As a therapist, when thinking about the reverberations of all the inhumane atrocities in our history, the first thing that comes to mind for me is the traumatic impact for so many people, and for generations after. We've learned from the ACE study (https://en.wikipedia.org/wiki/Adverse_Childhood_Experiences_Study) just how much a traumatic incident can impact a person for years to come - physically, mentally, relationally, economically, and socially. We've learned about trans / inter-generational trauma - how the physical and mental impacts of trauma can become hereditary, even for two generations past, even with the ability to skip a generation (just like any other gene, but reflecting a man-made genetic change via the body's response to stress and trauma).
Applying these two factors (without even exploring the depth of either) makes it difficult to wrap my mind around just how different the world would be today if billions of people who've endured trauma had never been faced with such adversity... how different would our health stats be? How would it impact our culture and society at large? How would my daily work be different?
When first learning about each of these smatterings of inhumanity and the resulting traumatic impact, I always feel the pain - as a physical experience - from thinking of the suffering so many have endured. Putting the pieces together of institutionalized / systemic racism, the patriarchy, all the corruption, all the fear-based attacks on humanity, trying to prevent others from flourishing, effectively preventing humanity from reaching its potential, time and time again... Trying to encompass all of that collective trauma within my mind feels like I'm being crushed under a tidal wave of tears and heartbreak and pain. The impact of the world's compounding trauma, compounded.
There are a multitude of books that explore this further... The Politics of Trauma, by Staci Haines; Trauma Culture: The Politics of Terror and Loss in Media and Literature, by E. Ann Kaplan; Trauma and the Memory of Politics, by Jenny Edkins; Shadows of Trauma: Memory and the Politics of Postwar Identity, by Aleida Assmann; Post Traumatic Slave Syndrome, by Joy DeGruy .... and many more good ones, I'm sure.