I was recently asked, in a comment after a blog post, this question.
"If Neanderthal DNA is 99.8% identical to modern human then when we look at a person’s DNA and say they have 1-4% Neanderthal, how do we know the rest of it isn’t Neanderthal as well since the rest of their DNA is identical??"
The short answer to that question is we have 100% the same DNA as Neanderthals which includes 100% of same genes. That is the truth of it right there. How can I make that statement? Read on to see.
In the Beginning
I believe it’s important when studying evolution to have a basic understanding of genetics and how changes can occur through time. In order to get an overview of how evolutionary change occurs we’ll start at the beginning.
The whole thing about DNA and genes and how closely we are to Neanderthals can be confusing for sure and the reason for that is mostly because the terms DNA, genes, genomes, base pairs, etc. and the roles they play are not fully understood by most people and plus the perspective you can look at it from varies too depending on how you want to make it look ( just like anything else, it’s called spin in the political world ).
Don’t go Bananas about this but…
Let’s just consider this, you share 50% of your DNA with bananas. Yes, you are half banana, just ask your spouse or significant other. You can google that right now and read all about it as it is a fun little thing that has made the rounds in science blogs, magazines and even mainstream news outlets. However, it is not actually true, darn it.
As far as your DNA goes you share 50% of it with your father and 50% with your mother and 50% with any and all children you have, that’s it, end of story. Sorry, but your spouse is not 50% of a banana however plausible that seems to you.
So, what’s the deal then if all these reputable sources report that? Is that total nonsense or what? Well the short story is that humans do share in the neighborhood of 50% of our genes with plants and that includes bananas. But genes only make up about 2% of our DNA so actually sharing 50% of our genes means we are only sharing 1% of our DNA with bananas not 50%.
Still you might think, sharing 50% of our genes with a banana? What’s up with that? And by the way how much of a banana is a Neanderthal anyway? I am going to start at the beginning of this story and at the end you will be able to connect all the dots and have a clear understanding of the roles of DNA, genes and how similar we all are to each other and our closest hominin relatives, the Neanderthals.
female Neanderthal in modern attire
All life on earth came from one source.
Scientists have been able to conclusively determine that fact. As a consequence, all life, plant and animal share portions of the same genetic heritage. The legacy of life on Earth stated about 3.8 billion years ago. While genes are a blueprint for each species and indeed each individual, there also is a commonality of regulatory requirements for all life in general and large portions the genetic blueprint that all of life shares is because of that. So, no matter the life form, even bananas, we share large parts of the same genetic footprint.
Genome Me This
A human genome is the complete set of DNA contained in the 46 chromosomes or 23 pairs of chromosomes in each human cell, 23 from the mother and 23 from the father. The 23 chromosomes from the mother constitutes one strand of DNA and the 23 chromosomes from the father also constitutes one strand of DNA.
As a measurement of the length of a single strand of DNA we use what are called base pairs. Each human DNA strand has 3.2 billion base pairs. Each individual gene can have several hundred base pairs to over 2 million base pairs but the totality of all the base pairs that genes have only comprises about 2% of human DNA.
DNA has the famous double helix form which resembles a spiral ladder. The sides of the ladder are made of sugar and phosphate that alternate along the length as in one sugar group, then one phosphate group, then one sugar group, then one phosphate group, etc. One end of a base pair attaches to a sugar group on one side of the ladder and the other end will attach to a phosphate group on the other side of the ladder. This is the basic building block of DNA and is called a Nucleotide.
The rungs of the ladder made from four types of nitrogen bases.
These nitrogen bases pair up for each rung of the ladder. A – adenine always bonds with T – thymine and C – cytosine always bonds with G – guanine.
So, going along the length of a strand of DNA the rungs of the ladder could look like this (next pic) stretched out 3.2 billion times with the four different combinations of nitrogen base. The order of these bases is what determines the DNA’s instructions or genetic code.
Every cell in your body has the same DNA but the base pair sequencing of your genes is different from anyone else, this is what makes each of us unique.
Believe it or not until fairly recently the 98% of your DNA that is not part of a gene was called ‘junk DNA’ and considered not to have much use. Now we know it is a vital part of our DNA and it is now called ‘non-coding’ DNA. ‘Non-coding’ because at this point in time we do not think it is involved in the genetic coding. Non-coding DNA is vital in many functions of RNA and other regulatory and essential roles such as controlling important metabolic processes. Turns out non-coding DNA is just as consequential for our biology as the coding DNA or genes. Non-coding DNA regulates the genes.
A gene is the basic physical and functional unit of heredity. Humans have approximately 20,000 genes in their genome. And as I have previously said each individual gene can have several hundred base pairs to over 2 million base pairs.
Genes reside at a specific location on their respective chromosome. Let’s look at eye color. It was once thought that eye color resulted from one gene but we now know there are several genes involved across multiple chromosomes. Two of the main genes for eye color reside on chromosome 15. And because chromosomes come in pairs there is a chromosome 15 from the mother and one from the father. One of those genes called OCA2 is at the same location in each chromosome of the pair in chromosome 15.
There are variations in genes called alleles. Alleles are forms of the same gene with small differences in the sequence of the base pairs for any given gene.
The gene OCA2 contributes not only to eye color but also hair and skin color and it has 380,335 thousand base pairs. There could be one or two of those base pairs that are not in the same order from individual to individual and that would give you the variation of eye color in humans. Likewise, with skin and hair color.
The OCA2 gene coming from the father will have a different sequence of base pairs than the OCA2 gene coming from the mother. Because the gene has 380,335 base pairs and it only takes a few or one here and there to be out of order to make a difference in appearance (however subtle) you can see there are infinite possibilities especially when you take into consideration that there are two of each gene. So, there are two OCA2 genes each having different base pairs out of sequence at different locations along the sequence working in tandem to produce how each one of us looks.
Allele variation is the basis for hereditary variation. Basically, if there were no allele variation in genes, we would all have the same eye color and for that matter hair color and all other variations of phenotype (the set of observable characteristics of an individual). So, alleles are a good thing and necessary for maintaining genetic diversity. Genetic diversity is important because it helps maintain the health of the population.
This next illustration is really great. It shows you the first 4 pair of chromosomes. Let’s say the lighter orange is from the mother and the darker is from the father. Then on the first pair it has a blow up of a segment along the DNA strand which has as an example of where 5 of the same genes (one from each parent) might be placed on that strand in the exact same position along the DNA. Then a second blow up shows a small sequence of base pairs of one gene from each chromosome of the pair. The highlighted yellow letters indicate a difference in the order of base pairs along that sequence which is the definition of an Allele.
And there it is right there. Allele variation is at the apex of species evolution. That’s why I went over it in the detail I have so far. To understand the difference between Neanderthals and Humans you really need the knowledge of how genetic diversity works.
Now we need to consider how that diversity gets passed along and how genes change through time eventually resulting in the evolution of species. And the next step in the pursuit of this story has to do with processes called Mitosis and Meiosis. Mitosis is the process of cell division in humans, mammals and all living organisms. Cell division to produce offspring is called Meiosis. In understanding cell division in humans, we need to take a close look at chromosomes as that is where the hereditary action takes place.
The first thing I have to address right off is the misunderstanding of the actual physical appearance of what a chromosome looks like. A lot of the time you see illustrations of a chromosome it looks like an X pattern like this…
The reason for that is the only time you can see chromosomes is during cell division, the rest of the time in their normal state they are invisible, even under a microscope.
This next illustration is what the 23 pairs of human chromosomes would look like at times other than cell division.
Chromosomes are made up of DNA tightly coiled many times around proteins called histones. Humans have 23 pairs of chromosomes, which means 23 from the mother and 23 from the father to make 46 chromosomes in each cell of your body except for gametes or reproductive cells (we’ll get to that in a minute). Chromosomes are named by number from 1 to 23. Each individual chromosome in a pair contains the same genes for numbers 1 to 22. This means that chromosome 1 from the mother contains the same genes as chromosome 1 from the father and the same length of DNA, they constitute pair 1. Chromosome 2 from the mother contains the same genes as chromosome 2 from the father and the same length of DNA and together they constitute pair 2. This goes on for the first 22 pairs and because of that they are called homologous chromosomes.
The 23rd pair is called the sex chromosome and in females both chromosomes of that pair are called the X chromosome or the female chromosome. In males the 23rd pair of chromosomes has one X (female) chromosome and one Y (male) chromosome.
Chromosomes are located in the nucleus of each cell. Each chromosome is made up of different genes which means each chromosome pair has a different and unique amount of DNA. For example, chromosome 21 is the smallest chromosome with about 1.5% of total DNA in the cell and chromosome 1 is the largest with about 8% of the total DNA. The 46 chromosomes contain the totality of your DNA and constitute your Genome.
The 46 chromosomes in the human cell bring up an interesting issue about the number of base pairs in a cell. There is confusion out there because of the 3.2 billion base pair figure for a single strand of DNA is often confused for the amount in the total genome. In a cell there are two strands of DNA, one from the mother and one from the father. This results in the real world of having 6.4 billion base pairs in each cell, which is of course twice the amount of genetic material. I bring up this point because as we shall see the total genome of 6.4 billion base pairs are involved in the hereditary makeup of offspring and therefore also in the evolution of the species.
Cell division is taking place all over your body all the time, even as you are reading this. Kinda of creepy to think about but there it is. In fact, if you look at the skin on your hands right now it gets regenerated or replaced approximately every month.
When cells divide each chromosome in a pair makes an identical copy of itself then they are called sister chromatids and it is during this phase of cell division that chromosomes become visible and take on the X shape.
All 23 pairs of chromosomes undergo duplication, the first 22 pairs of chromosomes are homologous chromosomes, the 23rd pair is not homologous because it has a X chromosome and a Y chromosome in the male. Homologous chromosomes as we have discussed are 2 physically different chromosomes in a pair that have the same genes but are not genetically identical because one is from the mother and the other from the father.
Sister chromatids are 2 copies of a single chromosome and so are genetically identical (they also are physically attached to one another).
As long as the sister chromatids are connected at the centromere, they are still considered to be one chromosome. However, as soon as they are pulled apart during cell division, each is considered a separate chromosome.
The next illustration shows the process of mitosis. For this illustration I have only used one chromosome pair but each pair of chromosomes in the cell undergoes the same process.
Step 1 is the cell before the process starts, it shows a pair of chromosomes, one from the male and one from the female. Step 2 shows how each chromosome of a pair will duplicate and form a sister. In step 3 the sister chromatids separate, then they pair up again with their counterpart and after all the chromatids from each of the 23 pairs have separated and found their partner it goes to step 4 in which the cell itself separates into two cells. Step 5 shows how we now have two identical cells, each of which is identical as the cell in step 1.
That’s a basic overview of the mitosis process.
Typically, when mitosis occurs each chromosome will duplicate exactly keeping the sequencing of base pairs identical. Mistakes during copying, or unequal division of the genetic material can lead to cells that are unhealthy or dysfunctional.
Meiosis only takes place in the sexual reproductive organs. Gametes are special cells created during the process of Meiosis. The human male organ where gametes are produced is called the testes and produces sperm, the human female organ where gametes are produced is called the ovaries and they produce eggs.
As we know humans reproduce sexually and as we’ve seen both parents contribute half of the genetic makeup to their offspring. This is accomplished when a gamete from the mother and a gamete from the father combine to produce a ‘zygote’. A zygote is a single cell representing a fertilized egg cell. This fertilization results from the fusion of a female gamete (egg) with a male gamete (sperm) this fusion creates a new cell, a zygote, with 23 pairs of chromosomes.
Meiosis cell division is different than Mitosis cell division in a very important way. The end result of meiosis cell division results in 4 cells instead of two and each of the 4 cells will have only 23 chromosomes instead of the 46 it started out with. These 4 cells are called gametes and each one has a different genetic makeup.
The meiosis process is also somewhat different between the male and female. Female meiosis is called oogenesis, male meiosis is called spermatogenesis. In the male the end result is 4 viable gametes, each ready to create offspring. In the female the end result is still 4 cells but only one is a viable gamete and able to create offspring. The one viable cell is called the egg cell or ovum and the other three cells are called polar cells.
Let’s look at an illustration of female meiosis. There are two instances of cell division in meiosis, commonly called meiosis 1 and meiosis 2.
Step 1; we start off in the ovary with a normal cell having 46 chromosomes or 23 pairs.
Step 2; just like in mitosis each of the 46 chromosomes duplicates to make a sister. However, a very important and vital difference in the process called ‘gene recombination’ takes place while the sister chromatids remain attached to each other.
This is how it works. Take chromosome 1 (pair) as an example, you have 1 chromosome from the mother and one from the father. They each duplicate and become sister chromatids, so in essence you have 4 chromosomes next to each other. Before the sister chromatids separate, the sister chromatids from one parent will physically overlap on top of the other. When this happens the DNA strands break apart and swap out sections of DNA and rejoin among the 4 sister chromatids. After recombination, the chromosomes still have the same genes arranged in the same order but the alleles have been rearranged so there is a new combination of alleles that did not exist before and is not identical to either parent’s genetic information. The unique combination of alleles that all sexually reproducing organisms receive from their parents is the direct result of recombination during meiosis.
A very simplified view of recombination looks like this.
Step 3; the cell undergoes cell division. In this cell division the sister chromatids stay attached but each pair of them separates and goes into one or the other of the new cells.
Step 4; the end result of the cell division on step 3 is that now you have 2 cells but each of them only has 23 sister chromatids instead of the 46 we started out with and at this point each half of a sister chromatid is not identical because of recombination.
Step 5; in step 5 the sister chromatids in each cell split apart and then each of the 2 cells undergoes another cell division to make 4 cells total. With this cell division only one of the sister chromatids goes into each cell.
Step 6; this is the final result of meiosis. You wind up with 4 cells, each containing 23 single chromosomes and because of recombination none of the 4 cells are identical to each other or to the cell in step 1. In the female, one of the cells becomes a viable egg or female gamete which is able to create offspring and the other three are called polar cells.
It is also worth noting that every egg produced by the female has the X chromosome for the 23rd chromosome which is of course the female chromosome.
Male meiosis happens in the same way until we get to step 5 and 6. A difference between male and female meiosis is that in the male, step 6, you end up with 4 viable cells able to create offspring (instead of one like with the female) and they are called sperm cells or male gametes. Two of these sperm cells will have the X or female chromosome and two will have the Y or male chromosome.
Recombination of genes during the process of meiosis creates genetic diversity. Each gamete receives a random copy of each recombined chromosome. You can see how all the random mixing of genes and recombining them allows for a nearly infinite variety of allele combinations.
How the evolution of species is accomplished.
In a word mutation. I am not calling you a mutant or anything but it is what it is. The process of evolution is of course layered in complexity like everything else but it does come down to genetic mutation.
Now that you have a clear picture in your mind right now of DNA, genetic structure, alleles and the process of meiosis to produce gametes it will be much easier to understand how mutation is the first step towards evolution and makes it all possible.
Mutations in cell division can take place throughout the body but only the mutations that take place in meiosis (in the gametes) or in the zygote shortly after fertilization affect evolution.
These are called hereditary mutations. Which makes sense because those are the cells that combine to produce offspring. A gene mutation is a permanent change in the DNA sequence that could be a change in a single base pair, or a much larger segment of DNA in a chromosome affecting multiple genes. Once the fertilized egg or zygote starts to divide each cell will have the mutation in the now growing offspring.
New alleles can introduce new and different features, behaviors, attributes into an organism.
It stands to reason that if the DNA never changes the species would never change. Even small changes to the DNA that are passed on to offspring over time can lead to big changes in a species. The mechanism for significant or even drastic change in the DNA is mutation.
Mutations can be detrimental or beneficial or have no effect at all, in fact the vast majority of mutations are neutral and do not evolve the species in one direction or another.
Wait, hold on dude you might be thinking, what’s the deal, isn’t Natural Selection the main driving force for the evolution of species? Natural Selection is "A" driving force for evolution but not "THE" driving force.
Mutations in the genetic code can make an organism more likely to survive and thrive in their environment. Those organisms then are more likely to pass along those genetic changes increasing the survivability of the subsequent offspring.
So, first you have the mutation and if that mutation helps the population survive better it stays in the gene pool and gets passed along. Natural selection can fine tune genetic changes but it does not cause them.
Let’s get practical and see how that applies to us.
Australopiths are one of the first species in the human legacy. They walked upright and were able to have greater use of their hands than previous species. Walking upright needed changes in the structure of the foot and pelvic regions as well as the spine and skull. Greater dexterity of the hands was also a result of genetic changes. These changes came incrementally over the course of tens of thousands of years.
reconstruction of Australopithecus afarensis
Being able to stand and walk upright was an advantage in the environment where the australopith lived. So those individuals that could do that the best were more likely to survive. The genetic changes that enabled the skeletal structure to change to enable walking and then running were passed along to offspring incrementally. It’s not like you have an individual that say walks like a chimpanzee and that chimpanzee has a titanic genetic mutation of DNA in their gametes and their offspring suddenly walks upright. Only in SYFY stories does that happen.
However, having said that, significant changes can occur over the course of thousands of years. Thousands of years in the evolution of hominins is quite fast as these things go considering the australopiths were around from about 4.5 million to 1.4 million years ago.
The time period of 2.2 million years ago (could be a few hundred thousand years older than that even) marked an extremely important time for the legacy of man. That is when the genus Homo became established after birthing from the australopiths. First in the genus Homo, Homo erectus, was quite a big jump up the ladder towards modern man from an australopith.
Homo erectus on the lookout.
Being able to walk upright (bipedal) turned out to be a such an advantage that Homo erectus grew taller by about almost 20 inches on average and could run fast. Rudimentary tool making was also such a big hit that the hands evolved significantly to refine that skill also. But by far the biggest and most significant change took place in the size of the skull and therefore the brain which basically doubled in size.
Let’s just take a look at the morphology (how they look) between the australopith and Homo erectus. The average australopith was about 3.5 to 4.5 feet tall, weighed about 65 to 70 pounds and had a cranial capacity of 400 to 500 cc. By contrast Homo erectus was equivalent in body size to modern man in every respect except cranial size. The cranial size of H. erectus was 1100 cc twice that of the australopiths. Modern man’s cranial size ranges between 1200 and 1400cc.
In fact, there are no differences below the neck between modern man and Homo erectus. Here is a picture of me standing in front of one of the most famous Homo erectus skeletons in the world, the Nariokotome Boy.
He was found in 1984 by Richard Leaky in Nariokotome, Kenya. The boy is presumed to have been about 10 years old and lived 1.6 million years ago. Except for the skull the boy looks very much like a modern human and it is believed he would have grown to be 6’1” tall (1.86m). Coincidentally I am 6’1” tall so we would have been the same height.
The Nariokotome Boy is in the Field Museum in Chicago. Right next to him is the most famous Australopith in the world, Lucy. Lucy was an Australopithecus afarensis from 3.2 million years ago. Here I am with Lucy. Quite a bit of difference in size as you can see.
The point I want to make here is that since Homo erectus the only significant evolutionary changes in man that have taken place are from the neck up. The change from an australopith to H. erectus was very big, I would even say huge.
It seems clear as clear can be that the genetic blueprint for the human legacy has been basically the same for over 2 million years except for the genes that control the cranium and the brain that fills it. Same genes but they have changed through time by the process of mutation to create larger and larger cranial capacity.
Even though there were some superficial differences in the body between modern man and Homo erectus if a Homo erectus were to dress in modern clothes and walk down the street it would not turn heads. People would not gawk or stare, at best some might think, hey, that guy has a small head, but that’s about it. People would not freak out and be alarmed at the site at all.
The next bump up from Homo erectus on the way to modern man is Homo heidelbergensis (antecessor) or Heidelberg Man (1.2 million years ago). Again, exactly the same morphology below the neck but above the shoulders the cranium on average for Heidelberg Man increases to 1250 cc (well within the range of modern man). So, it seems that being bipedal was a hit and having dexterous hands was a hit and a larger brain was a really big plus. So, what did the larger brain bring to the table that increased the survivability for hominins.
I think the biggest factor of having more cognitive capacity, starting with Homo erectus, was the ability to innovate and create a generalized tool industry and attain a consciousness that had a level of awareness enabling the species to transcend environment.
What do I mean by that? Most anthropologists would agree that the overwhelming success of humans had in taking over the world lies in their ability to adapt to all environments. Consider what we talked about with natural selection. The genetic mutations that manifest in changes helping survivability in an organism’s environment are the mutations that take hold and get passed along.
A titanic leap over that would be a genetic change that allows not only a higher rate of survival in the organism’s environment but a change that would help an organism survive in All environments.
I love watching the nature shows on television, they give us the chance to see the incredible variety of life across the planet. It is absolutely amazing to see the how many different types of birds, mammals, insect and other types of animals there are and how each species has evolved in their own environment and how that has shaped them. It does drive home the point however that the variety you see was in response to the individual species environment. Not all birds look the same because not all birds evolved to thrive and survive in the same environment or occupy the same niche in a given environment.
Tools made by Homo erectus found in China dated to 2.1 million years ago.
Starting with Homo erectus, man has evolved to thrive and survive in all environments. There is no definitive date on the age of H. erectus but a transitional jaw between the australopiths and H. erectus was found in Africa and dated to 2.8 million years ago. H. erectus lived in Africa, Europe, Eurasia, Asia and Southeast Asia and most probably Indonesia. There is conclusive evidence of H. erectus in China 2.1 million years ago. He was the original traveling man for sure, living in a wide variety of environmental conditions for over 2 million years (surviving several ice ages) up until 70,000 years ago.
Being bipedal, having dexterous hands along with rudimentary language was crucial but it was the cognitive reasoning that enabled him to think outside the box as it were, to transcend and adapt from any one specific environment to figure out how to survive in all environments.
This cognitive prowess was further enhanced with Heidelberg Man, appearing around 1.2 million years ago. And now we come to Neanderthals and Homo sapiens. The picture of the path to modern man is clear. Homo erectus birthed Heidelberg Man who birthed Neanderthals, Denisovans and Homo sapiens. Not only that but each of those later three species appeared at about the same time.
We know for a fact the Neanderthals and H. sapiens evolved with slightly larger brain sizes than Heidelberg Man, in fact Neanderthals had on average a larger brain size than H. sapiens. We have no skull fragment large enough of the Denisovan so we don’t know but we can guess they also shared a similar brain size. The reason we can guess that is DNA from Denisovans is in the human population of the Asian countries to even a greater degree than Neanderthal DNA is. It stands to reason that if humans were interbreeding with them, they pretty much looked and behaved like us just as the Neanderthals did.
Study of Neanderthal teeth
Within the last month a study of Neanderthal teeth has been widely circulated. This study suggests that the split between Neanderthal and H. sapiens could have started 800,000 years ago. Once again pushing the timeline back for both species. I am not saying that H. sapiens was birthed 800,000 years ago but the divergence between them and Neanderthals could have begun during that time frame. As we discussed you just don’t get a new species in one generation. It takes time, thousands of years at a minimum during which there are transitional species.
You can look at as a kind of stair stepping in which some changes are larger than others and some changes come quicker and some longer but as in the graphic above, species A does make it to species B at some point when the changes from species A are large enough to warrant a new species designation.
The Boule Curse
Let me just stop right here and say that there was a major, major disservice done to Neanderthals over a hundred years ago that still reverberates today. Even with the re-examination of Neanderthal remains and new fossil discoveries, including the mapping of DNA, Neanderthals have not been given their proper due. However, I am glad to say that finds just in the last couple of years and analysis of previous finds are completely turning the opinion of Neanderthals around.
misguided Neanderthal image
The mischaracterization of Neanderthals began with the nearly complete skeletal remains discovered in 1908 in southwestern France. A French paleontologist, Marcellin Boule, analyzed the fossil bones. He described the Neanderthal as an ape-like creature that walked hunched over with a shuffling gait. He also surmised they were of dull wit and brutish. He went so far as to say The shape of the skull indicated “the predominance of functions of a purely vegetative or bestial kind".
Unfortunately, Boule's mistaken analysis was accepted by paleoanthropologists for decades. It became the source for the common man's perception of the 'caveman'. This acceptance of the unfortunate diagnosis of the skeletal remains lingered up until relatively recently. It wasn’t’ until 1957 that a new look at Neanderthals began to take place. It is still hard for many Anthropologists to approach Neanderthals with an open mind and accept what we now know.
In reality the hunched over posture of the individual Boule studied was from severe arthritis in the spine that he suffered from. He also had other deforming infirmities such as rickets, which gave him bowing of the legs and a distorted face due to loss of teeth and part of his jaw. All of which Boule did not understand.
The Enlightened Neanderthal
120,000 year old shells, painted and pierced by Neanderthals
In the past year new findings from Spanish caves have prompted Dirk Hoffmann from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany to say “Symbolic thought seems to have been present among our distant cousins, too. This makes it possible that the roots of symbolic material culture may be found among the common ancestor (Homo heidelbergensis) of Neanderthals and modern humans, more than half-a-million years ago.”
Further study of paintings in the caves and other artifacts like shell jewelry made by Neanderthals are dating back to as old as 200,000 years ago. “The emergence of symbolic material culture represents a fundamental threshold in the evolution of humankind—it is one of the main pillars of what makes us human,”
furthermore Hoffmann concludes, “…leaves no doubt that Neanderthals shared symbolic thinking with early modern humans and that, as far as we can infer from material culture, Neanderthals and early modern humans were cognitively indistinguishable.”
A far cry from the brutish caveman of Boule.
Let’s take a look at the most recent findings about Neanderthals that are setting the view of them upside down and creating a consensus of opinion about their almost identical similarity with H. sapiens of the same era.
- Neanderthals made cave art
- wore and traded jewelry They put value in it
- used plantsas medicine
- They weren’t actually shorter, for instance, the Neanderthal gene variation associated with height influences only about 0.1 inch.
- They weren’t more or less hairy
- had bigger brains than sapiens
- had a greater lung capacity
- skilled toolmakers
- big-game hunters
- lived in large social groups
- built shelters
- wore clothing
- ate plants and cooked them
- made sticky pitch to secure their spear points by heating birch bark
- had a complex language
- care with which they buried their dead indicates some form of spirituality
- Red hair wasn't inherited from Neanderthals at all. It now turns out they didn't even carry the gene for it!
- Neanderthals differed in their hair and skin tones, much as people now do
- The blue eye gene appeared within the past 10,000 years in the general vicinity of the northern shores of the Black Sea, Neanderthals had died out long before that.
Many in the field of Paleoanthropology would classify Neanderthals as Homo sapiens neanderthalensis, a sub-species of Homo sapiens. Modern man would then be classified as Homo sapiens sapiens. And by the way Denisovans would be Homo sapiens denisovans.
The Hook Up
So, one day down by the river John, a H. sapiens male, meets Jennifer, a Neanderthal female. They fall in love and get married. Nine months later a daughter is born. She has 50% of her chromosomes, (her genetic code, her DNA) from her mother and 50% from her father.
Now as we have just seen the 23 chromosomes in each of her cells from the mother forms a pair with the corresponding 23 chromosomes from the father. The couple was able to produce a perfectly viable offspring.
The genes along the length of every chromosome in the gamete from Jennifer where aligned perfectly with the genes along the length of the corresponding chromosome in the gamete from John and they were able produce a zygote. No extra genes from either one were involved and no lack of genes from either one where a factor. Gene to Gene match up was accomplished even though the genes involved in matching up had different alleles and therefore represented different characteristics (like hair and skin color) they were still similar enough to be able to reproduce healthy offspring.
Wait, hold on dude, you might be thinking, if they are that similar why are they different species in the first place? I am not saying they are a different species; I am saying they are at best a sub-species and maybe not even that. Maybe they are just a divergent line from the same species.
Skull Throw Down
Let’s consider skull shape. The shape of the skull between Neanderthal and H. sapiens is one of the most distinguishing morphological differences they have. Neanderthals have an elongated skull compared to sapiens. You can also see from the next picture that the Neanderthal is slightly larger.
There are genes that regulate the size and shape of the skull. Neanderthals did not have a separate ‘long skull gene’ that H. sapiens lacked and H. sapiens did not have a ‘more rounded skull gene’ that Neanderthals lacked. They both shared the same genes that governed the skull shape but as we have seen there are variations in the genes called alleles that produce different characteristics like the shape of a skull. (On top of that the non-coding DNA is involved in the formation of genetic characteristics in ways we don’t mostly understand yet.)
Let’s take a look at some other skulls. This next picture is of three Homo heidelbergensis skulls. You can clearly see they are elongated and more similar to Neanderthal’s skull than a modern man’s skull.
Homo heidelbergensis birthed both Neanderthals and Homo sapiens. They both inherited the same exact genes but evolved variations in morphology followed from causes we have already discussed. So, looking at the previous picture of the Neanderthal skull vs modern man’s you might think that H. sapiens is quite a bit different. But let’s take a look at another picture.
The picture above is of an archaic H. sapiens dated to approximately 350,000 years ago. Notice the elongated skull and the heavier brow ridge too. This doesn’t look much different from Heidelberg Man or Neanderthal. It was after this time period (probably long after) that changes took place in the shape of the skull for modern man.
I am pointing this out because 350,000 years ago the morphological differences between Neanderthals and H. sapiens where not as pronounced as they seem to be when you look at them through the lens of seeing modern man compared to a Neanderthal. They were much closer and the differences could just have been based on regional variations instead of a full-blown species separation.
Even after the skull of Homo sapiens became more rounded it is not that Neanderthals and Modern Man actually looked all that different in the first place. In the following two photos experts using fossil skulls reconstructed what Neanderthals would look like cleaned up and in modern attire.
Forget About It
Any information about the timelines for Neanderthals and Homo sapiens you’ve read that comes from a source before 2018 is not going to be up to date. There have been too many new discoveries and analysis from data that has given us a new updated timeline for Homo sapiens.
Here is the updated timeline I would like you to consider regardless of what you have previously read about.
1.2 million years ago Homo heidelbergensis lived in Europe and Africa. There are now signs that as early as 800,000 years ago a new species began to develop as an offshoot of H. heidelbergensis, this was the very beginnings of Neanderthals.
At basically the same time two other closely related groups began to develop also, the Denisovans and Homo sapiens. Neanderthals developed mostly in Europe. The Denisovans in Europe, Siberia and Asia. Homo sapiens in Africa and Eurasia. One thing that has become exceedingly apparent but is still antithetical to mainstream Anthropology is how much these divergent groups interacted and interbred with each other right from the beginning.
For the longest time there was what seems now like a quaint notion that Homo sapiens left Africa about 60,000 years ago and took over the remaining world. Balderdash. Since the very beginning of the genus Homo, genus Homo traveled all over the Old World. Homo erectus tool kits have been found in China 2.1 million years ago. A Homo sapiens skull has been discovered in China reliably dated to 250,000 years ago. Tools that are the exact same as modern man’s were found in India dated to 385,000 years ago. Other circumstantial evidence has Homo sapiens in Eurasia as early as 500,000 years ago.
There never was an ‘Out of Africa’ movement as such. From Homo erectus on there was a continual flow of hominins moving all over the place. Pockets of hominins branching off from Homo heidelbergensis developed regional variations that would eventually become sub-species from each other. However, it’s clear they all interacted and interbred right up to the time when Homo sapiens became the last hominin standing.
In reality it was a very fluid situation as far as movement of populations go. I do think that predominately the Neanderthals developed in Europe and predominately Homo sapiens developed in Africa and Denisovans in Siberia and Asia. But they constantly interacted and bred together right from the beginning.
Homo sapiens did not hold up in Africa for hundreds of thousands of years and then make a jail break for Europe. You have this image of some guy standing in front of this huge horde pinwheeling his arm yelling, “Forward, forward, let’s go! Let’s go!” Then the masses start running, women and children and all the stuff they had in storage for a couple hundred thousand years.
Look at those skull pictures again. Neanderthal and Homo sapiens had basically the same shape and presumably so did Denisovans. At some point in time the more rounded skull developed for Homo sapiens. I believe this was also accompanied by a big change in the wiring of the brain and cognitive abilities. I think it was in conjunction with changes that produced an expanded consciousness.
I am suggesting the time frame for this around 200,000 years ago or less. This expansion in consciousness is what eventually led to Homo sapiens assimilating the other two sub-species - Neanderthals and Denisovans and out competing the remaining Homo erectus and Homo heidelbergensis populations.
This particular cognitive mutation could very well have developed in the African H. sapiens population or in some H. sapiens group somewhere else. In the long run it doesn’t matter in which specific geographical area it first took hold in because of the mobility and wide-ranging interactions across the old world. What matters is this change was a huge advantage for survival.
It ordinarily takes a certain amount of time for these changes to propagate and take hold within a population. However, at a given point in time a series of mutated changes can coalesce into quite a big change in a relatively short period of time as they play into each other.
This is what happened with H. sapiens, they went through a series of genetic mutations that resulted in an expansion of consciousness. This expansion of consciousness gave them a superior survival advantage over all the other hominins living at the time which resulted in the beginning of the tipping point for their demise. Those hominins who were not assimilated, lost out in the competition for the harvesting of environment resources in any given area.
Once Homo erectus established itself as a separate species, somewhere along the timeline of 2.5 to 2.2 million years ago, all hominins that followed inherited the same Genome. Same DNA, same genes. The reason they look different is because of the genetic variation caused by mutation of alleles.
Mutations are DNA copying errors. When they happen in the egg or in the sperm, they are the source of new alleles that are passed to offspring.
Advances in hominin culture is the result of mutations that affected cognitive ability. Except for some morphological differences above the shoulders, Neanderthals and early Homo sapiens were the same in appearance and behavior, allowing for regional variations. And as previously stated Neanderthals and early Homo sapiens were cognitively indistinguishable.
At some point in time, and I am suggesting about 200,000 years ago or less, hereditary mutations of those genes controlling skull shape and cognitive ability in Homo sapiens resulted in a rewiring of the brain and an expansion of consciousness ushering in what we now call modern man. In the rise to modernity Homo sapiens became the last hominin standing.
I think there is one other aspect to the story that we could talk about. Of all the populations in the world indigenous Sub-Saharan Africans have no Neanderthal alleles because their ancestors did not migrate through Eurasia. However, they still have the same genes and DNA.
I hope you will take the time to read a couple of related posts that are very interesting and also supplemental to this one.
We talked a lot about regional variation and this post is very enlightening because it has dozens of contemporary photographs of modern man showing what a wide variety of appearances there are across the world. You will really want to take a look at this post… https://thestudyofman.com/blogs/blog/the-many-faces-of-man
This post is also very interesting because it explores how Neanderthals would look in modern attire… https://thestudyofman.com/blogs/blog/what-neanderthals-really-looked-like-or-hey-good-looking