The Greatest Story Ever Told - the rise of human diversity

Many stories may claim the title of the the “Greatest Story Ever Told”: the Iliad, the New Testament or Darwin’s Theory of Evolution. My personal favourite has always been human evolution - how we came to be the way we are. Consequently, prehistory has been my favourite part of history for a long time. When and why did we start to speak? That was the topic of my PhD thesis. However, more recently my main focus has been not on the traits we all share, like language, a theory of mind and a liking for high-calorie foods, but on why we are so diverse. All animal species show some variation in behaviour and the science of Behavioural Ecology has made great progress to understand these variations. Often there is not one single optimal strategy for survival and reproduction but several. So, variation isn’t surprising. Yet, just as often there is one and only one optimal strategy and this makes the extreme variation in human behaviour perplexing.

Humans differ vastly in their traits and behaviours. While some people are high-risk takers and take a jump from the stratosphere, others are content leading normal lives, having a steady job that supports their family. From the point of view of evolutionary psychology

Our ancient environments weren’t as diverse as the possibilities modern society many stories may claim the title of the the “Greatest Story Ever Told”: the Iliad, the New Testament or Darwin’s Theory of Evolution. My personal favourite has always been human evolution - how we came to be the way we are. Consequently, prehistory has been my favourite part of history for a long time. When and why did we start to speak? That was the topic of my PhD thesis. However, more recently my main focus has been not on the traits we all share, like language, a theory of mind and a liking for high-calorie foods, but on why we are so diverse. All animal species show some variation in behaviour and the science of Behavioural Ecology has made great progress to understand these variations. Often there is not one single optimal strategy for survival and reproduction but several. So, variation isn’t surprising. Yet, just as often there is one and only one optimal strategy and this makes the extreme variation in human behaviour perplexing.

Humans differ vastly in their traits and behaviours. While some people are high-risk takers and take a jump from the stratosphere, others are content leading normal lives, having a steady job that supports their family. From the point of view of evolutionary psychology, these traits are most likely to have their origin in our ancestral environments. The biggest change in our environment happened with the advent of agriculture. Early farmers had to adapt to the hard farming work by becoming more focused on sustained rote work and becoming physically stronger (heavier than the more lightweight hunter-gatherers). An alien biologist might even have come to assume that foragers and farmers were different species, judging from their behaviour, social organization and appearance.

foragers (hunter-gatherers)	farmers
egalitarian	hierarchical
Patrilocal and matrilocal	Patrilocal and patrilineal
Out-group social (fluid band membership)	In-group social (family first, tribe, etc.)
Leadership (temporary)  based on competence	Leadership (permanent) based on nepotism
Loose (no strict laws)	Tight (strict laws)
Conformity is bottom-up	Demands conformity (top-down)
liberal	conservative
Non-organized religion	Organized hierarchical religion
Traditions are less important (fewer rites)	Traditions are valued (more rites)
Economic productivity on a short-term basis	Planned and organized economy
On-demand food production	Surplus food production
Communist (sharing economy)	Capitalist

Genetic studies show that early farmers didn’t mix with foragers, only later they got mixed, with herders contributing substantially to the gene pool too.

Unfortunately, there are few studies of personality in societies with pure ancestral economy. However, those few studies usually find only two distinctive personality types, e.g. provisioning and caregiving profiles for hunter-gatherers and hard-working vs sociable for famer societies. Basically, this is very similar to male vs female personality, even so, a certain number of each gender might have the opposite profile. I myself am a male with a lot of caregiving features.

	provisioning male	female
foragers	provisioning (entire group)	caregiving (entire group)
farmer	provisioning (family)	caregiving (family)
herder	provisioning/dominance	caregiving/creative

Marco del Giudice bases his model of personality on the fast-slow life-history spectrum. Herder types would be on the fast spectrum, famer types on the slow and hunter-gathers types would occupy the slow end of the spectrum.

Helen Fisher calls famer types “builders” and in MBTI they are called “defenders” (SJ). Here is an overview of evolutionary types: 

The greatest story, in a nutshell, thus goes like this: after the switch to agriculture people became “builders” and built the first cities in the fertile crescent. Uruk is considered to have been the first city. The early farmers first didn’t mix with other “tribes” and the first few thousand years of farming were a somewhat boring period. Then they started to mix with hunter-gatherer types, who brought a lot of innovation (most likely to make their lives easier in farmer societies). Hunter-gatherer types were the people who tried to innovate all the time, farmer types were (like still today) often averse to innovation and wanted to hold on to their tried and true traditions. They also mixed with herder groups, who brought a lot more “action” onto the historical stage. 

The city of Uruk was built by farmers, developed by hunter-gatherers and finally destroyed by fearsome herders.

These three “tribes” formed the basis of early high cultures with their usual tripartite social stratification. Over time, these tribes got more mixed up and we see the amazing diversity among humans we find today emerge.