## Metadata - Author: [[Richard Dawkins]] - Full Title: The Greatest Show on Earth - Category: #books ## Highlights - And the amazing thing about dendrochronology is that, theoretically at least, you can be accurate to the nearest year, even in a petrified forest 100 million years old. You could literally say that this ring in a Jurassic fossil tree was laid down exactly 257 years later than this other ring in another Jurassic tree! If only there were enough petrified forests to daisychain your way back continuously from the present, you could say that this tree is not just of late Jurassic age: it was alive in exactly 151,432,657 BC! Unfortunately, we don’t have an unbroken chain, and dendrochronology in practice takes us back only about 11,500 years. ([Location 1301](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=1301)) - Tree rings are not quite the only system that promises total accuracy to the nearest year. Varves are layers of sediment laid down in glacial lakes. Like tree rings, they vary seasonally and from year to year, so theoretically the same principle can be used, with the same degree of accuracy. Coral reefs, too, have annual growth rings, just like trees. Fascinatingly, these have been used to detect the dates of ancient earthquakes. Tree rings too, by the way, tell us the dates of earthquakes. ([Location 1308](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=1308)) - Let’s now turn to radioactive clocks. There are quite a lot of them to choose from, and, as I said, they blessedly cover the gamut from centuries to thousands of millions of years. Each one has its own margin of error, which is usually about 1 per cent. So if you want to date a rock which is billions of years old, you must be satisfied with an error of plus or minus tens of millions of years. ([Location 1315](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=1315)) - Experiments like this led Sperry to formulate his ‘chemo-affinity’ hypothesis, according to which the nervous system wires itself up not by following an overall blueprint but by each individual axon seeking out end organs with which it has a particular chemical affinity. ([Location 3357](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=3357)) - The living cell, too, is a great chemistry lab, and it has a similarly large store of chemicals. But they aren’t kept in separate bottles and jars on shelves. They are all mixed up together. It is as though a vandal, a chemical lord of misrule, entered the lab, seized all the bottles on all the shelves, and tipped them with anarchistic abandon into one great cauldron. ([Location 3426](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=3426)) - The swim bladder, then, is a coopted lung, which is itself a coopted gut pouch (not, as you might have expected, a coopted gill chamber). And in some fish, the swim bladder itself is yet further coopted into a hearing organ, a kind of eardrum. History is written all over the body, not just once but repeatedly, in exuberant palimpsest. ([Location 5238](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=5238)) - Viruses and tigers are both built by coded instructions whose ultimate message is, like a computer virus, ‘Duplicate me.’ In the case of the cold virus, the instruction is executed rather directly. A tiger’s DNA is also a ‘duplicate me’ program, but it contains an almost fantastically large digression as an essential part of the efficient execution of its fundamental message. That digression is a tiger, complete with fangs, claws, running muscles, stalking and pouncing instincts. ([Location 5597](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=5597)) - The difference between life and non-life is a matter not of substance but of information. Living things contain prodigious quantities of information. ([Location 5763](https://readwise.io/to_kindle?action=open&asin=B002LVVCQM&location=5763))