Around 2005, several mass publications expressed provocative statements. The journal Newsweek said, “Recent studies have shown that women and men are genetically distinguished as humans and chimpanzees.” A New York Times reporter argued that women and men should be considered as different species (cited in KUTSCHERA 2018: 220-221). KUTSCHERA (2018) agrees with this when he writes that men are 99.9% equal to each other, whereas men and women are only 98.5%. This difference of 1.5% between man and woman corresponds to that between man and chimpanzee (KUTSCHERA 2018: pp. 224 – 225, see also Fig. 1). He wants to “verify” the “fundamental difference” between men and women, which also shows up genetically in every cell. The problem with this statement, however, is that it is heavily distorted by KUTSCHERA (2018). Because his comparison man / woman and human / chimpanzee is a comparison between apples and pears (or in other words: between the genes of two individuals of a species and the total DNA between two species).
Fig. 1: Kutschera’s comparison between man and woman as well as between human and chimpanzee. Unfortunately, not much true. Source: KUTSCHERA (2018: 222)
Excursus DNA
DNA is often referred to as the “Book of Life”, with all the important information written to build an organism. This is undoubtedly an exaggeration of the role of this molecule, but that should not be an issue here. Every living thing, every living cell has DNA (see Fig. 2). It contains the information for the sequence of amino acids, the basic building blocks of proteins. The basic building blocks of DNA are so-called nucleotides, each of which has a nitrogen-containing nucleobase. There are four such bases: adenine (A), thymine (T), guanine (G) and cytosine (C). The DNA is present as a double helix. Two single-stranded DNA molecules are connected to each other by hydrogen bonding. The adenine of one strand always connects with a thymine of the other, and a cytosine always connects with the guanine of the other strand. Adenine and thymine, as well as guanine and cytosine are complementary to each other. The sequence of nucleotides (base sequence) stores the information for the amino acid frequency that is “read” from the messenger RNA. The RNA, like the DNA, is a nucleic acid in which thymine (T) is replaced by uracil (U). Three nucleotides always give the code for one amino acid (the nucleotide sequence of the messenger RNA is called the genetic code). Another type of RNA, the transfer RNA (tRNA), each has one amino acid in tow, attaches to the messenger RNA.
Fig. 2: Structure of the DNA.
The haploid DNA strand of a human has about 3 billion base pairs. In a 2012 study, the genome of 1092 humans were sequenced and compared. The people came from all over the world and both sexes. Although there are marked differences between individuals in the human genome, we are 99.9% alike and 0.1% different. (The 1000 Genomes Project Consortium 2012). A later study revealed a slightly larger genetic difference of 0.6% of all base pairs. This greater difference is due to the addition of “structural” variations. These include deletions (i.e., losses) of individual DNA segments, as well as insertions (inserting individual DNA segments) (The 1000 Genomes Project Consortium 2015). In total, over 324 million individual variations have been discovered. Of course, this high number comes from the fact that not every person carries all these variations.
But now comes the whole point: even if our DNA has 3 billion base pairs and is therefore very large (just for comparison: The Bible, which is certainly not a thin book, has about 4.4 million characters – including blanks and punctuation marks – this equals 0.14% of base pairs of one DNA stand), only a fraction of it is composed of genes. In humans, there are about 20,000 genes that can be read as proteins (EZKURIDA et al., 2014). That’s about 1.5% of human DNA (or 45 million base pairs, which is still 10 times as much as the Bible). The remainder of the DNA consists of non-coding DNA, also called junk DNA. But the term junk is misleading, because here are also many sequences that have a meaning for gene regulation. Many of the non-coding sequences also consist of repetitive units (so-called repetitive DNA) (International Human Genome Sequencing Consortium 2001). For those, who want to get an overview of the exact distribution of genes, can read this homepage.
Human-Chimp comparison
KUTSCHERA’S (2018) assertion that the genetic difference between man and chimpanzee is 1.6% is correct, but not complete, or outdated. He cites the study by WILDMAN et al. (2003). However, they compared human and chimpanzee DNA (with orangutan, gorilla, Old World monkey, and mouse comparison sequences) to only 97 genes. That is, not the entire genome was sequenced, only a fragment. While this fragment may be important and perhaps representative, it is by no means complete (while Kutschera compares all genes of man and woman in humans). But Kutschera does not mention this tiny but important fact in his work. WILDMAN et al. (2003) found that there was a 99.4% agreement for synonymous regions. These are so-called silent mutations, in which although a nucleotide is exchanged (base substitutions), the same amino acid is produced. The genetic code is redundant: there are 20 amino acids needed for our proteins. Since each amino acid is encoded by 3 nucleotides, there are 64 possible combinations with 4 different bases (A, T, C, G) (4 * 4 * 4 = 43 = 64). For example, a mutation in which one base is replaced by another may have no effect on the sequence of amino acids. For non-synonymous sequences, that is, there were changes in amino acid sequence, WILDMAN et al. (2003) found a 98.4% agreement. Because of these similarities, WILDMAN et al. (2003), by the way, suggest the hypothesis that humans and chimpanzees should be included in the same genus (chimpanzees and bonobos belong to the scientific genus Pan, people to the genus Homo). Interestingly enough, Kutschera does not tell us that, since he wants to prove that man and woman are genetically separate from each other like two different species. It does not fit into the picture that the authors he uses for his point of view state the huge similarities of humans and chimps as a whole (the do not consider humans and chimpanzees as the same species, but rather want to move into the same genus).
If one considers the whole genome of chimpanzees, the differences are already significantly larger. In 2005, the Chimpanzee Sequencing and Analysis Consortium published the genome of chimpanzees. A comparison of 2.4 billion base pairs revealed a 1.23% difference between humans and chimpanzees (The Chimpanzee Sequencing and Analysis Consortium 2005). However, this only takes into account the base substitutions. Structural changes such as deletions and insertions are not taken into account. If you add these structural changes, you get a difference of 3-4% (VARKI & ALTHEIDE 2005). In addition, there are processes such as duplications of genes, which play an important role in the evolution of new genes. Thus, DEMUTH et al. 2006 found that of the 22,000 genes in humans and chimpanzees, 1418 differ from each other. That makes a difference of about 6% (and thus larger than the difference between men and women claimed by Kutschera). Since the ancestor of man and chimpanzee separated 5-6 million years ago, we have according to DEMUTH et al. (2006) received 689 new genes (mostly by duplications) and lost 86.
Much more important than what and how many genes one owns is of course how, when and where they are used and what functions they occupy in the system of the developing organism. This will not be explained here. But, for example, a research group (OLDHAM et al., 2006) had studied 4000 genes in humans and chimpanzees that are simultaneously turned on in the brain. From this, gene networks were created for the species. A number of these networks, 17.4%, were found only in humans and not in chimpanzees (see also COHEN 2007).
Mind you: The greater genetic difference between humans and chimpanzees (4% differences in total DNA) changes, unlike some creationists claim, nothing in the close relationship between humans and chimpanzees!
DNA difference between men and women
But how does KUTSCHERA come up with the calculated 1.5% difference between a man and a woman? He cites a study by CARREL & WILLARD (2005) which shows that the genes of the second X chromosome are not completely silenced in women (we reported on X inactivation in part three). 15% – 25% of the X-chromosome genes escape this inactivation, which corresponds to about 200-300 genes. This has the consequence that in women individual genes are expressed twofold. Since in men the second X chromosome is missing, they are expressed only onefold. However, CARREL & WILLARD (2005) do not mention the man-woman = man-chimpanzee distinction postulated by KUTSCHERA (2018). But let us now take KUTSCHERA’s account: There are (depending on the literature) 19-22,000 genes in the human body and 200-300 genes on the X chromosome are different between men and women. However, they do not really differ, because even men have these genes on the X chromosome, the difference is that they are duplicated in women (for comparison, if I have an apple and the woman has two apples, she now has more apples than me, but no pears!). Of course, there are different versions of genes (called alleles) that can be different for each individual. But these 300 genes are not qualitatively completely new genes that do not occur in men, just different versions of existing ones. Only gene expression changes (that is, the amount that is produced) because women have more of this same gene. But anyway, for the sake of argument, we leave these 200-300 genes as completely new and not existing in the male genome. If we now add the genes on the Y chromosome (according to KUTSCHERA 2018 50), we come to a gene difference of 350 genes between men and women. That would be, based on 20,000 genes, a difference of 1.25% (250 genes) – 1.75% (350 genes) between the sexes. Above we have noted, based on the study of DEMUTH et al. 2006, that humans and chimpanzees differ in 1418 genes (I do not want to postulate completeness), that would be a difference of 7% for 20,000 genes (DEMUTH et al., 2006 assume 22,000 genes, giving a difference of 6.5%). We have 689 genes that the chimpanzees definitely do not have. Thus, the difference between man and chimpanzee is definitely greater than between man and woman, even under the postulate that the 300 non-inactivated genes of the second X chromosome of women are completely different genes than the men.
Based on total DNA, the difference between a man and a woman is reduced even more. Above, we found that a comparison of the existing DNA strands in humans and chimpanzees is 1.23%, adding the deletions (missing pieces of DNA), insertions (added pieces of DNA) and gene duplications, we have a difference of 3-4%.
In addition, we found that taking into account deletions and insertions, the difference between two distant people is 0.6%. If, for the sake of argumentation, we want to add the 1.5% gene difference between man and woman, we come to the following conclusion:
- Number of base pairs of human DNA: 3 billion (3,000,000,000)
- Number of genes: 20,000 = 1.5% of DNA = 1.5% of 3 billion base pairs = 45 million (45,000,000) base pairs encoding genes
- For the sake of simplicity, we assume that each gene is on average the same size (although unlikely, but much would not change in percentage anyway, if that were not the case): 45 million base pairs / 20,000 genes = 2250 base pairs per gene.
- 350 genes differ from man and woman = 350 genes * 2250 base pairs = 787,500 base pairs.
- 787,500 pairs of 45,000,000 base pairs (genes) = 1.75%
- 787,500 base pairs of 3,000,000,000 base pairs (total DNA) = 0.026%
- 026% + existing differences of 0.6% = 0.626%
However, another study discovered that 6500 genes are expressed differently between men and women. For example, gene expression in the genes that provide muscle formation is greater in men than in women. Other genes in the brain that also protect against Parkinson’s disease are more expressed in women than in men, whereby the latter have an increased risk of developing this disease.
However, it is naïve to say that all of these genes have the same influence on sex development. In addition, as the study by OLDHAM et al. (2006) found that most of these genes are also active in the brain – and we know that at least one third of all genes are active in the brain. But since our brain is not a “closed” system, but interacts with our environment and many genes are just epigenetically controlled, this difference of the differentiated gene expression of the sexes is relativized (why one should not conclude that they do not play a role). I refer here to the book by Jörg BLECH (2010): “Gene sind kein Schicksal (Genes are no destiny)”.
Incidentally, not all genes of the Y chromosome are “male-specific”.
On the Y chromosome there are only 45 genes left, all others were lost. Of these, 24 genes are also found in the X chromosome. However, not all of these 45 genes are still active, many are shut down and do not code for any proteins. Overall, the Y chromosome has only 27 genes encoding proteins, 17 of which are also found on the X chromosome, of which 14 also perform the same function on the X chromosome! Consequently, only 13 genes on the Y chromosome are really specific only to males. source
But even the difference in gene expression does not significantly increase the difference between men and women, especially since we have to assume that gene expression is also greater in chimpanzees and humans than between men and women (which, among other things, the study of the activity of the Genes in the brain has proved by OLDHAM et al. (2006)). The site iflscience.com quotes geneticist Jenny Graves, a respected professor of genetics at La Trobe University in Melbourne, Australia:
“But this often-quoted difference [between humans and chimps – internet-evoluzzer] is an average over the whole genome, only a minority of which consists of genes that code for proteins. It tells us little about which genetic differences are important.
Many obvious differences between humans and chimps, such as hairiness and perhaps even speech, may result from tiny alterations in one or a few genes. Differences in timing, or minor regulatory differences, may have massive effects on growth and development.
It’s naive to pretend there are no profound genetic and epigenetic differences between the sexes. But we’re not going to settle issues of how far-reaching the biological differences are just by counting gene differences. How these genes are regulated and their downstream effects are what make the difference between men and chimps, or men and women.” Source
It is questionable why Kutschera, a professor of biology, does not take these facts into account in his book, which claims to be backed by well-founded scientific sources.
Kutschera has given an interview with the fascist AfD politician Beatrix von Storch, who is known for witty pseudoscientific statements, e.g. that the sun should be shining less for climate change to stop. In an interview, at minute 8, Kutschera explains in his “special” way that total gender equality is only possible with the hermaphrodite earthworms, as both act as males and females in mating, but gender equality in this way is not possible in humans. Setting up social demands on account of such contributions seems almost absurd and would be ripe for a parody by Monty Python. Getting a picture with a fascist person like Beatrix von Storch is at least embarrassing.
In July 2017, Kutschera argued at kath.net against the “marriage for all” and feared in an interview that because of the adoption rights for gays and lesbians “state-sponsored pedophilia and child abuse” would come to Germany. The interviews can be found here and here.
Let’s summarize: The “dedicated” evolutionary biologist and super-professor Kutschera, this pioneer against creationism and German wannabe Richard Dawkins, pacts with the Catholic Church (which is a bunch of pedophiles themselves) for fear that a same-sex couple asking who will make the sandwich for them should educate children. I do not want to question his biologist’s competences, but to abuse his politicization of biology for dubious purposes is to be condemned.
Kutschera cannot be concerned with biological truths, but with political propaganda when making a pact with reactionary associations like the AfD and the Catholic Church. But he abuses his “biological knowledge”, although he wants to be in his book “politically neutral” (of course, his anticommunist conspiracy theories apart). Consequently, his book is to be evaluated, there is not much science there, as shown by his chimpanzee-man comparison.
Literature
BLECH, J. (2010): Gene sind kein Schicksal. Fischer Verlag
CARREL, L. & WILLARD, H. F. (2005): X-inactiviation profile reveals extensive variability in X-linked gene expression in females. Nature 434, 400-404. https://www.ncbi.nlm.nih.gov/pubmed/15772666
COHEN J (2007) Relative differences: the myth of 1 %. Science 316, 1836. http://academic.brooklyn.cuny.edu/biology/franz/biology38/_files/1836.pdf
DEMUTH JP, BIE TD, STAJICHt JE, CHRISTIANINI, N & HAHN MW (2006) Evolution of mammalian gene families. PLoS ONE 1(1) https://www.ncbi.nlm.nih.gov/pubmed/17183716
EZKURIDA et al. 2014: Multiple evidence strands suggest that there may be as few as 19 000 human protein-coding genes Hum Mol Genet. 2014 Nov 15; 23(22): 5866–5878. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4204768/
Iflscience.com: Differences Between Men And Women Are More Than The Sum Of Their Genes https://www.iflscience.com/health-and-medicine/differences-between-men-and-women-are-more-sum-their-gene/
International Human Genome Sequencing Consortium (Feb 2001). “Initial sequencing and analysis of the human genome“. Nature. 409 (6822): 860–921.https://www.ncbi.nlm.nih.gov/pubmed/11237011
KUTSCHERA, U. (2018): Das Gender-Paradoxon – Mann und Frau als evolvierte Menschentypen. LIT-Verlag
OLDHAM MC, HORWAT S & GESCHWIND DH (2006): Conservation and evolution of gene coexpression networks inhuman and chimpanzee brains. Proc. Natl. Acad. Sci. USA 103, 17973-17978. https://www.ncbi.nlm.nih.gov/pubmed/17101986
The 1000 Genomes Project Consortium (2012): An integrated map of genetic variation from 1,092 human genomes Nature. 2012 Nov 1; 491(7422): 56–65. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498066/#SD1
The 1000 Genomes Project Consortium (2015): A global reference for human genetic variation Nature. 2015 Oct 1; 526(7571): 68–74. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/
The Chimpanzee Sequencing and Analysis Consortium (2005): Initial sequence of the chimpanzee genome and comparison with the human genome. Nature 437, 69-87. https://www.nature.com/articles/nature04072
VARKI, A. & ALTHEIDE, T. K. (2005): Comparing the human and chimpanzee genomes: Searching for needles in a haystack Genome Res. 2005. 15: 1746-1758 https://genome.cshlp.org/content/15/12/1746.full
WILDMAN, D. E., UDDIN, M., LIN, G., GROSSMANN, L. I., GOODMAN, M. (2003): Implications of Natural Selection on shaping 99,4% nonsynonymus DNA identity between humans and chimpanzees: Enlarging the genus Homo Proc. Natl. Acad. Sci. USA 100, 7181-188 https://www.pnas.org/content/100/12/7181
