“There’s no selection for gentler males,” says the Swedish professor. And, not surprisingly, she does her best to make the intercourse as short as possible by kicking the male.īut the terrifying penis is here to stay. The female has also developed additional connective tissue in her genital tract, which provides partial protection. If you’re wondering whether the female simply puts up with this horrific piece of genital terror, the answer is that she would, all other things being equal, certainly be better off if the male did not use his spines. Violent penis could lead to evolutionary suicide So further studies of the beetle’s nasty penis are needed to identify which factors are included in the ejaculate, and how they function. This pocket typically contains sperm from many males, and Arnqvist’s idea is that the spines open the gates to the bloodstream for factors that make the female take more of the sperm into the sperm pocket. Rather, they are kept in special pockets, from which the eggs are then fertilised. Here, naturally, the sperm does not fertilise any eggs, so “it points to a rather complex mechanism,” says Arnqvist.įor bruchid beetles, and many other animals too, the sperm normally doesn’t travel directly to the eggs. This enabled them to demonstrate that up to 40 percent of the male’s seminal fluids flow out of the female’s genital tract and into the bloodstream.Īnd the longer the spines, the more of the male’s body fluids flow into the female’s blood. The scientists tagged the sperm using a mildly radioactive chemical.
#STRONG GORILLA PENIS FULL#
And again the researchers found that the males with the longest spines on their penises get the most offspring, independent of other factors such as body size.īoth groups of males produced the same result, and thus the theory of sexual selection after mating has been documented experimentally.īut the researchers are taking it one step further.īy dissecting the females after mating, the researchers could clearly see that the long spines cause severe damage and tear bleeding holes inside the female.īut why evolve such a cruel penis that hurts the female? It doesn’t appear to have much of an evolutionary advantage, yet the female beetles, strange as it may sound, are ready to mate again before a full day has passed. The male beetles were given a few days to recover, and then they were allowed to mate with females again. The longest penis spines are most important They then used a microscope to help them burn off spines individually with a precision laser. The researchers used a penis pump – a thin pipette tip with a small air hose – to inflate the penis. The latter is a complex procedure in which the male beetle is anaesthetised with carbon dioxide. They have bred males with shorter penis spines, and on some of the beetles, they shortened the spines themselves using lasers. In the new study, the biologists have therefore manipulated the penises directly. They found that the males with the longest spines on their penises fertilise the most eggs and get the most offspring.īut it remained unclear why this was so, and there could theoretically be other hidden factors at play. In 2009, Arnqvist and his colleague Cosima Hotzy anaesthetised male beetles from 13 countries and measured the length of their penis spines. This is where the bruchid beetle enters the picture. When you think about it, it makes good sense that the penis is longer, so that the sperm is delivered nearer to the eggs, or that the amount of sperm is high.īut this phenomenon is actually very difficult to get hard experimental facts on – because how do you isolate characteristics in for instance a penis and study their effect individually? ”Only in the past 10-20 years have we started to realise that it’s probably due to sexual selection in the male sex organs.” ”It’s a truly basic, widespread and important evolutionary pattern,” says Arnqvist. Many closely-related species can only be distinguished by the shape of the penis.īut how come teeth, limbs, brains or the body shape don’t evolve as quickly?
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