Progress is measured over long time scales, and on metrics related to the access to innovations by all, as Ford once noted. So it is natural for us to consider ourselves lucky to have lived "in the best of times".
Why, if you were born 400 years ago, e.g., you would probably never even learn what a hot shower is! And even only 100 years ago you could have been watching powerless as your children died of diseases that today elicit little worry.
I believe there is no controversy on the fact that the majority of human beings today live a life far better than what they did centuries ago.
And yet I cannot help asking myself a question. What does this adjective, "better", really means if we measure quality of life in terms of the amount of pleasure or pain we experience in our daily lives? For if we try to quantify quality of life by those metrics, we are immediately confronted with the fact that pleasure and pain are feelings that are directly related to amounts of neurotransmitters of different kinds released in our brain. For example, we well know that above a certain threshold of pain, we pass out - we are not wired to sustain arbitrarily high levels of pain, nor would it make any sense for evolution to have brought in that direction. And it is not like our orgasms today are better than those ancient Romans or Egyptians experienced.
In other words, the absolute scale of pleasure and pain, or if you prefer of happiness and sorrow, is directly connected to our biology, and it has not changed significantly over the time scale we are considering when we think at the progress of our race. We did, that is true, found a way to live three or four times longer than we once did, on average; but are we happy about the fact that our life expectancy is of 79 years (if you live in the US) or even 84-85 years (if you live in more advanced countries)?
No, we would like to live longer.
I believe the same held 10,000 years ago, when life expectancy was in the 30-35 years range - people were happy to live to 40 years, but would have liked to live longer. So my point is that we measure our happiness in a relative sense, within a range that has kept essentially the same as we made huge progress from the age of hunter-gatherers to the age of the stock exchange.
A list of neurotransmitters that modulate specific reactions in our brains includes:
Dopamine, linked to anticipation, motivation, reward-seeking, and learning from reward prediction errors;
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Serotonin, which modulates mood, satisfaction, social behavior, and resilience to stress;
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Endorphins, linked to pain relief and pleasure (especially during intense physical activity or pain);
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Oxytocin, governing social bonding, trust, affection;
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Cortisol , the master of stress and anxiety (with a negative valence);
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Norepinephrine, tied to arousal, vigilance, and fight-or-flight states.
A lot indeed happens in our brain, and the range of effects that these substances may trigger is wide. And human brains have gained access to none of these substances in larger amounts over the past millennia. What is true is that there are specific environmental and social factors that have made some dent in marginally improving the average level of those substances; but I can imagine that the same level of satisfaction and of serotonin and endorphins we get today by eating at a Michelin 5-star restaurant was available to individuals who could grab a piece of cooked meat 10,000 years ago.
What the above leads me to ponder is on the fact that our brain is essentially wired to be sensitive, and maximize, the derivatives of the substances that drive our level of pleasure or pain. It is always the derivative what allows us to search for improvements - whether it is to seek more pleasure or minimize pain, if we are biological systems, or to improve a utility function or minimize a loss, if we are talking about a machine learning algorithm.
In truth, evolution did not happen thanks to gradient descent mechanisms: it happened in discontinuous steps powered by genetic mutations. But within our brains, we are bound to be sensitive to relative variations -continuous ones, to be sure- of amounts of neurotransmitters that drive our happiness, depression, pain, lust, etcetera. To be precise, within neurological systems, reward prediction errors (especially in dopamine circuits) do operate somewhat like local gradient updates, so continuous improvements are powered by those mechanisms - but over long time scales, the real gains are stepwise.
So what does it really mean if we say that we live much better lives than we did 10,000 years ago?
I am not quite sure I can answer that question: to me it looks as if we have a lot of work ahead of us if we really want to re-engineer our brains to allow for a quantum leap in the level of satisfaction that our biological life can provide us. A long time ago somebody wired the brain of rats such that by pulling a lever they would experience a high pleasure stimulus, only to discover that the animals would then disregard eating and die of starvation as long as they had access to that lever.
Perhaps we need to look a bit further than that.
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