Human Evolution

[Athena]

I am providing the end of an article about human evolution. Overall it appears human evolving faster.

Sign Up The researchers looked for long stretches of DNA that were identical in many people, suggesting that a gene was widely adopted and that it spread relatively recently, before random mutations among individuals had a chance to occur. They found that the more the population grew, the faster human genes evolved. That's because more people created more opportunities for a beneficial mutation to arise, Hawks said. In the last 5,000 to 10,000 years, as agriculture was able to support increasingly large societies, the rate of evolutionary change rose to more than 100 times historical levels, the study concluded. Among the fastest-evolving genes were those related to brain development, but the researchers aren't sure what made them so desirable, Hawks said. There are other mysteries too. "Nobody 10,000 years ago had blue eyes," Hawks said. "Why is it that blue-eyed people had a 5% advantage in reproducing compared to non-blue-eyed people? I have no idea."

[freedom13]

The pace has been increasing since people started spreading through Europe, Asia and Africa 40,000 years ago. By Karen Kaplan, Los Angeles Times Staff Writer December 11, 2007 The pace of human evolution has been increasing at a stunning rate since our ancestors began spreading through Europe, Asia and Africa 40,000 years ago, quickening to 100 times historical levels after agriculture became widespread, according to a study published today. By examining more than 3 million variants of DNA in 269 people, researchers identified about 1,800 genes that have been widely adopted in relatively recent times because they offer some evolutionary benefit. Until recently, anthropologists believed that evolutionary pressure on humans eased after the transition to a more stable agrarian lifestyle. But in the last few years, they realized the opposite was true -- diseases swept through societies in which large groups lived in close quarters for a long time. Altogether, the recent genetic changes account for 7% of the human genome, according to the study published in the Proceedings of the National Academy of Sciences. The advantage of all but about 100 of the genes remains a mystery, said University of Wisconsin-Madison anthropologist John Hawks, who led the study. But the research team was able to conclude that infectious diseases and the introduction of new foods were the primary reasons that some genes swept through populations with such speed. "If there were not a mismatch between the population and the environment, there wouldn't be any selection," Hawks said. "Dietary changes, disease changes -- those create circumstances where selection can happen." One of the most famous examples is the spread of a gene that allows adults to digest milk. Though children were able to drink milk, they typically developed lactose intolerance as they grew up. But after cattle and goats were domesticated in Europe and yaks and mares were domesticated in Asia, adults with a mutation that allowed them to digest milk had a nutritional advantage over those without. As a result, they were more likely to have healthy offspring, prompting the mutation to spread, Hawks said. The mechanism also explains why genetic resistance to malaria has spread among Africans -- who live where disease-carrying mosquitoes are prevalent -- but not among Europeans or Asians. Most of the genetic changes the researchers identified were found in only one geographic group or another. Races as we know them today didn't exist until fewer than 20,000 years ago, when genes involved in skin pigmentation emerged, Hawks said. Paler skin allowed people in northern latitudes to absorb more sunlight to make vitamin D. "As populations expanded into new environments, the pressures faced in those environments would have been different," said Noah Rosenberg, a human geneticist at the University of Michigan, who wasn't involved in the study. "So it stands to reason that in different parts of the world, different genes will appear to have experienced natural selection." Hawks and colleagues from UC Irvine, the University of Utah and Santa Clara-based gene chip maker Affymetrix Inc. examined genetic data collected by the International HapMap Consortium, which cataloged single-letter differences among the 3 billion letters of human DNA in people of Nigerian, Japanese, Chinese and European descent. The researchers looked for long stretches of DNA that were identical in many people, suggesting that a gene was widely adopted and that it spread relatively recently, before random mutations among individuals had a chance to occur. They found that the more the population grew, the faster human genes evolved. That's because more people created more opportunities for a beneficial mutation to arise, Hawks said. In the last 5,000 to 10,000 years, as agriculture was able to support increasingly large societies, the rate of evolutionary change rose to more than 100 times historical levels, the study concluded. Among the fastest-evolving genes were those related to brain development, but the researchers aren't sure what made them so desirable, Hawks said. There are other mysteries too. "Nobody 10,000 years ago had blue eyes," Hawks said. "Why is it that blue-eyed people had a 5% advantage in reproducing compared to non-blue-eyed people? I have no idea."

Sign Up


Maybe the mystery originated in Africa.

[kubedawg]

Because blue eyed people reproduce more? There's no way to tell. Statistics are certainly not 100%

[Technosoul]

I do not see much mystery about the brain gene evolution. In my "unauthorized speculation" and some books that I do not have link for.

As people made use of rivers to grow food they did not have to migrate with the seasons, this gave some of them more spare time to think about things other then just spending all their time hunting, fishing, or gathering viggies. With some working the farms they had many who basically had nothing to do, so they became managers and rulers. Spare time allowed them to think about things, philosophy or how to build cities, and so they used their brain more to create their cities, kingdoms, schools, and governments. That spare time to think is also related to the fact that farming allowed them to remain on one location, while also venturing some trade with other locations for additional items they wanted to have.

The blue eyes must have happened for simular reasons of the white skin, part of the transformitive motion relative to the development of races.

Also vision in humans evolved from seeing things in black and white to seeing colors. Which might be a fairly recent event. People who collect native art from America know that that they always used black, white and red markings. As that is how it always was, the natives said. But it is speculated that the color red was the first color people saw, and that is why it was used. Later our vision evolved so we can see other colors. But I am not sure if that kind of reasoning is very scientific or not. Perhaps a lot of sailing or fishing in the blue ocean resulted in blue eyes? Another guess.

[Kuldeep]

What about other animals like cat, tiger, fish etc, which have colured retinas other than black, who possibly existed much before humans??

Technosoul explanations could have substance in it. Yes, not going by evoultion/mutation theory, otherwise also, most of the living beings learn everything from their parents, humans in particular. Knowledge of ancesters goes down the line to their offsprings. Different sections of society lived differently thus evolving different coustoms resulting in different types of people. Thatway their genes, RNA got muational transformation along with local customs and culture!!

[Nemiroff]

Perhaps (wild guess here) blue being all the way at the end of the spectrum, makes it more UV resistent then the other colors.

[Dieval]

I find it pretty interesting that they know the eye color of EVERY 10,000 year old person!

[Athena]

Hi my dear friends who perfer the scientific explanation to the religious explanation of how we come to be as we are. Here is nature's explanation for the selection blue eyes or brown eyes.

Understanding Genetics: Human Health and the Genome One theory is that people with blue eyes also tend to have lighter skin (the same pigment that makes brown eyes also makes dark skin). In places with less sunlight, lighter skin can help the body make Vitamin D. You need vitamin D to avoid bone diseases like rickets. In fact, lack of vitamin D used to be a big problem before refrigeration and vitamin D-fortified milk. So, lighter skin means you are less likely to get rickets. Let’s say you randomly get a mutation that gives you blue eyes and light skin. Now if you live where there isn't much sunlight (Northern Europe, for example), you will be healthier than your dark-skinned neighbors. ........ One idea is that light skin allows sunlight to destroy a vitamin called folate. You need folate to have healthy babies. If women don’t get enough folate while they are pregnant, the baby can be born with birth defects. And if men don’t get enough folate, they don’t make as many sperm. This would mean that people with blue eyes and light skin living in bright areas would have less healthy kids. So the genes for blue eyes would be less likely to get passed on in sunny places.

Note we can compensate with vitamin D in our milk and clothing covering our bodies, and increase everyone's survival in the different regions; making our differences less important.

As for Dieval"s question. We can know the eye color of any dead human as long as there is a sample of DNA. That is because we can read the chormosone. We know where the gene for different hair and eye colors is on the chormosome. So if we find a mummy in a desert or a bog, we can extract DNA from a tooth, and then read the chromosome, to know things like hair and eye color.

[Compugasm]

The pace of human evolution has been increasing at a stunning rate.

As population increases, so does mutation? Wow, thanks Captain Obvious!! Once you read that paper, and think how large populations of anything like fish, insects evolve.... Suddenly this paper isn't so amazing.

[loser]

The immune system does not work through random mutation. We build immunity from certain diseases because the immune system is triggered when these certain diseases invade the body. Immunity is very disease specific. We don't develop an immunity to smallpox when exposed to measles. There is a causality there that is inherit in all dynamics of life.

It is the same with adaptation. In fact, causality is inherent in all life and is the force behind any and every mutation. There is nothing random about it. If a child is forced to drink cow's milk even though it's body cannot process that mild adequately, mutations occur in an attempt of the body to process that liquid. Drink poison long enough (in less than fatal quantities) and the body would eventually (if possible) develop immunity for that poison. Adaptation occurs but not randomly.

I wonder, though. Are certain brains randomly crosswired so that the synapses misfire incessantly? Nah, there's a REASON why there is so much aberrant thinking in mankind.

This has made me think of a question. I'm going to start another post and try to link it to this one (if I can figure it out).

[Kuldeep]

Being not a biologist "mutation" or better "gene mutation" confuses me !! Whatever little I have read evolution of various species takes place due to gene mutation. Why exactly this gene mutation takes to develop specie after specie. ?? I am not clear at all. Being a man from science, I am to believe in evolution but half heartedly.

Since,I am confused as to what:

What evolutionists think about humans would evolve to; whether to some super-man, or giant, or hyper-man, or anything different specie in say another 1 million years ??? I really wonder !!! no!!yes !!

[Athena]

Quote by: Kuldeep Being not a biologist "mutation" or better "gene mutation" confuses me !! Whatever little I have read evolution of various species takes place due to gene mutation. Why exactly this gene mutation takes to develop specie after specie. ?? I am not clear at all. Being a man from science, I am to believe in evolution but half heartedly. Since,I am confused as to what: What evolutionists think about humans would evolve to; whether to some super-man, or giant, or hyper-man, or anything different specie in say another 1 million years ??? I really wonder !!! no!!yes !!

I googled gene mutations and this is the frist explanation offered.

What is a gene mutation and how do mutations occur? - Genetics Home Reference What is a gene mutation and how do mutations occur? A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome. Gene mutations occur in two ways: they can be inherited from a parent or acquired during a person’s lifetime. Mutations that are passed from parent to child are called hereditary mutations or germline mutations (because they are present in the egg and sperm cells, which are also called germ cells). This type of mutation is present throughout a person’s life in virtually every cell in the body. Mutations that occur only in an egg or sperm cell, or those that occur just after fertilization, are called new (de novo) mutations. De novo mutations may explain genetic disorders in which an affected child has a mutation in every cell, but has no family history of the disorder. Acquired (or somatic) mutations occur in the DNA of individual cells at some time during a person’s life. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation. Mutations may also occur in a single cell within an early embryo. As all the cells divide during growth and development, the individual will have some cells with the mutation and some cells without the genetic change. This situation is called mosaicism. Some genetic changes are very rare; others are common in the population. Genetic changes that occur in more than 1 percent of the population are called polymorphisms. They are common enough to be considered a normal variation in the DNA. Polymorphisms are responsible for many of the normal differences between people such as eye color, hair color, and blood type. Although many polymorphisms have no negative effects on a person’s health, some of these variations may influence the risk of developing certain disorders.

[gallo]

Quote by: loser The immune system does not work through random mutation. We build immunity from certain diseases because the immune system is triggered when these certain diseases invade the body. Immunity is very disease specific. We don't develop an immunity to smallpox when exposed to measles. There is a causality there that is inherit in all dynamics of life.

You are absolutely correct. The immune system does not work by a process of mutation. You do make one point on which I would like to expand. You said that we do not develop an immunity to smallpox when exposed to measles. However, we do develop immunity to smallpox after having cowpox. The two are so closely related that a case of either confers immunity to the other. It's just that smallpox is so much more virulent that it is fatal in a high number of cases, while cowpox almost never is.

It is the same with adaptation.

No, it's not.

In fact, causality is inherent in all life and is the force behind any and every mutation.

To say that mutations are random is not to say that they are uncaused. Of course they have causes - random errors in DNA replication, exposure to various radiations, exposure to certain chemicals. But the mutations, though caused, are not a directed response to the environment. For example, there is no logical way for decreased levels of sunlight to cause, as a response, the specific mutation that resulted in white skin. You see, such a mutation must necessarily take place in the gonads of some individual, which aren't exposed to sunlight anyway.

There is nothing random about it.

Actually, mutation is a random process. While they may be caused by environmental factors (as well as errors in DNA replication), they are not responses to the environment.

If a child is forced to drink cow's milk even though it's body cannot process that mild adequately, mutations occur in an attempt of the body to process that liquid.

Sorry. That's nonsense. If a lactose intolerant person drinks milk, they will not undergo mutations that will allow them to process lactose. In the past, before the development of lactose free substitutes such children usually died. A mutation such as you claim would have to take place in all of the millions upon millions of cells in the digestive system of the child. The mutation that conferred adult lactose tolerance happened in the gonads of some individual in the distant past. That individual never was lactose tolerant but his/her children were. That was an advantage for those who raised cattle and goats.

Drink poison long enough (in less than fatal quantities) and the body would eventually (if possible) develop immunity for that poison.

But, according to your premise, why wouldn't it be possible? In fact, such immunity to toxins are not the result of mutations. One example is that a heavy smoker can tolerate (even crave) nicotine (a toxic poison) at levels that would kill or nearly kill a non smoker.

Adaptation occurs but not randomly.

So now you are trying to use the same word with two different meanings. Although there is no clear distinction in the use of two similar words, lets just follow your lead here. What you are describing as an adaptation is not the result of a mutation. A mutation affects a single gene on a single chromosome in a single cell in a single organ. Thus, it can't actually cause a tolerance to lactose or a toxin. Lactose intolerance is not something that one gets over by drinking lots of milk since the cells of the digestive tract (all multi-millions of them) are incapable of producing the the enzyme necessary (lactase) to digest milk. Even if a mutation were to happen in an individual in the right place, a single cell cannot possibly produce enough lactase to make a difference. So let's call changes that individuals undergo in direct response to an environment "adaptations." However, let's call changes to populations of living organisms that are the result of a mutation in the gonad of an individual that was passed along to offspring in a gamete and offered a subsequent reproductive advantage "adaptions."

Sadly, biologists and geneticists don't actually make that distinction. Thus, those who have little understanding of the topic fail to make the distinction according to context. An individual adapts to changes in the environment biochemically. Such adaptations are not hereditary. Populations of organisms adapt genetically by random mutations and natural selection.

In the case of the toxins that you confuse with genetic intolerance, as I understand it, such tolerance is, in fact, a reaction of the immune system, just as smallpox immunity is.

I wonder, though. Are certain brains randomly crosswired so that the synapses misfire incessantly? Nah, there's a REASON why there is so much aberrant thinking in mankind.

And how is that even remotely related to this topic and your obvious misunderstanding?

This has made me think of a question. I'm going to start another post and try to link it to this one (if I can figure it out).

I'm sure you will, although I have little confidence that the connection will be logical.