Jared Diamond wrote about the isolation of neighboring tribes in New Guinea, and from his account it seems clear that the isolation is driven by behaviour. I quote from The Rise and Fall of the Third Chimpanzee (Chapter 13):

"When I was living among Elopi tribespeople in western New Guinea and wanted to cross the territory of the neighbouring Fayu tribe to reach a nearby mountain, the Elopis explained to me matter-of-factly that the Fayus would kill me if I tried. From a New Guinean perspective, it seemed perfectly natural and self-explanatory. Of course the Fayus will kill any trespasser; you surely do not think they are so stupid that they would admit strangers to their territory? Strangers would just hunt their game animals, molest their women, introduce diseases, and reconnoitre the terrain in order to stage a raid later.

        While most pre-contact peoples had trade relations with their neighbours, many thought they were the only humans in existence. Perhaps the smoke of fires on the horizon, or an empty canoe floating past down a river, did prove the existence of other people. But to venture out of one's territory to meet those humans, even if they lived only a few miles away, was equivalent to suicide. As one New Guinea highlander recalled his life before first arrival of whites in 1930, 'We had not seen far places. We knew only this side of the mountains. And we thought that we were the only living people.'

         Such isolation bred great genetic diversity. Each valley in New Guinea has not only its own language and culture, but also its own genetic abnormalities and local diseases. The first valley where I worked was the home of the Fore people, famous to science for their unique affliction with a fatal viral disease called kuru or laughing sickness, which accounted for over half of all deaths (especially among women) and left men outnumbering women three-to-one in some Fore villages. At Karimui, sixty miles to the west of the Fore area, kuru is completely unknown, and the people are instead affected with the world's highest incidence of leprosy. Still other tribes are unique in their high frequency of deaf mutes, or of male pseudo-hermaphrodites lacking a penis, or of premature aging, or of delayed puberty."

- end of quote -

If this were a permanent situation, I'd say one may be able to conclude that these tribes 'behave' as different species. However, there are many reports of New Guinean tribes occasionally waging war on each other, during which the winning tribe kills the men of the opposing tribe and steals their women and children. These women and children are then incorporated into their own population, leading to gene flow and genetic assimilation. Thus, on a longer time scale, it is clear these are not, and will not become, separate lineages.

It is completely out of the question that in an open, free and modern society, gene flow will become (and remains) so restricted that two species could evolve.

Wow its kinda interesting but I thought sapiens is the species category ? I have strong interest in biology but I gave back most of my knowledge to my secondary school biology teacher ... 

No offense but I guess it turns out now we got two groups of people who ate their food with mouth and another group of people ate with a mobile phone camera ... 

I'm Chinese and we share big plate of food so we have to wait those person take photo first before we can eat ... sometime they even scold us for eating the food before they can take a picture ... modern world I guess LOL 

Sometime I thought being a scientist was to improve the world to a better tomorrow ... yet technologies back stabbed us ....  

This could never happen, will never happen, and sociologically and politically, should never even be allowed to happen.

But to give an answer on scientific terms. It is impossible to categorise living things based on what "may" happen in the "future", absolutely impossible.

It was already predicted in "The time machine" by H.G. Wells 😊

Steven James Bartlett wrote about this in an appendix to his research monograph on the species problem: http://www.willamette.edu/~sbartlet/species_problem.html

I think the process is reversed and the races will disappear. H. sapisens will become only more homogeneous and uniform.

In history there are many examples of isolation (intelectual and behavioral) , for example caste in India. For thousands of years representatives of different castes is not possible to have offspring. This has not led to new subspecies or species of people.

this nonsense conversation, it is neither sophisticated nor funny  

Jared Diamond wrote about the isolation of neighboring tribes in New Guinea, and from his account it seems clear that the isolation is driven by behaviour. I quote from The Rise and Fall of the Third Chimpanzee (Chapter 13):

"When I was living among Elopi tribespeople in western New Guinea and wanted to cross the territory of the neighbouring Fayu tribe to reach a nearby mountain, the Elopis explained to me matter-of-factly that the Fayus would kill me if I tried. From a New Guinean perspective, it seemed perfectly natural and self-explanatory. Of course the Fayus will kill any trespasser; you surely do not think they are so stupid that they would admit strangers to their territory? Strangers would just hunt their game animals, molest their women, introduce diseases, and reconnoitre the terrain in order to stage a raid later.

        While most pre-contact peoples had trade relations with their neighbours, many thought they were the only humans in existence. Perhaps the smoke of fires on the horizon, or an empty canoe floating past down a river, did prove the existence of other people. But to venture out of one's territory to meet those humans, even if they lived only a few miles away, was equivalent to suicide. As one New Guinea highlander recalled his life before first arrival of whites in 1930, 'We had not seen far places. We knew only this side of the mountains. And we thought that we were the only living people.'

         Such isolation bred great genetic diversity. Each valley in New Guinea has not only its own language and culture, but also its own genetic abnormalities and local diseases. The first valley where I worked was the home of the Fore people, famous to science for their unique affliction with a fatal viral disease called kuru or laughing sickness, which accounted for over half of all deaths (especially among women) and left men outnumbering women three-to-one in some Fore villages. At Karimui, sixty miles to the west of the Fore area, kuru is completely unknown, and the people are instead affected with the world's highest incidence of leprosy. Still other tribes are unique in their high frequency of deaf mutes, or of male pseudo-hermaphrodites lacking a penis, or of premature aging, or of delayed puberty."

- end of quote -

If this were a permanent situation, I'd say one may be able to conclude that these tribes 'behave' as different species. However, there are many reports of New Guinean tribes occasionally waging war on each other, during which the winning tribe kills the men of the opposing tribe and steals their women and children. These women and children are then incorporated into their own population, leading to gene flow and genetic assimilation. Thus, on a longer time scale, it is clear these are not, and will not become, separate lineages.

It is completely out of the question that in an open, free and modern society, gene flow will become (and remains) so restricted that two species could evolve.

Hi Dilian,

Due to the lack of any substantial barriers to breeding between those of different intellect and social class, gene flow would continue to keep H.sapiens as a single species.

However, I think human speciation is an interesting thought experiment and shouldn't be discounted. By what mechanisms and scenarios COULD H.sapiens speciate?

• Alternative history scenario: if humans didn't develop the technological innovations to easily transverse geographical barriers to gene flow, maybe Africa, Eurasian, Australian, and Native American populations would slowly diverge over a long time span. Adapting to their local environments with gene flow restricted to the closed meta-population would slowly genetically differentiate to the point where they would be genetically distinct
• future scenario: Similar concept to the first, but imagine that humans colonise and terraform Mar. Then, by some cataclysmic event in which the technology for interspace travel was permanently lost, the gene flow between the Earthian and Martian populations would be halted. Over a long enough timespan, populations would genetically diverge and become genetically distinct species.

While those scenarios don't answer your question directly, I hope this helps 😊

Hi All

Sorry to tell you this, but I think this type of discution can cause us serious domage on scocial and human terms.