Were the first humans black or white?

[Syron]

Larger parts of the body were probably through evolution even after the separation of homo and pan covered by hair. How long we were furries may not be clear yet. Homo Erectus may still have been. We would have to ask paleo-anthropologists, they may have some ideas about.

Indeed.

And what do we define as first human? Afaik there is still a lot of scientific debate about this.

[Adar]

Skin color in different areas is almost totally controlled by sunlight, not the hotness or coolness of the climate or use of clothes. Lighter skin absorbs sunlight easier, but takes damage from the sun easier. Whites living in places with lots of sunlight would die off faster than black or brown-skinned people, but brown/blacks would not get enough sunlight, dying off more in the reverse climates. And as the gene pool narrowed, less and less people had the worse trait, making the prevailing skin colors correspond to sunlight exposure.

In a colder climate humans wear more clothing. Thus emulating the fur worn by chimpanzees.

There is actually a research project being conducted regarding D-vitamin deficiency among Somali women here in Sweden. There is no similar issues with their husbands despite the fact that they have the same skin colour. Differences in clothing and the men spending more time outside are the likely reasons for this.

A naked black person would get enough sun even here in Sweden, the problem is that he would freeze to death.

Research project (use google translate if you want): http://www.fou.nu/is/ckfuu/ansokan/46981

[Phier]

There is one thing I can say, for certain, without a doubt, no debate.

The first humans were NOT my color if they were in Africa, which we believe them to be.

Let me splain. I'm 1/2 Irish 1/2 English and 100% whitey. I can get a sunburn in a couple of hours. When people like me move to AZ or CO, they get skin cancer. When I go anywhere tropical I have on SPF 35+. At one point in CANADA during a heat wave, I was still getting sun poisoning and moved to SPF 45 (saved my ass, and to those articles in the popular press that say spf over 25 doens't matter, I say BS).

There was NO one like me in africa skin tone wise. It would be evolutionary suicide. I have two colors, red and white. I am tan for a DAY before I peel. To get tan I'd have to live in the sun and in the end I'd look like a prune with cancer.

I am a mutant from the first humans without any doubt

[Simetrical]

There are two possibilities here; the feature evolved separately (highly unlikely). Or our last common ancestor had a complex system for skin colour similar to the one human and the chimpanzees have.

Those aren't the only two possibilities. Genetics is more complex than that. There's a difference between a gene existing, and being prevalent. You can have a few oddballs hanging around in the gene pool who will end up dominating if selection pressures change around enough. For instance, some elephants have always been tuskless. Poaching has caused this adaptation to become extremely valuable, so now there are a lot more tuskless elephants. This feature didn't have to evolve; it already existed. It just became more prevalent when conditions were right.

So early humans could have overwhelmingly been dark-skinned, but with enough genetic diversity that they could rapidly become light-skinned if their environment changed.

This property is exactly what have caused human pigmentation to follow the climate so closely. We are never more than a few mutations away from becoming darker/lighter.

Mutations are not the cause of skin color changes in human populations. Skin color variation (as with most variation in sexually reproducing populations) is caused primarily by non-uniform distribution of preexisting genetic variations in the population. I.e., there were mutations long ago that made some people slightly lighter-skinned and some people slightly darker-skinned, and we just inherit some of those mutations from our parents. If a different skin tone becomes more valuable, the bearers of the better genes are more likely to reproduce, so they spread through the population without the need for mutation. This is why meiosis is so valuable: it allows much more rapid adaptation by populations than mutation.

Also, the wikipedia article support my theory. The article clearly state that the last ancestor we share with chimpanzees seem to have the same colouring properties as chimpanzees (" Jablonski and Chaplin note that there is no empirical evidence to suggest that the hominid ancestors six million years ago had a skin tone different from the skin tone of today's chimpanzees—namely light-skinned under black hair*.").

We were not talking about our last common ancestor with chimpanzees. We were talking about the first humans, who came millions of years after our last common ancestor with chimpanzees by anyone's definition.

I really don't understand what you consider yourself to be refuting in your post. Your 2nd paragraph is "Based on that, it's likely that our earliest ancestors had black skin, since they lived in Africa. Chimpanzees have fur, so the pressure toward dark skin doesn't apply to them, or only much less. The fur presumably stops most of the UV from getting to their skin anyway."

In my post I state "This also mean that the environment was the deciding factor of skin colour. Bushmen are living in an environment similar to what we think the earliest humans were living in." And the final statement of my post is "A not too wild guess is that our skin colour became increasingly dark as we lost our bodyhair and later had the reverse happen when we put on clothes and entered a colder climate."

This mean that our conclusions are in perfect agreement as long as you agree that Bushmen have dark skin.

I dispute this specific sentence: "We know that both humans and chimpanzees can have a variety of skin colours, this mean that our ancestors most likely also carried the same properties." It does not follow that just because modern humans and modern chimpanzees have a variety of skin colors, all ancestor populations of humans must have also had a variety of skin colors. As far as I can tell (evolutionary biology is very far from my fields of expertise), the prevalent theory is that the earliest humans were probably overwhelmingly dark-skinned.

[Adar]

Those aren't the only two possibilities. Genetics is more complex than that. There's a difference between a gene existing, and being prevalent. You can have a few oddballs hanging around in the gene pool who will end up dominating if selection pressures change around enough. For instance, some elephants have always been tuskless. Poaching has caused this adaptation to become extremely valuable, so now there are a lot more tuskless elephants. This feature didn't have to evolve; it already existed. It just became more prevalent when conditions were right.

So early humans could have overwhelmingly been dark-skinned, but with enough genetic diversity that they could rapidly become light-skinned if their environment changed.

Your "third way" does not make any sense i relation to what I said. Both Chimpanzees and Humans have a complex system deciding their skin colour which is also supported by the wikipedia article. Oddballs can make an uncommon phenotype common due to natural selection or genetic drift. They do however not turn a simple on/off phenotype into a complex system of interacting genes.

To quote the wikipedia article regarding the complexity of interacting genes deciding skin colour:

"
Several genes have been invoked to explain variations of skin tones in humans, including SLC45A2,[15][16] A recently discovered gene, SLC24A5 has been shown to account for a substantial fraction of the difference in the average of 30 or so melanin units between Europeans and Africans. ASIP, MATP, TYR, and OCA2.
Wide variations in human skin tones have been correlated with mutations in another gene; the MC1R[17]. The "MC1R" label for the gene stands for melanocortin 1 receptor, where gene "

Mutations are not the cause of skin color changes in human populations. Skin color variation (as with most variation in sexually reproducing populations) is caused primarily by non-uniform distribution of preexisting genetic variations in the population. I.e., there were mutations long ago that made some people slightly lighter-skinned and some people slightly darker-skinned, and we just inherit some of those mutations from our parents. If a different skin tone becomes more valuable, the bearers of the better genes are more likely to reproduce, so they spread through the population without the need for mutation. This is why meiosis is so valuable: it allows much more rapid adaptation by populations than mutation.

Here I need to once more refer you to the article you suggested I should read. In my original post I did not go down to the genetic level due to the lack of data on this issue but your article clearly state that mutations are a major cause of skin colour changes.

Harding found that there were zero differences among the Africans for the amino acid sequences in their receptor proteins, so the skin of each individual from Africa was dark. In contrast, among certain (European) non-African individuals, there were 18 different amino acid sites in which the receptor proteins differed, and each amino acid that differed from the African receptor protein resulted in skin lighter than the skin of the African (and other equatorial) individuals. Nonetheless, the variations in the 261 silent sites in the MC1R were similar between the Africans and non-Africans, so the basic mutation rates among the Africans and non-Africans were the same. Also, close examination of the haplotype variation among the non-Europeans (including East Asians) suggested that, among most non-European non-Africans, the most common variants were in the silent mutation positions (Harding et al. 2000 p 1355). Thus, at least at this locus, most non-Europeans share the ancestral function. The fact that relatively light skinned east Asians varied little genetically from dark skinned Africans at this locus supports the fact that skin color is a complex trait determined by several genes. Thus light skin among east Asians occurs by way of a different genetic mechanism than that among Europeans.
With regards to Europeans, the next question to ask would be: why were there zero differences and no divergences in the amino acid sequences of the receptor protein among the Africans (and other equatorial groups) while there were 18 differences among the populations in Ireland, England, and Sweden? (Harding et al., 2000, pp. 1359–1360) concluded that the intense sun in Africa created an evolutionary constraint that reduced severely the survival of progeny with any difference in the 693 sites of the MC1R gene that resulted in even one small change in the amino acid sequence of the receptor protein—because any variation from the African receptor protein produced significantly lighter skin that gave less protection from the intense African sun. In contrast, in Sweden, for example, the sun was so weak that no mutation in the receptor protein reduced the survival probability of progeny. Indeed, for the individuals from Ireland, England, and Sweden, the mutation variations among the 693 gene sites that caused changes in amino acid sequence was the same as the mutation variations in the 261 gene sites at which silent mutations still produced the same amino acid sequence. Thus, Harding concluded that the intense sun in Africa selectively killed off the progeny of individuals who had a mutation in the MC1R gene that made the skin lighter. However, the mutation rate toward lighter skin in the progeny of those African individuals who had moved North to areas with weaker sun was comparable to the mutation rate of the folks whose ancient ancestors grew up in Sweden. Hence, Harding concluded that the lightness of human skin was a direct result of random mutations in the MC1R gene that were non-lethal at the latitudes of Sweden. Even the mutations that produce red hair with little ability to tan were non-lethal in the northern latitudes.

We were not talking about our last common ancestor with chimpanzees. We were talking about the first humans, who came millions of years after our last common ancestor with chimpanzees by anyone's definition.

I find it highly aggravating that you try to nitpick my statements when you do not take the time to properly read what I state.

Read my posts again and you will see that my logic is: Both Chimpanzee and Humans have a complex system of deciding skin colour --> The last common ancestor for Chimpanzees and Humans was a specie with a similar system + Modern human colours are decided by environment --> The colour of our ancestors was decided by environmental factors, just like they are for modern humans --> Early humans were most likely coloured similarily to humans currently living in that area.

I dispute this specific sentence: "We know that both humans and chimpanzees can have a variety of skin colours, this mean that our ancestors most likely also carried the same properties." It does not follow that just because modern humans and modern chimpanzees have a variety of skin colors, all ancestor populations of humans must have also had a variety of skin colors. As far as I can tell (evolutionary biology is very far from my fields of expertise), the prevalent theory is that the earliest humans were probably overwhelmingly dark-skinned.

I think your confusing yourself with your own presumptions. I never said that there had to be a variance of colour inside of a population. I said that the LCA specie had a system deciding colour similar to the one chimpanzees and humans have today. The overwhelming skin colour of a population can be changed in a "few" generations due to environmental factors. Therefore we can guess that the skin colour of the first Homo sapiens was the colour we currently see among people living in a similar environment.

[Pallantides]

while inhabitants of cold northern regions have light skin.

People living arctic and subarctic climates tend to have somewhat darker pigmentation because of the high levels of reflected ultraviolet radiation.



1909,Sámi from Finnmark, Norway.

[Simetrical]

Your "third way" does not make any sense i relation to what I said. Both Chimpanzees and Humans have a complex system deciding their skin colour which is also supported by the wikipedia article.

There are a number of genes that affect skin color. You could call this a "complex system", I suppose. It's not a dedicated system, though, it's just plain old meiosis. I'm not sure what your point is here.

Here I need to once more refer you to the article you suggested I should read. In my original post I did not go down to the genetic level due to the lack of data on this issue but your article clearly state that mutations are a major cause of skin colour changes.

Harding found that there were zero differences among the Africans for the amino acid sequences in their receptor proteins, so the skin of each individual from Africa was dark. In contrast, among certain (European) non-African individuals, there were 18 different amino acid sites in which the receptor proteins differed, and each amino acid that differed from the African receptor protein resulted in skin lighter than the skin of the African (and other equatorial) individuals. Nonetheless, the variations in the 261 silent sites in the MC1R were similar between the Africans and non-Africans, so the basic mutation rates among the Africans and non-Africans were the same. Also, close examination of the haplotype variation among the non-Europeans (including East Asians) suggested that, among most non-European non-Africans, the most common variants were in the silent mutation positions (Harding et al. 2000 p 1355). Thus, at least at this locus, most non-Europeans share the ancestral function. The fact that relatively light skinned east Asians varied little genetically from dark skinned Africans at this locus supports the fact that skin color is a complex trait determined by several genes. Thus light skin among east Asians occurs by way of a different genetic mechanism than that among Europeans.
With regards to Europeans, the next question to ask would be: why were there zero differences and no divergences in the amino acid sequences of the receptor protein among the Africans (and other equatorial groups) while there were 18 differences among the populations in Ireland, England, and Sweden? (Harding et al., 2000, pp. 1359–1360) concluded that the intense sun in Africa created an evolutionary constraint that reduced severely the survival of progeny with any difference in the 693 sites of the MC1R gene that resulted in even one small change in the amino acid sequence of the receptor protein—because any variation from the African receptor protein produced significantly lighter skin that gave less protection from the intense African sun. In contrast, in Sweden, for example, the sun was so weak that no mutation in the receptor protein reduced the survival probability of progeny. Indeed, for the individuals from Ireland, England, and Sweden, the mutation variations among the 693 gene sites that caused changes in amino acid sequence was the same as the mutation variations in the 261 gene sites at which silent mutations still produced the same amino acid sequence. Thus, Harding concluded that the intense sun in Africa selectively killed off the progeny of individuals who had a mutation in the MC1R gene that made the skin lighter. However, the mutation rate toward lighter skin in the progeny of those African individuals who had moved North to areas with weaker sun was comparable to the mutation rate of the folks whose ancient ancestors grew up in Sweden. Hence, Harding concluded that the lightness of human skin was a direct result of random mutations in the MC1R gene that were non-lethal at the latitudes of Sweden. Even the mutations that produce red hair with little ability to tan were non-lethal in the northern latitudes.

The quotation doesn't make it clear when the mutations actually occurred. If they did actually occur after the departure from Africa, then in fact our skin color variation has absolutely nothing to do with chimpanzees', and they are separate mechanisms. That's what your quotation implies. If they occurred while we were still in Africa, or before, then it's as I said.

Both Chimpanzee and Humans have a complex system of deciding skin colour --> The last common ancestor for Chimpanzees and Humans was a specie with a similar system

I don't think this implication holds. Just because humans and chimpanzees have a characteristic in common doesn't mean that our last common ancestor had the same trait. Our last common ancestor was millions of years ago, plenty of time for convergent evolution on minor things like skin color. (Although I haven't seen anyone mention evidence that chimpanzees' skin color is regulated at all similarly to humans'.)

I also don't think the premise holds, or at least it's not worded well. We don't have a "complex system of deciding skin color", we have a complex system that decides our traits generally, namely genetics. One particular thing that's decided by our genetics is skin color.

Modern human colours are decided by environment

That's imprecisely worded, at best. Human skin color is decided mainly by genetics, not environment. However, selection pressure will cause human populations to shift genetically depending on their environment, at a pretty rapid pace. If you said "Modern human skin color is determined by genes whose distribution is strongly influenced by the environment of one's immediate ancestors", or something like that, I'd agree.

--> The colour of our ancestors was decided by environmental factors, just like they are for modern humans --> Early humans were most likely coloured similarily to humans currently living in that area.

I don't have a problem with this part.

I never said that there had to be a variance of colour inside of a population. I said that the LCA specie had a system deciding colour similar to the one chimpanzees and humans have today.

Why do you believe this? And what do you mean by "a system deciding colour"?

The overwhelming skin colour of a population can be changed in a "few" generations due to environmental factors. Therefore we can guess that the skin colour of the first Homo sapiens was the colour we currently see among people living in a similar environment.

Yes, I agree with this.

People living arctic and subarctic climates tend to have somewhat darker pigmentation because of the high levels of reflected ultraviolet radiation.

The reason I've heard cited is because they eat fish and so get their vitamin D from other sources. That's what the Wikipedia article says, citing a study. (As I say, this is all way outside my specialty, so I can't do much better than Wikipedia.) What's your source for this? It doesn't sound that implausible to me, except that people would surely tend to bundle up very heavily when there's lots of snow on the ground, so I'd think any extra UV intake would be pretty much negated.

[Viking Prince]

Not really a scientific observation, but why the limited choice of black or white. White and black are extremes of the spectrum of choices. Most Asians and western hemisphere indigenous peoples would be some shade of brown and tending towards the medium.

[Adar]

There are a number of genes that affect skin color. You could call this a "complex system", I suppose. It's not a dedicated system, though, it's just plain old meiosis. I'm not sure what your point is here.

The quotation doesn't make it clear when the mutations actually occurred. If they did actually occur after the departure from Africa, then in fact our skin color variation has absolutely nothing to do with chimpanzees', and they are separate mechanisms. That's what your quotation implies. If they occurred while we were still in Africa, or before, then it's as I said. [/QUOTE]

We need to use a vague wording, attributing it to "a number of genes" would fail to take into consideration epigenetics. Meisos is not the system deciding it. Meiosis is the creation of sperms and eggs, it decides what genes we are going to get but it does not tell us how genes actually function. In this case we are talking about how the genes work, not where they came from.

The quotation doesn't make it clear when the mutations actually occurred. If they did actually occur after the departure from Africa, then in fact our skin color variation has absolutely nothing to do with chimpanzees', and they are separate mechanisms. That's what your quotation implies. If they occurred while we were still in Africa, or before, then it's as I said.

They most likely occured somewhere around the time we left Africa. It's a too significant disadvantage to allow light skinned humans to start dominating a population in Africa. I think the problem is that you have difficulties accepting finer points of inheritance of genes.

The dark skinned early humans were a bottleneck regarding genetic variation in the genes deciding skin colour. Our LCA would have a genetic variation causing some LCAs to be lighter than others (just like on humans and chimps have on a specie level). The pre humans got a strong natural selection toward a darker complexion, reducing variation to levels similar to the ones we currently see among east africans. Humans leaving africa found themselves in an environment without this pressure, thereby allowing genetic variation to increase due to mutations.

I don't think this implication holds. Just because humans and chimpanzees have a characteristic in common doesn't mean that our last common ancestor had the same trait. Our last common ancestor was millions of years ago, plenty of time for convergent evolution on minor things like skin color. (Although I haven't seen anyone mention evidence that chimpanzees' skin color is regulated at all similarly to humans'.)

A few million years is not enough for convergent evolution on "a minor thing". Your also confusing a simple phenotype (skin colour) complex underlying causes. Humans and Chimpanzees are very genetically similar, having a completely different regulatory system for skin colour would be huge. I can only show you evidence that we both have the MC1R gene. But otherwise I suggest you learn about it through the same way as I have. Do a genetics course at university, they often use moderl organisms to understand things. They also very often mention similarities to humans.

I also don't think the premise holds, or at least it's not worded well. We don't have a "complex system of deciding skin color", we have a complex system that decides our traits generally, namely genetics. One particular thing that's decided by our genetics is skin color.

That's imprecisely worded, at best. Human skin color is decided mainly by genetics, not environment. However, selection pressure will cause human populations to shift genetically depending on their environment, at a pretty rapid pace. If you said "Modern human skin color is determined by genes whose distribution is strongly influenced by the environment of one's immediate ancestors", or something like that, I'd agree.

Now your just wasting time arguing sematics. You obviously understood the purpose of the sentence (except that your way writing it rules out epigenetics which might also have an influence) but your way of writing it is far longer. Needlessly expanding something that is intended to be short is not a good idea.

Especially considering that I further down the page give an extended explanation "The overwhelming skin colour of a population can be changed in a "few" generations due to environmental factors. Therefore we can guess that the skin colour of the first Homo sapiens was the colour we currently see among people living in a similar environment."

Why do you believe this? And what do you mean by "a system deciding colour"?

Becuase evolution rarely do the same thing twice on a genetic level. Phenotypes might very often be created by convergent evolution but genotypes are not. Chimpanzees and humans are highly similar on the genetic level. Almost all genes carried by humans have a chimpanzee ortholog and vice versa.

"A system deciding colour" is a vague wording to take into account all inheritory and environmental factors that give an individual his or her skin colour. Specifically listing out all factors is currently impossible due to our limited knowledge.

[DAVIDE]

Neanderthal child recontruction by Anthropological Institute of Zurigo

[Simetrical]

We need to use a vague wording, attributing it to "a number of genes" would fail to take into consideration epigenetics.

Why do you think there's a significant epigenetic contribution to skin color? As far as I'm aware, it's assumed to be mainly genetic. That's what all the links we've been discussing seem to say.

Anyway, in any hard science, you need to always use precise terminology no matter what. Precision is one of the hallmarks of science.

The dark skinned early humans were a bottleneck regarding genetic variation in the genes deciding skin colour. Our LCA would have a genetic variation causing some LCAs to be lighter than others (just like on humans and chimps have on a specie level). The pre humans got a strong natural selection toward a darker complexion, reducing variation to levels similar to the ones we currently see among east africans. Humans leaving africa found themselves in an environment without this pressure, thereby allowing genetic variation to increase due to mutations.

It wasn't clear to me why you were assuming that our last common ancestor has to have much variety in skin color, though. I wasn't saying it's not true, but I didn't see your logic.

A few million years is not enough for convergent evolution on "a minor thing".

Why not? I mean, it's enough for our last common ancestor to diverge into humans and chimps! Independently developing variation in skin color hardly seems like a stretch.

I can only show you evidence that we both have the MC1R gene.

So you're saying that specifically, we know that the MC1R gene is responsible for some skin color variation in both modern-day chimps and humans. That specific gene, therefore, was probably present in our last common ancestor: the assumption is that if a gene is present in two organisms and serves the same function, it was very likely to be present in their last common ancestor. Convergent evolution would have most likely used different genes to achieve the same purpose, so that's probably not what occurred here. Then I'm fine with that. I didn't see the evidence before that the actual genes involved were the same genes.

But otherwise I suggest you learn about it through the same way as I have. Do a genetics course at university, they often use moderl organisms to understand things. They also very often mention similarities to humans.

I would have liked to take more courses in all the sciences in college, but I wasn't about to spend six or seven years to get minors in all the hard sciences. I ended up only taking courses in math and physics beyond the basic level. I'd like to at least get some textbooks and study some of this stuff on my own, but sadly I don't really see myself having the time.

Now your just wasting time arguing sematics. You obviously understood the purpose of the sentence (except that your way writing it rules out epigenetics which might also have an influence) but your way of writing it is far longer. Needlessly expanding something that is intended to be short is not a good idea.

I don't think the sentence was clear at all. I would have completely misunderstood it if I didn't already know that skin color is strongly hereditary. It makes it sound like you'll get very dark skin if you just stay out in the sun a lot, since skin color is determined by environment. I only guessed what you meant because I knew that interpretation was completely incorrect on the facts.

Becuase evolution rarely do the same thing twice on a genetic level. Phenotypes might very often be created by convergent evolution but genotypes are not. Chimpanzees and humans are highly similar on the genetic level. Almost all genes carried by humans have a chimpanzee ortholog and vice versa.

Right, my issue was that I didn't realize the genotype here was the same as well as the phenotype. Perhaps you said it explicitly before and I missed it. In that case, sorry, I've been kind of tired lately and certainly didn't read all the links thoroughly.

Anyway, I think now we're in complete agreement, except that I think some of your wording was vaguer than it could have been. Maybe it's my fault, but it took me quite a few posts before I understood your reasoning.

[DaLeGiOnArY]

Ever seen the skin of a chimp? Dark brown. Hispanics came first beehatch!!!! XD

[Adar]

Why do you think there's a significant epigenetic contribution to skin color? As far as I'm aware, it's assumed to be mainly genetic. That's what all the links we've been discussing seem to say.

The problem is that we are currently surprised by the amount of things influenced by hereditary epigenetical functions. The articles are older than these discoveries, it is probably mostly genetical but we do not know for sure and therefore I try to avoid making a clear stance.

Anyway, in any hard science, you need to always use precise terminology no matter what. Precision is one of the hallmarks of science.

But this is not hard science. Mathematics have the advantage that it's an abstraction with terminology defined mainly by mathematicans. In biology we do not have that advantage. Even with basic concepts like "specie", "race" or "life" we lack a precise meaning of the word.

Lets take for example "specie" and how it is defined at wikipedia. In a scientific paper this would be solved by using a term like "genetic specie" and then a reference to the scientific paper first definining it. Thereby giving the word a precise meaning. This kind of methodology is not very practical in a casual science forum. The paper I am currently working on got roughly 80 references.

Spoiler Alert, click show to read: 

from wikipedia
The question of how best to define "species" is one that has occupied biologists for centuries, and the debate itself has become known as the species problem. Darwin wrote in chapter II of On the Origin of Species,
No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation.[7]
But later, in The Descent of Man when addressing "The question whether mankind consists of one or several species", Darwin revised his opinion to say
it is a hopeless endeavour to decide this point on sound grounds, until some definition of the term "species" is generally accepted; and the definition must not include an element which cannot possibly be ascertained, such as an act of creation.[8]
The modern theory of evolution depends on a fundamental redefinition of "species". Prior to Darwin, naturalists viewed species as ideal or general types, which could be exemplified by an ideal specimen bearing all the traits general to the species. Darwin's theories shifted attention from uniformity to variation and from the general to the particular. According to intellectual historian Louis Menand,
Once our attention is redirected to the individual, we need another way of making generalizations. We are no longer interested in the conformity of an individual to an ideal type; we are now interested in the relation of an individual to the other individuals with which it interacts. To generalize about groups of interacting individuals, we need to drop the language of types and essences, which is prescriptive (telling us what finches should be), and adopt the language of statistics and probability, which is predictive (telling us what the average finch, under specified conditions, is likely to do). Relations will be more important than categories; functions, which are variable, will be more important than purposes; transitions will be more important than boundaries; sequences will be more important than hierarchies.
This shift results in a new approach to "species"; Darwin
concluded that species are what they appear to be: ideas, which are provisionally useful for naming groups of interacting individuals. "I look at the term species", he wrote, "as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other ... It does not essentially differ from the word variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, and for convenience sake." [9]
Practically, biologists define species as populations of organisms that have a high level of genetic similarity. This may reflect an adaptation to the same niche, and the transfer of genetic material from one individual to others, through a variety of possible means. The exact level of similarity used in such a definition is arbitrary, but this is the most common definition used for organisms that reproduce asexually (asexual reproduction), such as some plants and microorganisms.
This lack of any clear species concept in microbiology has led to some authors arguing that the term "species" is not useful when studying bacterial evolution. Instead they see genes as moving freely between even distantly-related bacteria, with the entire bacterial domain being a single gene pool. Nevertheless, a kind of rule of thumb has been established, saying that species of Bacteria or Archaea with 16S rRNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA Hybridization if they belong to the same species or not.[10] This concept has been updated recently, saying that the border of 97% was too low and can be raised to 98.7%.[11]
In the study of sexually reproducing organisms, where genetic material is shared through the process of reproduction, the ability of two organisms to interbreed and produce fertile offspring is generally accepted as a simple indicator that the organisms share enough genes to be considered members of the same species. Thus a "species" is a group of interbreeding organisms.
This definition can be extended to say that a species is a group of organisms that could potentially interbreed - fish could still be classed as the same species even if they live in different lakes, as long as they could still interbreed were they ever to come into contact with each other. On the other hand, there are many examples of series of three or more distinct populations, where individuals of the population in the middle can interbreed with the populations to either side, but individuals of the populations on either side cannot interbreed. Thus, one could argue that these populations constitute a single species, or two distinct species. This is not a paradox; it is evidence that species are defined by gene frequencies, and thus have fuzzy boundaries.
Consequently, any single, universal definition of "species" is necessarily arbitrary. Instead, biologists have proposed a range of definitions; which definition a biologists uses is a pragmatic choice, depending on the particularities of that biologist's research.
Typological species
A group of organisms in which individuals are members of the species if they sufficiently conform to certain fixed properties. The clusters of variations or phenotypes within specimens (i.e. longer and shorter tails) would differentiate the species. This method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, we now know that different phenotypes do not always constitute different species (e.g.: a 4-winged Drosophila born to a 2-winged mother is not a different species). Species named in this manner are called morphospecies[verification needed].
Morphological species
A population or group of populations that differs morphologically from other populations. For example, we can distinguish between a chicken and a duck because they have different shaped bills and the duck has webbed feet. Species have been defined in this way since well before the beginning of recorded history. This species concept is much criticised because more recent genetic data reveal that genetically distinct populations may look very similar and, contrarily, large morphological differences sometimes exist between very closely-related populations. Nonetheless, most species known have been described solely from morphology.
Biological / Isolation species
A set of actually or potentially interbreeding populations. This is generally a useful formulation for scientists working with living examples of the higher taxa like mammals, fish, and birds, but more problematic for organisms that do not reproduce sexually. The results of breeding experiments done in artificial conditions may or may not reflect what would happen if the same organisms encountered each other in the wild, making it difficult to gauge whether or not the results of such experiments are meaningful in reference to natural populations.
Biological / reproductive species
Two organisms that are able to reproduce naturally to produce fertile offspring. Organisms that can reproduce but almost always make infertile hybrids, such as a mule or hinny, are not considered to be the same species.
Recognition species
based on shared reproductive systems, including mating behavior. The Recognition concept of species has been introduced by Hugh E. H. Paterson.
Mate-recognition species
A group of organisms that are known to recognize one another as potential mates. Like the isolation species concept above, it applies only to organisms that reproduce sexually. Unlike the isolation species concept, it focuses specifically on pre-mating reproductive isolation.
Evolutionary / Darwinian species
A group of organisms that shares an ancestor; a lineage that maintains its integrity with respect to other lineages through both time and space. At some point in the progress of such a group, some members may diverge from the main population and evolve into a subspecies, a process that eventually will lead to the formation of a new full species if isolation (geographical or ecological) is maintained.
Phylogenetic (Cladistic)[verification needed]
A group of organisms that shares an ancestor; a lineage that maintains its integrity with respect to other lineages through both time and space. At some point in the progress of such a group, members may diverge from one another: when such a divergence becomes sufficiently clear, the two populations are regarded as separate species. This differs from evolutionary species in that the parent species goes extinct taxonomically when a new species evolve, the mother and daughter populations now forming two new species. Subspecies as such are not recognized under this approach; either a population is a phylogenetic species or it is not taxonomically distinguishable.
Ecological species
A set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognize as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters.
Genetic species
based on similarity of DNA of individuals or populations. Techniques to compare similarity of DNA include DNA-DNA hybridization, and genetic fingerprinting (or DNA barcoding).
Phenetic species
based on phenotypes.[verification needed]
Microspecies
Species that reproduce without meiosis or fertilization so that each generation is genetically identical to the previous generation. See also apomixis.
Cohesion species
Most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. This is an expansion of the mate-recognition species concept to allow for post-mating isolation mechanisms; no matter whether populations can hybridize successfully, they are still distinct cohesion species if the amount of hybridization is insufficient to completely mix their respective gene pools.
Evolutionarily Significant Unit (ESU)
An evolutionarily significant unit is a population of organisms that is considered distinct for purposes of conservation. Often referred to as a species or a wildlife species, an ESU also has several possible definitions, which coincide with definitions of species.
In practice, these definitions often coincide, and the differences between them are more a matter of emphasis than of outright contradiction. Nevertheless, no species concept yet proposed is entirely objective, or can be applied in all cases without resorting to judgment. Given the complexity of life, some have argued that such an objective definition is in all likelihood impossible, and biologists should settle for the most practical definition.
For most vertebrates, this is the biological species concept (BSC), and to a lesser extent (or for different purposes) the phylogenetic species concept (PSC). Many BSC subspecies are considered species under the PSC; the difference between the BSC and the PSC can be summed up insofar as that the BSC defines a species as a consequence of manifest evolutionary history, while the PSC defines a species as a consequence of manifest evolutionary potential. Thus, a PSC species is "made" as soon as an evolutionary lineage has started to separate, while a BSC species starts to exist only when the lineage separation is complete. Accordingly, there can be considerable conflict between alternative classifications based upon the PSC versus BSC, as they differ completely in their treatment of taxa that would be considered subspecies under the latter model (e.g., the numerous subspecies of honey bees).

It wasn't clear to me why you were assuming that our last common ancestor has to have much variety in skin color, though. I wasn't saying it's not true, but I didn't see your logic.

I must admit that I find your normal way of questioning things highly annoying becuase it often look more like your wrong than like a serious point of debate. I very much prefer it when questioning things like in your last post "Why do you think there's a significant epigenetic contribution to skin color? As far as I'm aware, it's assumed to be mainly genetic. That's what all the links we've been discussing seem to say.
". Your latest post is in my opinion excellent for a constructive discussion and I hope you continue using this style of posting.

Why not? I mean, it's enough for our last common ancestor to diverge into humans and chimps! Independently developing variation in skin color hardly seems like a stretch.

I can build a house or a castle out of bricks. Combining the same building blocks can give very different results. The same principle is true when it comes to genetics, there are very few genes in our DNA that we do not share with chimpanzees. The major difference is that we combine them in a slightly different way and this is very hard to accept, even among biology students.

[QUOTE=Simetrical;5822622]
So you're saying that specifically, we know that the MC1R gene is responsible for some skin color variation in both modern-day chimps and humans. That specific gene, therefore, was probably present in our last common ancestor: the assumption is that if a gene is present in two organisms and serves the same function, it was very likely to be present in their last common ancestor. Convergent evolution would have most likely used different genes to achieve the same purpose, so that's probably not what occurred here. Then I'm fine with that. I didn't see the evidence before that the actual genes involved were the same genes.
[/quotes]

Perfect, now you understand the concept.

I would have liked to take more courses in all the sciences in college, but I wasn't about to spend six or seven years to get minors in all the hard sciences. I ended up only taking courses in math and physics beyond the basic level. I'd like to at least get some textbooks and study some of this stuff on my own, but sadly I don't really see myself having the time.

I think you made the right decision . I only stated that to show that for -as a biotechnician- theres a lot of this kind of evidence.

I don't think the sentence was clear at all. I would have completely misunderstood it if I didn't already know that skin color is strongly hereditary. It makes it sound like you'll get very dark skin if you just stay out in the sun a lot, since skin color is determined by environment. I only guessed what you meant because I knew that interpretation was completely incorrect on the facts.

Anyway, I think now we're in complete agreement, except that I think some of your wording was vaguer than it could have been. Maybe it's my fault, but it took me quite a few posts before I understood your reasoning.

I have noticed that you often seem to analyze one paragraph at a time and I probably have a habbit of putting support for my statements spread out over the post. This is probably a major source of our confusion and disagreements.

But the vagueness your never going to get out of me . I just don't want to appear exact on issues not fully explained yet.

[DekuTrash]

Ever seen the skin of a chimp? Dark brown. Hispanics came first beehatch!!!! XD

Stop, you're blighting a very informative thread.

And that's a gross stereotype of hispanics

[Richard]

I believe they resembled the Khoisan of Africa, so brown. Both 'black' and 'white' skin are later adaptations.

Ever seen the skin of a chimp? Dark brown. Hispanics came first beehatch!!!! XD

You might be better of in the thema devia...

[Chlodwig I.]

People living arctic and subarctic climates tend to have somewhat darker pigmentation because of the high levels of reflected ultraviolet radiation.



1909,Sámi from Finnmark, Norway.

its more likely that through the diet of these People they recive enough Cholecalciferol through thier food and therefore the skin never needed to become lighter.

Neanderthal child recontruction by Anthropological Institute of Zurigo

Homo Neanderthalensis is not Homo sapiens
considering that he lived mainly in colder climate
it can be considered that he had lighter skin, similar to todays europeans.

[Simetrical]

The problem is that we are currently surprised by the amount of things influenced by hereditary epigenetical functions. The articles are older than these discoveries, it is probably mostly genetical but we do not know for sure and therefore I try to avoid making a clear stance.

Well, we can restrict ourselves to the known causes of skin color variation, to remain concrete.

But this is not hard science. Mathematics have the advantage that it's an abstraction with terminology defined mainly by mathematicans. In biology we do not have that advantage. Even with basic concepts like "specie", "race" or "life" we lack a precise meaning of the word.

Lets take for example "specie" and how it is defined at wikipedia. In a scientific paper this would be solved by using a term like "genetic specie" and then a reference to the scientific paper first definining it. Thereby giving the word a precise meaning. This kind of methodology is not very practical in a casual science forum.

Why not? I'll grant it's not always necessary to clarify exactly what you mean by a species, but only because usually the details aren't relevant to what you're saying.

I must admit that I find your normal way of questioning things highly annoying becuase it often look more like your wrong than like a serious point of debate. I very much prefer it when questioning things like in your last post "Why do you think there's a significant epigenetic contribution to skin color? As far as I'm aware, it's assumed to be mainly genetic. That's what all the links we've been discussing seem to say.
". Your latest post is in my opinion excellent for a constructive discussion and I hope you continue using this style of posting.

I try to always be constructive and non-confrontational, but I'm not very good at it, I'm afraid.

Perfect, now you understand the concept.

I understood the concept before, just not the specific evidence showing that it applies to this case.

But the vagueness your never going to get out of me . I just don't want to appear exact on issues not fully explained yet.

Well, on the Internet you have no idea if you're talking to a Ph.D. in the subject matter or someone who's watched the Discovery Channel for years and thinks he's an expert. So I have to evaluate people's knowledge by what they say, to try to calibrate what I'm saying to the correct level of discourse. It wouldn't do for me to lecture a physicist on what a derivative is, but it also wouldn't do to expect a high school student to be familiar with Galois theory.

One of the most reliable indicators I've found of expertise in a subject is the use of correct, precise, well-known terms and concepts. (At least, one of the most reliable that I can infer from a few casual message board posts.) Using physics as an example, if someone talks only about "wormholes" and "infinity" and "parallel dimensions" and so on, I figure they probably have no idea what they're saying. If they mention things like the Hamiltonian of a system, the equipartition theoreom, or the generalized uncertainty principle (to pick one example from each of the three advanced physics courses I've taken), then I know they're more serious. Experts use jargon correctly without effort, other people tend to abuse it horribly.

So if I underestimate someone's expertise, I end up sounding condescending. If I overestimate it, I'm being unhelpful. Although I try to err on the side of overestimating, in the Athenaeum most people actually don't have much science background, so I do end up having to explain basic things a lot of the time if I want to clear up misconceptions.

Of course, in biology I know much less, so it's harder for me to detect expertise. But statements like "Modern human colors are decided by environment" aren't just vague. "Decided by environment" has a specific meaning in genetics, namely "having low heritability", which was clearly not correct here (and not intended on your part). And the difference was extremely relevant to our discussion. I genuinely did not understand what you were trying to say about the causes of skin color, while I would have if you had used standard precise terminology and given details. Eventually I understood by reading links you posted, and only because those did use standard terminology and did give details.

So I'm still going to say that precision is essential in any kind of science-oriented discussion, even a fairly casual one. Especially if there's any sort of disagreement.

[mp0295]

What Semtrical is saying is exactly what i learned in my genetics class.
I only have a junior level understanding for right now, but i dont see the relevance wo the chimps at all. Also i dont see why early Homo sapiens would become white. I dont see any factors promoting it even if the gene existed in some part of the populace.

And another thought when someone had said "Skin color is directly related to environment." i dont See that its more as a major factor under certain circumstances.

[Adar]

Well, we can restrict ourselves to the known causes of skin color variation, to remain concrete.

But that would be spreading false information. I am not going to be spreading incorrect information just to appear "concrete".

So I'm still going to say that precision is essential in any kind of science-oriented discussion, even a fairly casual one. Especially if there's any sort of disagreement.

The problem is that your not reading the entire post. In the case of "decided by environment" you had a more extensive explanation further down the page. You cannot read each individual sentence and then try to (mis)interpret it. I am fairly certain that the Tanakh is full of sentences that does not make sense unless you evaluate other paragraphs to properly intepret it. The same is true for essentially everything written in applied science.

[Playfishpaste]

Most frequently they were a light shade of tan.