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Background

We all know that our species evolve during and after the last ice age, (or is it sufficient to say that they evolve at the end of ice age?).

A. Initial Condition

Suppose I had another planet with similar ancestor of human-and-apes species, but they evolve on the beginning of ice age (in reverse of human evolution).

B. Desired End Result

The goal is the civilization starts with environments similar to ours (they starts at environment similar to our origins, but slightly warmer and with open fields of grass, similar to our starting environment), but at the moment they reached technological advancement similar to our current technology, instead of experiencing global warming, they'll experience global cooling.

C. Assumptions

The time-frame is around 250.000 years, from the warm era to glacial era, and that's the time the species have to evolve through, and assume that the end result of the species would be human-like.

Is the setting plausible? (the setting could allow evolution of human-like species) or should I consider different settings to evolve human-like species that their civilization at our current tech level is in the middle of ice age?


Note: Due to debate on comments, I would like to rephrase the question.


The Question:

Assume C, then,

  1. Is setting on A plausible to make end result similar to B?
  2. Or should I consider different initial condition to reach B?
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    $\begingroup$ It is considered polite to describe the reason for a downvote. $\endgroup$ – Magic-Mouse May 27 '15 at 10:11
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    $\begingroup$ @Magic-Mouse someone disagrees with the theory of evolution. (probably) $\endgroup$ – Vincent May 27 '15 at 11:07
  • $\begingroup$ @Vincent sure, but if that's the case this is still ideas about imaginary worlds, i don't down vote dragons just because i disagrees with them. $\endgroup$ – Magic-Mouse May 27 '15 at 11:22
  • $\begingroup$ @Hendrik Lie in my opinion the tech level is a problem. with the sort of tech level they have at hand the species will probably be able to survive through the global cooling without evolving at all. $\endgroup$ – Abhishek May 27 '15 at 11:25
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    $\begingroup$ So, yes, the setting is valid enough, there is no particular reason to think Ice Ages had much to do with human evolution. They did affect the timing of various migrations, which affected things like Neanderthals and Denisovans and possibly Home Erectus and so on, but your scenario does not go into that sort of detail. And anyway if you even suggested that interbreeding with Neanderthals and Denisovans is critical to evolution of civilization, everyone would assume you have a racist agenda to say that. $\endgroup$ – Ville Niemi May 27 '15 at 11:45
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As noted, anatomically modern humans evolved before the last ice age. The evolution of behavioral modernity took place about 50,000 years ago, and is still not fully understood. Perhaps the stress of living in an ice age environment promoted the traits that led to behaviourally modern humans.

The other possibility is that the ice age would lead to physical evolution, as small bands of proto humans are isolated by ranges of glaciers and live in different environmental ranges. Humans trapped in Europe might eventually evolve in ways similar to the Neanderthal people, who were physically changed in ways that favoured living in a cold climate (large noses to pre warm the air they breathed, shorter bodies and limbs to reduce surface area, etc.). Modern Inuit people have similar adaptations, and if they had been isolated more completely and for longer periods of time, they would probably have developed further adaptations to the cold.

Other groups of protohumans might have become adapted to foraging across the great steppes and savannahs of Asia and Africa, since the cold dry global climate would have limited the growth of forests. These humans would be much taller and long limbed, to allow them to cover long distances and run down prey. Once again, we see hints in some groups like the Maassai, who are generally much taller than similar populations.

How extreme these adaptations become wold depend a lot on factors like how hard and deep the ice age is, and more important, how long the various populations are isolated from each other. If we wait long enough, then these peoples will become separate species (although this might take tens of thousands of years).

One other factor to take into account is you suggest this takes place as the protohumans become technologically proficient. Even with Paleolithic technology, humans were able to adapt and overcome pretty extreme environments, including the arctic, and literally walked around the world, crossing oceans and seas along the way. This sort of adaptability helped humans survive and become the dominant species they are today, but also makes having isolated populations able to evolve in peace very unlikely. Homo floresiensis seems to have evolved into their final form after being isolated in their island archipelago anywhere from 100,000 to 1,000,000 years ago (there is a great deal of uncertainty about when they arrived and indeed what their actual evolutionary background is), but were apparently never in contact with our own Ancestors between their arrival and extinction 12,000 years ago. Other human species like the Neanderthals and Denisovans were indeed in contact with our Ancestors, and most peoples in the modern human family were in limited contact with each other through trade and exploration even in ancient times, so there was enough interbreeding and movement between populations to prevent humanity from evolving into different species.

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Is Your Setting Viable?

Yes. Actually, it looks like (modern) humans evolved before the last glacial period. The wiki article on humans say the first "modern" humans appeared around 200 000 years ago. The last glacial period was from 110 000 to 12 000 years ago. It looks like humans did evolve before the Ice Age!

Side Note

Evolution of the Human species is still happening. It happens when people mate, when people are born, and when people die. It happens when people value certain attributes over others. Evolution has happened and is happening as you read this very paragraph. The time scale, however, is very long. I wouldn't expect a new species of human to pop up tomorrow, or in the next 1000 years. In fact, the most recent estimate of the last human-chimp common ancestor was 5 to 6 million years ago.

That being said, we can see some differences in humans down the line from us. For instance, the ability to consume milk as an adult seems to be a recent evolutionary thing. In fact, it looks like the people who can do so are the mutants!

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  • $\begingroup$ Not only that, but 12000 years is quite short in evolutionary terms. Exact figures vary, but many agree that it's taken us longer than that to turn wolves into dogs. $\endgroup$ – a CVn May 28 '15 at 11:50
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    $\begingroup$ Not only did humans evolve before the last glacial period, we might have caused it through the reverse greenhouse effect! I just recently read about this theory. en.wikipedia.org/wiki/Megafauna#Effect_on_methane_emissions $\endgroup$ – Sam Kauffman May 29 '15 at 3:37
  • $\begingroup$ It's not just milk either :) fair skin is another recent adaptation, and I've recently spent a fascinating half hour reading about the various different kinds of adaptations some people have to living at high altitudes. $\endgroup$ – Ynneadwraith Feb 14 at 16:59

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