- The worst day in the entire history of life on Earth happened in the northern springtime. On that day, the last of the Age of Dinosaurs, a roughly seven-mile-wide chunk of rock that had been hurtling towards our orbit for millions of years slammed into Earth’s midsection and immediately brought the Cretaceous to a close. The consequences were so dire that survival in the hours immediately following impact was merely a matter of luck.
- Of course, life wasn’t totally extinguished on that day 66 million years ago. Some species survived, emerging into a transformed world. We can’t help but draw our own history to this specific moment, the dawn of the Age of Mammals, when fuzzy beasts could finally flourish. Dominant dinosaurs suffered a stroke of cosmic bad fortune, and our mammalian kin inherited a planet where they would no longer have to fear death in reptilian jaws. The image is of a great ecological cast change, different players continuing the evolutionary story. It’s a very appealing distortion.
- Evolution and extinction are bound together in these small, often-invisible interactions between species, the connections that continually shape the unique nature of life on our planet. In our present moment, we are not only playing a role in which lineages will survive and which will disappear. Our actions are also cutting through life’s web, affecting entire communities and ecosystems that will test the resilience of more species than we’ll ever count.
- The history of life on Earth cannot be encapsulated as a balance sheet of losses and gains through time. Nor can our present moment be understood as different groups of creatures ceding the way for each other as life climbs the rungs of progress. The reality, like life itself, is messy. Comprehending what transpired 66 million years ago – or even in this moment – requires that we look beyond the details of what we can discern from a given species in isolation. Every fossil bone we uncover and carefully cradle in a museum grew from nutrition derived from other forms of prehistoric life; and those food sources, in turn, built their tissues from plants that took up essential components from the soils, enriched by the decay of yet other creatures that came before. Wherever we find life, one existence touches another, enmeshed and setting the conditions for what might appear tomorrow.
- Riley Black is a science writer and author of several books, including Skeleton Keys (2019), Deep Time (2021) and The Last Days of the Dinosaurs (2022). Her bylines have also appeared in publications such as National Geographic, Slate, The Wall Street Journal and New Scientist, among others.
- Of course, this is a taster for the author's latest book.
- That said, it's interesting enough. There are a couple of warnings.
- The first is methodological - that we shouldn't interpret geological history too much from our own perspective, as though it's all about us.
- Secondly, that ecosystems are much more complex and interconnected than we might expect, and the removal of even one species can have a ripple effect. One such was that the loss of a top predator may lead to disease spreading through its prey species (because the sickly ones are not culled as the easiest to catch). Large animals trample vegetation as well as consume it - their removal has a major impact on plant species.
- Also the application to the present day. The asteroid strike 66m years ago was an instantaneous event (whereas the effect of vulcanism took - say - a million years to develop). The present extinctions happening as a result of human activity are happening in a geological instant.
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