The primary male hormone, Testosterone, has a bad reputation. Many people, basing their opinion on unsubstantiated rumor and misunderstood fact, think that the big old T encourages antisocial behavior, increases aggressiveness, and leads to sexual addiction. Some have gone so far as to propose the existence of a so-called “Testosterone Poisoning” that afflicts millions of men across the world; however, although testosterone can be attributed with influencing behavior, the truth is much more complicated than that.
Testosterone is one perhaps the single most important hormone in the male body. Nevertheless, in addition to regulating many processes in the male body, it is also present, to a significantly smaller degree, in the female organism.
But is Testosterone exclusively human? Not at all; in fact, Testosterone is found in the majority of vertebrates and has been around, in an evolutionary sense, since the first jawed animals arose in the deep waters of the primeval oceans. All sex hormones, but especially Testosterone, have an ancient evolutionary history.
A perfect example is the case of the famous Homo neanderthalensis, or Neanderthal. The earliest fossil records place the rise of the Neanderthal at around 450,000 years ago. For various reasons, including mounting evidence of interbreeding between humans and this extinct species of archaic humanoid, we know that the Neanderthal’s body produced Testosterone in much the same way as ours.
How much Testosterone did the Neanderthal male produce? How high were their levels compared to modern humans?
NEANDERTHALS AND TESTOSTERONE LEVELS A DIFFICULT QUESTION!
Arriving at a definitive answer to this question is not an easy task. Although science enjoys access to ample fossil evidence, it is virtually impossible to perform the necessary tests to measure hormonal levels. Nevertheless, because the two species are closely related and because we thoroughly understand the human physiological traits that are regulated by Testosterone, we can compare the physiognomy of the two species and draw educated conclusions.
In humans, Testosterone is the primary steroid hormone acting as the regulator of the most basic physiological characteristics that define virility. These characteristics include, but are not limited to, muscle mass density and strength, the presence and quantity of body hair, the size and density of bones, etc.
Testosterone also plays an essential role in the development of the human sexual drive and intricacies of the species’ sex dynamics. Additionally, Testosterone levels determine, to a degree, the health of the hypothalamus and pituitary gland, as well as the strength of the cardiovascular system.
Socially, the presence of testosterone will influence a person’s ability to actively confront challenges, fall in love, focus on problem-solving, act aggressively towards others, etc.
TESTOSTERONE’S INTRINSIC ROLE IN NEANDERTHAL PHYSIOLOGY AND BEHAVIOR
Based on a review of 75 cranial, dental, and postcranial Neanderthal characteristics and early modern humans we can infer certain things about Testosterone levels.
As we know it, Neanderthal lineage includes mid-facial prognathism, posterior position of the foramen, increased retromolar space, large supra-oval fossa, a significant juxtamastoid presence in conjunction with a small mastoid process, an occipital bow, double ciliary arches that are reduced in absolute volume and vertical thickness, and a brain that was significantly larger than that of Homo Sapiens.
A similar pattern is observed in the evolution of postcranial morphology. Most theories for the appearance of these traits have tended to emphasize the need to produce large amounts of physical force and to conserve heat in the cold climates that Neanderthal inhabited. Find out more about Neanderthals Wikipedia
Further evidence that Neanderthal bodies were adapted to cold climates can be seen their broad hips, the distal segments of the shorter extremities, extremity length in relation to trunk length, larger total joint surfaces and thickness of long bones.
One particularly insightful observation regarding Neanderthal physiognomy is that they index fingers of that were significantly longer than their ring fingers, especially when compared to those of most living humans. This observation is significant because the medical community knows that the longer the ring fingers are compared to the index finger represents a mark of increased levels of prenatal testosterone exposure. In other words, higher levels of Testosterone increase the length of the ring finger in comparison to the index finger, which results in a low index to ring finger ratio. Therefore, we can assume with a fair degree of confidence that Neanderthals had higher levels of testosterone than modern Homo sapiens.
Recently, more evidence suggesting increased levels of Testosterone in Neanderthals was released by a group of scientists in the United Kingdom. Basing their theory on analysis of fossil remains, the research group concluded that Neanderthals were far more competitive and promiscuous than early modern humans.
Another evolutionary theory that can shed some light into the question of Neanderthal Testosterone levels is that of the development of the human chin. The human chin is unique amongst apes and all archaic human fossil records.
Some experts suggest that the appearance of the human chin was not due to the influence of mechanical forces such as chewing, but rather from extensive evolutionary adaptation involving the size and shape of the human face; which has also been linked to hormonal levels.
This theory is further substantiated by other theories that attempt to explain the change in behavior that early man underwent when society shifted from a hunter-gatherer modality to that of the highly cooperative and socially adept network society. It is believed that at this juncture in human history, males became much less aggressive and thus were able to fight less and form alliances more readily. This change, experts suggest, was due to a rapid decrease in early man’s hormonal levels, especially Testosterone.
Did Neanderthal have higher T levels than modern man? We will never know for sure, but there’s plenty of sound Paleo-Archaeological evidence to suggest they did.
- Stringer, Christopher, and Clive Gamble. In search of the Neanderthals: solving the puzzle of human origins. Thames and Hudson, 1993.
- Rozzi, Fernando V. Ramirez, and Jose Maria Bermudez De Castro. “Surprisingly rapid growth in Neanderthals.” Nature6986 (2004): 936.
- Christiansen, Kerrin. “Behavioural correlates of testosterone.” Testosterone. Springer, Berlin, Heidelberg, 1998. 107-142.
- Vermeulen, Alex, Lieve Verdonck, and Jean M. Kaufman. “A critical evaluation of simple methods for the estimation of free testosterone in serum.” The Journal of Clinical Endocrinology & Metabolism10 (1999): 3666-3672.