Post No.: 0120
Homo sapiens (who have been around for only ~200,000 years so far, or at least a number of this order of magnitude as the best estimate at the time of writing) only started to cluster into living in cities over the last ~6% of the specie’s existence, which is not long in evolutionary or geological terms – although ‘long’ or ‘short’ in evolutionary terms depends highly on the selection pressures present in the inhabited environments and the rate and usefulness of new mutations introduced – in some ways humans have evolved greatly in this time (e.g. lactose tolerance in some parts of the world) and in other ways humans have not. But overall, Homo sapiens have not genetically changed much in this time – well they remain the same species after all. Yet the lives of most Homo sapiens today are very different to the lives of Homo sapiens many thousands of years ago.
Ancestral humans, compared to their primate cousins, started to walk upright, which freed their hands for developing tools. Humans also have complex language abilities. But some other animals also utilise tools, have complex languages, and even use forms of farming, medicine and mutually beneficial symbiotic relationships akin to having pets, for instance (the more we learn, the less humans seem fundamentally unique in the animal kingdom). So, arguably, the biggest development for humans was building fires, which helped human ancestors to ward off fuzzy predators, keep warm, sterilise water and most of all cook (essentially pre-digest) food to increase the efficiency and bioavailability of the food obtained. Humans could get more nutrients from the food they ate with far less chewing and digestion time, which is also a vulnerable time because your bodily systems aren’t optimised to fight or flee whilst you’re trying to digest food (hence it’s not recommended to swim or exercise straight after just eating a meal). And hand-in-hand with this skill of lighting and building fires was a culture to pass on this skill to the next generations. The skill of being able to light a fire using naturally-found materials is not genetically inherited but culturally inherited/socially learnt – a person most probably won’t know how to light a fire without at least seeing someone else successfully do it first.
Cooking/pre-digesting food made humans more physically efficient with their calories and time, and so, via gene-culture co-evolution, humans genetically evolved to have smaller teeth and jaws, a smaller digestive system, less hair, smaller (untrained) muscles but bigger brains, which probably evolved in conjunction with being more social creatures, which better allowed humans to culturally learn from and teach one another other skills such as complex spoken and written languages, agriculture, technologies, medicine and so on, which further augmented the ability to adapt, feed and survive in a variety of different environments (the ‘Matthew effect’ of compounding advantages, or ‘the rich get richer’). If a species doesn’t need something to survive anymore then it’ll potentially lose it (e.g. if a species doesn’t need large jaws to chew uncooked meat or tough/hard raw vegetation anymore then it’d be inefficient to maintain such features), and if something is beneficial for survival and reproduction then it’ll potentially gain more of it (e.g. larger brains for better transmitting social and cultural information).
Fire to cook food and make digestion easier and faster, and agriculture, for instance, freed up time for humans to do other things too, such as philosophise and invent new things, and record thoughts and ideas in writing in order to teach and learn things that could be passed on from one generation to another or one place to another. And this is how religious and other cultural memes can spread (see Post No.: 0054 for more).
Thanks to language, and then technologies like the printing press, audio tapes and the Internet to store and share information, humans have a remarkable ability to pass information on from one individual to another and from across generations. No person can remember everything so writing and other forms of recording act as extensions of our memories, and a reproduced book or tape can simultaneously teach a lot of people wherever they are in the world too, or even people who are not yet born. Most humans lucky enough to go to school spend the first 16 years or more of their lives trying to pack their brains with some of the information that humans have collectively accumulated over the past few millennia or so of recorded culture so far, before they maybe try to create, discover or reframe new and useful knowledge of their own to pass onto the next generations. Meow.
So a major difference between humans and other animals on Earth so far is that humans inherit not just genetics from their parents but the surrounding accumulated culture too – at least to the extent humans inherit it because we are learning more and more that some other animals on this planet exhibit a bit of what can be described as culture too, with skills being passed on from generation to generation culturally (e.g. from parent to offspring, or copying whoever seems to be successful in hunting or mating). This means that each generation of humans doesn’t need to start afresh, solely with their own individual genetic endowment, in discovering knowledge or inventing things (a ‘dual inheritance theory’ of genes and culture).
Because of the advantages of culture/learning and teaching, humans evolved to be more and more social – realising that organisms are often stronger working together than the mere sum of their individual parts. Human genes shaped human culture, and now human culture began to shape human genetic traits and instincts too (e.g. theory of mind, conformity bias and prestige bias – the tendencies to follow others in a group and pay particular attention to those who appear to be successful or whoever everyone else seems to be paying attention to – instincts that help people to copy and learn from others (for better or worse)). Genetics and culture continue to shape each other bi-directionally hence a gene-culture co-evolution. (This is not to say that these are exclusively human traits e.g. other social animals like rhesus macaques seem to exhibit theory of mind too, which for one thing helps them to become better thieves i.e. they know it’s best to snatch things when they think their victim won’t notice!)
So the current relatively large and complex brains of humans are arguably a product of evolutionary pressures to become ever better social learners and teachers – humans evolved to become better at adapting. But humans are such a cultural species now that, equipped with just their genetic inheritances, they’d struggle to survive or function well in the environments most of us currently live in i.e. humans are born with the expectation of culture – a newborn or even 4-year old human offspring won’t likely survive on her/his own, without help. No other animal species raises their offspring for nearly as long as humans do before they can or are allowed to ‘fly the nest’. Humans spend a long period of the first part of their lives learning, which has its advantages in the long run.
Naturally, it’s not only culture that co-evolves with genes – technology (which I suppose is a subset of culture) will also co-evolve with genes; or more generally, all genes co-evolve with the environments they inhabit. Everything that evolves essentially co-evolves with whatever’s in its environment that also evolves (whether the genes of other species of animals or plants, or cultural memes) – where everyone and everything else is in the environment of everyone and everything else i.e. ‘I (or my species) am in your environment and you (or your species) are in my environment’ (e.g. pollinator insects co-evolved with flowering plants because they were and are in each other’s environment). So if a species genetically evolves and cultural memes evolve, and this species utilises culture, then there’ll be a gene-culture co-evolution. Humans are still evolving today, and part of what will shape the direction(s) this evolution will go is the cultural influences at play (e.g. increasingly sedentary lifestyles, medical technologies, laws and trends).
Humans are particularly predisposed to learning from members within their own ingroups though, especially from their immediate peers and authorities such as their group/family elders. Some cultural inheritances are more-or-less species-wide, but many are local adaptations to the local environment (e.g. particular hunting technologies and techniques, own forms of social organisation and social norms) – and this is where religion and the variety of different religions we see, that at least all started locally somewhere, come into the picture.