres in depth. Similarly, biology can be inferred from fossilised land-based organisms. For instance, we are beginning to map the fine variations in the external skeletons, or exoskeleton, of living beetles. Beetle

as distant as the Cambrian. The logarithmic-style time travel employed in this chapter perhaps settles the nerves all the more - to begin with, it’s nice to make reconstructions of ancient but recent periods, periods we can test. Now we can be confident of the wealth of biological information we have extracted from Cambrian fossils, but this information ceases abruptly and simultaneously in all parts of the world as we split rocks formed before the Cambrian, beyond that auspicious borderline of

Worms are ubiquitous but hide a plethora of phyla, such as the ‘ribbons’, ‘peanuts’, ‘arrows’, ‘acorns’ and flatworms. Ribbon worms, as their name suggests, are ribbon-like in appearance and seem quite placid until they make their presence known with their powerful jaws. Peanut worms are less dangerous and have a swollen rear end. Its similarity to a peanut is questionable, but a brownish colour is the norm. The acorn analogy is even less convincing, although arrow worms are more appropriately

central axis of the lens - the peripheries bend light too much. So to focus both sets of rays simultaneously, the retina must be in two places at the same time. This is impossible. But fishes can see by focusing very sharp images - the question is ‘How?’ There is only one solution here, and Maxwell worked it out. If the curves, or rather tangents, are made less steep by flattening the lens, the focal point moves too far from the lens - a huge eyeball would be needed to house the retina. So if

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