Are humans sentient?
The definition of sentient is “able to perceive or feel things.” However that doesn’t help much towards measuring sentience. One long standing idea for measuring sentience is the Turing test where an AI is compared to a human. However that test is not useful for evaluating humanity.
Similarly a number of tests that are applied to animals work by assuming humans are sentient and looking for human like reactions.
A better test is “growth beyond original programming” which is used frequently enough in media to be a trope. This test can be used for humanity if we consider our original programming the population of the earth. Instead of just waiting to grind against some eventual upper Malthusian limit, human world wide birth rates are down.
Now one can argue that our original programming might have included the subtlety of not reproducing under stress (animals in captivity sometimes don’t reproduce). Perhaps humans will just enter a holding pattern where birth rates increase at some lower bound and decrease as things feel crowded again.
Certainly the baby boom after WWII shows original programming, OP, includes logic around family size. OP would also include group logic like that used by ants or wolves to be less concerned with reproducing individually when relatives are handling it (and we are all related).
Disentangling any human activity from OP is difficult. The sexual selection of evolution would have built into OP a wide variety of artistic capabilities that like peacock plumes show the owner has game. Story telling and religion were also powerful tools for organizing humans and so increasing population.
Nor does any small subset of humanity escaping OP prove that subset is sentient. Diversity is a strong enough component of evolution to account for OP allowing outliers.
Would a different from OP goal like lessening the Anthropocene human led destruction of the environment and most non-human creatures on the planet indicate sentience? Maybe or maybe helping save the environment would just make a good story to tell a potential human mate.
But pairing a goal of saving the world with a falling birth rate would certainly be a good indicator for human sentience. Failure to do so is how an AI in the Matrix judged humanity as not anymore sentient than a virus. (Which is fair — if we name ourselves homo sapiens and are not sapient then maybe we have the categorization of our species wrong.)
In Kurt Vonnegut’s Breakfast of Champions a character becomes convinced that only he is sentient and the rest of humanity are just machines. Could some fairly large subset of humanity be sentient but remain hidden in a sea of less sentient humans? Could sentience be a matter of culture or training?
Culture is, after all, humanity’s best shot at modifying original programming. Culture is programming not stored by DNA and not subject to evolutionary constraints other than it must be created and accepted by humans.
To some degree then “growth beyond original programming” is purely a test of culture. Sentience requires adopting a culture beyond that of a simple self replicating organism like a virus.
The degree to which culture can override OP is the subject of social constructionism. The ideas of preserving nature or having a harmonious balance with it are social constructs. Even many of the pressures behind the current decline in birth rate are social constructs as are the attitudes towards women practiced by societies bucking the birth rate trend.
So one could argue that reaching over 8 billion people was not purely OP but a more cultural event. Measuring growth beyond original programming requires understanding OP. Are declining birth rates a sign of sentience or dissatisfaction with a prevailing culture that was already a display of sentience? Are some cultures more or less aligned with OP?
We can’t be certain what base human nature was prescribed by OP but reaching 8 billion and then pulling back before reaching 9 (the UN low population project linked above) would certainly be a more convincing demonstration of sentience than reaching a more Malthusian cap.
However not everyone may agree that sentience is a desirable human trait. For some pure OP lifts the burden of responsibility that comes with sentience. Culture may give humans the ability to be more than machines created by evolution but is that what we want?