that there was no colonization.
What would be happening today in these places ?
Harare
Capetown
Lima
Delhi
Melbourne
Of Course, I mean the areas that presently named as such.
Would we be looking at pristine jungles teeming with flora and fauna with native populations like the Zulu,Matabele, Maori and Aztec living in harmony with nature only taking from it that they need to ? One example being the native population of North Sentinel Island in the Andaman and Nicobar island chain.
Would there still be violence as in tribal wars ?
What would the population numbers be like ?
Diseases ?
This subject came up in a discussion I had with some colleagues from West Africa.
What would be happening in the good ol’ US of A and Canada ?
Human nature being what it is, those places would likely have many of the same human caused ills they have now, but at least the indigenous people would be the ones determining that future; reaping the rewards and disasters of their own making.
No population of humans has ever lived in that way.
Nothing much. Olduvai Gorge would be pretty crowded, though.
What would happen if there was no colonization? Starting when in history? Are we talking population growth without expansion?
Yes. Population growth and nature.
I guess without major transoceanic voyages as with the
European expeditions in the 14th century to find spice routes
That’s why I cited the Sentinel islands. Reputed to be almost totally isolated from the outside world. What would have been the present state of continents like S.America and Africa if left untouched with their pre 14th century native populations.
Would we be looking at gigantic herds of elephants , lions and other extinct animals ?
My friends that I talked about were of the opinion that the African continent would have been doing just fine with its original inhabitants . Of course technology was never part of the discussion. Just the ‘what if’ part. 
My friends despite having left their countries years ago still retain an extremely strong tribal identity.
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You seem to be assuming that urbanisation and agriculture only arise as a consequence of colonisation. This is completely wrong.
“Uncontacted” and “uncolonized” mean two completely different things, and I’m not sure how it would’ve even been possible to get to the 21st century without the people of the Old World discovering the New or vice versa.
It’s a little easier to imagine a timeline where the relationship between Europe and the rest of the world is strictly trade-based with limited migration, but as @Elmer_J.Fudd said, we’d still wind up with a world that looks a lot like the one we have today, except that maybe the Aztec Empire would be a global superpower.
Apparently long-range aircraft, satellites and the space program in general never develop.
I am trying to imagine.
I am pretty sure there were city like population centres and agriculture before colonization as proven by places like Mohenjo Daro and Harappa or the place in Rhodesia where they found the stone falcons.
Do you think urbanization is an inevitable thing when it comes to humans ?
Cahokia was larger at its peak than London was at the time, and their civilization hadn’t even developed the wheel or written language.
Elephants and lions are extinct?
Curious- What was the population of London in 1350 CE (and wasn’t that back when the Black Death was winding down?)
Roughly 70,000 before the Black Death and 40,000 after, per this cite.
Of course, Cahokia was already long past its prime by then - its peak was in the 11th century, when it rivaled London’s population of around 18,000.
Not to mention the city-states of Central America.
From The Dawn of Everything by Graeber & Wengrow:
In his Five Letters of Relation, written between 1519 and 1526, Hernán Cortés recounts his entry to the mountain-ringed Valley of Puebla, on the southern tip of the Mexican altiplano.
The valley at that time sheltered numerous native cities, of which the largest included pyramid-studded Cholula, and also the city of Tlaxcala. …
Cortés estimated the population of Tlaxcala and its rural dependencies at 150,000.
‘There is a market in this city,’ he reported back to Charles V, ‘in which more than thirty thousand people are occupied in buying and selling,’ and the province ‘contains many wide-spreading fertile valleys all tilled and sown, no part of it being left wild, and measures some ninety leagues in circumference’.
Also, the ‘order of government so far observed among the people resembles very much the republics of Venice, Genoa, and Pisa for there is no supreme overlord.’
Then there is the ‘social housing’ at Teotihuacan.
What we see after AD 300 is an extraordinary flow of urban resources into the provision of excellent stone-built housing, not just for the wealthy or privileged but for the great majority of Teotihuacan’s population. These impressive apartments, laid out in regular plots from one end of the city to the other, were probably not an innovation of this period. Their construction on a city-grid may have begun a century or so earlier, as did the razing of older and more ramshackle dwellings to make way for them.
The evidence suggests we should picture small groups of nuclear families, living comfortable lives in single-storey buildings, each equipped with integral drainage facilities and finely plastered floors and walls.
Each family seems to have had its own set of rooms within the larger apartment block, complete with private porticoes where light entered the otherwise windowless rooms. We can deduce that the average apartment compound would have housed in total around 100 people, who would have encountered each other routinely in a central courtyard, which also seems to have been the focus of domestic rituals, perhaps jointly observed.
Most of these communal spaces were fitted with altars in the standard style of civic construction (known as talud-tablero), and the walls were often brightly painted with murals.
Each block was initially laid out to similar scale and dimensions, on plots of roughly 3,600 square metres, although some deviated from this ideal scheme. Strict uniformity was avoided in the arrangement of rooms and courtyards, so in the last resort each compound was unique.
Even the more modest apartments show signs of a comfortable lifestyle, with access to imported goods and a staple diet of corn tortillas, eggs, turkey and rabbit meat, and the milk-hued drink known as pulque (an alcoholic beverage fermented from the spiky agave plant).
In other words, few were deprived. More than that, many citizens enjoyed a standard of living that is rarely achieved across such a wide sector of urban society in any period of urban history, including our own.
Well, you mentioned Delhi. Are you under the impression that India had no cities until the British colonised it? How do you explain China’s many megacities, given that most of it was never colonised?
The political history of India would be very different if it had not been colonised, and it might now be multiple independent states. It might be a much wealthier region without the economic destruction visited on it by colonisation. But in terms of agriculture, in terms of urbanisation, I don’t see much reason why things would be very different from the way they actually are today. India already had both of these things before the British arrived.
You might also look at Ethiopia, never colonised apart from a brief Italian occupation in Mussolini’s time. Compare it with other countries in the region that were colonised - Somalia, maybe Kenya. There are differences, but they don’t involve a lack of cities in Ethiopia, or a lack of agriculture.
Given that none of those peoples lived “in harmony with nature” or in “pristine jungles”, I can safely say the answer is definitely “No”
Also, it’s Cape Town.
Given that a major cause of “tribal” 
violence in Southern Africa was the introduction of maize from the colonized Americas, probably quite a bit less so.
Zimbabwe. Both the place, and the actual name of the country.
I’m with you on this point. I wonder of Japan is a good example - an autonomous and mostly closed society, which obviously had contact with other countries but in a much more limited sense, and so has a highly distinctive culture that has only become more ‘westernised’ with the advent of opening up/TV/Trade/globalisation/WWII in the last 80 years or so.