It has been shown that racial differences are likely due to adaption to different areas of the earth. Different physical attributes were needed in different areas, leading to physical differences via natural selection.
Is it possible that different areas could have required different mental attributes, leading to differences in thought patterns and abilities. (E.G. One group would have to be smarter to survive in more extreme conditions, and have a greater need of ingeniuity.)
ATTENTION: THIS IS NOT INTENDED TO START ANY TYPE OF WHITE/BLACK/POLKA-DOT SUPREMECIST DEBATE. I AM INTERESTED ONLY IN REASON AND LOGIC. IF YOU HAVE AN EMOTIONAL RESPONSE TO THIS, PLEASE REFRAIN FROM POSTING A REPLY.
The reason I ask is because of a reference in my Anthropology book. It states that human brain growth is believed to be a result of necesity… living int he savanah required more intense thought processes than an arboral lifestyle.
a qualified yes.
yes, selective pressures could have led to different mental processes. however, any such differences would be meaningless today, because humanity has been mixed much to much for prehistoric differences to thrive.
jb
To me, at least, it is difficult to imagine a natural environment where intelligence is not selected for. Humans don’t really have a heck of a lot besides problem solving abilities, manual dexterity, and complex social organization going for them; regardless of whether they live in the jungle, desert, arctic, plains, etc.
Incidentally… about muffinman’s mention of brain growth, I seem to recall that neanderthals had a greater cranial capacity than anatomically modern humans… is this correct? If so, what does it imply about the advantages of human brain growth?
There are certainly physical differences between people from different parts of the world that arose through natural selection. I don’t think very many people would argue that differences in skin color, body build and things like sickle cell trait arose through natural selection in different environments.
But you have to be careful about attributing apparent differences between races to adaptation to different environments. Earlier in this century there was a period of time when many of the best professional basketball players were Jewish and a lot of people tried to explain that by saying that the Jews had spent their history living in an environment where natural selection had somehow favored the development of genetic mental and physical traits that gave them a special advantage at playing basketball. In hindsight, though, it’s pretty obvious that the reasons for their success were mostly cultural and environmental (as opposed to genetic). I think if you attribute any non-physical traits (or even certain physical ones) that people from a particular part of the world have to evolution, you are in danger of making that same kind of mistake. A whole lot of people have made mistakes like that in the past. This doesn’t prove that different races don’t have different aptitudes, but it’s a good reason to be skeptical.
If you’re interested in this topic I’d recommend The Mismeasure of Man by Stephen Jay Gould.
There was a news item a few months ago about a recent study which showed that Australian aborigines had 50% better memory than did some other ethnic group (presumably whites). Researchers theorized that millennia of an oral, nomadic culture required greater memory. People who forgot the directions to the good hunting grounds they went to last winter ended up starving to death before they could reproduce. The study seemed to confirm anecdotal evidence about the excellent memories of the aborigines, who are alleged to have stories about small islands which sunk into the ocean 10,000 years ago!
Wevets said that it is hard to imagine a natural environment which does not select for intelligence. Actually, there are many. Note that 99.999% of animal species aren’t too bright, not to mention all of the non-animal species! The shark is a good example of an animal that is just about as bright as it’s going to get. It manages to survive just fine based on instinct and the small amount of brains it does have. Any further intelligence would require more resources, which would divert resources from the rest of the body. For humans, the greatest problem with superior intelligence is the brain size it requires, which makes childbirth much more dangerous and deadly.
I agree with the idea that every (natural) envrionment selects for intelligence.
Possibly, the thought is that as some environments tend to select for certian physical characteristics like being thinner or darker haired also select for certian mental attributes like being ambidextrious or good depth perception. I could buy the idea if there were very marked differences between human “breeds”, as there are huge differences between the various Dog breeds. That is, if there were a kind of human that had huge sinuses and a really big nose, I would have to guess that its olfactory center in its brain is accordingly developed to use the equipment. I would guess that the smell part of a bloodhound’s brain is better developed than that of, say, a French Bulldog. BUT, since the variations between “breeds” (sub-types) of humans are much, much less than Dogs or other creatures, I must conclude that there aren’t any significant differences in the various brains, either.
The actual physical differences between the various subtypes of humans don’t really seem to have much effect on their ability to survive in and cope with their environments. This is especially so when we factor in the use of the brain to learn and modify the environment.
IMHO, the Aussie aboriginies test out better for memory because they use their memory. It’s a developed and exercised facility. There’s some native group in Northern Mexico that runs everywhere (for cultural reasons). One could argue that they’re “better selected” for running, but they’re good at because they do it all the time.
Please note the rest of my post, where I mention what little else humans have going for them evolutionarily. I thought it was pretty clear that I was talking about selection in humans (the subject of the thread, after all).
And I addressed that in my last sentence. In order for people to get smarter, they need decent sized brains (Actually, brain size doesn’t really correspond with intelligence, but rather language ability, which is a major aspect of intelligence, and the one that sets us apart from most animals). This increases the risk of death during childbirth. It’s a tough trade-off. A tropical island with abundant natural resources would most likely not require increased intelligence, and thus select for the status quo, or even decreased intelligence/smaller heads. I think Arjuna34 has it right: intelligence is needed to compete with other hominids, not the environment. This is why us giant-headed homo sapiens beat out all of our cousins.
You could easily make the arguement that nothing, tropical island or tundra, requires increased intelligence, and I would agree with you. But evolution does not act on what is required: if an organism does not have what is required, it is dead before it reproduces, and is therefore evolutionarily irrelevant. Instead, evolution acts to optimize what is favorable relative to the competition.
So let’s consider the tropical island: Abundant resources? Perhaps. But I think that scenario is an illusion: tropical islands often have open niches at high trophic levels for a couple reasons: slow or nonexistent rates of colonization and immigration, and insufficient area to support high-level predators. The reason the hypothetical people might do well is the lack of competition, not the abundant resources; after all, there are ecosystems with higher primary productivity than tropical islands, and these people with decreased intelligence might not do well in them. In fact, I think that a population of people on such a small tropical island would do poorly, because the population would likely grow and exhaust its resources in Malthusian disaster, much as occurred on Easter Island, which may not be quite the island you were thinking of, but I think still serves to make a point.
Now put some additional intelligence into the mix; say enough to provide boat-building to travel from one island to another, or enough to limit the population’s numbers socially (debateable whether humans have sufficient intelligence to do this), and then I think there would be a more successful population on the island, don’t you agree?
I also agree with Arjuna. But to an organism, other organisms - even of the same species - are part of the environment.