I see a lot of discussion here at EvC that seems to revolve around looking at critters two different ways. I believe an example can be seen in
this post.
As an admittedly somewhat uneducated lay person looking at a great big pile of data and trying to make some sense out of it, it appears to me that when we look at the fossil record we see two different things going on.
The first is that critters evolve, and over periods of time separated sufficiently from one another there will be enough of a difference between two critters to call them different species. However, if we could look at all the intervening steps, it would likely be difficult to tell much difference between adjacent critters. This is due to the selective filtering of traits across a population. Gradually some trait is added or subtracted from the population as a whole.
In that case, it is only when looking at samples separated by long periods of time that the changes are significant enough to say, "These are different species."
A second method is one species splitting into two species. The most common example of this is when a population becomes geographically separated into two or more isolated groups. In this case each group evolves slightly differently and we find a point in the record where we see two or more related yet unique species, both existing concurrently.
In the former case we see but one species at any given point in the record, but multiple species when examined over longer periods of time, each species occupying an ordered position along the timeline.
In the later we see one species at one point in the timeline but multiple species at a more recent point. (It can also go in reverse where we see a division and then one or more of the daughter populations disappearing)
When it comes to humans, it seems to me that when looking forward down the path of Human evolution, we will only see the former
until we leave earth and colonize other worlds or
possibly (and I give this a very low probability) unless there is a major catastrophic event.
Is there a reasonable scenario for Humans to become split and isolated over a period of time long enough to result in two separate species other than our moving off world?
Edited by jar, : fix awkward sentence
Aslan is not a
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