Human Origins

The Hybrid Hypothesis




Dr Chris Millar
Ballarat, Victoria, Australia

1: Human origins: Are we hybrids?

“Die Stimme der Vernunft ist leise.”
(“Reason speaks softly.”)
— Sigmund Freud

This section is a little different from others on this site, because it’s about the findings of my own research. I am a University of Georgia trained geneticist (M.S., Ph.D.) who worked in various genetics laboratories at the University of Georgia and conducted research there from 1989 to 2007 (see my Google+ profile). During those years I also taught biology and genetics at UGA.

Thanks! This is just a note to thank the innumerable visitors who have expressed interest in this theory. Your questions and comments are always welcome. Please just send in a message via the contact page.

My work focuses on hybrids and, particularly, the role of hybridization in the evolutionary process. Here, I report certain facts, which seem to indicate that human origins can be traced to hybridization, specifically to hybridization involving the chimpanzee (but not the kind of hybridization you might suppose!). You can access detailed and documented discussions supporting this claim from the table of contents. But I’ll summarize the basic reasoning here, without a lot of citations and footnotes (see below).

Rebuttals. The following rebuttals address the most common objections raised against the hybrid theory of human origins:

Rebuttal of Prothero's comments >>

Rebuttal of PZ Myers' comments >>

A comment from the website Skeptophilia:
“All I can say is that I'm beginning to get very, very tired of so-called “scientists” and their groupies thinking and talking like religious fanatics, and of existing “acceptable” scientific theories increasingly taking on the stained patina of dogma. McCarthy appears to have the credentials; why don't those who disagree with his “outlandish” conclusions answer him with scientific rigor, rather than ad hominem?”

Will a wild pig uproot the Tree of Life?
An article in the Los Angeles Review of Books, where longtime science journalist Greg Critser examines the hybrid theory of human origins.
Read more…

External links. If you wish, you can read news articles about the hybrid theory of human origins:

My theory of human origins: Rationale

— Karl Popper

So why do I think humans are hybrids? Well, first of all, I’ve had a different experience from most people. I’ve spent most of my life (the last thirty years) studying hybrids, particularly avian and mammalian hybrids. I’ve read thousands of reports describing them. And this experience has dispelled some mistaken ideas I once had about hybrids, notions that I think many other people continue to take for granted.


Read more about mules >>


An email from a physicist:

Dear Gene,

Thank you again, I've read your profound considerations with the greatest interest. I think nowadays the situation is worse than it used to be at Darwin’s age. The case of physics (cosmology and high energy physics, above all) is emblematic: big science, massive investments involving thousands of researchers, industrial operations essentially leading nowhere. New ideas cannot filter through, they would too badly damage ongoing business. Even people iconized in the first part of their life like Fred Hoyle, Dirac, Einstein have been in the latter part considered kind of nuts since they didn't abjure independent thinking to adore any ‘standard model’ idol, like present-day believers.

Your proposal in this environment is very courageous, and the huge and admirable work you carried out to supplement and document it vigorously goes in the direction of re-establishing sensible science in one of the most relevant subjects for human society.

The aim surely deserves the effort.


An email from a supporter: “Dear Dr. McCarthy, I admire your work as you described in your recent newsletter. I was surprised by the reaction of the chattering biologic community and was pleased by your calm reaction to it all. Now I know what Darwin went through. You have my support and if this old biologist/physician/urologist can help please let me know. I've directed all my bio friends to your site.”

Sequence data. And I must now emphasize a fact that I, as a geneticist, find somewhat disappointing: Though there are other ways of detecting them, with nucleotide sequence data, it can be very difficult to identify later-generation backcross hybrids derived from several repeated generations of backcrossing (and this would be especially true of any remote descendants of backcross hybrids produced in ancient times, which is what I'm proposing humans may actually be). To better understand why backcross hybrids are hard to analyze with sequence data, take a look at this diagram:

Genomic effects of repeated backcrossing:

Instead, as is the case with other later-generation backcross hybrids, the most revealing data is of an anatomical and/or physiological nature. And this is exactly the kind of hybrid that humans seem to be, that is, it appears that humans are the result of multiple generations of backcrossing to the chimpanzee.

The thing that makes backcross hybrids hard to analyze using genetic techniques is that, in terms of nucleotide sequences, they can differ very little from the parent to which backcrossing occurs. It’s important to realize, however, that a lack of such differences does not prevent them from differing anatomically. Sequence differences are not necessary for anatomical differences to be present. An obvious example of this phenomenon is Down’s syndrome. Individuals affected by Down’s regularly exhibit certain distinctive anatomical features, and yet in terms of their nucleotide sequences they do not differ in any way from other humans. To detect someone with Down’s syndrome, sequence data is completely useless. But with anatomical data, detecting affected individuals is easy. This issue is discussed in more detail in a subsequent section. The key fact is that with Down’s syndrome the differences that we see are due to differences in the number of genes present, that is, dosage differences, and not to differences in the nucleotide sequences of those genes. Dosage differences of this sort are exactly what hybridization typically produces.

Human infertility. Another observation that appears significant in connection with the theory of human origins here under consideration is that it has been well known for decades that human sperm is abnormal in comparison with that of the typical mammal. Human spermatozoa are not of one uniform type as in the vast majority of all other types of animals. Moreover, human sperm is not merely abnormal in appearance — a high percentage of human spermatozoa are actually dysfunctional. These and other facts demonstrate that human fertility is low in comparison with that of other mammals (for detailed documentation of this fact see the article Evidence of Human Infertility). Infertility and sperm abnormalities are characteristic of hybrids. So this finding suggests that it's reasonable to suppose, at least for the sake of argument, that human origins can be traced to a hybrid cross. It is also consistent with the idea that the hybridization in question was between two rather distinct and genetically incompatible types of animals, that is, it was a distant cross.

Methodology. The chimpanzee is plausible in the role of one of the parents that crossed to produce the human race because they are generally recognized as being closest to humans in terms of their genetics (here, I use the term chimpanzee loosely to refer to either the common chimpanzee or to the bonobo, also known as the pygmy chimpanzee; the specific roles of these two rather similar apes within the context of the theory of human origins now under consideration will be explained in a subsequent section). But then the question arises: If an ancient cross between the chimpanzee and some parental form “X” produced the first humans, then what was that parent? Does it still exist? What was it like?



So in the specific case of humans, if the two assumptions made thus far are correct (i.e., (1) that humans actually are hybrids, and (2) that the chimpanzee actually is one of our two parents), then a list of traits distinguishing human beings from chimpanzees should describe the other parent involved in the cross. And by applying this sort of methodology, I did in fact succeed in narrowing things down to a particular candidate. That is, I looked up every human distinction that I could find and, so long as it was cited by an expert (physical anthropologist, anatomist, etc), I put it on a list. And that list (see next page), which includes many traits, consistently describes a particular animal. Keep reading and I’ll explain.
Next page >>

— Richard Feynman

Human Origins - The Hybrid Hypothesis - ©