Do major historic events have a lasting impact on humankind's objective happiness? In his book "Sapiens - a Brief History of Humankind", Harari argues that the biochemistry of "happiness" in any person can only move within bounds, dictated by genetics.

He also argues that happiness only improves momentarily when objective circumstances improve, and only e.g. a degenerative disease or permanent physical pain can result in lasting change. This seems to be widely accepted and is backed by numerous studies.

I could not, however, find any studies supporting his statement that events such as the agricultural revolution had no lasting impact on humankind's objective happiness.

Are there any scientific studies on the biochemistry of happiness of generations that lived before and after major historic events like the cure of a disease that affected large parts of the studied community?

Whats psychology's take on human happiness throughout history?

Please suggest edits, as I am no expert on any of this.
Depends what you mean by "objective happiness". If we use the term in the way that it's used by Kahneman etc., meaning that


  In the special conditions of the clinic or laboratory it is sometimes possible to
  obtain continuous or almost continuous reports of experienced utility from patients or
  experimental subjects. Continuous measures are of course impractical for the
  measurement of objective happiness over a period of time. Sampling techniques must be
  used to obtain a set of values of moment-utility that adequately represents the intended
  population of individuals, times and occasions. For example, a study of the objective
  happiness of Californians should use a sample of observations that reflects the relative
  amounts of time spent on the freeway and in hot tubs. Techniques for sampling times
  and occasions have been developed in the context of Experience Sampling Methodology
  (ESM) (Csikszentmihalyi, 1990; Stone, Shiffman and DeVries, 1999).


It's hard to imagine getting such data retrospectively from ancient or even just past populations.

Ref quoted: Kahneman, D. (2000). Experienced utility and objective happiness: A moment-based approach. In D. Kahneman &amp; A. Tversky (Eds.), Choices, values and frames (pp. 673-692). New York: Cambridge. University Press and the Russell Sage Foundation.

Generally, diet and/or physical trauma leave a bone recod for archeologists to study. Alas I'm not aware of neurochemistry of past populations being ammenable to study (other than comparative studies across current species, e.g. humans vs apes).