Probably from conception on but we don't know that either.
Even before conception.
Let's say nature gives us life blood as embryo that is equivalent to mothers milk or something on that order in our mothers womb so that we can mature and grow into babies.
Human babies.
From conception on.
Then at birth nature provides us with mothers milk to get us going some more for the first couple of years.
Mother and baby also seeking out foods and sharing with one another from early on.
Natures perfect plan.
Eating and drinking natures provided food and drink.
In the womb and mothers milk is very high in fat and lactose.
Sugar and fat.
So we start out of a very high fat high carb diet.
No doubt full of nutrients and everything we need to prosper and grow to maturity.
Mind, body and soul.
Perfection.
Nature.
In that state of "high" from the sugar we quickly gain strength and stamina and our minds and bodies senses and instincts in full bloom and auto mode.
Including our rest and sleep.
All part of the human lifestyle.
The fat nourishes our mind and body to perfection.
Pooping and peeing the whole way.
Mammals from internal eggs to live births and beyond.
That sugar and fat we are living on gives our little hands and lips and eyes and feelings and senses
everything we need to seek out and enjoy life.
We get more and more milk as we prosper and grow and demand and need.
Mother and child both eating more and more to provide for one another.
The warmth and the holding and the cuddling of one another are much a part of this existence.
The rest of the group and family and siblings and father very much a part of this existence and very intimately involved in everything happening.
Seeking and finding and sharing with one another all along the way.
Providing for themselves and one another.
Laughing and playing and having fun the whole way except under times of stress or importance to other focuses.
Now in the real world mother and baby will consume only the foods that nature has provided in whatever locale this group is living in and has taken themselves to over the centuries and currently.
Moving about as needed and desired.
We can't live on rock and we can't live in the water.
We need ground and water and vegetation and other life to feed on.
Natures food and water and vegetation and other life to feed on.
The ratio of sugars and starches in our diet and available to us so that we can all prosper and grow and maintain life like the baby.
There is no coffee and kool-aid or pop or tea or milk other than mothers milk.
We eat bugs and eggs and plants and plant life and just about every other animal around us as our need and desire to eat and grow continues.
Just like the tree and the plant that thrive and grow on water and minerals and the sun to make their babies.
Nicotine and alcohol and caffeine do not exist as a food or drink source.
Sugar is available to us in plant life and in minute amounts in animal and other life we choose to eat that is around us.
Simple enough.
Natures perfect plan.
All living things.
All living species.
Plant and animal alike.
All living things and organisms.
The grass grows where it is arid and it's food and drink and foundations provide.
Desert sand provides nothing.
No grass except where more hospitable elements provide.
Bugs and worms and other life the same way.
Our environment.
From the skies and ground and even under and beneath the ground.
Up in the trees and the mounds and rock.
Life is everywhere that it isn't.
Everything thriving as best it can.
The eagle grasps the mouse or the fish or the rabbit to feed on.
It brings them to it's babies to young to fly.
They prosper and grow.
Natures perfect plan.