Well, I'm not at all sure we will colonize Mars. See my Ten Reasons NOT To Live On Mars - Great Place To Explore and quite a few other posts on the topic.
I think by the time we have the capability we may well see things differently and may not want to colonize Mars, may well prefer space settlements in orbit around Mars, perhaps paying for themselves by exporting ice mined from Deimos - or just scientific settlements like the ones in Antarctica, studying Mars, with occasional hardy tourists and such like visiting them from Earth.
Also, we are likely to need to put it off at least for some decades, maybe longer, because of the enormous expense hard to justify - at least if you want a reasonable chance of living humans there (my opinion there of course) - but more importantly, because it's hard to see how it can be done consistent with planet protection. We don't want to land on Mars just to find life that we brought there ourselves. And as for terraforming, it may not be possible at all, since Mars is in many ways different (lower gravity, less light levels, no magnetic field, ionizing radiation, no continental drift etc etc) - and also, just adding random life, whatever you have in a habitat, is surely not the best way to start, if it is possible.
So - but I think can answer it more generally instead. If for some reason we have separated populations of humans, perhaps on other planets, or perhaps even on Earth itself, well - it takes of order a million years to evolve a new hominid. Depends what you mean by a separate species also, as there is clear evidence now that especially modern humans and Neanderthals interbred. Maybe others did also. See the Human Family Tree
But - a few million years anyway. That's assuming just normal processes of natural selection.
Of course would be hugely speeded up if you had humans engineering their own DNA. Assuming we had the ability to decode how it works and construct a new genome - maybe even in just one generation in the future - or - well just a few generations at least.
And there have been times when more than one tool using hominid has co-existed in the past. Indeed from the fossil record, it now seems that we live in rather unusual times to have only one remaining species of tool using hominid. As recently as 13,000 years ago we shared Earth with a small group of Homo floresiensis
I think by the time we have the capability we may well see things differently and may not want to colonize Mars, may well prefer space settlements in orbit around Mars, perhaps paying for themselves by exporting ice mined from Deimos - or just scientific settlements like the ones in Antarctica, studying Mars, with occasional hardy tourists and such like visiting them from Earth.
Also, we are likely to need to put it off at least for some decades, maybe longer, because of the enormous expense hard to justify - at least if you want a reasonable chance of living humans there (my opinion there of course) - but more importantly, because it's hard to see how it can be done consistent with planet protection. We don't want to land on Mars just to find life that we brought there ourselves. And as for terraforming, it may not be possible at all, since Mars is in many ways different (lower gravity, less light levels, no magnetic field, ionizing radiation, no continental drift etc etc) - and also, just adding random life, whatever you have in a habitat, is surely not the best way to start, if it is possible.
So - but I think can answer it more generally instead. If for some reason we have separated populations of humans, perhaps on other planets, or perhaps even on Earth itself, well - it takes of order a million years to evolve a new hominid. Depends what you mean by a separate species also, as there is clear evidence now that especially modern humans and Neanderthals interbred. Maybe others did also. See the Human Family Tree
But - a few million years anyway. That's assuming just normal processes of natural selection.
Of course would be hugely speeded up if you had humans engineering their own DNA. Assuming we had the ability to decode how it works and construct a new genome - maybe even in just one generation in the future - or - well just a few generations at least.
And there have been times when more than one tool using hominid has co-existed in the past. Indeed from the fossil record, it now seems that we live in rather unusual times to have only one remaining species of tool using hominid. As recently as 13,000 years ago we shared Earth with a small group of Homo floresiensis
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.3k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0