The baculum is a bone that forms in the connective tissue at the base of the penis. It appears in some animal groups and traces its origins to more than 95 million years ago. The baculum is built from tissue that shapes the corpus cavernosum just above the urethra. Some scientists debate whether it is true bone or a calcium buildup within the erectile tissue, since in many species it is not connected to the rest of the skeleton.
Only five orders of mammals carry penile bones. The baculum occurs in rodents, bats, certain carnivores like cats, dogs, bears, fur seals, and walruses, in insectivores such as moles and shrews, and in a few primates including some New World monkeys and tarsiers.
The baculum comes in a wide range of shapes and sizes. It can be a simple tube or take on a rake-like form with unusual projections.
In terms of size the walrus holds a record with a baculum around 75 cm long. At the opposite end are very small primates where the bone is only a few millimeters long, and even in larger primates like chimpanzees and bonobos the baculum typically measures 6 to 8 millimeters.
The exact reasons for this variation and the precise function of the bone remain debated. One idea suggests the baculum shields the urethra and provides mechanical support for the penis when an erection is moderate or weaker. Another theory proposes that the bone helps trigger ovulation in the female during mating, potentially boosting fertilization chances.
There are also ideas that the baculum may help widen the cervix during intercourse to allow more sperm to reach the uterus and to reduce competition from rival sperm. A related idea is that the bone could promote longer mating to increase the odds of successful fertilization. Researchers from the University of California note that bone functions vary across species, and the baculum has appeared and disappeared independently multiple times in evolution. This suggests several of the roles above could be valid in different contexts.
People also had it but it disappeared
The baculum formed in primates about 50 million years ago and is found in the lineage that includes monkeys and humans. It disappeared roughly 2 million years ago in this group.
The loss has been linked to changes in social structure and mating competition. In humans, shorter mating duration reduces the need for a penile bone to support an erection during intercourse.
Among primates, the size and presence of a baculum correlate with the depth of genital penetration. Longer intromission tends to favor a larger bone to maintain erection. In humans the typical duration of vaginal penetration is around five minutes, which lessens the need for extra support from a baculum. The shift toward monogamy and reduced partner competition are seen as factors in the disappearance of the bone in humans.
Another view, offered by an anthropologist, links the disappearance to the adoption of upright walking. It is suggested that changes in body posture and mobility during the evolution of bipedalism contributed to the loss of this bone in our lineage. While no fossil baculum has been found in early hominins, virtual assessments imply a gradual disappearance as bipedalism developed.
There is also a narrative that the baculum may carry symbolic explanations in ancient writings. Some researchers joke about cultural myths that try to explain the absence of a bone in human anatomy, though this remains outside scientific accounts.
Why are they selling
Today the baculum piece can appear in markets, particularly in relation to walrus bones. It is offered in various forms and at a range of prices. In some places it is promoted as a natural artifact, sometimes polished and engraved. The price reflects the material value and the craftsmanship involved in finishing.
Market listings often present the baculum as a souvenir tied to northern communities. In traditional practices, some cultures carved the bone for decorative items or amulets believed to carry symbolic power. Among certain indigenous groups, the bone has been used in ceremonies and as cultural objects. Opinions on its usefulness vary, and beliefs about potency have appeared in various regions.