Silverback gorillas are extremely strong and can easily lift 600 kilograms, so why is their penis only 4cm long?

Silverback gorillas are the strongest species of hominids, and can grow up to 2 meters tall and 230 kilograms. The strongest males have white hair on their backs, which is the silverback gorilla . The life of a strong man is not easy. He is often used as a representative of primates to fight against various beasts by many netizens on forums. It seems that everyone recognizes the strength of gorillas.

However, in stark contrast to their huge and strong bodies, the gorilla’s penis, which is a symbol of “masculinity” in the eyes of humans, is very shabby, only 4cm long. If you measure it, it is about the length of two little fingers, and looks like a short and thick mushroom.

Why is this? Today we will study this question.

Evolutionary history

Most people probably know that the development of an organ depends on how useful it is . For example, the elephant’s trunk is very long. This is because elephants, as huge animals, cannot eat everything or they cannot survive. They must separate nutritious food from ordinary plants. And the elephant’s limbs need to support the huge weight, so they can only evolve a flexible trunk to replace the work of “hands”. Therefore, among all animals, only elephants can evolve the most powerful trunk.​

Naturally, the penis is also an organ, and the determining factor of whether it is developed is naturally “how useful it is”. So what is the most important function of the penis? Of course, it is for reproduction. The earliest penis appeared in the Devonian period 400 million years ago . Male individuals named Microbrachius inserted their pelvic fins into the female’s body to inject sperm, which greatly increased the chance of fertilization. Before that, organisms directly sprayed reproductive cells into the seawater and let them fertilize freely.

However, it is obvious that this advantage is not obvious, because most fish still use in vitro fertilization, and only a very small number of fish have evolved ovoviviparity with internal fertilization , and sharks are one of them. However, in vitro fertilization was completely abandoned after animals landed on land. Because of the loss of water environment, organisms evolved amniotic membranes to reproduce the water environment with the water contained in them, so that male animals could not spray sperm directly on the surface of eggs, so internal fertilization became the mainstream.

Female animal

This requires a structure to transport semen into the female animal’s body, and the role of the penis becomes important. All terrestrial animals are amniotes , so they theoretically have to have a penis.

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Interestingly, we have discovered that some complex animals do not have penises. Although ducks have penises long enough to open wine bottles, chickens do not. The mating process of chickens is just to put the male and female cloacae together and then spray sperm directly into them. Chickens without penises seem to reproduce well, which shows that even if sperm needs to be delivered to the female body, it is not necessarily necessary to have a penis. So what special function does the penis have?

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Tintin, violence, competition

If we observe another annoying little animal, the bed bug, we can get some inspiration. The penis of a male bed bug looks like a needle and is used like a needle. Female bed bugs do not have a reproductive tract at all. When reproducing, the male bed bug uses his penis to directly pierce the abdomen of the female and inject sperm into it. This extremely inhumane method has supported the existence of bed bugs for hundreds of millions of years. It can be seen that in natural evolution, as long as it can achieve the purpose, “it is not useless.”

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From the case of bedbugs, we know that one of the reasons for the existence of penises is probably to coerce females . The counterexample to this is clearly reflected in the racial characteristics of Silverback gorillas: although male Silverback gorillas are strong (up to three times the weight of females), they are gentle herbivores. An adult male gorilla forms a stable family with several female gorillas. Except for fighting with neighboring males over boundary issues, there is no fighting between males over mating.

Male gorilla

This means that the only male gorilla in the family has a monopoly on mating rights , and the female has no potential suitors at all. Since they have a monopoly, mating does not require “coercion” or “competition”, so as long as the penis can be focused, it is completely OK, and being big and thick is completely a burden. This is also very obvious in other species that monopolize mating rights. For example, male lions only need a few seconds to “work” each time, and as long as they can pass on their family line, why bother with so much effort?

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However, the situation is completely different for chimpanzees, which have the second largest penis among hominids. Females will mate with multiple males during the breeding season, so those with larger penises provide a better customer experience, can prolong mating time and increase the chance of fertilization, are easier to rape females to create more fertilization opportunities, and have genes related to being able to scrape out the semen of other males. This is why the chimpanzee’s penis has evolved to be more “majestic.”​

It can be seen that the more developed an organ is, the more intense the competition around this organ in evolution . The size of the penis is not a sign of male strength. Animals of similar size between males and females will have larger penises. Animals in which males have an absolute size advantage do not need to invest in this small tube.

By the way, humans have the largest penises among the hominids. Guess…what happened hundreds of thousands of years ago?