After humans, who will rule Earth?

There are two fundamentally incorrect assumptions in this question. I want to clear these up before I answer the question. These assumptions are:

  1. That humans reign over Earth.
  2. That it is possible to “reign” over Earth.

The only people who think that human beings “reign over the Earth” are human beings. No other species of animal or vegetation gives a small vertebrate’s posterior about our so-called supreme status. To say that we are somehow masters of this planet seems extraordinarily self-congratulatory. When evaluating our place in the order of things, regardless of whether we love what humanity has achieved or hate what humanity has done to the world, we tend to assume a special status for ourselves. The philosopher Nick Bostrom has called this the Anthropic Bias[1]. It is the tendency among human beings to be biased in favour of their own species when dealing with our place in the universe.

When we remove our regard for ourselves from the equation, we find that we are just another animal species among a whole lot of others. Large parts of the planet remain inaccessible to us. A host of natural phenomena remain outside our control. There are diseases we can’t cure and social pressures within our own societies that we are yet to overcome.

Reign over the Earth?

Try “barely managing to survive while surrounded by death and acquiring bloated ideas about our self worth”.


Second, the idea that any one species can reign over the Earth is itself suspect. The Earth is a place of diversity and it takes a complicated system of interlocking subsystems to make it work the way it does. Humankind has indeed managed to put itself outside the reach of some of these systems (certain evolutionary pressures for example), but we have also trapped ourselves inside certain other bubbles of our own making. We still need the resources the Earth provides to survive and to keep our social wheels turning. All the species that we have conveniently assumed to be beneath us, still feed us, clothe us, and go into the very structure of our everyday lives.

This “reign over the earth kind of thinking comes from a very human place — the idea of conquest and dominion. Human history (the most recent bits) is full of wars, empires, and expansions. These, along with fictional retellings of them, have filled our heads with biased thinking. It is a species-wide feedback loop that keeps us from thinking of ourselves as a cog in the natural wheel (as opposed to being the showrunner). If this thought makes you feel small and insignificant, it is only because you have been living with a false understanding until now.


And now that my rant about the question is over, here is my actual answer:

A lot depends on the circumstances of human extinction of course. If for example, human beings vanish due to some kind of cosmic radiation, there is no reason to assume that chimpanzee or any species of ape will survive to take over where we left off. If we vanish in the wake of an extinction event such as the ice age, evolutionary pressures might wipe out all animal species larger than a rat because the amount of food required to sustain large bodies will be impossible to find. Even if our collective end comes at the hand of a virus that only kills humans, that still doesn’t mean a species will come to occupy the space we currently occupy. Our position in the natural order isn’t a space that exists independent of us. It is simply the way we live. Other species might never become what we are, choosing to live in a different way by making a different kind of space for themselves.

Having said that, there is a species of microscopic animal known to human beings as Tardigrades[2]. It is old — positively ancient — and has been in existence since long before the advent of humankind. It will not reign over the earth after humans go extinct, it already does reign over the Earth. It has “reigned” for a long time. You just didn’t know it.

(Image source: BBC — Tardigrades return from the dead)

Tardigrades are invisible to the naked human eye. And if that was not enough, they are invulnerable. They can survive being boiled, frozen, crushed. They can even survive in airless outer space. On the TV show Cosmos, astrophysicist Neil Degrasse Tyson said that if aliens ever came around to visit Earth, they might think of Earth as the “planet of the Tardigrades”.

Footnotes

[1] Anthropic Bias – complete text

[2] Facts About Tardigrades