From what I've read both about Cro-Magnon people and research on modern social problems, we miss small group interactions. We are overwhelmed with simply too big masses of people. We are "programmed" to feel good in max 100 persons groups, to feel good. I remember the research on Bonobo apes, which was seen as very similar to human issues, that when their living space was overcrowded their social interactions suffered - violence, abandoning the young and various other unhealthy behaviors were noticed.

We live in overcrowded towns and cities, bombarded each day with information about more people, we have hundreds of "friends" online, trying to remember and know them all, we are proud to have big friend groups and interact with thousands of people over the years.

It is seen as one of the sources of anxiety, depression and social phobias. We do best in small groups, where all the members know and care for each other, bonding through common difficulties, life events, death and births.

Other issue, which is actually not that "old" - but for the past hundreds of years we have lost the contact with natural birth and death. People used to see, witness and care for the just born and the just deceased. All socializing was educational, all play was educational, all actions were emotionally binding. There was no sending a child to a stranger to learn the basic social rules, survival knowledge, knowledge about animals and plants. it was passed from one generation to another, naturally.

ETA: Just another aspect of the social interactions we have now. There are still cultures and communities that live with a different style, but especially in America it's very strong conflict. I am talking about the cult of individual achievement. The emphasis on an idea, that all depends on you, you are responsible, you have to do everything. One person is seen as the winner, as if s/he didn't come up on the backs of others. On the other hand in other cultures, especially more traditional, the emphasis is on the group, teamwork, team achievement. The success is common, no need for individual rat race. Of course the flip side is the danger of canceling any right to individuality and being forced to give up own wants/dreams for the sake of the needs of a group.

If you read about hunter gatherers you will be amazed about how much the (psycho)social contexts differ. And this past-present mismatch is probably more difficult to change than the dietary one. You alone are responsible for what you eat (normally), but you need a lot of people to change the social context.

some, 'easy' and fun recommended reading (although some maybe taken with a little grain of salt):

The Old Way by Elisabeth Marshall Thomas (on the Bushmen of the Kalahari)(Also by same author: the Harmless People)

The Forest People by Colin M Turnbull (on the Congo forest Bambuti pygmies)

Another one, talking about childhood and parenting, although quite academically:

Hunter-Gatherer Childhoods

Time spent outdoors in natural surroundings.

Hunting, fishing, and gathering wild foods.

Sitting around fires.

Making your own tools with your hands.

Living in small kin groups.

Seriously, I think that anybody wanting to call themselves Paleo should at least get out and try to catch a fish and eat it, or better yet, take up hunting. It's an object lesson in what you are.

I think most successful tribes had respected 'jobs' for all the commonly occuring personality types, like shaman, hunter, planner, leader, fighter, clown, etc. I am basing this mostly off of what I know of native American culture, but would guess that similar happened in other tribes. Each person's nature was respected and valued. It was not often that someone would get stuck doing a job for which his/her nature was not well suited.

Children learned naturally by doing, not sitting in chairs staring at scribblings and listening to the teacher drone on. Children naturally learned what was essential and also gravitated naturally towards learning more about what they were interested in. They learned because they wanted to learn. They did not learn because someone nagged them into it, although peer pressure probably had a strong roll.

Outlets were in position for common stress inducing situations and age appropriate strivings. Many tribes have challenges for young men wishing to prove their manhood. It was an outlet for all that testosterone. In today's culture, you see the authorities telling young kids to simply not do any of which they feel a natural drive, and so you see the kids sneaking around, drag racing, illicit sex, etc, to get their thrills. A successful culture has allowed outlets for such drives instead of simply ordering kids to suppress them.

Other outlets where rituals and shamanic cleansings and drug travels. Such things were controlled and overseen by the shaman and as such, were not easily overused. Most ancient drugs were also less pleasant and were considered more of an ordeal and a learning experience, than a simple minded method of fun. These experiences took preparation and were not thought of lightly.

Tribes that did not develop balanced traditions that allowed humans to be more happy and satisfied were probably at a considerable disadvantage and more likely to die out.

I think child-rearing is the big one. Now we have no idea what to do when our kids are born but sex, childbirth, breastfeeding would have been witnessed by a child as they grew up so it would all come naturally to them in time. Also once the child left the mother (of their own volition not because they reached a certain age) as they started to crawl and toddle they would have been part of a larger group of children of all ages only returning to the mother to suckle when they needed it which would have gradually lessened. A mother would not 'wean' a child, the child would just suckle less and less until it was only an occasional comfort thing. I think that the pace of maturity would have been set by the child rather than by society or the parents. Parents would just get on with their day to day lives and the children would join in as much as they wanted or were able to. I think we do our children a great deal of damage when we 'abandon' them to a cot, pram and bottle when they really need constant contact and then make them the centre of our attention as they grow up. Children are not genetically programmed to be the centre of attention but to be observers, followers and copiers of adults. They should be part of our lives not the other way round. Anyone interested in this should check out http://www.naturalnurturing.org.uk/

I'm with Melissa, sex is a big one, not just quantity.

Also, the community upbringing of children. My personal opinion is that this had led to, a lack of respect for others, broken moral compass, missing social skills. The list goes on... Don't get me started on lazy parents

Education. Our current system is lacking due to lack of community involvement.

Crime. Back to respect as well as you're less likely to steal cheat or abuse your extended family.

The Volunteer attitude. It's severely lacking around here.

Getting even should only be done with those that have been nice to you.

Dancing, drumming and singing. Intimate knowledge of local flora, fauna and weather patterns. Storytelling instead of screens. Seasonal migration to follow local hunting and fruiting cycles. I could go on and on.

Whooping your kids ass in public for being stupid. Grok did that. Grok also probably left kids behind, sometimes you should.