Actually, less complex animals can evolve at a startling rate, like on the order of a couple of centuries. Even more complex animals like birds can differentiate enough in a millennium to be different species.
Examples, please? I am not aware of any biological species of birds that have originated in the past 1,000 years. There are probably some that have differentiated in the past 10,000 years, however.
Um, chromosomal abnormalities (also known as mutations), passed on to subsequent generations are exactly what differentiate species.
I don’t believe a single additional digit can qualify as a separate species, however since the offspring is still able to reproduce with the offspring of 5-digited individuals.
It could be construed as a “sub-species”, as could the isolated, starved population if it could be differentiated from the larger, less isolated whole.
Wouldn’t geography alone be enough to make a species, then? As an example: Consider as our two populations the inhabitants of North America and of Europe. Yes, individuals of the two populations are perfectly capable of interbreeding, but a North American is much more likely to breed with another North American than with a European. Even in the cases where a North American and a European do breed, one might argue that the one had first become a member of the other population.
That’s what you think, Chronos
I can’t say I’m too impressed. Chomsky has discovered kwashiorkor.
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All I can say is, cite? I am aware of some evidence suggesting that poor nutrition during pregnancy can cause health problems to crop up much later in the baby’s life. However, I’m unaware of any medical evidence indicating that your poor nutrition will somehow affect your grandchildren.
We all have chromosomal abnormalities so, um, the poster you were replying to was exactly right. Alot of them get passed on to subesequent generations and the great vast majority of the time do not end in new species.
Truth Seeker I think Chomsky may be right about the effects of malnutrition. Consider Europe in the middle ages. We know from the size of the suits of armor, and the size of the chairs, that people of that time and place were shorter and smaller then the Europeans of today. The increase in height and size came about gradualy. The average hight/size of adult humans has, I gather, been increasing very slowly throughout history. The increase was caused (mainly or entirely?) by improved nutrition.
During the middle ages, there must have been at least some people who got plenty to eat, and a not too unbalanced diet. Yet that minority appearently had children about the same size as everyone else. Throughout history, there must have been a few people here and there who got resonably good nutrition. Yet they don’t seem to have had extra-big, extra-tall children. Surely this would have been noticed if it was occuring; we’d have some sort of record of it. It would seem that it’s true that it takes a number of generations of good nutrition to undo the damage done by generations of poor nutrition.
So what’s the definition of “species”? The African pygmies aren’t considered a separate species, so why should these Brazilian people?
P.S. I’d guess that the children of the minority who got good nutrition were probably a bit bigger and taller then was average for the time and place – but doesen’t it seem unlikely that they produced children who were the average hight/size of today’s developed-world humans? I don’t find it at all hard to believe that it takes generations of good nutrition to undo the damage done by genrations of bad nutrition. OTOH, perhaps I’m wrong to think that people in the past who got plenty to eat (the rich and powerful) were getting good nutrition? Maybe they were getting lots of food, but not enough… what? Protein? The right mix of vitamins/minerals? But it seems likey that the rich and powerful would have been able to get plenty of meat, which should have provided enough protein at least.
Yes, agreed, they’re not really a separate species! As I said in an earlier post, “Granted, they can presumably make babies with ‘regular people’ and so are not technially a separate species. But it would seem that we have a group of people who are enough smaller then whatever’s normal for their region that they are being called pygmies, and whose brain size is aprox. 60% of the current human norm – due to generations of abysmally poor nutrition.”
I think the point is that there is a group of people in Brazil who have diverged so far from the norm that they appear to be a different species. In appearance, and in brain size, they’re as different from the average developed-world human of today as the average developed-world human of today is different from, I’d guess, whichever pre-human species immediately proceeded Neanderthal. Homo Whatever. I don’t really know my prehuman species that well.
I think the point is that the existance of this situation is an indication that something is wrong. No group should be that deprived.