Development: the teenage years - early and late bloomers

The early years of a human being are often crucial for future development. Life trajectories are often set in utero regarding a person’s testosterone levels and his/her ability to cope with stress, just to name two examples. Childhood adversity is a high-risk factor for later mental disorders  It is therefore not surprising that research in development has been so focused on the early years.

However, the onset of many mental disorders (e.g. eating disorders, social anxiety, schizophrenia and bipolar disorder as well as the symptoms of BPD)  is typically mid-adolescence to early adulthood, i.e.around  the time when our evolutionary ancestors would have started reproduction. This indicates that reproductive potential or rather a lack of it might be involved.

There is considerable variation as to the onset of puberty. It is reasonable to assume that this variation has at least partially evolutionary origins and I have argued that it depends on our ancestral mode of subsistence and the expected lifespan related to it:

r/K theory and life history studies would predict the following traits (at least among males):

Shortest lifespan (pastoralist)	medium (farmer)	Long lifespan (HG)
Most risk-taking/least fearful		Least risk-taking/most fearful
Low empathy/low sensitivity		High empathy/high sensitivity
Earliest onset of puberty		Latest onset of puberty
Least paternal investment		Most paternal investment
Most sociosexual		Most pair-bonded
Higher sexual dimorphism		Lower sexual dimorphism
Most in-group social		Most out-group social

As can be seen from this table pastoralist types are typically early bloomers, whereas hunter-gatherer types are typically late bloomers. This pattern might be broken, i.e. by the absence of a father, which typically accelerates the onset of puberty.

Here are some typical behavioural patterns:

Early bloomers: tend to neglect school and social norms due to high risk-taking potential, become status aware and interested in status symbols (branded clothes, motorbikes, etc.) and show off how cool they are (use of illegal drugs, etc.) tend to form cliques and gangs; due to high in-group sociality tend to exclude “losers” (i.e. teens not cool enough).

Late bloomers: typically continue their childhood, read comics while their early bloomer peers already go out, smoke and drink alcohol. As they are cautious and non-risk taking, they actually might become intimidated and socially withdrawn.

Late bloomers might typically lose their former early-bloomer friends who start to mock them for not being cool, e.g. wearing the wrong clothes when girls, or being “gay” when male. The late bloomers are typically out-group social, i.e. they are unlikely to be part of any group or clique. If the late bloomers are introverts they might end up with no friends at all and become easy victims for early bloomers, who enjoy displays of status to their peers. Often these bullies are actually quite intelligent who start to do badly at school due to a lack of interest and blame the nerds (typically late bloomers) for setting high standards in class.  

Even when not being bullied, the late bloomers might become extremely insecure and shy due to a feeling of not belonging or being weirdos not understanding mating behaviour. As late bloomers tend to be more monogamous or at least more choosy, they easily become disgusted by their peers’ mating behaviour, which often involves frequently changing partners and might decide to stay out of the “mating-market” (at least for a few more years).

Hunter-gatherer types are typically less sensitive to gossip and trends, they accentuate their gender less and are cautious. These traits make them less attractive for teenagers who are highly sensitive to social rejection and strive to have cool friends. Hunter-gatherer females often don’t understand why their peers suddenly are so “bitchy and often start to feel more comfortable around boys. The same is true for hunter-gatherer males who do not necessarily share their peers’ passion for talking about girls, football and cars.  

These developments usually take their toll on hunter-gatherer type self-esteem and perceived reproductive potential. Being egalitarian other teenagers are often perceived as a threat and social anxiety and depression might be a frequent outcome.