Any twenty year old woman knows that the continents move and that the planet Earth is part of one of the many galaxies that populate the universe. They will be unaware of many details – or not – such as the reversal of the polarity of the Earth’s magnetic field which, etched into the rocks, shows the expansion of the ocean floor; or the speed and form of rotation of the galaxies, which suggest the potential existence of dark matter. However, the basic data is there. Plate tectonics and the existence of a universe teeming with galaxies are not standard knowledge, but they are fairly close. That woman can walk into a bar, talk to anyone about it, and no one will look at her as if she were crazy.
However, if their great-grandparents did the same, they would, at best, be met with surprise or disbelief. In fact, only a century ago such theories did not exist. A hundred years ago, the «Great Debate» took place, in which astronomers Harlow Shapley and Heber Curtis discussed their respective ideas about what the hell nebulae were. Shapley argued that the whole universe was within our galaxy, the only one in existence, while Curtis proposed the bold idea that nebulae were celestial bodies like our galaxy, just far – very far – away from it, which implied a huge universe. Although this idea had been proposed before – by Immanuel Kant, for example – science did not give a satisfactory answer until the beginning of the twentieth century.
«We rarely take a leisurely look at the impressive acceleration of scientific and technological knowledge over the last 150 years»
Our great-grandparents did not dream of galaxies, much less of tectonic plates generating earthquakes, mountains, and volcanoes. Plate tectonics theory is surprisingly recent, cooked up by science in the middle of the last century. Alfred Wegener himself, who proposed continental drift in 1912, died without the understanding of the scientific community. And yet, despite his youth, these theories taught to us in school now seem so evident and coherent that we tend to think they are much older. This is the point I wanted to make: we rarely take a leisurely look at the impressive acceleration of scientific and technological knowledge over the last 150 years (in an informal survey that I conducted at the beginning of the year on Twitter, only a third of the participants correctly stated that Wegener’s theory of continental drift was developed in the twentieth century; the rest indicated that this theory was from the nineteenth, eighteenth, or even seventeenth century). We have all assimilated that, in the Western urban world, a child’s life – his habits, games, technology – and his access to knowledge are very different from those of their parents, and are light years away from those of his grandparents. However, this tremendous intergenerational disparity is in itself a remarkable novelty.
The lives of our ancestors 10,000 or 20,000 years ago were exactly like those of their ancestors 20,100 years ago, and the latter lived in essence in the same way as their ancestors 25,000 years ago. And so we could go back thousands of years. Teenagers 20,000 years ago would get perfectly along not only with their parents, but also with their great-great-grandmothers. Such stasis is the norm in most species, but it has disappeared in ours. Cultural accumulation changes what we are and what we do from one generation to the next and, as far as scientific knowledge is concerned, changes occur so quickly that we tend to imagine them as distant theories or very recent developments.
Imminent ecdysis was the term used by Thomas Henry Huxley to refer to the great knowledge shift that was to be produced by evolutionary theory, based on the ecdysis - cuticle moulting - of many invertebrates.