The role of trade-offs in the evolution of senescence

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Spoiler alert: we are all going to die! Death is certain in all organisms: from bacteria, to us humans, and to the millenarian Bristlecone pines. However, the driving question in ageing research is not so much the end point, death, but rather what happens to our bodies before we reach that destination. Specifically, why do we become more fragile and decrepit prior to death? This increase in mortality risk and decline in fertility with age, known as senescence, has a strong influence on our lifetime agenda: the age at which we graduate from school, are expected to get married and have babies, get a permanent job and retire from it, to mention just a few. All of these are critical events in our lives that are established by governments using, among others, estimates of senescence rates of each country's human populations. When senescence is a bit slower, as in Northern European countries, and governments start to contemplate the idea of reducing the number of work hours per week while postponing the age at retirement, as it is currently being hotly debated in Germany and Denmark.Get ready to be jealous: it turns out that senescence is not universal! Some animals and plants out there do not experience it. Yet, since the early inception of ageing research, the main theories to explain the occurrence of senescence have treated senescence itself as unavoidable and unescapable. My colleagues and I have recently disproved this fundamental tenet of life history theory in a publication in Nature. We have shown that, in fact, most plants and many animal species do not become more decrepit as they age. This finding drastically reshapes the direction that ageing research has taken historically. It is indeed a particularly exciting time to partake in ageing research because our finding has provoked a paradigm shift, forcing ageing research to move on from the question "Why do we senesce?" towards "Why and how do some species senesce but others do not?".Do you wish to understand why we humans age? How about stepping away for a bit and examining how other species manage to escape senescence? My research will examine the mechanisms by which animal and plant species senesce or escape senescence. I will determine the aspects of a species' anatomy, physiology, habitat and evolutionary history that make it more or less vulnerable to ageing. To do so, I will examine the roles of physiological and macro-evolutionary trade-offs in the evolution or escape of senescence across the tree of life examining senescence trajectories in over 2000 animal and plant species from a database that I have developed in the last decade, and a set of long-term demographic datasets of species with complex life histories such as carnivorous plants or orchids with the ability of long-term dormancy (like a bear). Findings from this research are likely to pinpoint the habitats, abiotic conditions and features of taxonomic groups that allow species to operate at high performance levels for longer.