December 8, 2022 | Jerry Bergman

Why Sex Is Binary

The new Woke claim that “Human Sex is Not Binary”
ignores a massive amount of scientific literature


by Jerry Bergman, PhD

“So God created man in his own image, in the image of God created he him;
male and female created he them (Genesis 1:27).
“Jesus said, … from the beginning of creation, ‘God made them male and female.’” (Mark 10:5-7)

Christian, Muslim, and Jewish faiths all accept the Scriptures in Genesis 1:26 which teach that the pinnacle of God’s creation—mankind—was called forth into existence by Him. Humans were created separately from the animals. We are also told that there is a separation of humans into two sexes—male and female—wholly complementary, yet each sex uniquely bearing God’s image—the imago Dei. Humans bear the image and likeness of God as male and female.[1]

The New View: Human Sex is Not Binary

Professor Agustín Fuentes is a primatologist and biological anthropologist teaching at Princeton University. He was formerly the chair of the Department of Anthropology at the University of Notre Dame. Fuentes is not a believing Catholic (and I have no idea why Notre Dame would hire him) or a conservative Christian, but rather he is a woke liberal who opposes the idea that human sex is binary (i. e., only two sexes exist, male and female). He wrote:

At the recent U. S. Supreme Court confirmation hearings for Ketanji Brown Jackson, Sen. Marsha Blackburn triggered controversy when she asked Jackson to define the word “woman.” After Jackson declined, several Republican congress people chimed in with definitions for “woman” that ranged from dubious to shocking, including “the weaker sex,” “someone who has a uterus,” and “X chromosomes.”[2]

Although an evolutionist, Professor Fuentes writes that these binary sex

notions haven’t evolved much since 1871, when naturalist Charles Darwin told the world that “man is more courageous, pugnacious, and energetic than women, and has more inventive genius.” Most 19th- and 20th-century evolutionary theories (and theorists) asserted that evolution created two kinds of creatures—male and female—and individuals’ behavior and nature reflected this biological binary.[3]

He believed that dividing humans into two sexes is wrong because

the commitment to a simple binary view creates a fictitious template for a “battle of the sexes” that manifests in mis-education about basic biology, the denigration of women’s rights, the justifications of incel [men who are unable to attract women sexually] and “men’s rights” violence, and the creation of anti-transgender laws.[4]

Since he believes that humans are animals that evolved from some ape ancestor, he used animals to argue against the binary view of humans, writing:

When one looks closer at the biology of sex in animals, including humans, it is clear that Darwin, biologist E. O. Wilson, geneticist Angus Bateman, and various Republican politicians are minimally way off base and mostly flat out wrong.… Biologically, there is no simple dichotomy between female and male. As I demonstrate in my book Race, Monogamy, and Other Lies They Told You, brains are no more “sexed” at birth than are kidneys and livers…. When it comes to raising kids, humans don’t come in two kinds. Rather, we evolved to be a collaborative and creative community.[5]

Since humans are animals, he implies it is normal to behave like animals, including rejection of monogamy, thus practicing promiscuity as is common among animals. Professor Fuentes focuses on animals with whom humanity shares close relations, such as chimpanzees. He concludes that growing up human means growing up in a world of varying gender expectations, body types, reproductive options, family structures, and sexual orientations. According to Professor Fuentes,

instead of listening to people who are misogynistic, sexist, or homo/transphobic today; or politicians who base their ideologies on a biological sex binary and myths about its evolution, … [the fact is] we can and should be open to a serious understanding of biology and its better options for human flourishing. The simple male/female binary does not effectively express the normal range of being human. Understanding this and incorporating it into our education, lives, and laws offers better possibilities, greater equity, and more joy for human society.[6]

In his Editorial in Science, “The Descent of Man, 150 years on,” Professor Fuentes argued that Darwin “offers a racist and sexist view of humanity.”[7] Fuentes went on to claim that Darwin was a sexist of the worst kind.[8]

Fuentes adds that “Darwin thought he was relying on data, objectivity, and scientific thinking in describing human evolutionary outcomes. But for much of the book, he was not. ‘Descent’, like so many of the scientific tomes of Darwin’s day, offers a …  sexist view of humanity”. The problem was that The Descent of Man was “one of the most influential books in the history of human evolutionary science.”[9] One concern of Fuentes is that Darwin believed sex is binary, and he labels one who believes this as a sexist.

Attacking Darwin was sure to reap a pile of protests, which is exactly what has happened with Fuentes. Darwin said some very sexist things, but his belief in human binary sex was his belief that was most aggressively attacked by Fuentes.

Responding to Darwin’s Belief that Human Sex is Binary

Ulrich Kutschera, professor of biology in Freiburg, Germany, correctly observed that some of what Fuentes wrote is incorrect:

Fuentes argues that Darwin “offers a racist and sexist view of humanity” and  “there is no biological coherence to ‘male’ and ‘female’ brains, and “‘survival of the fittest’ does not accurately represent the dynamics of evolutionary processes.”[10]

Kutschera effectively responded to the false claim of Fuentes that “differences between male vs. female brains (and other biological features) are not based on convincing data.” To refute this claim Kutschera refers

to the “Organization for the Study of Sex Differences (OSSD)” This interdisciplinary society of experts in the area of “Sex & Gender-Research” publishes a journal titled “Biology of Sex Differences” (Vol. 1/2010; Vol. 12/2021). On the Internet-page of this peer-reviewed periodical, hundreds of Online-articles can be down-loaded that corroborate what Darwin wrote 150 years ago: The fact that men and woman differ from each other in numerous biological and psychological features.[11]

Actually, not one single trait has been confirmed that is identical in males and females as the book covers reproduced below all illustrate:

A few of the many books that document the differences between human males and females.

MRI comparisons consistently document differences between the sexes.

Brain Differences

A recent study of 1,065 brains found differences between male and female brains were so profound that scientists predicted that the brain belonged to a man or woman with 93 percent accuracy.[12] Another evaluation of 949 brain scans found a stark difference in the architecture of the brain that documents a neural basis for why men excel at certain tasks and women at others. Men are better at learning and performing a single task (cycling or navigating); women were better at multi-tasking. Women are better than men on tasks related to attention, word, and facial memory. Men are better on spatial processing and sensory motor speed.[13] This research is evidence that male and female brains complement each other in life, work, and raising children.

Trait Differences

Other research determined that women’s pupils are nine percent larger than men’s, which gives rise to the saying that mothers, and female teachers, have “eyes in the back of their heads.”[14] Men have fewer rod visual cells and women have better color perception than men.[15] Men are 17 times more likely to be color blind (1-out of-12 men are color blind, compared to only 1 in every 200 women). Men have greater sensitivity for fine detail and rapidly moving objects because they have higher concentrations of androgen receptors in their visual cortex, resulting in 25 percent more neurons than females. Women have much better high-frequency hearing and listen by using both sides of their brain, whereas men are more likely to listen with only one side. Women have a better sense of smell because female brains have 50 percent more olfactory neurons. Women also have a better sense of taste due to more neurons in their brain taste center.[16]

Embryonic Differences

Research on 118 fetuses, between 26 and 40 weeks old, found significant differences between males and females in 7 of 16 functional connectivity networks.[17] These observations confirm the fact that sexual dimorphism in functional brain systems emerges very early during human gestation.

For years, only males were tested to determine the proper drug dosage of drugs, such as the sleep drug Ambien. It was then determined that a much higher level of women taking Ambien were too sleepy to drive safely in the morning after taking the drug. Research found that women metabolized the drug differently than males. Consequently, women obtained twice the proper dose. This over medication produced a rash of traffic accidents in women. A major reason for the difference is due to male and female hormone differences. Another example is that women have lower levels of alcohol dehydrogenase, (the enzyme that breaks down ethanol), thus alcohol has a stronger, earlier effect in women than in men.[18] Now all new drugs must be evaluated on both sexes to determine dosage.

Genetic Differences

X and Y chromosomes differ dramatically in size and content

Except for enucleated cells, every healthy normal human body cell is either male or female. Given 100 trillion cells, the average human has 200 trillion chromosomal differences compared to the opposite sex. The male Y chromosome contains 200 plus genes and the X chromosome contains over 12 times as many, or 974 genes. These 974 genes produce many major genetic differences between the sexes.

After a fertilized egg (zygote) is formed, thousands of other genetic differences are created by imprinting.[19] Imprinting is where certain genes are switched off in males and other genes are switched off in females.

Social Differences

One of the many results due to this difference is that females tend to choose careers that produce more personal rewards, even though the pay might be less. Males choose better-paying careers over those they prefer, because income is often for them a major career consideration. Research continues to find evidence of built-in male and female differences. This confirms the Biblical teaching that God created human males and females for different, but compatible, roles.[20]

As a whole, women make better neurosurgeons due to their superior fine-muscle coordination. Men make better diesel mechanics due to their superior gross-muscle coordination. Women lean toward careers focusing on people, such as teaching and healthcare. Males tend to work with things, and are oriented to the engineering, manufacturing, and agricultural professions. In spite of spending millions attempting to get women to earn degrees in welding and men to earn degrees in early child care, these efforts have failed.

Exceptions Prove the Rule

Conversely, some women make better diesel mechanics than most men, and some men, like Dr. Ben Carson, make better neurosurgeons than most women. This fact, though, does not make a woman diesel mechanic a man, nor Ben Carson a woman. Studies have consistently found that in every society, differences in how men and women organize their verbal and visual-spatial abilities exist, and some, but limited, cultural influence exists. Males and females display major biological differences from zygote to death.

Gender reassignment surgery treatment cannot change these many differences between the sexes. Male testosterone surges during puberty up to 40 times greater than in females. Males have a lifetime physical advantage of producing vastly greater muscle mass, bone density, more fast-twitch muscle fiber, larger hearts and lungs. Because most healthy women want to be different than males, they spend a billion dollars a year for cosmetics to look less male and more feminine.


How a well-educated, widely published Princeton University professor could ignore the vast literature that demolishes his major claim is baffling. His claims are refuted by both Scripture and science. It is obvious that he is attempting to support the newest academic fad, a far too common problem in academia today. The vast literature on the many major differences between males and females is very clear and well-documented.

A biological family is the basis of society. Both sexes are interdependent, but distinct. Children need both.


[1] Johnson, Jeff. 2015. Male and Female He Created Them: Genesis and God’s Design of Two Sexes. Focus on the Family.

[2] Fuentes, Agustin. Opinion: Biological Science Rejects The Sex Binary, And That’s Good For Humanity., 11 May 2022.

[3] Fuentes, 2022.

[4] Fuentes, 2022.

[5] Fuentes, 2022.

[6] Fuentes. 2022.

[7] Fuentes, Agustin. “The Descent of Man,” 150 years on. Science 372(6544):769, 2021.

[8] Fuentes, 2022.

[9] Fuentes, 2021.

[10] Kutschera, Ulrich. Science letters., 4 August 2021.

[11] Kutschera, 2021.

[12] Xin, Jiang, et al. Brain Differences Between Men and Women: Evidence From Deep Learning. Frontiers of Neuroscience (See section on brain imaging methods), 8 March 2019.; Anderson, Nathaniel,  et al. 2019. Machine Learning of Brain Gray Matter Differentiates Sex in a Large Forensic Sample. Human Brain Mapping 40(5):1496–1506, 1 April 2019.

[13] Ingalhalikar, Madhura. Sex Differences in the Structural Connectome of the Human Brain. PNAS (Proceedings of the Natural Academy of Sciences) 111(2):823-828, 2013.

[14] Rieger, Gerulf, and Ritch Savin-Williams. The Eyes Have It: Sex and Sexual Orientation Differences in Pupil Dilation Patterns. PLoS One 7(8):e40256., 2012.

[15] Females Distinguish Colors Better While Men Excel At Tracking Fast Moving Objects., 2012.

[16] Oliveira-Pinto, Ana V., et al. Sexual Dimorphism in the Human Olfactory Bulb: Females Have More Neurons and Glial Cells than Males. PLoS ONE 9 (11):e111733 DOI: 10.1371/journal.pone.0111733, 2014.

[17] Wheelock, M., et al. Sex differences in functional connectivity during fetal brain development. Developmental Cognitive Neuroscience. Volume 36., April 2019.

[18]Yoon, Seonghae, et al. Effect of CYP3A4 metabolism on sex differences in the pharmacokinetics and pharmacodynamics of zolpidem. Nature: Scientific Reports. |, 2021.

[19] Stump, J.B. What’s the Difference?: How Men and Women Compare. William Morrow, New York, New York, 1985.

[20] Bergman, Jerry. Male-Female Differences Supported by Scripture and Science. Acts and Facts 47(6), 2018.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,800 college libraries in 27 countries. So far over 80,000 copies of the 60 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

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