Fossilised mammal skull fossils and lower jaw retrieved from Corral Bluffs, Colorado, dating from the aftermath of the mass extinction of species 66 million years ago. Photo: HHMI Tangled Bank Studios/Handout via Reuters.
The ongoing coronavirus pandemic has given humankind another occasion to recall the many threats it faces, and has faced, through time. Such thoughts are only fitting today because crises are often opportunities to reinvent and reimagine the way we live on this planet. One good place to begin is by looking deeper into the messages past life forms have left behind for us.
In palaeontology, an index fossil is any fossil that has a wide geographic distribution, indicating that the creature to which it once belonged was once abundant but was present for a relatively shorter period in the geological record. That is, the species that has a wide geographic distribution typically ends up surviving for shorter periods of time – likely because its abundant presence also exposed the species to more, and more variegated, threats, so failed to withstand the vagaries of the environment and adapt, and ultimately went extinct sooner than would be normal.
Will the remains of Homo sapiens sapiens one day be identified as index fossils? We are Earth’s most widespread and dominant species, and as the pandemic is showing us now and climate change promises to for the rest of this century, there is a good chance that we will perish from the face of Earth sooner than would be ‘normal’.
In all likelihood, we became a superior species 60,000 years before present (BP), when we came to dominate other living organisms and learnt to use our natural resources for reasons other than what our biology demanded. Probably 11,000 years BP, we invented agriculture and learnt to select crops that suited our needs, for food and trade otherwise, and domesticated several wild animals and reared livestock. (Both these timespans are but a blip on the geological clock.)
Later humans – who called themselves Homo sapiens, which translates ironically to ‘wise man’ in Latin – cleared forests and more specifically selected plants and animals to feed themselves as well as accumulate wealth and power, culminating in industrialisation. The human population grew even as humankind’s social and political structures expanded in devious ways, eventually to the extent that we encroach indiscriminately on the planet today. Now, in this moment, our dependence on our not-entirely-natural environments is gradually, yet steadily, rendering us more sensitive to environmental changes – so much so that we seem to be hurtling towards a point of no return.
Much earlier in geologic history, some 2.4 billion years ago, a species called cyanobacteria exerted such a great influence on the environment that its own activities poisoned itself, and possibly many other anaerobic organisms, to death. Cyanobacteria aren’t extinct and continue to survive but they’re far less abundant. Back then, Earth had much higher levels of atmospheric carbon dioxide, which the photosynthetic cyanobacteria fixed, thereby releasing vast amounts of hydrospheric and atmospheric oxygen that eventually affected their abundance.
Studies have shown that cyanobacteria were both widespread and populous in Earth’s ancient oceans but dwindled because their population drove up oxygen levels in the atmosphere. The parallels with humanity here are unmissable – but with one significant difference: cyanobacteria were unicellular creatures and so lacked the faculties to be aware of the cataclysm to befall them. (It is a completely different story that their actions provided favourable pathways for organic evolution that eventually lead to the creation of Homo sapiens sapiens.)
We, the wise ones, have been fairly cognisant of our influence on the planet for well over a dozen millennia. But we continue to remain in denial of the naked reality. The vast majority of climate scientists agree that human activities are causing the climate to change, in increasingly perceptible ways, but most of their exhortations are restricted to the scientific literature. Around the world, politics is concerned predominantly with relatively pettier issues like wealth accumulation and defence spending even as it has become exceedingly important for us as a species to recognise that we’re in danger, and act accordingly.
Climate change is certainly inevitable, just as much as human activities are accelerating it. Simply knowing this doesn’t make us intelligent. Instead, that will be determined by the way we survive the change.
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The recent euphoria related to colonising potentially habitable worlds elsewhere in the Solar System, if not the galaxy or the universe, is the product of a misplaced conception. Such dreams are really the consequences of false hope engendered by ambitious but impractical projects undertaken by the richer space-faring nations.
Visiting a potentially habitable exoplanet or mining a resource-rich one is one thing but to conflate these possibilities with opportunities for humans to settle different worlds is quite another.
Even our focus vis-à-vis planets and asteroids within the Solar System has primarily been in terms of extracting resources or for finding signs of life, such as in Martian subsoil or the subterranean oceans of Europa. Even when we fling our gaze to the farthest planets, it seems to be accompanied by whispered questions about potential habitability.
The scientific community clearly understands today how improbable the idea of settling another world is at the moment, but most non-experts – the people – are being fed a more fantastic narrative. Even if we consider the resource potential of extraterrestrial bodies, they can be significant only in terms of the amount of metals and minerals of strategic importance they host. The majority of the natural resources humans consume come from our own planet.
Earth is about 4.5 billion years old. The time-bound evolution of different spheres – the lithosphere, the hydrosphere, the atmosphere and the biosphere – for over 2.5 billion years was required for unicellular eukaryotic organisms to take shape. Another 1.5 billion years later, the first animals with hard parts appeared in the geologic rock record. For the last half billion years, plant and animal life gradually but continuously evolved to their present forms and distribution, punctuated by multiple mass-extinction events. And for the last 2.5 billion years at least, plate tectonics and volcanic activity has been continuously recycling resources from the surface to the mantle and back.
All together, the conditions required for Earth-like life forms to evolve on an Earth-like planet include the availability of such a planet within the habitable zone of its host star, a history of finite evolution of multiple spheres of the planet, just enough heat to maintain liquid water at least in the sub-surface, a magnetosphere to filter harmful stellar radiation, a comparable gravitational field to support Earth-like life forms, rotational and revolutionary periodicity to maintain stable diurnal and seasonal weather and climate, geological activity, and so forth.
Unless all these conditions, and others besides, are fulfilled, it would be foolish to think that humans could ‘escape’ Earth and live elsewhere. We can at best survive.
Axiomatically, the people of Earth should make a concerted effort to understand Earth’s uniqueness and preserve it. It’s important that our political leaders and planners not fixate on economic growth but consider tradeoffs between growth and sustainability, to improve the quality of human life without laying waste to the lives and homes of other creatures.
Instead of cutting out chapters from school textbooks, Earth science should be made compulsory in schools, to suitably educate young minds about the perishable nature of humans as a species and the importance of preserving Earth’s natural environment. The coronavirus pandemic has provided us with an opportunity to do just this. We need to act.
Anand Rajagopal teaches geology at IIT Dhanbad.