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Recent Evolution

RoyLatham
Posts: 4,488
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7/7/2012 1:37:59 PM
Posted: 4 years ago
Humans have evolved as much in the last 40,000 years as they did in the previous 3 million years. the pace of evolution has picked up substantially in the last 10,000 years. The lecture by Prof. Hawks (47 min video) explains it clearly.

The reason for the increased rate of evolution is the increase in the size of the human population. Beneficial mutations are rare, so a larger population produces more beneficial mutations, which are then selected. The rise of agriculture about 10,000 years ago brought a huge increase in the human population, hence even more evolutionary change. The past 10,000 years has brought better hearing, smaller brain size, the introduction of blue eyes and light skin color, smaller teeth, and wider skulls.

One interesting aspect is the identification of parallel paths of evolution. About a dozen genes are involved in the evolution of light skin in Europeans. East Asians also have evolved lighter skin in the past 10,000 years, also with about a dozen genes involved -- but a different dozen genes. Africans have evolved resistance to certain types of malaria, as have southeast Asians -- but the mechanisms are entirely different.

There is a possibility that smaller brain size does not mean we are getting more stupid. It's possible that there is selection for greater efficiency. No one knows for sure.

Fascinating stuff.
belle
Posts: 4,113
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7/10/2012 3:02:23 AM
Posted: 4 years ago
wha? evolution is change in gene frequencies and presumably lighter skin is caused by some underlying genetic changes... how is it not evolution?
evidently i only come to ddo to avoid doing homework...
Ore_Ele
Posts: 25,980
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7/10/2012 3:19:59 AM
Posted: 4 years ago
At 7/10/2012 3:02:23 AM, belle wrote:
wha? evolution is change in gene frequencies and presumably lighter skin is caused by some underlying genetic changes... how is it not evolution?

Depends on the definition of evolution.

http://en.wikipedia.org...

Not too surprising, the theory of evolution has evolved over the years.

Most don't consider it a simple change in the DNA code, since that makes it literally no different from adaptation. In fact, it would imply that you are an evolved form of your parents (since your DNA is different). Of course, such a view is has no scope, and so no scientific value.

Since evolution talks refers to the different species, it is considered the change from one species to another. Not to say, as some on this forum have said, "a bird into an elephant," but that one species may change so much over the generations, that it is a genetically different species to its ancestors.
"Wanting Red Rhino Pill to have gender"
belle
Posts: 4,113
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7/10/2012 3:28:14 AM
Posted: 4 years ago
At 7/10/2012 3:19:59 AM, Ore_Ele wrote:
At 7/10/2012 3:02:23 AM, belle wrote:
wha? evolution is change in gene frequencies and presumably lighter skin is caused by some underlying genetic changes... how is it not evolution?

Depends on the definition of evolution.

http://en.wikipedia.org...

Not too surprising, the theory of evolution has evolved over the years.

Most don't consider it a simple change in the DNA code, since that makes it literally no different from adaptation. In fact, it would imply that you are an evolved form of your parents (since your DNA is different). Of course, such a view is has no scope, and so no scientific value.

Since evolution talks refers to the different species, it is considered the change from one species to another. Not to say, as some on this forum have said, "a bird into an elephant," but that one species may change so much over the generations, that it is a genetically different species to its ancestors.

individuals don't evolve, populations do. your parents genes get shuffled around and put inside you, but for the most part because its a random process (each gene has an equal chance of ending up in the offspring) and people tend to have multiple children, that doesn't change the overall frequency of genes in the population. i suppose you could call it a difference between macro and micro evolution, but those two are just the same thing on different time scales. calling something an adaptation is basically saying that it is the result of natural selection, so even if its usage as a verb is redundant with the word evolution, its still useful as a noun for describing traits that arose through the evolutionary process.

anyways, the word has many meanings depending on who you ask, but textbooks have drilled into me over the years that at base, evolution is a change in gene frequencies. all the different species and such that we see are higher level manifestations of those changes.
evidently i only come to ddo to avoid doing homework...
RoyLatham
Posts: 4,488
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7/10/2012 8:43:35 AM
Posted: 4 years ago
At 7/10/2012 2:03:52 AM, Ore_Ele wrote:
lighter skin and such is adaptation, not evolution. Just saying.

I think the professor has it right. Evolution is a shift in the statistics of genetics, for example the decrease in brain size of humans over time. Species evolve without becoming new species. If there was no evolution within a species, we'd never get a new species.
Mirza
Posts: 16,992
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7/10/2012 12:42:28 PM
Posted: 4 years ago
At 7/10/2012 8:43:35 AM, RoyLatham wrote:
for example the decrease in brain size of humans over time.
Correct. That explains the continuously lower average IQ in the world. I wish overpopulation were a myth, but it isn't. Humans add too many disasters, and now that they get more monkey-headed? Shame.
belle
Posts: 4,113
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7/10/2012 1:24:00 PM
Posted: 4 years ago
At 7/10/2012 12:42:28 PM, Mirza wrote:
At 7/10/2012 8:43:35 AM, RoyLatham wrote:
for example the decrease in brain size of humans over time.
Correct. That explains the continuously lower average IQ in the world. I wish overpopulation were a myth, but it isn't. Humans add too many disasters, and now that they get more monkey-headed? Shame.

http://en.wikipedia.org...

you mean the continuously higher IQ scores that have been recorded ever since the test was introduced?
evidently i only come to ddo to avoid doing homework...
Mirza
Posts: 16,992
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7/10/2012 1:30:20 PM
Posted: 4 years ago
At 7/10/2012 1:24:00 PM, belle wrote:
At 7/10/2012 12:42:28 PM, Mirza wrote:
At 7/10/2012 8:43:35 AM, RoyLatham wrote:
for example the decrease in brain size of humans over time.
Correct. That explains the continuously lower average IQ in the world. I wish overpopulation were a myth, but it isn't. Humans add too many disasters, and now that they get more monkey-headed? Shame.

http://en.wikipedia.org...

you mean the continuously higher IQ scores that have been recorded ever since the test was introduced?
No. http://suite101.com...
Mirza
Posts: 16,992
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7/10/2012 1:31:15 PM
Posted: 4 years ago
By IQ I'd extend that to intelligence, too. IQ scores are not enough to determine intelligence. (The latter is most probably decreasing.)
tBoonePickens
Posts: 3,266
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7/10/2012 6:09:54 PM
Posted: 4 years ago
At 7/10/2012 1:31:15 PM, Mirza wrote:
By IQ I'd extend that to intelligence, too. IQ scores are not enough to determine intelligence. (The latter is most probably decreasing.)
That would certainly be so in the Muslim world; however, that's not the case in the Western world!
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.
RoyLatham
Posts: 4,488
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7/11/2012 11:18:51 AM
Posted: 4 years ago
Decreasing brain size does not mean decreasing intelligence. Watch the lecture. It's possible that evolution is making brains more efficient; there is no scientific data on intelligence over 40,000 years.

IQ scores measure the ability to do well on IQ tests. The scores correlate well with certain other abilities, like doing well in conventional schools and succeeding in many professions. Therefore the tests are useful. It's fair to say that what is measured by IQ correlates well with most measures of success, but certainly not all.
Mirza
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7/11/2012 12:16:21 PM
Posted: 4 years ago
At 7/11/2012 11:18:51 AM, RoyLatham wrote:
IQ scores measure the ability to do well on IQ tests.
I agree when you say this, but some people apparently don't understand what an IQ test is. (Talking about some of our fellow DDO'ers.) Doing well on an IQ test means you do well in recognizing patterns, have a good short-term memory, and so forth. That's why one with an IQ of 150 will far more easily understand a mathematical equation than one with an IQ of 110.

That being said, IQ tests will hopefully improve by a great margin in the following decades. Some people might be so intelligent that they perfect their answers on most test categories, but fail one some others that are useless or based on knowledge rather than intelligence, and these two are FUNDAMENTALLY different.
belle
Posts: 4,113
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7/11/2012 4:40:48 PM
Posted: 4 years ago
Personally I think the problem with IQ tests is that there are so many factors other than intelligence that will effect success in life and even success on the test itself... Our measures have no good way of accounting for that as the interactions are really far too complex to keep track of atm. The whole field of IQ testing is kind of in a mess though because saying that one person it more intelligent than another is seen to imply that they are more valuable, and that is incredibly politically incorrect. On the other hand some people claim that there really is no such thing as a generalized intelligence, but rather posit a bunch of specialized modules for completing specific tasks. I am interested in seeing how that debate plays out. Maybe there's a module for "generalized reasoning" that evolved fairly recently but that isn't particularly powerful compared to other modules that operate more subconsciously and that we interpret as intuition... Anyways... IQ isn't the end all be all of anything... We're not even sure what we're measuring exactly... Brain science has a ways to go
evidently i only come to ddo to avoid doing homework...
Mirza
Posts: 16,992
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7/12/2012 2:46:29 PM
Posted: 4 years ago
You both got it correct. For one, brain size is not necessarily determining one's intelligence. Einstein had an estimated IQ of 160, but he allowed his brain size to be examined after his departure from this world. The size was average.

There are insects with brains that are nearly invisible to the naked eye. The abilities they have are too many to mention. Some of those abilities can inspire human technological process.

With regard to the meaning of intelligence, I think every genuine scientist would understand that intelligence is a very broad and complex ability. Some scientists raise questions like whether or not fast-talk means one is very intelligent, or similar things to that. I think we know about intelligence in other ways, though. We know that if certain parts of our brains function better, we will have more ways of say, gaining knowledge or being intuitive.

What I think most educated people on the matter of intelligence can agree on is that understanding and problem-solving are fundamental parts of intelligence. However, many don't seem to mention intuition - I think it is undeniable that this ability is part of intelligence.