But bear in mind that even when the standing genetic variation exists to allow such rapid evolution, an essential feature of evolution within “a few generations” is massive wipeouts where most of the population has no descendants. So if you expect innate changes in chimp or bonobo behavior to happen quickly, you must envision a scenario where the selective pressure is so strong that most of the population dies without reproducing.
The far more widespread misconception about evolution is that it involves individual organisms changing. It does not, it involves individuals with disfavored genotypes ceasing to exist.
I would question the idea that this misconception is “far more widespread”, since it requires a complete lack of understanding of how natural selection works - clearly evolution cannot change an individual.
Well, in any event it’s the more fundamental issue, and it’s not one you addressed your hypothesis that chimp or bonobo populations could evolve so quickly. Evolution means changes in the genetic composition of populations, not changing individuals. A rapid evolutionary change means that a lot of individuals don’t pass their genes to the next generation. A change in innate bonobo or chimp behavior within “a few generations” would require not only that the necessary standing variation exists in the population, but also that the selection is so strong that most of the population is wiped out, and that the offspring of the few individuals with the relevant behavioral phenotype expands rapidly to replace them. It’s certainly possible, but it’s not something that you can infer from experiments with anole lizards.
No - just that they don’t reproduce. And the scenario in question was a number of chimps being thrust into bonobo society, or vice versa.
A bonobo in chimp society would have to adapt to a much more aggressive society, as much as its biology would allow, or be killed by chimps. And a chimp would have to adapt to a more peaceful bonobo society, learning their social language, or fail to attract any mates.
We know from apes raised hy humans that ape behavior is fairly high plasticity, so I expect that individuals would be able to adapt enough to live in the other apes’ society. Whether they and their young would be able to successfully and reliably reproduce, however, would depend strongly on their ability to fit in with the other apes, so if a biological factor is hindering them, it should be strongly selected against.
My point is that these are really opposing hypotheses. Strong selection pressure means a hostile environment in which a large proportion of a population dies without reproducing. This can lead to either rapid evolution or extinction.
You’re trying to thread the needle to reconcile your two suggestions here, but the bottom line is that rapid evolution of behavioral traits will tend to occur when the transplants are generally not able to fit in successfully with the host society.
But in any event it all becomes somewhat confused if we’re talking about the transplants interbreeding with the host population. They then no longer exist as a separate evolving population.
The evolutionary changes I’m talking about are not behavioral, since I’m assuming as you note that this will be mostly a cultural change that’s achieved by the first generation. I’m talking about accompanying physical changes, like bigger teeth, etc
The big question would be to what extent the differences in behavior between chimps and bonobos are innate, vs. to what extent they’re cultural. For animals as intelligent as Pan, the cultural component could be very large indeed.
And from what I understand, the major difference that leads to the two being considered different species consists only in what side of the river they’re on. To truly answer the question of whether they’re separate species or subspecies, we’d need to see how they would react to each other in the wild (if, for instance, they found some easy way to cross the river).
Group dynamics in baboons appears to be culturally transmitted, at least in one observational setting: when all the aggressive males in a troop died from contaminated meat, the troop dynamic changed and the changes persisted past the later deaths of those troop members present at the initial event.