[ 17/4/20 ]
In millions of different ways at may different scales.
At the level of landscape, culture tends to define what we choose to do with landscapes generally. I live in a culture where farming tends to be grasslands grazed by dairy cows or sheep (a cultural thing). In China food production tends to be dominated by the swamp grass their culture cultivated (rice).
So much of China has seen hillsides turned into swaps (paddy fields), while in New Zealand most swamps (over 90%) have been drained and turned into grass paddocks.
That sort of cultural influence on ecosystem is seen everywhere on the planet now, effecting every level of ecology (even down to micro-plastics in ocean ecosystems).
At the level of us as individuals, and our biological processes, the influences are huge.
Just briefly consider 2 different examples – diet & stress.
All biochemical processes drive off diet at some level. Many only require some sort of energy source (like sugar or starch), but many others require critical substances from our diet. Many of those substances we give the label “vitamin”. The amount of vitamins we get plays a huge role in many different biochemical processes, and that is usually a function of diet, which has a strong influence from culture.
Taking just one example – vitamin C. We cannot make it. Most animals can. Goats for example can, and a 70Kg goat makes about 10g a day if reasonably healthy, and up to 100g per day when fighting disease. We have to eat it. Our immune system works essentially the same as a goat, but does not have enough vitamin C to work as quickly as a goat’s in most of us, so we tend to get much sicker much more frequently than goats do. The amount of vitamin C we get is strongly influenced by our culture. Thence our ability to fight disease when we encounter it.
For most people, most of the time, vitamin C is the rate limiting factor in their immune system function. I take about 15g a day normally, and up to 100g per day if I feel my body is trying to combat something (it is impossible to get that much from a natural diet, so I take it as a supplement of pure L-Ascorbic acid dissolved in luke warm water).
Similarly stress. It seems very likely that the stress response evolved to allow us to devote all available energy to fight or flight when necessary (temporarily suspending many maintenance systems). That was great for our ancestors who would only infrequently encounter such things. Not so good when mortgages and job insecurity and financial system insecurity are constants in our lives. A vast number of changes in our bodies and brains result from such things.
Everything effects everything else, but the degrees of influence can vary hugely between individuals and contexts – for a vast range of reasons.
We are far more complex than we are capable of conceptualising in detail, and sometimes simple approximations can work well enough frequently enough to be useful.
For a detailed answer to parts of your question go to the psychology, biochemistry and neuro-physiology sections of your nearest university library. You won’t be able to keep up. New material is being added faster than anyone can read. We are that complex.